Introduction: DIY Solar Garage
Welcome! In this Instructable, I'd like to show you how I installed my own grid-interactive solar array, so that you can too!
To start with, this is a "Grid-Tie" or "Utility-Interactive" solar system. That means that I'm WORKING WITH my electric utility to be a producer of energy with them. (Off-Grid is great too, but it's not what we are talking about today!)
In a grid-interactive system, a home is already connected to the power utility and remains connected to the utility but also has the ability to create and use solar energy. If more power is still needed, it can be brought in from the power utility. If MORE solar is being created than is being used, it gets exported to the utility, and the producer of the energy gets credited for it!
My dream was to be able to produce all the electricity my home uses, and in the summer when solar production is at a peak, actually EXPORT renewable energy to my neighborhood! This is a FULLY PERMITED system, inspected by my local building inspector and approved and working with my local power company. It has plenty of safety features and a legal agreement with my power company regarding how power is bought and sold from each other.
My house also happens to be on a busy road, with plenty of traffic going past. Even though I'm a Do-It-Yourselfer, I wanted my solar to look GOOD! One of the more common arguements I hear against solar is that people don't like the look. I wanted to do a good job, as my solar would basically be a billboard for renewable energy due to how many people would drive past it every day!
This solar was also part of a larger project - the complete demolition, expansion, and rebuilding of my garage. My old detached garage was falling down and needed to be replaced. My Dad, brother, and I built a new garage, complete with insulation, heated floor, loft storage space, electric car chargers, and a roof designed to hold solar panels. New construction is an ideal time to plan for solar!
This Instructable will cover the design and installation of the Photovoltaic Solar system.
If you would like, you can get started by watching this extensive video I made on the solar aspect of the project.
- 24 Helios brand 260 watt panels (6.24kW)
- Enphase brand M215 micro-inverters
- Iron Ridge brand racking system
- S-5! brand clamps for metal roofing
- Final cost of $6,523.70
- A simple economic ROI of 6.5 years or less
- Fully Licensed and Permitted
- Saves $1,000 per year
To see live and historical power production of my solar, please visit the public information link at: https://enlighten.enphaseenergy.com/pv/public_sys...
Step 1: Planning
The first step is of course TO PLAN!
I usually start almost any project by learning all I can about the subject. That means hitting the library, reading through the web, and taking classes.
I already had some experience in electricity from working on DIY Projects such as building a Solar Powered Kids toy car and a full size street-legal electric car. I had also taken a non-credit electricity class through my local technical college, and a course on Photovoltaics through the Midwest Renewable Energy Association. Although you don't need to be an electrician to work with solar, you do need a general knowledge of AC and DC electricity and safety.
This particular project will be a net-metered, grid-tie system using micro-inverters.
Net metering is the process in which you can export power to the grid and get credited for it. The power company bills you only for the difference in how much power you create versus how much power you use. Most the United States has requirements that the power utility MUST allow you to sell power to the grid. Hawaii does NOT allow export back to the grid (although you can have solar and be connected to the grid at the same time, just not export) and several States have other specific local rules. For details please visit here and contact your local power provider. If laws or regulations are ever changed, existing solar installations are typically "grandfathered" and continue operation under the original contract with the power utility. Before beginning a grid-tie solar project, contact the power utility to find out what requirements they will have. They may specify a maximum size, safety equipment required, or other specifics.
One of the first things you want to know is how much electricity you actually USE.
A great place to start is to look at your utility bills. On an electric bill, there will be a usage listed with the units being in kWh or kilowatt-hours. A kilowatt-hour is a unit of ENERGY, a certain amount of power used for a certain amount of time. If you have a 100 watt light bulb and you leave it on for 10 hours, that's one kWh of energy. (100 watts x 10 hrs = 1,000 whrs = 1 kWh)
The United States national average home uses about 900 kWhs of electric energy per month. We tend to use less than that, as confirmed by looking at my monthly bill. Some bills also show historical use. That's nice to know, as you can compare your energy use this month versus the same month last year.
Many homes tend to use the most electricity in the summer (do to air conditioning) and solar is a good match, as it produces the most energy in the summer as well.
We are typically using around 600 kWh of energy per month, and ideally I would want a solar array that would produce that much power. At 30 days in a month, that's 20 kWhs per day that I would like to produce on average.
HOW MUCH SOLAR?
How much sun a certain location gets in a day varies quite a bit depending on location and weather. Fortunately, that information is only a click away, thanks to the internet. How much sun a place gets, per day, on average, is called "Solar Insolation". Take a look at a map to see how much sun you get where you live! In my area, we get 4 to 4.25 sun-hours per day. If I want to create 20 kWhs per day and divide by 4, I get roughly 5kW. So, I'll want about a 5,000 watt solar array. But that's only if everything is PERFECT! In the real world, the solar panels might not face perfectly south, get dirty, or have shading issues. So, I'd really like at LEAST a 5,000 watt system.
Here are some resources which I found extemely helpful when researching and designing my system.
- Non-Profit Renewable Energy groups, such as the Midwest Renewable Energy Association - Training, classes, and great educational resources.
- Technical or Community Colleges - Non-credit classes can be very useful at low cost!
- PV Watts - Online solar calculator to help you predict how much power you can create.
- HOME POWER magazine - Print and online renewable energy magazine for professionals and DIY alike.
- Renvu.com System Designer - Mail order supplier of solar components has a fantastic tool to help you design a system and create a parts list and total cost estimate
- Iron Ridge Design Assistant - Racking manufacturer has a great software tool to help you calculate not just which parts you would need, but also calculates wind loads and snow loads.
- Solar Design Tool - Software for permiting including single line diagrams. They have a free trial. I used the free trial to design my system, and didn't pay anything at all.
- YouTube - YouTube can be a great source of information, but sometimes the hard part is finding the right source! I found that Webinar style videos from equipment manufacturers were very good. Videos by do-it-yourselfers could be inspiring, but often didn't show best practices or details of the systems. There's also some great videos by equipment dealers. The altE store sells solar components, but also does a great job helping EDUCATE the public about solar.
- Renvu.com - Best overall internet mail-order prices for solar components. They also have that great design tool that helps you create your own system and export a parts list and budget from it. I bought many of my components from them.
- Werner Electric - This is a local electric distributor in my area. These are the types of companies where electricians buy their supplies and materials. They sometimes have a small retail store or walk in parts counter. I bought all my racking through them and was able to get shipping from one location to another for free. Although the local branch didn't carry any solar components, they always have trucks going from one location to another. The racking is 14 feet long, and normally would have a special freight fee if shipped by Fedex or UPS. By ordering it through a local branch of an electrical supplier, I could just pick it up at will call and save all shipping costs. They also had a salesperson there who specialized in renewable energy, who I could ask a few questions of. Look to see which electrical supplier is in your area who can get you solar related components
- e-Bay - If you know exactly what you are looking for, e-Bay sometimes has great deals. I purchased 24 brand-new micro-inverters from an e-Bay seller. They were brand-new, exactly the number I was looking for, and exactly the number the seller was clearing out. I got a good price and a great transaction. Always to your due diligiance and check the seller's rating and reviews to make sure they are trustworthy and that you get exactly what you are looking for.
- Local Hardware or Home Improvement Store - For basic electric items, nuts and bolts, and all the other items you are forgetting, it's nice just to run to the local store to get them. It's also nice to NOT pay shipping and be able to return any items not used.
- Local Solar Companies - You might have some solar companies right near you which may be an excellent resource! I ended up buying my solar panels from a local solar company, and just picked them up on a trailer to save on shipping charges. Shipping solar panels from out of state may have cost me up to $600.
After taking a look at my own electric use, learning all I could about solar, and even finding some good resources and places to buy the solar equipment, I still needed to know exactly how well my site would work with solar.
So, let's do a Solar Site Assessment.
Step 2: Site Assessment
You need to know if your location is appropriate for solar or not.
Not all locations are.
A site assessment is really just a good look at your location of where you are planning to put the solar and seeing if it is a good match or not. Concerns are typically shading, lot lines and set backs, roof condition (if solar will be mounted on a roof,) locations of underground and overhead utilities, and location and distance to connection to the grid.
PUT SOLAR PANELS IN THE SUN
Solar doesn't work everywhere. You can't put a solar panel under a rock and expect it to produce power. Neither can you place it in the shade. Ideally, solar needs a clear, unobstructed view of the sun for as many hours of the day as possible. In the northern hemisphere, that means solar panels should face south. They should also be on an angle to match the height of the sun in the sky as much as possible. Make sure you mount your solar panels someplace sunny! My yard is pretty shady, and the only really sunny spot is my garage. My plan was to mount the solar on the south face of the garage roof. In designing the garage, we made sure that anything that broke up the roof (sky lights, chimney, vents, etc.) was on the north side, leaving the south side to be a large blank slate for the solar.
SOLAR PANEL ANGLE
Solar panels are commonly tilted to the same angle (or at least with 15 degrees of that) as the latitude of your location. For example, I'm in south-eastern Wisconsin in the United States at about 43 degrees north latitude. Having my solar panels mounted at 45 degrees would be pretty much ideal. In the summer, the sun may be higher than that, but in the winter, it would be lower. On average, I'd be producing an ideal amount of power.
(In a location closer to Equator, a flatter or lower pitch arrangement is great. The further north you go, the steeper you want to mount your panels.)
In my case, I built the garage with the plan to install the solar directly on the roof. We designed it with a sturdy structure to support the weight of the panels, and had it roofed with metal (instead of asphalt shingles) for long-lasting durability. If you plan to install solar on your roof, make sure the roof decking and shingles are in good condition. If neccessary, re-roof or complete other repairs BEFORE installing solar. I was surprised to learn that a metal roof with solar weighs LESS than a plain roof with just asphalt shingles! If you have concerns about the load-bearing ability of your existing building, consult a professional roofer or engineer.
My roof is a little less than 7:12 pitch. That's not as steep as I would like it to be for ideal solar access, but I was limited by local building codes. (A steeper pitch would have meant my height would be taller than a legal 18' limit for a garage.) Although not a perfect angle to the sun, it's still a GOOD angle, and the garage otherwise faces due south.
For a grid-tie system like mine, we want the angle to give good average year-round production. In off-grid setups for charging batteries, solar panels should be angled for maximum gain in the month of the year that uses the most energy compared to what the panels can produce. That's typically (but not always) a winter month like December or January.
My property is somewhat narrow and runs north-south. My next-door neighbors have a row of nice large maple trees right on the property line. Clearly, these would shade the solar panels at some point during the day at least part of the year. I also have a pine tree in the front yard. Late in the year (near the winter solstice) the shadow of that tree might reach all the way to the garage.
But how would I know if these shadows would effect my solar system or how far they would reach?
A great tool for this is something called a Solar Pathfiner. I borrowed one from a friend, and used it to check how shading would effect my system. The device itself is a reflective dome with a compass and tripod legs. A person inserts a piece of black paper inside which is printed with the angles of the sun through the year based on their latitude. By looking at the reflection of trees, buildings, and other obstructions in the reflection in the plastic dome, a person can trace those out on the paper and see how much of the sun will be blocked at any time during the year. The paper is also printed with numbers representing what percent of solar energy is created during that hour of the day. By counting the sections blocked by obstructions, a person can figure out what percent of solar power is blocked for each month of the year.
In my case, I definately had some shading, and it was the worst in the winter months. The upside of that is the winter months are when there's the least sun, and thus the least solar power production anyways!
Overall, I still had a very good view to the south from 9 AM until 3 PM every day. That's the "solar window" when most of the power production is going to be created. Power production is less outside
Besides using a tool like a Solar Pathfinder, you can also simply observe your property at different times during the year. When building the new garage, the roof was in place before this last year's winter solstice. I set up a small camera on a ladder to create a time lapse. That way, I could see how the roof was shaded and when.
MICRO-INVERTERS HELP MAXIMIZE POWER IN PARTIAL SHADE SITUATIONS
Because I knew that I would have some shading issues, I chose to use micro-inverters for my system. An inverter is a device that takes Direct Current (DC) from the solar panels and converts it to Alternating Current (AC) as is typical in most homes from the power utility. In traditional inverter systems, solar panels are connected in series (one to the next to the next to the next) to get to higher voltage and is then converted to AC at the inverter. One limitation of that system is if one solar panel is shaded, it becomes the weak link in the chain, and reduces the current from ALL the panels in series, limiting total power created.
Alternatively, a micro-inverter is a small unit mounted right at the solar panel. It converts the power of one panel to AC, and then that AC power is combined (in parallel) to feed the home. If one panel is shaded it does not effect the power production of any of the other panels.
Besides considering shading, you will also want to measure and sketch the area you plan to install solar. If it's on a roof, confirm the construction and quality of the roof, and make sure the roofing material is in good condition. Also measure the distance from the solar array location to the point it will connect to the grid (often the main Utility Meter.)
You will also want to inspect your main electrical breaker panel, see how many spare spaces are available and the capacity of the panel and bus bar capacity if known. You will need to know this information for designing the solar system and filling out paperwork required by the utility and building inspector.
Step 3: Proposal and Permitting
I live in an area where building permits are required from local authorities before home construction or remodeling. I also needed my utility's permission to connect with solar. The utility would properly credit me for any energy I created and exported to the grid. The system also needed to be shown that it was safe and within other parameters required from the power utility.
Because of this, I needed to create a proposal for my power company and get an electric permit from my town.
To plan my system, properly design it, including using the right size wire, etc., and create paper-work to present to the AHJ and Utility, I used the following software tools:
- PV Watts online solar calculator
- Renvu Instant Design and Quote
- Iron Ridge Design Assistant
- Solar Design Tool
These are all free online tools available to anyone.
I used the Solar Pathfinder to know how much loss I could expect from shade, and I used PVWatts to calculate how much power I could expect to produce in my location during any given month, and in total over a year.
Here's a video showing how to use the PV Watts solar calculator from the National Renewable Energy Lab.
(Please view the software demonstrations FULL SCREEN and in HD to view all computer monitor text.)
(After six months of solar electric production, I checked the estimates from PV Watts versus my real world energy production. As long as I including the shading information from the Solar Pathfinder, the predicted energy production was almost dead-on!)
Since I knew how much power I used (from my electric bills,) and how much power I COULD expect to create (as calculated with PV Watts,) I could start deciding what components I might want to use.
I found that one of the places with the best mail order prices was Renvu.com. That web page also has a great software tool to help DIY'ers design their own system.
I used Renvu's design tool to help me decide that I wanted a system with 24 solar panels (maximizing how many fit on the roof) using micro-inverters (to help with the shade.)
Here's a video showing how to use the DIY Kit Designer on Renvu.com
I also wanted to double-check the materials I would need to mount the solar panels. The Iron Ridge Design Assistant is a free tool which helps you design the racking system to mount the solar. This includes information on snow loads and wind loads, ensuring that your solar panels neither collapse a building nor get blown off the roof! Your building inspector will appreciate seeing those numbers and know that some engineering thought was put into your system.
Here's how to use the Iron Ridge Design Assistant.
The last really great online tool I found to help me plan my system was at SolarDesignTool.com. This is full-blown solar design software for professionals. The best part is that there's a FREE 30 day trial. I used the free trial to design my system and export a professional report in PDF format to give the the Building Inspector and Power Utility.
Here's a walk through of the SolarDesignTool software:
Since I now had my plan, I could get the ball rolling with the Power Company.
The Utility would end up having me fill out two forms: PSC 6027 and PSC 6029. These are both part of the Distributed Generation Interconnection Agreement. The first form being an application, and the second being the completed agreement itself. I would have to specify to the utility what equipment I would use, the total power of it, and other details, including proving that I have appropriate levels of property insurance. I filled out and submitted the PSC 6027 form and also attached an application packet which included a map of my property, proposed location of the equipment, a single-line diagram of how the equipment would be wired, and PDF spec sheets of every piece of equipment I would use. I was told that an electric utility engineer would review the proposal and get back to me. Most of what I gave to them (particularly the single-line diagram) was generated in the SolarDesignTool software. I manually created my own map of my property, using a screen grab from Google Maps, to show the proposed location of the solar panels, AC disconnect, and other key pieces of equipment.
The total paperwork that I submitted to the Utility was:
- Cover Letter
- Site Plan (map showing property, property lines, solar equipment, etc.)
- PSC 6027 (Interconnection Agreement Application)
- Solar Array Diagram
- System Summary
- Electrical Single Line Diagram
- Individual PDF spec sheets of all equipment to be used
- Equipment Grounding Technical Brief
The Distributed Generation Interconnection Agreement is actually a CONTRACT. It specifies the relationship between the Power Utility and the Distributed Generator (which is now me.) While it's always possible that rules or regulations of grid-tie solar power change in the future, this contract guarantees your particular arrangement.
I also needed to get an electric permit. In the solar world, there's something called the "AHJ" - that's the Authority Having Jurisdiction, and it varies from one area to another, but commonly, it's the local building inspector. Ahead of time, I sent the building inspector the same packet of information that I sent to the utility. I had already worked with the building inspector for the general construction of the garage, so he knew who I was, what I was doing, and that the solar was part of the plan from the start. I met with the building inspector and asked if he had any questions/comments/changes on what I was planning to do. He did not, he simply asked that I get an separate electric permit specifically for the solar, which cost me $100. On the electric permit, the licsensed electrician doing the work must be listed, along with his/her liscense number. It's usually the contractor who pulls permits, not the home owner. I had already contacted the electrician who did wiring in my garage, got his liscense number, and arranged for him to come out sometime in the future when I was ready to wire the solar.
After about two weeks, I heard back from the power utility. They approved my proposal with no changes, questions, or comments. Putting in the time on the paper-work was well worth it. It felt great to know that I had planned everything out correctly from the start.
I know that this entire step has felt like a LOT of WORK and a lot of PAPERWORK. Keep in mind that MOST of this information needs to be known in the first place to properly design and install a solar system. Actually providing that information to the power company isn't all that difficult. Likewise, whatever you have for construction requirements in your area, you want to make sure your system is safe and properly installed, whether or not a building inspector will be looking at it.
The utility would later come out to reprogram my Utility Meter. In my area, we have "smart meters" which communicate directly back to the utility. They are digital and designed to read only for power PULLED from the grid. The utility made a software change to my meter so that it could read and track separately the power pulled from the grid AND power created from my solar and back-fed to the utility.
I would also be allowed to make a "load-side connection". A load-side connection is the simplest and most cost effective way to connect solar power in to a house. An additional circuit-breaker is added to a panel and AC power is fed IN through that breaker. There are some limitations to this. For example, the total input breakers can't add up to more than 120% of the bus bar capacity. (Read this to learn more.) The input breaker also needs to be placed at the far opposite end from the main breaker of the panel. I double-checked and confirmed that my power and bus bar capacity was appropriate.
It's VERY important to work with your AHJ and Utility to understand how they require connections to be made. Also, make sure you understand the agreement with the power utility in terms of how electricity is billed and credited.
Some utilities may require that a second meter is added. The original meter will show energy you use, and the new second meter will show power exported to the grid. Adding a second meter should be performed by a professional electrician.
During a web search, I found a PDF file from another utility company which gives VERY specific instructions in how they want distributed generators to connect to their system. (Please see the attached Alliant DG Specs.pdf file.)
HOW DO I GET PAID FOR MY SOLAR?
Power utilities vary in how they pay for electricity that the homeowner exports to the grid. In many cases, the home-owner buys at retail, but is only credited or paid for the "avoided cost" of energy exported. Avoided cost is the cost at which the utility would have had to purchase the electricity from somewhere else. In essence, it's the wholesale cost. In my area, that's 3 or 4 cents per kWh.
Some utilites may also have an annual "tally-up". Credits from overproduction of electricity may only be carried over for up to a year, and then a check is written out for the credits, or in some cases, they are just cancelled out. Sometimes the month at which you begin to produce solar power can can be important. For example, you wouldn't to produce excess energy all summer, hit your annual cut-off, and then have to pay for electricity all winter.
I'm fortunate in that my local public utility credits me the full value of any electricity I export. In the summer, I can create and build up a credit. In the winter, I will use more electricity than I produce, and will draw down that credit. I have no electric bill in the summer, and may only have a relatively small electric bill in the winter
- Alliant DG specs.pdf
Step 4: Racking
So how do the solar panels get attached to the roof? They don't. The panels are actually mounted to a racking system which attaches to the roof.
All components used in a racking system should be either aluminum or stainless steel - materials that can hold up to a life-time of the elements. A few non non-structural components can be plastic, such as rail end-caps. If plastic zip ties are used, they should be of the UV resistant type and under the solar panels where they are protected from the sun.
I chose the Iron Ridge brand of racking components. I had seem samples of their materials and spoken with a representative while visiting the MREA's Energy Fair. Their system looked good, and it was carried by my local electrical supplier. The Iron Ridge components were also certified to work with the integrated ground system in the Enphase micro-inverters. By electrically bonding the racking, frames of the solar panels, and the micro-inverters themselves, the entire system is properly grounded WITHOUT requiring a separate heavy copper cable. (This was one thing I wasn't sure if the utility or building inspection would allow or not, but neither took any issue with it. Grounding this way saved material cost and labor.)
I chose the Iron Ridge XR-100 racking. This is their "flagship" material. It's a sturdy aluminum extrusion with slots to accept bolt heads. It's available in stock several lengths. I chose the 14 foot length. My garage is 29 feet wide, but the solar panels wouldn't be going all the way to the edge. Two pieces of 14' racking with a splice between them creates a 28' long piece. I would have three rows of solar panels. Each row requires an upper and a lower piece of racking, so I would need 12 pieces total. I ordered them in through my local electrical distributor and picked them up with my car and trailer to save freight charges. I now drive an electric car, and it felt pretty good to use that vehicle to pick up the materials that would eventually power that car straight from the sun!
I have a metal roof on the garage, so I would use special attachments to connect the racking to the roof itself. I chose S-5! brand clamps. There are quite a number of different styles of metal roofs, and the clamp must match the roofing style. Mine is a "Nailing Strip" metal roof, the profile of which looks something like a capital letter A. The "N" type S-5! mini clamp was the one I would need for my roof.
Typically, a person needs to calculate home many points of connection there are between the racking and the roof itself. That is based on wind and snow load of an area, the sturdiness of the racking system, and the structure of the roof. Fewer points of attachement saves time and money, as well as fewer HOLES in a roof! More points of attachment means more cost of materials and time spent to install them. One thing I loved about the S-5! clamps is that they are NON-penetrating. They do NOT put holes in a roof, rather, they "pinch" onto the standing seam of the metal roof.
The roofing material has a seam every 16 inches, and the clamps can ONLY go on the seams. So, my choices for spacing the clamps was easy - 16, 32, 48, 64, or 80 inches. 16 inches would be every seam - complete overkill. 80 inches is 6'8", that was just a little longer than the maximum span listed for the product based on my wind and snow loads. I sketched out several layouts and found that going to every 48 inches made things nice and easy for me in terms of how the seams of the roof layed out. It was easier to center the panels and space them out, while only using a few more clamps. I could then make a sketch of which seams of the roof would have a clamp.
Using the Iron Ridge Design Assistant, I now knew how big my solar array would be, and I essentially centered it on the roof. I used a tape measure and pencil to measure from the bottom edge of the roof up, and made a mark. I did that on both ends of the roof. Next, I installed an S-5! clamp on the two ends of the roof. Then, I stretched a string taught between the two. That gave me a nice straight line so that I could arrange all the clamps in a row. (I could have also snapped a chalk like, but my yellow string was nice and bright. Blue chalk on a green/blue metal roof would never show up!)
For each clamp, I loosened the set screw all the way, placed the clamp against the seam, pushed against it, and gave it a smack with a rubber mallet. This would snap the clamp into position. I then tightened the the set screw. The first few, I used a torque wrench to make sure those screws were to the correct tightness. Once I had done a few, I had a sense of it and simply drove the screws.
With the clamps in place, I then added the L-foots, and bolted them in place with the included hardware. The L-foot is exactly what it sounds like, an L shaped piece that connects the S-5! clamp to the racking.
Next, I was finally ready to attach the racking itself. I simply set the racking over the bracket, put a bolt from the racking to the L-foot, and tightened down the nut. I actually ended up using two different types of bolts. There is a square-head bolt, which slides into the racking from the end, and can't fall out, and there's a T-head bolt, which can slip right into the groove on the racking, but can also accidentally fall out before it's properly tightened. The T-head bolt was easier to use, as I didn't have to plan ahead sliding the right number of bolts into the end of the racking before installing it.
I also needed to create a splice to connect one piece of racking to the next. This was very simple. I just slid the splice component in, drove in two self-tapping screws, slid the other piece of racking on, and drove in two more screws. Easy-peasy.
The metal roof was steep and slippery. I literally could NOT stand on it without sliding down. However, once I had the first piece of racking in place, that gave me a place to stand and prevent me from sliding off the roof. From there, I could install the next row of racking. I did this one row at a time. When the row was finished, I moved up onto it and worked on the next row up. In this way, I got to play a real-world Donkey Kong game, building my way up the roof. I spend most of that time sitting on my butt. I also always had a cardboard box with me. That gave me a place to hold the S-5! clamps and my tools, and it stayed nicely against the racking. I was also rock-climbing harness, which I hooked to one of the fully mounted rails as fall-protection. I later purchased a full fall harness and auto-retractor.
Once the racking is otherwise installed, I also added plastic end caps to the rails. Those are mostly cosmetic and give a finished look.
Note: The S-5! metal roofing clamps are difficult to remove and reposition. Always confirm their location before installing.
Step 5: Micro-inverters
Advantages of Micro-Inverters:
- DC to AC right at the panel
- NO HIGH VOLTAGE DC POWER
- Rapid Shut-Down - In case of a power failure, ALL current is cut all the way back up to the solar panel. A great safety feature and a future requirement for all solar arrays.
- Wiring Simplicity - All required wiring is just 240V AC wiring - stock and trade of any electrician
- Distributed - If one micro-inverter fails, all the rest still function
- Shade-Tolerant - Each panel is independent of the rest. One shaded panel does not reduce production of other panels
- Plug-and-Play, just plug into trunk cable
- MPPT - Each inverter automatically maximizes power output, regardless of voltage
- Easy Expansion - additional inverters can be added in the future with no other special equipment
- Panel-Level Data - Micro-inverter systems can tell you how much EACH INDIVIDUAL panel is producing. Great for data-nerds and for trouble-shooting
- Integrated Grounding (specific to this brand/system) No additional heavy copper cable/lugs/ground-rods.
DIS-Advantages of Micro-Inverters:
- Cost (typically cost more than a plain series string inverter)
- Cost of Accessories - The trunk cable and required communications gateway are not inexpensive. Communication gateway is required no matter how few or many micro-inverters are in the system
- Hard to Access - Micro-Inverters are on the roof. If one needs to be replaced, one must climb the roof and remove a solar panel. Series inverters are usually mounted at working height on a wall, easily accessible.
- NO SOLAR POWER WHEN THE GRID IS DOWN. This is a safety feature, but it also means that the solar panels create ZERO power during a blackout. If you specifically want solar to charge batteries when power is otherwise NOT available, you do NOT want to use micro-inverters.
Because I have a reliable power company (power outages are extremely infrequent) and I have some shading issues, I dedided to go with micro-inverters. I also like how I only needed to deal with AC power (not high-voltage DC) which meant that any electrician could help me with the project, without any solar experience at all.
The micro-inverters use a proprietary "trunk" cable. This is special AC wiring with quick-connects for the micro-inverters every 40 inches. Those quick connects are commonly called "drops" and the cable is ordered based on how many "drops" you want. I ordered 24. I cut the cable into three sections, each with 8 drops on it, and attached the cable to the rail with plastic clips and zip ties. (This will all be under the solar panels, so sunlight degrading the plastic is less of an issue.)
Each micro-inverter is plugged in to the quick connection on the cable. Those connections have a gasket and are weather-tight.
The trunk cable has two ends. The west end will go into junction boxes to connect the wiring together. The east end is simply cut and hanging there. Each of those three cut ends gets an insulated termination on it. It's important to make sure that's a good weather-proof connection. If the system isn't working, that's a common point to check and troubleshoot.
The overall process of installing the micro-inverters is very simple. I just laid out the trunk cable, zip tied it to the racking, and bolted the micro-inverters near their connections and plugged them in.
The micro-inverters also have removable stickers on them with their serial numbers. I peeled those stickers off as I installed the inverters and placed them on an included sheet of paper which showed the locations of the inverters. This would later be used for mapping, showing individual inverter stats, and troubleshooting if necessary.
- Grounding simplified.pdf
Step 6: Solar Panels
The solar panels for this project are Helios brand 6T series 60 cell 260 watt solar panels. Each one produces about 30 volts. These are mono-crystalline panels with a silver aluminum frame. Each one weighs about 50 pounds and is 6.5 feet long by 39" wide. That's small enough for one person to carry on his shoulder or two people easily set in place on a roof.
Every solar panel manufactured has a spec sheet available. (Please see the attached 6t-255.pdf) Those sheets will always list all of the details of the panel including its electrical and physical characteristics. Using that information, a person can plan out their system. For example, by knowing how wide each panel was, I could know the width of the racking material I would need to mount them.
The cost of solar panels can vary quite a bit. Always make sure to consider shipping costs as well. In some cases, a loading dock might be required as a pallet of panels might come in a very large truck without some other way of unloading.
Ideally, I wanted to buy American made panels, save on shipping, and get a good deal.
There was a company called Helios, which was a U.S. manufacturer located only about 30 miles from my house. Unfortunately, they are now out of business. I located a small rural solar company which had a stock of new Helios panels available for sale. We drove to that business, bought the panels, loaded them on a trailer, and brought them home. I paid $150 per panel. For general solar panel purchasing, I'd recommend that you take a look at what's in stock and on sale at Renvu.com.
A few years earlier, I had gone to Helios to buy a single large solar panel which I used on my daughter's playhouse. While there, I got a few shots of inside the factory. It was neat to be able to purchase locally made solar panels and actually see the panels I use being made.
Here's my brother and I taking the trip to go get the solar panels for the garage.
Step 7: Wiring and Conduit
Before wiring, a person needs to know where the wires are going and what type and gauge to use!
One of the first steps is doing circuit calculations. Because I was using Enphase micro-inverters, I first consulted their materials. (Please see attached PDF files.) The trunk cable uses 12 awg wiring, which can only handle a certain amount of current. The Enphase PDF lists that up to 17 micro-inverters can be used on a single circuit. Since I have 24 micro-inverters, I would need two circuits. Due to the physical layout of the panels (3 rows of 8 panels each) it seemed to me that the best way to divide up the panels was for one row of panels to be a single circuit and the other two rows to be the second circuit. I would simply have one section of trunk cable on each of the three rows, going to the west side of the roof, and meet in a junction box. The Enphase materials specify how to do a calculation to make sure you are using appropriate wiring, and that thicker wiring is required if the wire run is long, has too much current going through it, etc. I did those calculations and confirmed that I could use 12 awg wiring.
One thing I had a bit of difficulty in finding information on was Junction Boxes and how to make and install them. I couldn't find much good information in online videos, and they aren't main components, like solar panels, where the manufacturers provide installation materials. I eventually found that most solar installers are using basic off-the-shelf outdoor rated plastic electrical boxes. I would need three boxes, one for the end of each of the three rows. For the top box, I used a two-gang outdoor box. For the other two, I used a 6"x6"x4" outdoor box.
I drilled holes in the boxes for 3/4" conduit and for the trunk cable to enter the box. That cable went through a weather-proof "cable-gland" which tightens down around the cable. I drilled through the plastic boxes into the aluminum racking with self-tapping stainless steel screws. I mounted the boxes so that they would not stick up above the racking to interfere with the solar panels. There's enough room at the bottom of the boxes for the conduit to travel UNDER the racking to run down the roof. All the boxes, wiring, and conduit are up off the roof.
The junction boxes and conduit will all be UNDER the solar panels, where they will be protected from the heat and UV damage of the sun.
I made use of PVC conduit as it is easy to cut and glue - perfect for a do-it-yourselfer. I had no experience bending metallic conduit. The 3/4" conduit travels down to the lowest piece of racking where it makes a 90 degree turn to the west edge of the roof. At this point, I supported the conduit by binding it to the racking with large stainless steel hose clamps. Unlike plastic zip ties, stainless steel won't degrade at all with exposure to sunlight.
AROUND THE EDGE:
I wasn't sure exactly of the best way to make the conduit go around the edge of the roof and make the transition of going down the wall. I purchased a large bag of assorted PVC elbows, 45 degree angles, and LB pulling bodies so that I could experiment with going around that edge. In the end, I decided that two LBs allowed me to get the conduit as close to the building as possible, which looked the best. This was also part of the solar system easily viewable from the house. I made sure to get my wife's opinion on how the conduit looked before permanently gluing and mounting it. Once she liked it, I completed the work.
Most Power Utilities, including mine, require an external AC Disconnect. This allows utility workers and emergency personnel (Firefighters!) to disconnect the solar array if the need arises. Because I had two circuits, I also needed to COMBINE the two circuits into a single larger one. I chose a box which would both combine the circuits AND allows for AC disconnection. This box was the Midnite Solar AC Disco. It has space inside it for up to three 240VAC circuit breakers, and is lockable in the OFF position. I purchased the enclosure with two 20A circuit breakers. I put the box on the wall, marked the location, and then drilled a hole through the wall. I pushed a short section of conduit through the wall. This connects into the BACK of the disconnect to pass the power from outside the building to inside.
I installed the two 20A breakers and finished running the conduit down the roof and to the disconnect box.
I really like this combiner/disconnect. I think it looks nice and it does it's job properly. Some utilities or building inspectors may require that you use a dedicated AC disconnect and a dedicated Combiner. Make sure you know exactly what they want before beginning the project.
ELECTRICIAN AND WIRE PULL:
I hired the same electrician as did the general wiring in the garage. I did as much of the electrical work myself as I could, before he came over to save time and cost. I already had the junction boxes in place on the racking and the conduit running down from them. The electrician supplied the wiring, and had several different colors on spools. He put them on a roller stand to unroll. I got on the roof and the electrician stayed on the ground. We pulled wiring from the spools, up to the first junction box. I ran a fish tape from the top box to the middle box, and then used that to pull the wiring to the top box.
Inside the top box, I made the connection from the four wires of the trunk cable to the four wires we just pulled up through the conduit. This was simply stripping the wires, twisting the matching colors together, and completing the termination with a wire nut. At the middle box, I repeated the same process, this time with the other bundle of wires. The two groups of wires were bundled together with electrical tape to make sure I could keep track of which was which. We also used a different color wire (purple instead of red) for one of the hots to differentiate the two groups of wires. (Yes, purple wires are to code! Red and black are the most common, but other colors can be used, although not white or green!)
At the bottom box, I cut the wires of the second bundle, stripped them, and then combined both ends of the cut wires with the bottom row of solar trunk cable. This electrically combined the middle and bottom rows together into one circuit.
While I was working on the roof, the electrician finished installing the combiner/disconnect box and fed 10 awg wiring from it to the breaker panel. That wiring goes through a 30A breaker into the panel at the end opposite of the main fuse.
When I was finished making connections on the roof, we pushed the end of the wiring down through the conduit to the disconnect box and made the connections at the two 20A breakers.
My total fee for the electrician and materials (mostly the wire) was $431.92. I had done very little household wiring before and NO serious solar wiring. It was nice to have a professional there to look over my work and confirm that I was doing everything correctly. I was also required to have a licensed electrician to do the final hook up and get the electrical permit in the first place.
FIRST SOLAR PROJECT:
When I asked the electrician how many solar projects he's worked on before, he said "None, this is my first, but it's just 240VAC wiring, that's what I do all day."
One of the reasons why I wanted to use micro-inverters is because all of the wiring is the same type generally used in households. Electricians and building inspectors are already used to it, whereas they might NOT feel knowledgeable or confident with high voltage DC.
The utility may have specific requirements for labels or signage at the meter, the breaker box, or disconnect box. You need to comply with whatever those requirements are, and they are for safety after all! In my case, I only needed a few simple signs, but they did have to be specifically red and with a certain font size and style. I placed an order with an online sign-making company to have plastic placards made for my system. I happened to use https://www.pipemarker.com, but there are many companies that can made signs for you, anywhere from a local-sign shop to pre-made signs on eBay. I attached the signs to the disconnect box and utility meter with permanent double-sided tape.
Step 8: Installation Day!
Here comes the exciting part, actually INSTALLING the solar panels!
We already had the racking, conduit, and wiring installed. Once the panels were in place, the system would be nearly finished. I was very excited.
Still, one major challenge is that my roof is steep and slippery enough that a person simply can not walk on it. A person could sort of climb around on it and use the racking to keep from slipping off, but not actually freely walk. To install solar panels, a person needs their hands free to carry the panels.
So, I decided that I would rent a lift. That would allow for bringing the panels directly to the location on the roof where they would be installed. A person could stand on the roof, grab the panel, and install it in place WITHOUT having to walk around carrying it.
After taking a look at rental prices, I realized that the roofer who I had install my metal roofing owned a lift. The cost of hiring him, WITH his lift, and his truck to bring the lift and take it away when done wasn't all that much more than for me to rent a lift in the first place. On top of that, I would get a top-notch lift operator and a professional who is used to working on roofs and making sure that things are straight and level. The roofer charged me $650 for the lift rental and all labor.
On a roof with better walkability, one person could simply slide a solar panel up a ladder where another person could grab it, carry it to where it needed to be installed, and put it in place.
We made an appointment for a day of when the roofer could come out. I also arranged for my brother and a friend to come out and lend a hand at the same time.
The roofer also brought out his apprentice. It was the roofer, apprentice, and I on the roof, and my brother and friend on the ground. The apprentice ran the lift. The ground crew would carry a solar panel, set it on the basket of the lift and strap it in place. (That was just a precaution, in case the wind kicked up while the panel was being moved to the roof.) The apprentice would maneuver the lift to the correct position on the roof, and the roofer and I would take the panel and set it in place. I would connect the two wires from the solar panel to the micro-inverter. I also looped the excess wire and zip-tied it to the racking. Then, we would bolt the panel down to the racking with the Iron Ridge UFO bolts.
We started at the top right corner and worked our way to the west and then the lower rows. We started with the east side because I figured that was most visible from the road, and I wanted that corner to lay out nice and look good. Making a row of solar panels straight isn't easy. Although we would line up the top edge of the next panel with the one before it, it was still easy for a row to angle up or down. It really just needed to be eye-balled. We did find that the panels are perfectly manufactured. If one was a little out of square, it quickly make the whole row off.
It was also good to have somebody on the ground always looking at the panels as we put them down to make sure they all looked straight and level.
Panels are spaced side to side by the bolt going between them and holding the panel down. Once we completed the top row, we used a piece of 1/2" plywood as a spacer. We would slide the middle row panels UP against the scrap plywood, which was against the top row. That gave us an easy way to ensure consistent spacing.
Once we figured out the details of getting the panels night and straight with each other and evenly spaced, installing the panels went very quick. We started at 7 in the morning and were done by lunch!
I was plenty of work to design the system, install the racking, micro-inverters, and wiring, but with the panels in place, there was a HUGE sense of accomplishment.
Step 9: Commissioning and Testing
COMMUNICATIONS GATEWAY AND ACTIVATION:
Inside the garage, I installed the Enphase Envoy. The Envoy is a communications gateway. It communicates to the micro-inverters and to the internet. Communications to the micro-inverters is through Power Line Communications. The power cord of the Envoy simply needs to be plugged into an outlet which connects relatively directly to the power from the micro-inverters. When I had the garage wired for power, I had a dedicated electric outlet installed right next to the breaker panel just for this purpose. (Sometimes circuits with electric motors on them can cause issues with power line communications.)
The Envoy also needs to be connected to the internet. This particular version has both wireless and LAN connections. I already ran networking cables to the garage, but I was pleased to see that my household wireless router seemed to work just fine reaching the Envoy.
(I later found out that a common problem with solar power monitoring systems is that they stop working when somebody changes their wireless router password! In the communications gateway, the password just needs to be updated, and it works fine again!)
I had already set up an account for myself at Enphase.com. I also downloaded an app for my phone. It's the Enphase Installer Toolkit. That app allows a person to connect from a smart-phone directly to the Envoy over wireless. From there, the installer uses the app to associate the particular Envoy with the micro-inverters and to a particular account. Remember those bar code stickers we pulled off the micro-inverters? Those serial number are entered into the app to associate the inverters to the Envoy. It's sort of a pain to type all those serial numbers. Fortunately, there's also a photographic feature in the app which allows you to take a photo of the bar code to enter the micro-inverter's serial number.
I turned on the power to the micro-inverters. (Remember, they aren't actually creating any power yet.) After waiting a few minutes, I could see the inverters show up and communicate with the app software. (It took a few longer to be "discovered" than others. The data over power lines is sort of a slow trickle - it is NOT high-speed big data!) The very last step is to actually activate the inverters to have them create power. I did that, just to see that all was working correctly, and then put the inverters back into the "don't make power" mode. Most utilities will allow you to activate grid-tie solar just to test it, but after that, it needs to be off until they approve and test the system.
I was amazed to see the electric inspector the next morning. He took the cover off the breaker box and looked at the connection from the solar. He also looked inside the disconnect box and confirmed that the size and type of wiring was correct. He did NOT go on the roof, ask for a panel to be lifted up or anything else. He was there and gone in less than ten minutes and left me with a signed Post-It stuck to the breaker panel saying "Solar: Approved" and a signature.
TESTING BY THE POWER COMPANY:
As soon as I nailed down a date for the actual solar panel installation, I also let the power company know that the solar system would be ready for testing and approval. They were there the next day!
My customer contact who I had been working with for the PSC forms was there, along with an electrical engineer and another guy. (The third guy was likely just another utility employee who hadn't yet had an opportunity to inspect an electrical system.)
NO MAN IS AN ISLAND:
The main concern from the Power Company's point of view is SAFETY. In the case of a power failure, if my solar was creating power and sending it back over the grid, it could go through a transformer and be converted to very high voltage. A utility worker, just doing his job trying to get the power back on somewhere on the other side of town, might touch a wire that he "knows" if off but instead suffer a lethal shock from my solar system!
To prevent this type of danger, all Grid-Tie inverters have built-in a feature called "Anti-Islanding". The inverter MUST sense that there is grid power available. Only then will it activate and create power. In event of a power failure, the grid-tie inverter senses the loss of power and IMMEDIATELY SHUTS DOWN. Even after power comes back on, the inverter will wait five minutes before it activates again.
The main thing the power company really wanted to do was test the anti-islanding feature.
I finally got my chance to throw the big red switch into the ON position, but it was anti-climactic, as we still had to wait five minutes before the solar would make power. In the mean time, the engineer was trying to decide the best way to check to make sure the inverters would shut down. The inverters themselves were up on the roof, and the Envoy device didn't have any kind of display on it.
They decided to pull off the cover of the conduit that lead from the disconnect box to the main breaker panel. That way, the wires could be pulled out and the engineer could attach his clamp-on ammeter.
Once the five minutes was up, we could see power displayed on the ammeter - about 20 amps.
The engineer then turned off the main breaker to the garage, simulating a blackout. Instantly, the inverters stopped producing power. He then turned the main breaker back on, checked that the ammeter still read zero, and looked at his wristwatch. Yep. He confirmed that it took the full five minutes before power was was again created by the micro-inverters.
With that, I was done! I had passed electrical inspection and the power company had approved and tested my system! I couldn't be happier!
My customer contact took me over to my utility meter and showed me exactly how it was now programmed to work. Instead of ONE number which always went up, there were now TWO numbers tracked by the meter. The first was of course the original - how much power I was pulling from the grid. The new number would be how much power I SENT to the grid. At the end of the month, the one number would be subtracted from the other, and that's what I would pay for on my power bill.
The meter also has and animated dash on it. The speed of the movement of that dash represents how much power I'm using, but new now was the fact that it could also animate the OTHER DIRECTION! Right then, the dash was moving quickly from right to left. On that sunny summer morning, I was already creating far more energy than I was using!
I would have to wait for two billing cycles before I saw the full effect of solar on my electric bill, but I was pleased when I did. The power company OWED me $40!
Step 10: Solar Production
One of my favorite features of the micro-inverters is the level of information there is about the solar production.
This system uses a web page to track and display information about the system. Another great feature of that is the ability to remotely view the information and also to share it.
If you would like to see how much power my solar array is making right now, please view the public link!
As the system owner, I have access to even more information, including seeing how much power each individual solar panel is creating and tracking total energy over different amounts of time.
From June 2017 to December 31, 2017, my system output 4.17 Mega-Watt-Hours of total energy. That's almost 600 kWh's per month on average, exactly what I was shooting for!
The software also allows me to run reports, get monthly values, and export data as comma separated values, useful for pulling information into spreadsheets.
The software also allows for basic animations. Below is an animation of one particular day in June, not long after installing the system. Notice how power increases to a maximum in the middle of the day and then tapers off. It's pretty obvious to see when the shadow of my neighbor's tree-line sweeps across the panels. (No sound on this video.)
Step 11: Financials / Budget
BUT HOW MUCH DOES SOLAR COST?!?The truth is that solar can have a wide range of cost, depending on what size your system is and which components you use. Financial Incentives can also have a LARGE impact on the cost of your system.
My system cost me $10,590.48 before incentives. I know that because I tracked every receipt. I made a spreadsheet and had a folder to keep all my reciepts in. I wanted to make sure to know how much I spent in the end. I also needed to know the exact cost because I would need them for incentives. (Please see Solar Budget.pdf for details of spending.)
FEDERAL TAX INCENTIVE
In many places, there are financial incentives for installing renewable energy, such as solar power. The big one currently in the United States is the Federal Residential Renewable Energy Tax Credit. That is a 30% tax CREDIT on the total cost of a solar system. (It also covers wind, heat pumps, solar hot water, and more!) Please keep in mind that the tax credit tapers down to a lower percent in 2019, and is completely gone in 2022. So, if you want to save some money on solar, do it now!
This is a TAX CREDIT, not a deduction, so it really means cash in your pocket when you do your federal tax return. If the credit is greater than your tax liability, the credit can carry over to the next year.
STATE / LOCAL / UTILITY INCENTIVES
Besides the Federal incentive, there are many different types of State, Local, or Utility incentives. These vary by your location and who your power utility is. In Wisconsin, we don't have any state incentives for solar. We do have an incentive for energy conservation through a program called Focus on Energy. Focus is funded by profits from power utilities, and the funding has to go back into energy efficiency. We sometimes see LED light bulbs or water-saving showerheads the store with special rebates. Those are through the Focus on Energy Program. I contacted my utility to double-check if there were any incentives I didn't know about, and they confirmed that the Focus on Energy program was the only one. Funding for this program has been decreasing the last few years, and it's never guaranteed for the next year.
To see what financial incentives might be available to you for renewable energy, please visit: http://www.dsireusa.org
Essentially, the Focus on Energy Residential Renewable Energy Incentive will write a rebate check for 12% of the total system cost, up to $2,000. Applicants need to first fill out forms to reserve the incentive, and then once the project is completed, submit paperwork to actually ask for the money. This particular program actually has some relatively strict details. For example, the solar panels must be mounted within a certain number of degrees of true south and can't have more than a certain percent of shading. The applicant also must be a customer of a particular utility, so an off-grid system wouldn't be able to apply. The program covers parts and labor, although if a person wants to install solar panels themselves, they can't bill for their own labor. The wording of the application also made it sound as though only a professional solar company couldn install the system. I called the office and confirmed that a do-it-yourselfer COULD do the work and get the incentive, although all costs must be carefully accounted for.
I filled out all the paperwork originally for the reservation of the funds, and then the application to recieve them once the solar was installed. About two months later, I finally got the check in the mail for $1,270.86.
Please note: The Federal 30% incentive is to be applied AFTER any other rebates or incentives. So, my system cost is:
Out of pocket: $10,590.48
Minus Focus on Energy rebate check: $1,270.86
Multiply by .30: $2,795.89
Subtract that 30% = $6,523.74
My total system cost ends up being $6,523.74
Please take a look at the attached budget file for a full break-down of all costs.
Of course, I still needed to have that $10,000+ in the first place. That is a reasonable sum for a person to save for, just like saving for a good used car. It could also be paid for with a Home Equity Line of Credit. In fact, my family had been paying down our mortgage agressively, so we had plenty of equity. We were also funding building the new garage. We decided to fund that by taking out a new mortgage. By refinancing, we were able to get a lower interest rate on our home loan, and take out cash as part of the process. That money went to pay for building the new garage and funding the solar array. The new garage and solar raises the value of our property, which we will recoup if we sell our house. Interest on a mortgage is tax deductable, which lowers the effective interest rate on the mortgage loan. Money such as the Focus on Energy rebate just goes right into paying for the solar.
RETURN ON INVESTMENT
Nobody ever asks what the Return On Investment on a sports car is. Most things in life aren't bought as an investment, but rather because we want them, whether that's a fancy car, a tropical vacation, or solar panels. However, everyone always wants to know what the ROI is on a solar system. The final cost of the system will be $6,523.74. My power production estimates indicate the the solar should save me very close to $1,000 per year. Simple division shows that the solar should take roughly 6.5 years to pay for itself.
On retirement investment planning sites, the "Rule of 72" is sometimes used to calculate how long it takes for money to double. Or, if you know how long it takes the money to double, you can calculate the interest rate. Dividing 72 by the number of years it takes money to double tells you the interest rate. If the solar panels pay for themselves in 6.5 year, that's an effective rate of an 11% investment. Not only is that a good interest rate (comparable with investing in the S&P500) but it's also a sure thing. If electricity rates go UP, it's an even better return.
MORE SECRET SAVINGS
Another financial aspect sometimes overlooked is the LACK of taxation. In general, one of the larger taxes we pay in the United States is INCOME tax. However much income I earn, I have to pay some percent of it (say, 15 or 25%) to run the government.
Here's the amazing part; For anything I NEED but I don't BUY, I'm saving the value of that income tax. For example, if I need to pay $100 a month to an electric bill, I actually need to work enough to earn the money to pay for it PLUS the income tax on it. If I was in the 15% tax bracket, I'd have to earn about $118 to pay my income tax AND the $100 utility bill. If I were in the 25% tax bracket, I'd have to earn about $133 to pay taxes and the $100 electric bill! (Essentially, I'm saving another one-third on the solar panels, or accelerating their pay off. If taxation is considered, it can make the solar panels pay for themselves 20% to 33% faster. than you otherwise might think)
I'm not saying don't pay your taxes... It's just very interesting to me that NOT buying things has a larger effect on total cost than one might think. Taxation is ALWAYS a consideration in retirement accounts (IRA vs Roth-IRA, etc.) and it should be considered in other things that can become an asset.
I was feeling pretty good after I got my electric bill for the first FULL month of solar. The power company OWED me $40! I would get that as a credit, and it would just roll over to the next month.
Step 12: Solar-Powered Electric Vehicles
ELECTRIC CARS LOVE SOLAR!
America has a love affair with cars, and there's lots of places where it's pretty tough to get around at all without one! Cars also cost a lot of money and burn plenty of fossil fuels.
My secret weapon is to drive an ELECTRIC CAR! I built my own back before I could buy one, and I now drive an economical USED commercially-built electric car. (Electric MOTORCYCLES are a blast too, and even MORE efficient!)
My current ride gets the equivalent of 112 miles per gallon, but the best part is how CHEAP electricity is. In my area, electricity is 13 cents per kilowatt-hour. That translates into roughly $1.00 per gallon if it was gasoline. On top of that, electric prices are very stable compared to gasoline, which has been anywhere from $2.00 per gallon to nearly $5.00 per gallon in the last decade.
Another great thing is that electricity has the ability to be even cheaper. Many utilities offer a "Time of Use" plan which raises the cost of electricity during the day (when a person usually isn't home) but REDUCES the cost at night (when most people charge an electric car.) Potentially, that can bring the cost of charging an electric car down to 50 cents per gallon equivalent. In very rare cases power utilities will also BUY BACK excess electricity at that same HIGHER RATE. You could sell electricity at premium rates during the day, and charge your car at night when nobody is using power, so it's dirt cheap!
It gets even better!
If I considered the fact that my solar is a "sunk cost" (I already spent the money and can't get it back...) the cost of charging an electric car is FREE!
Of course, I DO count the money I spent on it, but once the solar panels cover their own cost (in about 6.5 years) the electricity produces REALLY IS FREE. Now think about how much money is NOT spent on gasoline!
Current gasoline prices in my area (as I write this, remember how volatile those prices are! For current gas prices, check out GasBuddy!) is about $2.44. I track my mileage for work and know that I travel very close to 10,000 miles per year in my electric car. (Many of those are very short trips, where gas cars get the WORST fuel economy.) The average car in the United States right now gets about 25 mpg. If I was driving an Average car for 10,000 miles, I would use (10,000mpg/25mpg=400 gallons) 400 gallons of gasoline. At $2.44, that's $976 spent in gas. (I'd also have to pay for oil changes and other maintenance that gas cars have which electric cars don't.)
So, by making my own electricity and putting it into an electric car, instead of a gasoline one, I'm saving almost $1,000 per year! The more miles I drive, the more I save! On the other hand if instead of driving an average car, I drive an efficient one, the savings are less. At 45 mpg, I'd only use 222 gallons of gasoline, and spend about $542 in gasoline. Still, think about what you could do with an extra $500 a year!
I've run the numbers in different ways, trying to fairly factor in the cost savings of the synergy of driving an electric car running on solar power. The numbers I have come up with range from financially effecting a solar project in a range of NOT AT ALL (you had to spend extra to BUY that electric car after all...) to cutting the ROI in solar in HALF!
In my project, I've figured that it could get the ROI of my solar down to as little as 3.5 years, but again, it all depends on how you look at it.
No matter what, I LOVE the feeling of powering my car straight from the sun.
Speaking of which, CAN we power a car straight from the sun?
In the middle of the day, my solar array can produce over 5,000 watts of power (or about 20 amps at 240V.) The charger built in to my car uses less than 16 amps (3300 watts.) So, in the middle of a sunny day, I can directly charge the car and have power left over! The left over power is usually enough to power my house with still just a little to back feed to the grid.
But how LONG does it take to charge the car? Usually a few hours, and no more than five hours if the battery is completely exhausted. The battery pack is a capacity of 16kWh. On a nice sunny summer day, I can produce more than 32 kWh of energy - DOUBLE the maximum of what the car can use. I did make sure to install two electric car charging stations in my garage, one on either side. That allows me to charge while in either parking space, have a friend stop by and charge at the same time, or make sure that I'm already set for when we want to replace our hybrid with a plug-in hybrid or Battery Electric Vehicle (BEV) in the future.
As we still have limited public infrastructure for charging plug-in cars, I also make sure to SHARE my solar-powered charging stations with other electric drivers by using an app called Plug-Share. It's been fun to meet new, adventurous people who are out traveling in electric vehicles!
When building the garage, I installed 3 NEMA 14-50 240V electric outlets. These are most common at RV parks, but are also used for other high current applications. In a garage, they are great for plugging in a welder. Teslas also include an adapter to this connector with their portable EVSEs. Because of that, a Tesla can actually charger faster at one of my garage electric outlets then they could at a public J1772 charging station!
Both my charging stations are wired so that they can just plug in to the NEMA 14-50 outlets. I can also take one with me when I tow my camping trailer to a camp-ground. I just plug in and charge where RVs would normally plug in for shore power.
For more about electric vehicle projects, please visit: 300MPG.org or my YouTube channel.
Step 13: Passive Solar Thermal Doors
Besides supporting the Photovoltaic solar array, the garage will also be used for storage and as a workshop.
In our cold winters, I want to be able to heat the garage. I don't need it to be at room temperature, but even 40 or 50 degrees F. is luxurious when it's ZERO or below outside!
Instead of burning fossil fuels, I wanted to be able to get some direct solar gain. In the winter, the sun is low in the sky, so the best place for solar gain is through a south-facing vertical surface. To get this heat and light into my garage, I built a Solar Thermal storm door to go over one of the garage doors. The garage doors themselves are well insulated, filled with polyurethane foam.
To make the solar thermal doors, I first built a basic wood frame. This was using 1x6 lumber (measuring 5.5" x .75") and 3/16" thick plexiglass. I purchased the lumber from a local lumber yard and the plexiglass from a local plastics distribution company. I already had hinges and other miscellaneous hardware and materials was purchased from the local hardware store.
The opening of the garage door is 7 feet high by 9 feet wide. Two pieces of 4'x8' plexiglass would be enough to fill in the area as the wood frame would fill in the width. I would have to cut the plexiglass down to a height of less than 7 feet to fit.
To build the wood frame, I cut the 1x6 lumber to size on a chop saw, and drilled holes in the corners to accept wood dowels and glue. The frame was then pegged and glued, and I used ratchet straps to clamp them together, making sure to measure from corner to corner to ensure that the frame was square.
Next, I used a router to cut a groove or "rabbet" around the inside edge of the wood frame. This was just a hair deeper than the thickness of the plexiglass.
I left the plexiglass at its full 48 inch width, but had the cut the length shorter. To do that, I measured the plexiglass, made my mark, then clamped down a straight edge. I scored the line multiple times with a sharp-edged tool. (50 times with a carpet knife!)
Next, I bent the plexiglass on the score line over a hard edge - a board running the full width of the plexiglass. The plexiglass snapped on a nice clean line.
Next, I ran a bead of caulk on the inside of the groove routed into the wood frame and carefully laid the plexiglass in place.
After that, I cut additional blocking from the 1x6 lumber to make reinforcements for the corners. Those were screwed in place to cover the plexiglass (helping hold it in place) and to cover and reinforce the corner joint.
Next, the door was put in position, shimmed up into place, and then held there by attaching hinges to the door and the frame. The second half of the door was then put in place, and planed a bit as needed to match the frame and other half of the door. Once it fit well, the second half was also secured to the doorway with three hinges.
I screwed some additional blocking on the inside of the doors to provide on overlap for the doors to press against each other. A pressure-treated 2x4 was cut to length and placed on the floor, running the full width of the doorway. This acts as a threshold for the doors. I installed bolts to hold the doors shut by sliding into the threshold on the bottom and into a hole in the blocking at the top.
Self-stick 3/16" foam weatherstripping completes the seal between the doors and the existing garage door frame.
At night and on cloudy winter days, the insulated garage door is left down to keep heat in the garage. During sunny winter days, the insulated garage door is raised to let in the heat and light, providing for a cheerful and warm garage workshop. The heat gets absorbed by the 5 inch thick concrete slab, which is insulated below by two inches of foam insulation. The doors can be removed for the summer.
The glazing on this pair of swinging doors provides an area of approximately 4.15 square meters. Sunlight is generally considered to be 1,000 watts per square meter (on a clear day, perpendicular, at sea level.)
This acrylic plexiglass glazing transmits 92% of the light hitting it. In theory, I could gain up to about 3.5 kW of heating power in the middle of a clear winter day. That's roughly equivalent to the amount of power I can produce in the winter with my my ENTIRE solar panel array, but in a much smaller area and cost!
PV panels are VERY inefficient compared to just direct sunlight for heating purposes.
If I also enclosed the OTHER garage door with glazing, I could double my solar gain!
(Although at the expense of ease of moving a car in and out.)
To see a full detailed write-up on just the Passive Solar Garage Door, please visit that Instructable.
Step 14: Trouble-shooting and Lessons Learned
Installing my own solar array and watching it produce power for the last six months has been a GREAT learning experience. Is the system perfect? No, I made a few mistakes and have learned from them. Here's a few of the key things I learned:
RACKING UP MISTAKES
I accidentally left the rails LONGER than I originally meant to. The plan was for the metal roofing clamps all to be one standing seam closer to the middle. The rail would then cantilever past the edge of the last solar panel, supporting it, but with only a small piece of rail exposed. No metal roofing clamp would be exposed beyond the solar panel. When I went to lay out the clamps in the first place, I put them at the far ends, to better stretch a string to line up the rest. I accidentally then used those same roofing ribs on rows continuing up from there. By the time I realized what I did wrong, it was sort of too late to pull off and reposition the clamps. I also realized that rails sticking past the edge of the solar panels could be a good thing. They act as rungs on a ladder, allowing me to be able to access the roof, which I otherwise would NOT be able to. Whether rails run to supports out past the edge of the solar panels, or to supports hidden just under the edge of the panels, either way will hold the panels just fine. It's really more of an aesthetic choice than anything. Still, I originally planned it one way, but accidentally did it the other - WHOOPS!
We have excellent power service in my area provided by a co-op, publicly-owned (municipal) electric utility. Blackouts are extremely rare, and brief when they do happen. Battery-based solar systems add significant expense and maintenance. Because of that, I just wanted a grid-tied system. The main draw-back of a grid-tie system is that it can not and will not produce power when the grid is down!
Which is why it was ironic that one week after I installed my system, we had a blackout
The blackout only lasted about an hour or so. It was during the day and in the summer, so I hardly even noticed the blackout happening! (I didn't have any lights on in the house anyways!) Power was back on relatively quickly. I had no urgent need for electricity. The refrigerator would even stay cold if I left the door shut.
Even though there was a blackout, I think my only real loss was the value of the electricity I could have produced, which I estimate at 39 cents.
In the past, I've experimented with using electric vehicles as backup power supplies. That's exactly what I did in the last black-out, five years ago. I now have an electric car with a battery of much larger capacity than my electric motorcycle ever had. I'll probably experiment in the future using that as an emergency electric power supply.
CIRCUIT BREAKER WOES
About a month after installing the solar, I also ran into another issue. At that point, I was checking the software to show the solar production about every other day. When I checked it, I saw that ONE-THIRD of my system was completely NON-OPERATIONAL! The Enlighten software showed that the top row of my panels was black - producing ZERO power. Trouble-shooting this was fairly simple. Recall that I have TWO circuits, one is the top row of panels, and the other is the lower two rows of panels. It seemed obvious to check the breaker. I opened the cover of the Midnite Solar Combiner/Disconnect, and sure enough, one breaker had flipped. I couldn't see any reason why it had, so I simply reset it.
My system resumed producing power again.
A few weeks later, it happened again. One-third of my power production dropped out. This time, I had changed a preference in the Enlighten software so that I would get an e-mail immediately if there was any drastic change in my system. It alerted me to the condition, so I reset the breaker with no real loss of power production.
I still had no idea what was wrong - everything in my system was properly installed, I had done my math to make sure I used correct wire sizes, etc. Not long later, I saw a friend who has worked in renewable energy education for a long time. I told him about my breaker woes, and his response was "Have you checked the breaker itself? Maybe you just have a bad one."
No, I had not. It never occurred to me that a circuit breaker could simply be bad. I powered off my system, and SWAPPED breakers between between the circuit 1 and circuit 2. Eventually, the same circuit breaker popped again, this time taking out 2/3rds of my solar panels. The trouble was indeed just a bad circuit breaker. I ordered a new one and replaced it. I've had no issues since.
Shadows cast onto the solar panels are definitely a concern. In the time that I've had my solar up and running, I've been able to track my real-word production and compare it to my estimated production from PV Watts. I also originally used the Solar Pathfinder to calculate how much power would be lost. Using the Solar Pathfinder can be a little subjective (a shadow lands just on the edge of a line, etc.) but my original calculations said that I would loose 7% of my total energy production due to shading.
After running the real-world numbers on my 6 months of production, I got 93% of my original estimate. Add in that 7% loss from the shading, and it was DEAD on!
Keep in mind that I would have lost even MORE production had I NOT been using micro-inverters.
While a COMPLETELY open and non-shaded location would be IDEAL for solar, I'm still very happy with the results. Never let the perfect be the enemy of the good!
WINTER SNOW AND COLD
I truly had no idea how much the snow might effect my system. Is my roof steep enough for snow to just slide off? Will the panels produce no power after the first snow of the season? I would have to wait and find out.
The first snow of the year was really just a light dusting. The solar panels actually COULD produce power, even with a thin layer of snow on top! (Although MUCH less than without it!) The next snow was a little thicker, and it was pretty obvious that the snow wouldn't simply slide off. I experimented a bit, and realized that I could reach the lowest row of panels with a broom while standing on a step ladder. Not ideal, but at least I would get 1/3rd of my production instead of almost none.
I found a "Roof Rake" on sale and bought it. ($28) The roof rake is an extendable aluminum pole with a plastic blade on the end, not unlike a snow-shovel. By reaching up to the roof with the device, I can pull the snow down from the bottom two rows of panels. If I really stretch, I can get a little snow off the highest row of panels. Even getting SOME snow off the highest panels does increase the power production.
So far, I've noticed that the BIGGEST issue with snow in my area so far is NOT the snow itself, but the CLOUDY weather and short days that accompany it. On an extremely overcast day, solar power is minimal. It almost doesn't matter if there is snow on the solar panels or not!
On the other hand, if there is snow followed by a period of COLD and SUNNY weather it IS advantageous to clear the snow. In single-digit (F) temperatures, even direct sunlight will not warm the panels enough to melt the snow off. Solar cells also have a characteristic of producing HIGHER VOLTAGE the colder they are. That means it's possible for them to produce MORE POWER than they otherwise would, due to the cold.
If you live in a cold wintery area which gets plenty of snow, but also has clear sunny winter days, you will want to make a special effort to be able to clear snow from your panels. Likely the easiest way to do that is to have the solar panels on a ground mount (where they are easy to reach) or mounted at a steep enough angle for snow to self-clear. Snow seems to stick around on my garage panels at 30 degrees, but slide right off the solar panel on the Solar-Powered Swing-Set, mounted at 45 degrees.
I also recently posted an image of my solar production with sunny skies but still snow covering the upper row of my panels. A friend who also has a similar size solar array and the same weather, noted that he only produced a third as much power on the same day as I did. The main difference between the two systems was that he has a series-string inverter, and I have multiple micro-inverters. ALL the snow has to be cleared from ALL the panels on my friend's system, otherwise he suffers SIGNIFICANT reduction in electric energy produced.
Snow on Solar Panels Video:
Using a Roof Rake:
One thing I did realize about a solar system - DON'T WORRY ABOUT IT!
It's VERY easy to try to constantly monitor the power output of the system. In the first few days of production, I was CONSTANTLY checking the status of my system. After a few weeks, I'd only check it every other day.
After six months, I'm mostly just thinking about my monthly power bill. It will be interesting to get an entire year's worth of data on the system. After that I'll be able to compare one month's production to the same month last year!
Although some systems allow you to see very detailed information, it's usually unnecessary and certainly doesn't need to be viewed every day. I DO recommend that you check your system on some sort of regular basis. You wouldn't want the system not working and only notice once you get a high electric bill! Setting up an e-mail alert in case there is an issue is a nice feature of my system.
The main thing to remember is to not get hung up on data. IT'S A GAME OF AVERAGES. Some days are cloudy or rainy. Some days are sunny. On average, I'll make more power in the summer, and less in the winter. Overall, I'm still producing plenty of energy, and in the end have next to nothing for a power bill.
IS SOLAR RIGHT FOR YOU?
Is a grid-tie solar array right for you? I don't know, you'll have to ask yourself that question. One thing I can say is that I'm loving it, and it really feels like one of the best things I've done in a long time. Not only am I saving money, but I'm also reducing the use the use of coal and other non-renewable fuels. I'm also greatly reducing my use of gasoline with the electric car (again, great cost savings!) but I'm not getting that automtive fuel from coal or nuclear either.
Not all locations are ideal for solar. Maybe you live in a heavily wooded area. Many power companies do offer programs where you can purchase renewably-created energy through the grid. The source of that energy might even be the left-over power coming from my house!
Check for yourself if solar could work for you. Take a solar class, consult on energy professional, or even use an online tool like Google's Project Sunroof!
DO IT NOW!
The best time to have done anything is yesterday. The second best time is RIGHT NOW. The cost of solar panels has dropped precipitously over the last few years. We are at the point in which most professional solar companies make most of their money off LABOR, not equipment. If you can design your own system and physically install it, you have just ELIMINATED the single largest cost of a system!
I originally started planning the new garage and solar over four years ago. At the time, my Focus on Energy rebate would have been more, but the cost of solar components were more expensive as well, more or less becoming a wash. I currently estimate my simple financial return on investment at 6.5 years or less. Had I installed solar 3 years ago, it would have already half paid for itself by now in savings on my power bill!
Some incentives will be going away soon. The United States Federal Tax Incentive will be reduced over the next several years, and be completely eliminated by 2022!
The time for solar is NOW!
I did it, and so can you!
PS: You can always follow all of my projects at 300MPG.org!
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Epilog Challenge 9