Introduction: Solar Powered Refrigerator!
Here is an after the fact implementation of how I power my refrigerator from the sun. This off grid system has been working great since may 2013. It is truly reassuring to know my groceries are safely stored regardless of utility power.
I have fulfilled the electrical code requirements (NFPA 70, TTS-171 Part 1) and power utility mandates for my area. If you have to perform the same on your home, all relevant certifications and approvals are needed.
Remember for solar power systems, bigger is always better. Never go borderline else your system will not be reliable for off grid applications.
Grid tie is NOT ALLOWED in my country. Also don't ever assume you will have utility power during a nationwide disaster (bad weather, riots, energy rationing, terrorism etc).
Here is a detailed write up on how I solar powered my entire home: https://www.instructables.com/id/Solar-Powering-My-...
Step 1: The Refrigerator.
Ideally an inverter refrigerator is the best bet but my old refrigerator needs 300watts when on. Basically any fridge will do but the more energy efficient means a smaller solar setup is needed.
There are the rare dc powered refrigerators that are actually more efficient than the inverter types. However should this unit fail on me, there are none sold in my country. I want to be able to go to a store and buy a replacement or repair my unit if possible in the event of failure.
Step 2: The Solar Panels.
I use eight 225watt monocrystalline panels to power my home and by extension, the refrigerator. They are wired 4 in series and 2 strings in parallel. I harvest up to 8kwh per day with these panels.
Mounting the panels on the roof can be via manufacturer mounting solutions or you can make your own with rigid pvc. I actually did a hybrid approach.
Here is how I perform cleaning of my panels" https://www.instructables.com/id/Maintenance-cleani...
Step 3: The Charge Controller.
I have an outback fm80 charge controller to route energy from the panels to the batteries. Mppt chargers are more efficient and economical for large solar systems.
Step 4: The Batteries.
I use 16 lifepo4 batteries at 25.6v. They are all wired in parallel with an energy meter per pair of batteries. Each battery has a switch for isolation. For the work I did on my battery bank, please read: https://www.instructables.com/id/Lifepo4-solar-stor...
My refrigerator uses 1.2kwh per 24hour period. My battery bank has 4kwh capacity.
My country's climate is hot. Lead acid batteries, although cheaper, have failed in less than 10months of use. If your maximum temperature is below 25C then you should be able to use lead acids. I have long abandoned lead acid technology in my home and car. Lifepo4 is safe, powerful and environmentally friendly.
Step 5: DC Distribution.
With the appropriate sized conductors, I have circuit breakers to protect all my components and also provide easy isolation for maintenance.
The attached chart shows the conductors sizes for DC power.
Step 6: The Inverter.
To get 120vac from 25.6vdc I have a 1000watt power bright pure sine wave inverter. Always use pure sine wave especially for motor applications.
Step 7: The AC Distribution.
I made a panelboard with din circuit breakers to get power to my house loads. I have a breaker dedicated to the kitchen area. Since my refrigerator uses 2.5Amp the circuit breaker for it is 6Amp single Pole. Here is how I built the panelboard: https://www.instructables.com/id/DIY-Circuit-breake...
Also in the panelboard I have an automatic transfer switch (ATS) shown at the bottom of the pic. This switch is controlled by my home automation system which will switch to utility power if the batteries get depleted.
My local power utility is actually my backup power source.
The control system for my home is detailed here: https://www.instructables.com/id/Creating-a-home-au...
Step 8: Powering the Refrigerator.
The outlet for the fridge is protected with a motor protector. This is only needed should I switch to utility supply. The inverter gives clean power.
So that is how I powered my refrigerator via the sun!
First Prize in the
Renewable Energy Contest
Participated in the
Beyond the Comfort Zone Contest
Question 5 years ago on Introduction
I am looking for someone who has successfully developed a solar powered cooler that can be used for keeping medicine or even infant formula fresh in areas of the world that have no access to refrigeration. Can you adapt your instructions to help me accomplish this?
Answer 1 year ago
Coolatron makes 12v coolers/fridges that work fairly well in remote areas. I believe they keep around 17degres C below the surrounding temperatures when operating normally.
Answer 5 years ago
Yes definitely. I just emailed you. We must talk in real-time.
3 years ago
Can we get an update on how it's working in 2020
Reply 3 years ago
I would be interesting in this as well.
4 years ago on Step 5
I wanna do mine
Question 4 years ago
Thank you very much for sharing all this information. Being in an off-grid region, I have already been using a 12 volt set-up , just for lights in the house. Works fine.
Now, i try to budget for the fridge. I'm a little confused with your description...
You talk about a 300w fridge. And after, you say : " My refrigerator uses 1.2kwh per 24hour period." , is it possible ??? I understand do not work 24hs continuously. But 1200 wh / 24hs = 50w . Does this means that it use only 50w / 300w = 16% of the time ???
Or is it that my knowledge is very bad, and so , please help me understand .
By the way , by any chance, do you know the fridge capacity ??? ( in gallons , liters ???)
Answer 4 years ago
Just use a watt-hour meter.
6 years ago
Very nice. Answers a lot of the questions that I have about a day-to-day system. I'm not comfortable though with building my own transfer switch. I love that it is automatic and is something that has dis-satisfied me with local solar vendors. Is there a commercial ATS that you could recommend? Are the requirements different if you want to default to solar and use mains as the backup?
I couldn't tell from scanning your instructable what the profile is for failover.
Reply 6 years ago
Check your electrical suppliers for ATS. My default source is solar and the fail back is utility.
Reply 5 years ago
But how about having scaled down versions each powering different gadgets. A set-up for the TVs, another set up for the fridge and water dispenser, a pure 12 volt set up for the lights and another smaller set up for charging USB devices. I envisage that may be less fund guzzling.
Reply 4 years ago
It is my future trying, also. I have been running lights on 12 volt set for more than 10 years, with good results. My next step should be the fridge. I believe that it requires 24 volts panels, and a serious battery bank.
On a very far future, all the house ( A/A ; kitchen appliances etc ... ) would be added on a different set-up.
5 years ago
hi, how much did it cost you to do this system? I want to do it for a small shed, that has a chest freezer, Tv and lights.
7 years ago
is 1000 watts enough?
Reply 7 years ago
Reply 5 years ago
For the whole house or the fridge alone?
5 years ago
Pheew! Sadly, LifePO4 cells are a luxury in my area. I have thought of Li-ion as an alternative because I should be able to salvage for cells in used laptop batteries, but then I'll also be wary. I've mistakenly shorted a Li-ion cell during a tweak and I wouldn't imagine having hundreds of it hanging on a wall in my home. AGM has less lifespan but that's what's affordable, easily accessible and readily available. I'll have to check your other 'ible on the entire solar set up. Good job.
6 years ago
Super Insulation can make this simpler in my opinion. I am in Africa a lot, about 3-4 months per year. By the way ,about 1/5 the planet lives off the grid. And, they have freezers, seldom have fridges. But I am going to do an experiment soon for what I see, or call "super insulation." I am going to measure electrical use for 30 days as they use normal. The add about 2 foot thick insulation around the sides. They are the same as Americans, they do not want things to look silly. Then make a night blanket about a food thick. This will cost about 15 USD because they use some form of grass to make beds, not normal, but normal for the off grid 1.5 billion. The off-grid are just in time eating.... Here is a too expensive, but great idea, using thermal mass, or the cooling of the earth method, very old tech, just forgotten, nothing new. There has been in the ground cellars for cooling since the beginning of time. Thanks, Andy Lee Graham of HoboTraveler.com - I am in Tours France, and will go to Togo on August 15, 2016 again. http://mikeshouts.com/groundfridge-underground-ref...
Reply 6 years ago
6 years ago
one perspective I would like to share is that the cost/payback rate of solar should not necessarily be looked at as a benefit, because it largely seems to be a detractor. Solar is expensive, can be very expensive, but the cost of not going solar is eventual and increasingly fast-paced destruction of the environment caused by an increasing reliance on dirty fuels and energy sources. You can finance a $17,000 (us$) car for about $250 a month, which is not cheap, but people do it all the time, and in fact people finance much more pricey vehicles all the time. You can buy you solar set up in chunks. Save for a few months and buy the distribution components, then later the panels, etc. I know this is not the most convenient, but it makes it feasible. You can also down size the system and make it modular, so the it can be expanded upon later; buy the components that have to be for a larger system, then only buy a couple batteries, maybe one solar panel, then later add other panels, batteries, and so on. To give you an example of the effectiveness of this method, I make less than $20,000 annually, I pay about $1,500 in monthly expenses, which includes car cost mentioned earlier, and over the course of the last six months I have saved approximate $700 to build a homemade CNC mill. I opened a savings account at a new bank, that has no transaction capabilities. $35 from every paycheck, from each of my 2 jobs, gets automatically deposited into the account, and unless I go to the bank to withdraw it, I don't have access to it. Any payment from any side jobs I do to make extra cash gets deposited here as well. So, every few months, I make a larger purchase towards my CNC mill. The same principle can be applied to the purchase of a solar power solution. When looked at like this it becomes a simple matter of timing and patience. I hope this helps.