Introduction: DIY Home Solar: Planning a Solar Array (Beginner's Guide)
Maybe you've considered solar energy - even if only for a brief moment - only to dismiss it as too complicated and too expensive, or maybe you're seriously considering a project, but don't know where to start. With this Instructable, I hope to demystify the (not-really) intimidating process of installing solar panels in your home. We'll review the parts of a solar panel system, the things you need to consider when you're planning, and how you can save money on (and even get free money for) your project. At the end of the day, you'll know what to look for and what to keep in mind with any solar project.
Why Go Solar?
If you've been thinking about going solar, there's no better time than now to do it. Government financial incentives are still ripe for the picking, the cost of photovoltaic (PV) cells is falling every day, and you'll probably be the first person on your block to make the jump. Adding solar energy to your house is an excellent project for several reasons: You'll save loads on electricity, and may even be able to sell some of yours back to the utility company; you'll reduce your carbon footprint; and if you're installing in a remote location (such as a cabin), you'll have much less to worry about than you would with a gasoline generator. You'll also support a growing industry, and in doing so, help contribute to the worldwide adoption of this wonderful new energy source.
Throughout the guide, I'll be providing links to articles from SolarTown.com's learning center. This guide is meant to be very broad, so that you know what to keep in mind and what to plan for. Once you start researching individual products, though, you'll probably want a little more specific information. Hopefully, these links will address your questions. If anything you need to know isn't covered, feel free to surf over to our community page and ask an expert solar installer.
Step 1: Parts of a Home Solar Energy System
The hardest part of starting a project like this is knowing what to buy, so we'll look at a list of parts before we get into the nitty-gritty.
This article is going to assume that you'll be building a grid-tie (or "on the grid") system. Grid-tie means that your house will still be connected to the utility company. The biggest benefit of staying on the grid is net metering: If you're producing excess power, you can actually sell it back to the utility company. Since your system will help produce green power for the grid, and reduce the overall strain on the utility company, they'll buy it from you at a huge premium. Because you're still on the grid, you'll still have power on cloudy days.
What do I need?
These are the parts of a grid-tie system, in order:
1. Solar Modules (aka PV Panels) collect energy from the sun and turn it into direct current.
2. Power Inverter turns the DC from the panels into AC that your appliances can use.
3. PV Disconnect lets you cut off power so that you can work on the system without electrocuting yourself.
4. Your home's breaker box is where the solar energy connects to your house.
5. Net meter connects your house to the grid, measuring how much power you take from - or give to - the power grid at large.
You can buy panels, racking, inverters, and more at SolarTown. As we continue through this article, we'll look at some of the products that are available and what each will cost. If you feel overwhelmed by all of the different options, we sell packages that include panels, racking, and the inverter at discount prices, so give that a look as well! You could have a 5kW system for $35,000. Try not to let the price tag turn you off - we'll look at government programs to help cover the costs in step 7.
Now that you're familiar with the vocabulary, we can get to planning your solar array.
Step 2: Load Calculation
Knowing how much power you need is the first step to planning your array. Since solar panels are measured by how much energy they can absorb, this will tell you how many panels to buy, how efficient they need to be, and (perhaps most importantly) how much space you're going to require. Don't worry, this process doesn't require more than your utility bills and some basic math.
First, check out your utility bills to see how much energy you usually consume. Typically, this number falls around 900 kWh each month, but it varies wildly from household to household.
Next, find out the "peak sun hours" of your area. This number is a measurement of how sunny someplace is. On the West coast, this number is between six and seven hours; on the East coast, between four and five. The National Renewable Energy Laboratory has an excellent insolation map. Follow the link for Photovoltaics under U.S. Solar Resource Map.
All that's left now is to do the math. At 900 kWh each month, you're burning 30 kWh each day. Divide this number by the daily peak sun hours. If I use 30 kWh in a day, and there's five hours of sunlight, then I need 6 kW worth of panels to match all of my usage.
Step 3: Choosing Panels
There are two basic kinds of panels: Crystalline andthin-film. Choosing one or the other has major consequences for the rest of the installation process, so we'll look at the differences between the two before we make any decisions about how to mount them.
Crystalline modules are the big blue panels that usually come to mind when you think about solar power. They're very efficient and very durable. A 40 year lifespan is more than you can ask of many home improvement projects, and gives you more than enough time to make your money back in savings. A drawback of crystalline is installation. These cells require a somewhat elaborate racking system. We'll cover racking on the next page.
For a 6kW system (fully power an average household), crystalline panels would cost about $16,500: You would need 25 panels supplying 240W each. 240W panels cost $660.
Thin-film comes on a roll of flexible material. Though crystalline modules are more popular, thin-film is gaining a strong foothold in the market due to its ease of use. The two biggest advantages of thin-film are cost and convenience, since installation is as simple as slapping the module onto a smooth surface. One major drawback of thin-film, however, is durability - Thin-film usually only lasts around 25 years. Compared to crystalline, thin-film is usually more efficient in the dark, but less efficient in general.
For a 6kW system using thin-film, you would need 44 panels supplying 136W each. The panels cost $472, so the total would be $20,768. Although the thin-film panels are slightly more expensive, you don't have to buy expensive racking for them.
Keep the differences between these two modules in mind as we discuss location considerations on the next page.
Buy solar modules at SolarTown.com
Consumer Guide to Buying Solar Panels
Comparison of Several Leading Solar Panels
Comparison of Thin-Film and Crystalline Panels
Blog: Aesthetics of Solar Panels
Step 4: Solar Panel Racking and Location Considerations
If you go with crystalline modules, solar module racking (the bits and pieces that hold your panels in place) may be the most important part of your project. Here, we'll discuss a few things to keep in mind while you determine where you want your solar panels to go. If there's too many obstacles to crystalline panels, you'll definitely want to consider thin-film instead.
Roof mounts are especially great since they're aesthetically pleasing and don't take up any space in your actual yard. There's a lot to consider with roof mounts, however. Most importantly, you'll need to think about the actual strength of your roof. If you live in an older house, you might have to get your roof redone before you can start bolting PV panels to it. Thirty panels weighs an awful lot, and it'd be a shame to have the whole thing come crashing down into your living room. Besides the strength of your roof, you'll need to make some decisions as to whether it's the most effective location.
Your goal is to expose the solar panel to as much sunlight as possible. First and foremost, this means you need to avoid shade - one panel in the shade can affect the efficiency of the entire system. Be sure to keep details in mind: Will the neighbor's big oak tree grow in the next ten years? Will something that's out of the way at this very second be casting a shadow later in the day? You also need to consider the qualities of your roof. In order to get the most direct sunlight, your panels should point towards the equator (South, in the Northern hemisphere) - will your roof accommodate this? And is the roof big enough to hold your panels? Another, more obscure consideration is your homeowner's association. Some people think solar panels are an eyesore (personally, I think they make your house look great) and may have banned them in your neighborhood.
If it looks like a roof mount isn't the best idea, you have nothing to worry about. If you're concerned that your roof isn't stable enough for thirty crystalline panels, you may want to consider thin-film. If your roof has too much shade, you can still rack the panels in your yard.
Ground installation is very easy, since you don't need to spend the day mucking about on your roof. Ask yourself if you have the land to sacrifice for the panels, and again, pay attention to details when you're picking the site. Two not-so-obvious considerations are soil and wind - You don't want your big, expensive solar array to be sucked into a sinkhole, and you don't want it to blow away like a giant sail. One of the big advantages of a ground install is that you can have the panel on a pivoting pole, so that it follows the sun. These movable mounts are expensive, but they'll significantly increase the output of your system.
Now that you know what panels you want and where to put them, things get pretty easy from here on out.
Homeowners Associations and Solar Panels: Can They Live in Harmony?
Step 5: Solar Inverters
Picking an inverter for your system is pretty important. Fortunately, there's not too much room for error. You need to make sure that you're buying a grid-tie inverter, rather than off-grid. You'll also need to check the wattage rating to make sure it can handle your solar array. Finally, you can consider buying micro inverters. Remember how I said that a single panel in the shade can affect the efficiency of your entire system? A micro inverter system uses a small inverter for each panel, instead of one inverter for all of the panels. The shoddy performance of one panel won't be able to affect the rest of the system.
For our hypothetical 6kW array, we could use a 6kW SunnyBoy inverter - $3,999.00 at SolarTown.
Now that you've picked panels and inverters, the hardest parts of the planning phase are over. Whew!
The Good, Bad, and Ugly in Inverters: All the Questions You Need to Ask
Step 6: The Net Meter and Battery Backups
As you know, your power meter measures the amount of electricity you take from the grid. It is very likely, however, that you'll need to get a special meter that is able to spin backwards - without it, you can't accurately measure the amount of energy you're giving back to the grid. In most cases, you can call your utility company and they will provide one of these meters for free. As I said before, having a power station in the middle of the grid - even a tiny one - takes a lot of load off of the system, and the utility company will gladly assist you with your solar home.
Although solar battery backups are outside of the scope of this article, I find it necessary to at least mention them and why they are useful. First, battery backups are good in the event of a blackout. Unfortunately, your solar panels will not power your home if the lights shut off. This is to prevent your system from frying a lineman who's repairing the grid. A battery blackout will let you keep your refrigerator running while the power's out. Second, if you are running an off-grid system, you'll need the batteries when the sun's not shining.
Step 7: Finances, Installation, and Some Final Phone Calls
As you may be aware, the Federal government will provide you with a hefty grant to reward you for being a part of the transition to renewable energy. Just how hefty, you ask? The incentive program will cover 30% of your costs. Not bad, right? For more free money, be sure to check out North Carolina State University's DSIRE. Many states, towns, and utility companies provide additional grants, tax breaks, buyback programs, and low-interest loans to help offset the costs of solar energy. DSIRE maintains an up-to-date list of these programs.
Installation and Regulation
Before you begin, you'll need to make sure that what you're doing is legal. Call your local government and find out what kind of building permit you need - often, for renewable energy, they will waive the permit fee. Also be sure to contact an electrician. Even if you are installing the entire system yourself, you'll need to have it inspected, just to be safe. An electrician can help with problems or opportunities you may have missed. Be sure to read DSIRE carefully - It has some information on state and local regulations.
Another thing to double-check on DSIRE is the installation requirement for any incentive programs you may apply for. Although I'm sure that the most Instructables users will opt for a DIY solar installation, you may not be qualified for state or local grants if you don't hire a government-approved contractor to do it for you. That said, a do-it-yourself solar project is both fun and rewarding! Check out the further reading for some advice on DIY solar.
Going Solar: What Are the Economic Incentives?
Solar Installation Challenges: My First Person Report
What You Need to Know When Selecting a Solar PV Installer
Step 8: Conclusion
We hope you've found this guide to be helpful and informative. Home solar energy isn't terribly complicated, and with government incentives, it isn't terribly expensive either. In the long run, you can save a lot of money on your energy bills, and even make money by selling power back to the utility company. Once you know the parts of a solar array, the entire process is much less intimidating - it's just a matter of adapting the formula to your specific situation. Stop by SolarTown.com for more learning articles, solar news stories, affordable solar modules and components, or if you have any questions for a solar expert. Thanks a lot for reading, and have fun with your solar project!
For the next part of our DIY home solar installation, visit the second piece on Instructables called (how to select the right solar rack)
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