This project is a simple and cheap way to integrate renewable energy into your home by turning your appliances into solar electric hybrids. Here is how it works. A solar panel (or any other renewable power source) charges a storage battery. A control circuit continuously monitors the battery's voltage. When the battery is fully charged, the circuit automatically turns on a power inverter and switches the appliance from running on grid power to running on the energy stored in the battery. Then when the battery's voltage drops too low, the circuit automatically switches the appliance back to grid power until the battery is recharged.

This design doesn't require any modification to the appliance or your home's electrical system. It can work with any power source that is capable of charging a 12V battery (examples: wind turbines, bike generators, etc.). But most importantly the system is scalable. This design is set up for outputs of up to 75 watts, but by swapping out parts for ones with higher power ratings you can power larger appliances or multiple smaller appliances at the same time. This lets you build a system that fits your energy needs and your budget.

I am still trying to make improvements to the design. So if you have any questions, problems or suggestions please leave a comment. I would really appreciate the feedback.

Step 1: System Overview

Here are the five basic parts of this system:

1. 12V Solar Panel (or other renewable power source)
2. 12V Rechargeable Battery
3. Control Circuit
4. 12V Power Inverter
5. Automatic Switching Circuit

When assembled, the solar panel, battery, and inverter plug into the control circuit. The automatic switching circuit plugs into the inverter and the wall outlet. Then the appliance plugs into the automatic switching circuit.

The solar panel, battery, and inverter may be purchased off-the-shelf from a variety of locations. The last two parts of the system (the control circuit and the automatic switching circuit) will need to be constructed. This is detailed in later steps.
<p>Would it be possible to run a pump and grow light for Aquaponics using a system like this and if so, what kind of power would I need to do this? (looking at doing this for our son's science fair project) Thank you. So far you are the only one I can find to has shown how to make single appliances solar run. </p>
You can run any kind of low power appliance with this system. However, if you are just powering a pump and grow light, then I would recommend using a 12 volt system instead of a 120 volt system. You lose a lot of efficiency in the inverter and they sell 12V pumps and LED lights. Also if you use a DC system you can use transistors to switch the power instead of relays which will also increase the efficiency. You could also have the option of powering the pump directly with the solar panel.<br /><br />If your son can send me the details of the project that he wants to do, I could give you some more specific answers. My email address is DIYHacksAndHowTos@gmail.com
<p>how much time will it take to charge a 18 Ah, 12 volt battery using a 4 W solar panel?</p>
Well a 12 volt 4W solar panel will produce about 3 amps. So it would take at least 6 hours to make 18 amp-hours. But it will typically take longer than that because the charging process is always a little slowed down. Also you probably won't have full direct sun all day.
Great instructable but I would like to add some tips/ considerations. <br><br>Since you are making an investment in just a little Solar, I would recommend considering some efficiencies to minimize energy waste. That being said, the inverter.... DO NOT GET at Harbor Freight, I think anywhere else, will be more efficient then Harbor Freight (My Solar Professor and I have had this discussion before). If there wasn't a budget constraints you would want to purchase a pure sine wave inverter but we have life to deal with and life is a money hungry individual!<br><br>Solar panels....go on eBay and purchase Solar CELLS, and get the tabbing and bus and solder them in series (tab back to front or positive to negative respectively), if in the future you want to add more Solar, it may be more cost effective to wire yourself (you would have to do the math though because there is the task of encasing). <br><br>Charge controllers.... the harbor freight version(if that was even mentioned in the instructable) is a waste of money! you're better off going on eBay and ordering them for $7-15 being shipped from Hong Kong. <br><br>Perhaps the key thing to remember in any Solar system big or small, is the 2nd law of thermodynamics &quot;Every energy has inefficiencies&quot; that being said, don't undersize your system. As energy is captured and transmitted through the various components it loses strength at each component so it best to account for those losses by capturing more at the beginning I.e. the Solar collector. A good starting point will be researching all the components within the system, efficiencies. once you determine that, then I would recommend stepping up the minimum input after the inefficiencies are accounted for in the minimum and I would recommend increasing your energy storage for cloudy days. I wouldn't recommend going with a 12V system as you are achieving nothing if you are using it at the same time you are gaining it so I would recommend considering a 17-18V system and a good rule of thumb is to have about a 50% discharge rate.<br><br>Just a few thoughts for consideration. In no way am I being the devil's advocate of this instructable as I believe it's very good, I'm just merely adding a few considerations in addition to what was being outlined!
<p>Thank you</p>
<p>I have a hot tub that runs a circulation pump continuously. I have a 500w wind turbine and 120w solar panel. matching batteries and charge controller.</p><p>Do you think the switching circuit would be effective as I'd love to run the tub on solar/wind energy for the majority of time.</p><p>cheers,</p><p>Ross</p>
It could be. But you wouldn't be able to use the solar panel and the turbine at the same time. Just make sure that all the components are rated high enough for the load that they will be subjected to.
<p>thanks for quick response. <br><br>Actually I have a hybrid charge controller that can connect both turbine and panel.</p><p><a href="http://www.ebay.co.uk/itm/30A-Auto-12V-24V-Wind-Turbine-Solar-Power-Hybrid-Controller-Regulator-Inventer-/231466251668?pt=LH_DefaultDomain_3&hash=item35e476b594" rel="nofollow">http://www.ebay.co.uk/itm/30A-Auto-12V-24V-Wind-Turbine-Solar-Power-Hybrid-Controller-Regulator-Inventer-/231466251668?pt=LH_DefaultDomain_3&amp;hash=item35e476b594</a></p>
<p>To be honest, I am not sure how my system would interact with that charger. When the charger is on it will momentarily change the voltage of the battery and might mess with the switching sensor. </p>
<p>well hcc connects to the battery and then battery connects to the inverter, so your switching circuit would connect to the inverter. </p><p>Think I'll give it a go, making sure relays, etc are uprated high enough to take the pumps max setting. Sould be fun :) It will either work or not, so we'll see.</p><p>cheers for your help</p>
<p>Good luck. Let me know how it goes.</p>
<p>This seems like a fun little project. I always like to try and find new ways to save on my utility bill. This just might do the trick. Do you know how well these panels work on these house-hold items?<br><br>http://www.solarrfp.com/index.php/solarbasics</p>
<p>It all depends on the wattage rating of the panel and the wattage rating of the appliance. Any panel can work on any appliance. But the bigger the solar panel is the better.</p>
<p>i brought solar panl size(mm)50 w X 100h ,and try it for charging my mobile but its shows high woltage and chargerr error ..any solution for it</p>
Cell phones typically need 5 volts to charge and most solar panels are going to output more than that. Use a 5V voltage regulator such as a LM7805<br>http://www.radioshack.com/-5v-fixed-voltage-regulator-7805/2761770.html#q=7805&amp;start=1<br>
<p>i brought solar panl size(mm)50 w X 100h ,and try it for charging my mobile but its shows high woltage and chargerr error ..any solution for it</p>
<p>i brought solar panl size(mm)50 w X 100h ,and try it for charging my mobile but its shows high woltage and chargerr error ..any solution for it</p>
<p>Great project and thank you for share it! I want to build this system as a UPS system. My question is that what happen when the grid <br>is down and the battery isn't fully sharged?!</p>
If the battery voltage is below the set voltage, it will connect the appliance to the AC outlet whether or not the AC outlet has power.
<p>Awesome instrucable Brother!</p>
<p>How can I integrate a wind turbine with this system ? </p>
Just use the wind turbine to charge the battery. You may need a charge controller that is specific to the wind turbine. But this system is designed to work between the battery and the appliance. It doesn't matter how the battery is charged.
<p>So any suggestions for size when i am trying to do this for a desktop computer?</p>
<p>I honestly don't recommend doing this for sensitive electronics like computers. The power fluctuates when it switches modes. That doesn't matter for a lamp but it could cause problems for a computer.</p>
<p>I don't see a problem with using it on computers. Most power supplies in computers are switch mode supplies that are used precisely for conditions such as ever changing voltages and unreliable power sources. One concern I do have is that a modified or full sine wave inverter should be used. The standard square wave can do some damage to regulator components designed for AC full sign wave frequency use.</p>
<p>wicked nice</p>
<p>wicked nice</p>
<p>hey ive done this project but i do not get stable output from the inverter. The relay in the switching circuit just goes on and off all the time. The battery gives constant 12V but the inverter dosent. What should I do?</p>
<p>When the inverter turns on and starts power from the batter, the battery's voltage will drop. And then the inverter is disconnected, the voltage will go up a little. So if your two voltage points that are set by the resistors are too close together, it may go back and forth very rapidly. So first, try making a bigger difference between the two settings. The high voltage should be somewhere around 14 volts. The low point should be about 11.5. This effect also is more dramatic the smaller your battery is. So a larger battery may help.</p>
<p>how can we test if this circuit is working or not on the bread board?</p>
The easiest way to do it is to make different battery packs with different voltages. 8 AAs make 12 volts. 10 AAs make 15 volts. This lets you try out different voltages to test when the system switches on and off.
<p>Thank you for the help but again i am having some trouble. Now i am trying to set the potentiometer but if i set the value to 8600 ohms between wiper and positive terminal, i get 440 ohms automatically between negative and wiper. How do i get 1400 ohms on the negative side?</p>
The exact values are not really important. What really matters is the ratios. If you adjust it so that they ratios are the same as the ones listed it should work. Or you could simplify things and just used fixed value resistors with the appropriate ratios. You won't find exact values so just get close.
<p>Sorry to ask such a silly question but what is &quot;8600&acirc;&quot; and the other values in that potentiometer section u described. I mean is that ohms or something?</p><p>And how do we set two values in one potentiometer, like between positive rail and wiper and negative rail and wiper?</p><p>Plz do answer. I am having a hard time getting this :P</p>
Yes. That was supposed to be ohms. The text editor messed up the symbol. Use a multimeter to measure the resistance between the pins and adjust them until they match up with these values.
<p>I would like to know what type of house hold appliances can i use in the house? We will be moving to a house that solely working with solar panels? Will i be able to do washing with a top loader,or even do ironing? Please help this is all new things to me. I was use to electricity.</p>
The system that I describe in this project isn't really suitable for powering a whole house. But with any solar system, you need to balance the power ratings of the appliances to the power rating of the inverter, the battery and the solar panel.
<p>This is awesome. I an going to try this form my laptop!</p>
<p>I think this is a brilliant idea, I woud just like to know if its possible to &quot;over charge&quot; a battery? I'm just trying to think of what could go wrong. Because if this goes as well as I'm hoping it will, I plan to make this into a small house system where all of my electronics run solely on solar power.</p>
If you set the charge controller circuit properly, then it shouldn't over charge the battery. The main advantage of this system is that it can work on a small scale, if you intent to power your whole house, then it would be more efficient to use a professional system that is designed to power a whole house.
<p>This is going to be my first follow thru instruct able. NO experience doing circuit boards but this project is PERFECT for my needs. I am have a problem with the control circuit list.The optional items what are they needed for and what happens if not used? How about a picture of the backside of the board? So I can see the traces please.</p>
The optional parts are for a charge controller circuit that prevents the battery from being over charged. But this isn't necessary if you regularly turn on the appliance. Sorry, I don't have the original board anymore. I gave it to a friend. So I can't get any new pictures of it. You will just have to follow the circuit diagram.
<p>This is BRILLIANT! Any guidence on the improvements you suggest?</p><p>THANK YOU!</p>
VERY NICELY done! I do have a comment / question: We decided to use the complete kit because it came with &quot;compatible&quot; lights that just plugged into one of the adapters on the inverter that came in the kit. <br> <br>We put one on the back porch and the front porch, and bought a cute, very small Kitchen cabinet. We painted the cabinets to match the house and BOOM, we are off and running! <br> <br>The cabinet was PERFECT because it had two shelves - one for the inverter, and one for the battery. We were using the existing lights - two came with each kit. We hung one set on the back porch, and one on the front porch. So, the battery started charging, and within hours, had lights on the front and back porch! <br> <br>Our first set of lights blew out most likely about two months later. We went BACK through the instructions, and could find nothing. We tested the solar panel by charging another small battery. It was charging fine. We found something to plug in one of the other ports on the inverter, no issue. So, I went to the store to find bulbs to fit in there; there is nothing else to fit in there that is the correct voltage. ANYWHERE. <br> <br>So, called HF - and they said, yes, we can send you new replacement bulbs at no charge AND it would take six weeks to get them. What was I going to say but ok. So, new bulbs come, we plug them in - they last two weeks and *poof* they die again. I called again; they said it would take four months this time. They had stopped using those bulbs and that inverter in the kit. <br> <br>At one point shortly after this, the inverter did die. So we called for a new inverter. Got one after 3.5 months (of course, still waiting on the light bulbs). We hooked up the new inverter. Tested the other parts of it, it seemed to be fine. New bulbs finally came - they worked for less than a day. We gave up on getting more bulbs. <br> <br>The front porch bulbs lasted nearly a year. Then they died. We never tried to get them replaced. In the meantime, we moved the back panel to our chicken coop, and use a small water pump for emptying out the excess water barrel, if needed, or reuse the water in the yard. <br> <br>We still use the front porch panel as a trickle charge battery charger for the horse trailer and scooter batteries. But we are not using the inverter. <br> <br>Is this why you are not buying the kits? Have you ever had similar problems with your inverters? Thanks!!! <br> <br>
u know that harbor freight buys from a Chinese company all u have to do is look up alibaba.com to find yr type of light bulb. while yr there u might find other things as well
My experience says that an inverter needs space for cooling (air), never inside a cabinet, unless there are 2 fans (in an out blow, computer type). Above this, if the label says a wattage, never connect more than the 80% of this number of watts. <br>Following this rules my 80W inverter works for 4 years... and counting.

About This Instructable


537 favorites


Bio: My name is Jason Poel Smith I am a Community Manager here at Instructables. In my free time, I am an Inventor, Maker, Hacker, Tinker ... More »
More by DIY Hacks and How Tos: Bubble Bath That Never Runs Out Of Bubbles Magic Wand Flashlight Controlling Halloween Effects with DIY Infrared Remote Controls
Add instructable to: