Picture of How to Make Any Home Appliance Into a Solar Electric Hybrid

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.
Great instructable but I would like to add some tips/ considerations.

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!

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).

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.

Perhaps the key thing to remember in any Solar system big or small, is the 2nd law of thermodynamics "Every energy has inefficiencies" 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.

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!
cgrishnackh3 months ago

Thank you

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.

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.



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.

thanks for quick response.

Actually I have a hybrid charge controller that can connect both turbine and panel.


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.

well hcc connects to the battery and then battery connects to the inverter, so your switching circuit would connect to the inverter.

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.

cheers for your help

Good luck. Let me know how it goes.

RoseH15 months ago

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?


DIY Hacks and How Tos (author)  RoseH15 months ago

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.

KAILASHD6 months ago

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

DIY Hacks and How Tos (author)  KAILASHD6 months ago
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
KAILASHD6 months ago

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

KAILASHD6 months ago

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

hassang27 months ago

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
is down and the battery isn't fully sharged?!

DIY Hacks and How Tos (author)  hassang27 months ago
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.
AnuR47 months ago
jcastaneda58 months ago

Awesome instrucable Brother!

SaraF29 months ago

How can I integrate a wind turbine with this system ?

DIY Hacks and How Tos (author)  SaraF29 months ago
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.
neil.freidberg11 months ago

So any suggestions for size when i am trying to do this for a desktop computer?

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.

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.

SparkySolar10 months ago

wicked nice

SparkySolar10 months ago

wicked nice

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?

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.

how can we test if this circuit is working or not on the bread board?

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.

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?

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.

Sorry to ask such a silly question but what is "8600â" and the other values in that potentiometer section u described. I mean is that ohms or something?

And how do we set two values in one potentiometer, like between positive rail and wiper and negative rail and wiper?

Plz do answer. I am having a hard time getting this :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.
yolande131 year ago

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.

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.

This is awesome. I an going to try this form my laptop!

I think this is a brilliant idea, I woud just like to know if its possible to "over charge" 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.

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.

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.

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.
boardsmm1 year ago

This is BRILLIANT! Any guidence on the improvements you suggest?


tygger2813 years ago
VERY NICELY done! I do have a comment / question: We decided to use the complete kit because it came with "compatible" lights that just plugged into one of the adapters on the inverter that came in the kit.

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!

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!

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.

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.

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.

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.

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.

Is this why you are not buying the kits? Have you ever had similar problems with your inverters? Thanks!!!

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.
Following this rules my 80W inverter works for 4 years... and counting.
luvasu luvasu3 years ago
I've different solar panels (7) up to 105W, feeding several 7Ah and 12Ah batteries, up to 186Ah, using a 10 Amp control charger (near to the limit 9.7 Amps)
On use (nightime) 4 inverters (120+120+80+80 W), sometimes at the same time, but not often.
Only mi first 7Ah battery has been replaced after 8 years duty, because not recharging above 4 VDC. (Similar to the one showed in a picture above).
My battery replacement is mandatory after 10 years duty (that one was a surprise).
None of my components were part of a commercial kits. I just assembled it from off the shelf parts. I haven't been running my system very long but I haven't had much problems with my lamp setup.
Oh, you are showing the kit in the final photo. Please let me know if you had similar issues.
Any idea if this would work by converting a propane water heater to solar electric hybrid?
It isn't really a good idea to use a solar panel for heating. It would be far more efficient to use a solar collector like these: http://www.instructables.com/tag/type-id/?sort=none&q=solar+hot+water
if any possible to connect the solar system into normal home inverter. if it is possible means how it is?
youcantoo2 years ago
What is the switch time for the relay?
The switching time just depends on the relay that you use. I couldn't tell you the exact timing for the relays that I used but in many cases it can cause a noticeable fluctuation in the output. So this kind of design is not suitable for for sensitive electronics. I just used it to power a lamp.
youcantoo2 years ago
Don't use car batteries for your project. They were never designed to handle the requirements of a solar or wind powered system. Yes they maybe cheaper to buy. The car battery was designed to handle the initial load of starting your car and then be charged back up. A solar/wind system does not do this. You will find a car battery will last a short period of time under these circumstances. What was cheap to buy the first time then becomes a expensive replacement cost. Consider paying more up front for a deep cycle battery. You can even buy good used deep cycle batteries like forklift or golf cart batteries. They will well out last a car battery and yu will be money ahead.
useful13 years ago
This seems like a setup I can use. Thank you for posting it with clear instructions.

If I understand it correctly, it seems like an always "on" setup, meaning that when the batteries are topped off, you'll use battery power. Once the battery reaches "low", it switches to the power on the mains from the electrical company.

The relay switches is what controls the path the electricity takes.

Couldn't the problem that "involves regularly cutting power and switching to a second power source that may be out of phase", be solved by adding a UPS backup after the automatic switching circuit and before the light bulb? (as shown in your diagram)

- U
Really if you are using a UPS there would be no need to have the switching circuit as the ups has it already has that sort of circuit built into it.
DIY Hacks and How Tos (author)  useful13 years ago
Actually a UPS was my original concept for this project. In my original design, I took a UPS, and disabled the internal charging function by adding a diode after the battery. I set up the battery to be charged by a solar panel. Then when the battery was charged the control circuit would just cut off the grid power from the UPS and it would smoothly switch to the battery power. I decided to go with my current design because I was able to make it a little cheaper.
useful12 years ago
Just wanted to say, I built this system 2 months later and seems to be working great. The only part that I found frustrating was setting the value of the variable resistor on pin 2, to adjust when the control circuit switches off the relay going to the inverter.

Every time, I kept trying to test the value of pin 2 while the inverter was on, the relay would click and I could not get an accurate reading of the voltage while the system was under load. It was pretty frustrating. The only way to set the low end, was to use up the battery power until it reaches somewhere near 11V and turn the dial down until it clicked off.

But even then, I still don't know what the voltage reading is coming into pin 2.

DIY Hacks and How Tos (author)  useful12 years ago
Thanks. I'm glad to hear that someone else was able to get it to work.
orenyny2 years ago
Great project thank you! My question is if it is possible to do a hybrid that will keep the battery charged (from those 12V sources you mentioned), but if they run out (no wind and no sun) it will top of the battery from the grid.
In addition, it will be tied to the grid so if the battery is full and the solar pannel is generating electricity, it will feed into the grid, and finally, when the grid is down, use the battery (emergency).

DIY Hacks and How Tos (author)  orenyny2 years ago
There are a couple of devices that are similar to your description. I grid-tie inverter would let you go directly from the solar panel to the grid without needing a battery. On the other hand, an Uninteruptible power supply would let you keep the battery charged with the grid and then use it if the grid goes out.
TakashiMoto2 years ago
I'm not terribly good with schematics, could you post a pic of the underside of the control circuit board please?
I'm also having a hard time with figuring out the orientation of the relay on the breadboard, thanks so much!
I will try to get another picture added. But in the mean time, you can get a good idea from the breadboard layout on step 8. All circuit parts were purchased from RadioShack (see step 5). So you can just align them the same way that they are in the picture. I hope this helps.
Is this the same relay? pinout and all?
I sourced one a bit different but i have to move things around.
Those panels look like thin film silicon panels, which tend to be the cheapest type of solar panel, but only run about 7 to 8 percent efficient. Currently the most efficient panels available to consumers (at 20 percent efficient) is the Sunpower E20 at 327 watts, at about 17 square feet of panel (including the gaps between cells and the frame. These panels run between $700 and $800 per panel (by the way, it is a mono crystalline silicon panel, which tend to by more expensive and more efficient).

Just thought I would add a little useful info

Ultra Computers
The question is: are those 20%-efficient cheaper than 3x the price of the 7%-efficient ones?
If it's more than 3 x as expensive, then might as well get three cheaper ones (if space allows)..
it will be cheaper and gives the same output.. or, in other words, it's more cost-efficient...

cheers.. :)
chuckyd3 years ago
Instead of using a converter, it would seem more efficient to use appliances that work off the same voltage as the battery/collector. There are several 12V appliances made for campers and motor homes.
While 12V appliances exist for campers and motor homes, the reduced voltage means they usually have less efficiency and greatly increased cost. A 12V DC household refrigerator will run you several hundred dollars and have insulation so thick the interior will be considerably smaller than an AC refrigerator of the same general size. There are much cheaper 12V DC refrigerators, but they tend to be of the "improved ice chest" variety rather than an actual refrigerator.

An inverter allows you to use a wide range of Energy-Star appliances which are much cheaper than DC appliances, and get more use, and storage, out of your appliances.
Big deal. Just work on putting as much effort into DC appliances as has been put in AC appliances. If power is run through an inverter for an "efficient" appliance, is it still considered effecient from the other side of the inverter?

With the cost of inverters and the power lost in the process, it seems that eliminating the inverter would be more efficient.
ereus3 years ago
It should be borne in mind that AGM batteries are not suitable for inhabited environments due to any release of gas.
webgiant ereus3 years ago
So get a sealed AGM battery. Problem solved.
gargoyle1693 years ago
Not trying to pee in anyones Wheaties but the system displayed herein is a Harbor Freight special. Not really in the spirit of Instructables.com. The entire package comes in a NON Recycled cardboard box with instructions!!!

"We have a "be nice" comment policy. Please be positive and constructive with your comments or risk being banned from our site. "

So I'll be nice and ask a constructive question, What is the cost per watt of this system, and what is the power density of the amorphous array? Then there is the matter of the 85 dollar AGM pile that Da Freight is peddling with this thing,, what is the reccomended c/20 rate versus dollar/watt ratio?

These are the real economics of DIY alternative energy.
While the solar panel and the inverter that I used where purchsed from Harbor Frieght, no part of this project came from a kit. I think the confusion came from the picture in the final step. I just wanted to use a picture of a solar panel and system that was larger than my current setup to illustrate the idea of future delopments and improvements. But unfortunately the picture that I selected was that of a solar kit from Harbor Frieght. This was a poor choice on my part and I am sorry for the confusion. I have changed the picture to fix this.

In regards to your question, I used a 5 watt panel, 75 watt inverter and a 7 Ahr battery and was able to build the system for about $150 using parts from RadioShack. If you order the parts online you should be able build this setup for under $100. As my design lets you select the components that fit your needs, the performance is entirely dependent on the panel battery and inverter that you select.
A very nice, classy response to a not-so-nice comment. That's not easy to do. A well made instructable, and a well-moderated comment section. Good job!
dmarsh553 years ago
CHALLENGE: apply this technology to a more heavy duty appliance. I have a 29 cf Kenmore Energy Star refrigerator/freezer, the label says 115V. We get semi-frequent power outages here, and of course our utility company is going up on our rates. Show us how to rig a set-up for this.
DIY Hacks and How Tos (author)  dmarsh553 years ago
There is no reason that this kind of system couldn't power a refrigerator. It is just a matter of making sure that all the components are rated high enough to handle the needed load. But for that kind of application you would have better luck getting an Uninteruptable power supply rated for your refrigerator's power, and many increasing the battery size.
Great idea! Another great challenge would be to build a hybrid system that powers the large AIR CONDITIONING unit for the house I live in!

In Kansas we've been having temperatures of 100 to 105 degrees each day this summer and our utilities bill has gone through the roof. Even if this potential rig cost $400-$500 I would still end up saving money over the course of the summer.
Nove-Noga3 years ago
I spent four years working in a Las Vegas lighting shop. It was our job to help keep this the brightest city on the planet. Our rule of thumb for low voltage and transformer applications: Never exceed 80% of the rated output.
Already my apologies for the English, but I have a question, I'm using a 300W Inverter (not pure sine) then when I start it (power on), right from the beginning, it's seeking more than 5A at the starting pike.

So, then made ​​in the design, does not allow a current output over 2A, at the output of the regulator (It's the 1 design, before the all relay switch, that commute the DC and the AC).

Could anyone help me get around this?

Thank you and best regards to all!
You may need a different regulator or a different inverter. Sorry that I can't be more help. Good luck.
Already my apologies for the English, but I have a question, I'm using a 300W Inverter (not pure sine) then when I start it (power on), right from the beginning, it's seeking more than 5A at the starting pike.

So, then made ​​in the design, does not allow a current output over 2A, at the output of the regulator (It's the 1 design, before the all relay switch, that commute the DC and the AC).

Could anyone help me get around this?

Thank you and best regards to all!
jolshefsky3 years ago
I like that it's all DIY. I've been a go-to person for answering questions about solar setups for camping for a little while and I recommend people get a charge controller with a load switch. That accomplishes most of what you have in your control circuits (but good for you for DIY and explaining how it all works!)

My only minor quibble is about the power inverter. All the cheap inverters are "modified sine" which is a +180V/0V/-180V/0V wave that delivers the same amount of electrical power. It works fine for CFL's and most switching power supplies that just make the line voltage DC then work from there, or for resistive loads like incandescent bulbs and heaters (or, even direct line-powered LED light strings). But for transformers (e.g. plug-in brick transformers, and many many appliances) and AC induction motors (e.g. fans, pumps), the modified sine is completely inadequate and leads to lots of waste heat and potential damage to the appliance.

I have been recommending that people instead spend the extra money and get a "pure sine" inverter (I have a 300W Samlex brand that works very well). They are a lot more expensive per-watt, but especially for a small starter system, you really can't realistically use more than 75 watts or so for any appreciable time (that 7AH battery would be dead in in an hour at 75 watts, and realistically should only be run for about 30 minutes or so; a 500W coffee maker would kill it before one pot is done). The pure sine inverter will work fine with all appliances including things that people are likely to use like chargers for phones, iPods, or batteries, laptop power supplies, monitors, TV's, and audio amplifiers.
mikeasaurus3 years ago
Great build, this is something I want to try sometime.
kd1s3 years ago
Nice job on an ATX! Vendors like APC will charge a pretty penny for these.
brjasper3 years ago
Neat little project. I'd posted before I read everything through, but I'd still suggest a small grid-tie inverter that would feed power back into the mains for the whole house. You can get some small ones fairly cheap as inverters go.
DIY Hacks and How Tos (author)  brjasper3 years ago
You're right. A grid tie inverter would be better both in terms of efficiency and simplicity of the system. My goal was to design a system that was cheap and easy to incorporate into a home. I was able to build my prototype for under $200 using parts from RadioShack. If you order the parts online you can make it for under $100. This is a fair amount cheaper that most grid tie inverters. But if you can afford it, and local regulations allow it, a grid tie inverter is the way to go.
triften3 years ago
Neat! We are generally low idle power consumption (during the day), but we do have a reptile with some heat/UV lamps. This would be neat to set up.

My only suggestion is that you use a full 15A or 20A relay depending on the circuit you are plugging in to. You want the breaker to pop before the relay melts/catches fire/otherwise fails.