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My home has been solar powered since June 2013 and the power system has proven its reliability. I'm a proud owner of an OFF GRID solar power system. I decided to publish this instructable to let fellow DIYers know the basics to design and install a system such as mine. Dont expect an exact copy of my system if you decide to go this route. You need to know your home layout, load demand, budget constraints and future power requirements.

During this instructable I will use basic electrical terminlogy.

Notes to remember in this instructable:

1. My country does not permit grid tie. I cannot provide technical help on grid tie questions.

2. The entire design and installation I performed myself. In your case you will either need to be competent in electrical installations or hire an experienced electrical professional to do it.

3. I have fulfilled code (NFPA 70, TTS-171 Part 1) and power utility requirements.

4. Owning a power harvesting system means you are responsible for it. You can't expect to always call someone should there be issues during operation. Take control!

5. This is technical only instructable. I shall not answer financial questions.

Now let's continue on how I implemented my off grid power system. Remember when it comes to solar, the BIGGER the BETTER!

Step 1: Calculations!

Cables:

Sizing of cables (AC and DC) is very important to have as low a voltage drop as possible. For my home I used 2% maximum voltage drop from any supply Breaker to the furthest load. You can use a more tighter requirement and its no problem; your cables will have to be sized larger. The attached chart is an example I used however remember PVC insulated cables dont carry as high an amperage as XLPE. Also there are other types of insulators and temperature ratings for them all. Consult your cables' datasheets or simply use the worst case scenario charts. Also stick with copper conductors please.

For simplicity I refer to the AC ampacity chart to indicate what wire sizes to use. Please note that DC ampacity for the same cable is higher due to the fact there is no SKIN EFFECT for DC. Take for example the wiring in cars. For the headlamps, alternator, starter etc. notice the cross sectional area difference for the equivalent amperage on an AC system. Using the AC chart for DC cable sizing means you will have a lower voltage drop which is good.

A basic guide I have used well over the years is 5amp per mmsq of copper cable. My cable runs are less than 100ft and that estimate has worked out great. For example if I needed to pass 50amp dc then I would use a 10mmsq copper conductor. For longer runs, the cable chart would be recommended.


Breakers:

Molded case breakers are typically permitted to run a maximum continuous current of 80% their nameplate rating (unless its a 100% rated Breaker). Breakers for DC are differently rated than AC Breakers. Should you wish to use an AC rated Breaker for DC service, the general rule is the maximum DC voltage is 1/5th the AC voltage rating on the Breaker. Exceeding that limit means the breaker will not properly extinguish the arc during opening operations. Always check the cutsheet for the Breakers you select to verify operation at DC. Also dont oversize your Breakers else you defeat your protection (eg. 15A breaker for a 2 amp load).


Solar Panels:

I used a rule of 4 hours usable sunlight to size my panels. The energy demand for a 24 hour period needs to be determined. You can either use the utility energy meter and average your usage during the week or use standalone meter. The power utility meter is the easiest method.

For example if you use 1000Watt-hours of energy for a 24 hour period, then the panels you need will be (1000/4 =) 250Watt of panels.

You can assume 6 hours or more of usable sunlight to carry your cost down but I prefer more power to provide for my needs.


Batteries:

The Watt-hour demand for a 24 hour period is the minimum size the battery bank should be. Battery watt hour is volts x amp-hours. A larger battery bank means better voltage regulation at the input terminals of your DC loads eg. inverters, DC lighting, DC Fans etc.

Step 2: Installing the Solar Panels.

I installed my panels on the roof of my home. There are OEM mounting kits for this or you can make your own with metal or rigid PVC. I actually did a mixture of both. I have a total of 8 panels, each rated at 225Watt.

The optimum angle for installation varies around the world. For me it's 15degree from horizontal so mounting directly on the roof worked out great for me. I have panels facing the east and west to capture the sun from dawn to dusk.

It is a good idea to install the panels where you can access them for cleaning but for the most part they are maintenance free and have long service life (20+ years). An interesting side effect of the panels on my roof is the shade they provided actually made the house a bit cooler. Mind you I have a single level, 3 bedroom home (not big but its my home).

https://www.instructables.com/id/Maintenance-cleani...

If you have alot of shade from trees then you need to address this first or have an alternate location to harvest sunlight from dawn till dusk.

I made a penetration in my roof's sheeting and ran the power cable through it. I put strain relief and lots of silicone on the penetration. The panels are actually installed over that penetration so water ingress is not a problem.

If you wish, you can install a sun tracker for maximum harvesting. These are expensive and should not be installed on roofs. Why? Strong enough wind blows and your roof will suffer if it hasn't already from the weight of the tracker and panels. Trackers also require maintenance so these pointers you need to keep in mind.

Step 3: The Solar Charge Controller.

I originally had a morningstar MPPT 60Amp controller but it failed after a month in service. I just threw it in the garbage, angrily, warranty be damned. I have in service since mid 2013, an Outback MPPT FM80. I firmly trust this controller and will recommend it anyday. I also recommend MPPT type rather than PWM to get more energy into the battery bank.

You can have multiple charge controllers into the same battery bank. Each controller will need to have its own set of solar panels.

The outback FM80 can accept up to 150VDC so I wired 4 of my panels in series. I have a parallel connection of two of those strings and this is fed into the outback. My outback is currently maxed in this configuration. Always know the maximum open circuit voltage for your panels to know how many can be wired in series to your mppt charge controller. Never exceed the maximum input voltage to the mppt (you know what will happen!).

Using an MPPT controller means you can use smaller cables to deliver the power into the controller.

It is important to have a Breaker before the input to the outback for protection and maintenance.

Here is a free piece of timeless advice; the breaker to the battery bank needs to be turned off last and also it has the be the first one to turn on. Why? If solar power is present on the input without battery control power, your expensive charge controller will go bye bye! Trust me I know!

Step 4: The Battery Bank.

I used lithium iron phosphate (Lifepo4) to store the harvested energy. It's a 25.6v 160amp hour bank.

The details on this bank is covered in my instructable below:
https://m.instructables.com/id/Lifepo4-solar-storag...

Generally the higher the battery bank voltage the better once you can get a compatible inverter.

It's critical to have short circuit protection for each battery or battery string. A circuit breaker is a good means of doing this. Also for maintenance or upgrades, throwing a breaker off will facilitate this. Don't ever wire up a battery bank without protection!

LifePO4 has no toxic components, offers long service life (more than 2000 cycles@100% DOD according to the manufacturer), does not vent gasses, offers 4 times the power density at a third the volume compared to lead acid. Its perfect for installation in living areas. I personally overcharged a LifePO4 cell for 5 weeks and all that came out was brown electrolyte. No burning, gassing, irritating smell. I truly love this battery chemistry!


Also people, please don't use SLI batteries. These are shallow cycle and used only to start engines. You Want deep cycle batteries. Lifepo4 batteries are actually suited for both uses but it's up to you to decide what Your budget can provide. Lead acids are cheaper up front but don't have good lifespan, safety, environmental impact or discharge characteristics as Lifepo4.

Step 5: DC Wiring and Breakers.

I used flexible cables to route power to and from my battery bank. These type of cables are easily obtained from electronic stores or even car audio shops. Again the larger the cable to better however don't go so large that the wire cannot fit in a breaker or connecting lugs.

The breakers I used are DIN rail mounted type. These are quite low cost from Amazon. All my DC breakers are single pole. The negative of the DC power system is tied to a shared connection point. Only the positive is protected with the breakers.

Step 6: The Inverter.

Most household appliances and loads use AC voltage Whether it's 120v or 240v. I strongly recommend using only pure sine wave inverters to power these devices especially those with motors.

Some 120v inverters such as the transformer-less type are more efficient but do not allow the neutral output to be connected to the neutral of your utility! The neutral output when measured to ground will always have a voltage difference. The utility neutral will be tied to ground and reads 0v between ground.

Basically when using 120v inverters with non zero voltage neutral (relative to ground) you will need to use a two pole transfer switch. One pole for live, the other for neutral. If you don't have a utility supply to your home then you obviously won't need a transfer switch.

Do not be tempted (transformer less inverters) to connect the neutral to the ground connection. The inverter will fail because of this (yes I know this first hand).

If you wish to avoid all that headache just buy the transformer type inverter and these would have a neutral output of zero volts. Read the manual for your inverter carefully!

Step 7: AC Panelboard and Transfer Switch.

The output from my 120v inverter I wired to a panelboard I built complete with an automatic transfer switch. Below is the instructable I published for that project:

https://m.instructables.com/id/DIY-Circuit-breaker-...

You can purchase a panelboard complete with transfer switch if you prefer but for my needs I preferred to build it.

The computer control of the automatic transfer switch ensures the loads in my home will have power should the battery bank voltage drop too low. Below is the instructable I published for that automation project:

https://m.instructables.com/id/Creating-a-home-automation-system/


Having proper protection will keep everyone and everything safe in the event of a fault.

Here is a good piece of information. There are two ways to tie an alternate supply to your home.
1. A breaker interlock kit. This is basically a mechanical plate that prevents the main and a sub breaker from being on at the same time. This can be defeated and allow paralleling of two non sync sources! Very dangerous and I strongly recommend not using this method even though it is low cost.
2. A transfer switch physically allows only one of two sources to send power to a load. There is no possibility of paralleling here. Very safe and robust.

Step 8: Energy Efficient Loads.

Having all my lighting as LED helped greatly. I still have my standard refrigerator and washing machine. If at some future point those fail, for sure I'm gonna get me the inverter versions of those appliances for better energy savings.

All TVs in an off grid home should be LED. Even the computers should be the low wattage type even for desktops.

Most importantly is the human mindset. Use your energy sparingly. Dont assume there will always be energy available. Be wise and economize.

Step 9: Enjoying Off Grid Living and Planning for the Future!

For the most part I live off grid although I have the ability to use utility power when I need it, especially for large intermittent loads. To make life simpler and more enjoyable, I automated my entire home to handle all solar loads.

An installation like this is a long term investment and will pay off for itself. In my country electricity is very cheap so the payoff period is extremely long however I did this project as a labor of love and not really to have financial savings.

If you are nomadic and move around then this instructable may not be for you, unless you live in an RV or boat. I recently installed a small wind turbine generator to augment my harvesting capabilities. Check it out!
https://www.instructables.com/id/Installing-a-wind-turbine-to-power-my-home/


Using green energy rules!

<p>Good article and advice. Do you have knowledge in PLC contactor control for string sets switching battery banking for charging, fault, online and off line?</p>
<p>Great!</p><p>Hi friends. We must use the sun and wind power, instead of fossil. The fossil is causing all kind of disasters, especially ozone layer. In addition, causing high temps, health conditions, respiratory illness.</p><p>I am working in a similar project, with a variance; its hybrid, sun and wind.</p><p>I live in The Caribbean and we have a lot of water and sun.</p><p>Be kind, be good, be all you can be, but never surrender.</p>
<p>Caribbean rules!</p>
Hey, I am doing a similar build and would like to bounce some ideas off you and your experience . Send me a mail on skgoorf@gmail.com if you're keen on helping me out .
Another write up - more good stuff . Did you do a write up on how you sizes and designed your system ?
<p>Yup. Check my profile.</p>
Sorry inverter- not system.
Hey great ible! Question - how do you tie your inverters to your house electrical panel - if you I use any of it at all?
<p>I made a separate panel with an automatic transfer switch. This panel accepts the power (120VAC) from my inverter and distributes to my home loads.</p>
<p>Boleh saya tahu berapa kos bagi pemasangan panel solar dan peralatan untuk aircornd</p>
<p>This complete off grid solar energy harnessing step by step system explanation with all requisite accessorial lllustration is really encouraging , a wonderful idea. Thanks lot</p>
Thank you!
Okay what &quot;country&quot; are you in already??
<p>its in the dudes &quot;username&quot;</p>
Trini... DAD?
<p></p><p></p><p></p><p>It might be interesting parallel to the collector and connect one windmill at least a small for yachts so that the bad weather we have electricity.</p><p></p><p></p><p></p>
<p><a href="https://www.instructables.com/id/Installing-a-wind-turbine-to-power-my-home/">https://www.instructables.com/id/Installing-a-wind-turbine-to-power-my-home/</a></p><p><a href="https://www.instructables.com/id/Small-wind-turbine-generator-teardown-upgrade-and-/">https://www.instructables.com/id/Small-wind-turbine-generator-teardown-upgrade-and-/</a></p>
<p>How long will your battery last? My solarmaster battery lasted only a little more than 2 years and the cost of replacement is more than the cost of power it generated. Some battery can last up to 10 years but the cost is too high, and I'm afraid I will be paying more than being connected to the grid.</p>
<p>Perhaps it's about independence and not so much dollars.</p>
<p>Typically 2000 cycles at 100% DOD. That may translate to about 8 years with the way my software manages the house.</p>
Have you ever considered a dual axis for your pv system for more efficiency? Ive made that project before for school and you get about 15+ extra efficiency to the whole system
<p>Bravo. Thanks for sharing.</p>
Thanks!
Ty. Great Instructable. Directions are clear and show your hands on experience. I am looking forward to following your lead.
<p>Pretty much agree with you @leonearl50</p>
Thank you kindly.
Good.instructions. I didn't find anywhere, is there a way to switch from the solar system to electric operators without going through 0 power?
The automatic transfer switch in my diy panelboard does that for me. Bumpless transfer of power. No different to a desktop ups. My house power system was originally a huge ups which I added a solar charge controller plus my own custom home automation system.
<p>This is very informative and very useful in my country. Thank you very much to the author. More power to you Sir.</p>
Hey thanks!
<p>thank you ,very good info...</p>
Thanks!
Nice Instructable.<br>Your design is very neat :) <br>Its really helpful for all.
Thanks for the appreciation.
<p>good to have this simple steps.</p>
<p>I have been wanting solar power for a long time! Someone give me a $ number I will be needing! I want someone to come an install a solar power with grid tie in! I have a house that is 1400 square ft! </p>
I pay 110 a month in lease of 35 250 W panels. down was 500. took almost a year. I'm still tied to the grid as I use a lot of juice. all in all, I'm saving $300+ a month in electrical bills. but be careful, they will try to undersize your inverters or clip your power.
<p>Here is the best way to wire your battery bank in parallel for equal charging &amp; discharging rates.</p>
<p>Great Instructable. </p><p>I thought I was the only one who learned from his mistakes :) It's a great way to acquire knowledge (but can be expensive). I experienced both the charge controller &quot;POP&quot; when connecting the batteries after the panels, as well as the inverter &quot;CRACKLE&quot; after trying to power the AC input of a small trailer (neutral-to-ground bonding). MOSFET's have the most awesome smell when you release the &quot;magic smoke&quot;.</p>
<p>HAHAH! good one but experience like that is the sometimes the best teacher.</p>
<p>I can't tell if you have a fuse or a breaker between the batteries and the inverter. A fuse much cheaper replace than an inverter. My first off the grid system (in 1990) was a 45 watt panel. You can now get 300 watts for the same price!!</p>
<p>I can't tell if you have a fuse or a breaker between the batteries and the inverter. A fuse is much cheaper to replace than an inverter. </p><p>My first off the grid system (in 1990) was a 45 watt panel. You can now get 300 watts for the same price!! </p>
Hi. i am yousuf from Pakistan. here we are facing lot of electricity shortages cause 6 to 7 hours shut down daily basis, also high electricity cost. <br>As solution i wish to switch independent solar system (want to avoid supplier power) .<br>it is requested to you kindly email me solution. or connect via whatsup &lt;923417679929&gt;<br>i have under 1kw load. <br>2 ceiling fan 2 x 110w =220 w<br>energy saver 20w x 4 = 80 w<br>Refrigerator it about 300 to 350 watt i don't know initial torque. <br>Led tv about 90 w.<br>i like to know how much solar panels and batteries will need to full fill 24hrs requirement.<br>Local solar dealer suggest me 8x300w panels with 5KVA hybrid ups transformer type which is actually 2.5KW. and 4 batteries of 200Amp.<br>i don't know proper calculation, sunlight in out region is maximum its about 10hrs. <br>kindly advice as per above given load.<br>Also if i add AC of 1 or 1.5 ton tan what to do.<br>regards<br>M. Yousuf<br><br>
<p>As a rough figure a 100W panel will produce on average about 450Whrs/day</p><p>I would suggest you start with 1kw of panels 10x100w easy to move, 300W are over 50kg each , you can always increase the number latter, same with batteries, 100AHrs should be enough (12V) if not buy more latter. </p><p>Inverter is tricky, some sold as pure sine wave are not, can make TV buzz, and cause other trouble, fan is noisy and ants can get inside, find someone who has already bought one and does not make noise on TV.For size of inverter calculate what the max power you will use at one time, 2kw may be enough.</p>
One more thing hybrid system is on 24 volt. Leave AC calculation i just saw your solar AC post i will review it.
<p>You forgot to add that this may not be suitable for all houses because trees and other buildings can cause shading. Also it depends which direction your roof is facing as to the efficiency.</p>
<p>Where I live in northern USA, the sun sits on the horizon in the winter and is directly overhead in summer at lunchtime...what a variance...soo I have to compensate. I have my panels situated so I can wash them often and clear the snow for greater efficiency. They do not work well when dust and snow hinder them. It would also be nice to make a panel that is cooled by water as the high temps reduce the output. In other words, a low temp solar water pre-heater/solar panel. Be creative mates </p>
<p>Nice write up. But what do you use your power for ? Do you run your refrigerator on it?<br>a deep freeze? computers? well pump ? I have been living off grid for most of 30 years. My current system is 6kw solar panels 2 sw4024 inverters one morning star mppt and one xantrex mppt controller as well as 2 old style PWM controllers AND a 1000AH 24 volt battery bank. I find it works awesome and we have plenty of power. I am hoping that more people will take your advice and go solar. They need to remember nothing is free and your paying for your power up front rather than monthly.</p>
<p>I have a small solar system with very efficient 12 vdc led lights and 12 vdc water pump and 12 vdc to 120 vac xantrex inverter pure sine wave for a Rinnai wall heater and a xantrex modified sine wave for a refrigerator. I also have a 2000 watt xantrex modified sine wave inverter for running high powered motors (saws, planer, fans, etc). I am not a religious anti-grid fanatic...my electric bill runs about $25/month. I have multiple inexpensive panels situated close to panels and devices thus eliminating lots of wiring that can cause power inefficiencies. Lead acid batteries are safe and inexpensive and last a long time. Think practical and experiment if you have the time. BTW, most 12 volt led lights will run directly from a 12 volt battery and will have the ability to fit most lamps. Be creative...be practical...life is too short to be a Don Quixote. People have lived without electricity for an awful long time so stop whining and enjoy the ride.</p>
<p>&lsquo;For the most part I live off grid although I have the <br>ability to use utility power when I need it, especially for large intermittent <br>loads.&rsquo;</p><p>I wonder just how sustainable it is to only use utility <br>power for those occasional large intermittent loads. Eventually the power company will decide it <br>is not worth them maintaining their expensive poles and wires for such <br>infrequent use. My situation is a good <br>example of this dilemma, being at the end of a 2 kilometre utility owned line <br>and the only customer on that line.</p>

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Bio: I'm a Trini hobbyist who enjoys making new projects, doing repairs at home, exercise and improving existing systems. I relish publishing my projects on ... More »
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