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If the conditions were ideal, would it be possible for a 100W solar panel to operate a refrigerator? Modern refrigerators are energy efficient so some believe that it might be feasible. But is it, and would it be a good idea in the first place? In this guide we will look at the numbrs and find out.
A 100 watt solar panel produces an average of 500 watts a day, which is not enough because a refrigerator needs 1200-1500 watts to start. But with a few 100 watt solar panels and a 200ah battery, you can run the refrigerator for 24 hours.
How Much Solar Power Does a Refrigerator Need?
Refrigerators come in all shapes and sizes. Portable models need as little as 60 watts and can run off DC power. You can connect these directly with the Renogy 100W 12V Monocrystalline Solar Panel and run it for as long as there is enough sunlight available. As long as the panel can generate at least 60 watts an hour the fridge will run.
For larger refrigerators we need to look at its amp draw. To calculate its power usage:
volts x amps = watts
A refrigerator that draws 5 amps an hour running off 110V is 550 watts.
110V x 5A = 550W
This does not mean the refrigerator consumes 550 watts an hour. To get a more exact measurement we need to know its duty cycle and surge watts.
The refrigerator duty cycle determines how long the fridge runs. If its duty cycle is 0.5, that mean the refrigerator runs only 50% of the time. If the figure is 0.6 it runs 60% of the time and so on.
A 0.5 duty cycle refrigerator that consumes 5 amps will only pull them half the time it runs. So it draws 275 watts an hour instead of 550.
Does this mean a 100 watt solar panel will work? While the refrigerator may use 275 watts, its compressor needs 2 to 3 times that to start. So a the appliance draws 550 watts, the surge watt demand will be 1650 watts.
The more energy efficient the refrigerator, the more energy you can save. No matter what appliance you run on solar power make sure it is Energy Star compliant. The difference it makes in power consumption is significant.
How Many 100W Solar Panels Do I Need to Run a Refrigerator?
So a 100 watt solar panel is not enough to run a typical kitchen refrigerator. For a 12V portable camping fridge yes, but how many panels would you need to run a standard home refrigerator for 24 hours?
Refrigerator kwh per day / solar panel output per day = number of solar panels needed
Imagine you have a refrigerator that consumes 1.13kwh a day.
1.13 kwh is 1130 watts. Assuming there are 5 hours of sunlight and our 100 watt solar panel produces 100 watts an hour, we get:
1130 / 100 = 11.3
We need 11.3 or rounded off, 12 x 100 watt solar panels to generate enough power to run the refrigerator. But even if you could install a dozen panels it will not work. Why?
Solar panels cannot run a refrigerator for 24 hours because they do not produce energy at night. What you need to do is charge a battery with the solar panels and run the fridge off the battery.
Do i Need Batteries to Run a Refrigerator?
Yes you need a battery – or several of them- to power a refrigerator. How many depends on the power consumption of your refrigerator and how long you need to run it.
A 200ah 12V lithium battery can run a refrigerator for 24 hours. At the end of 24 hours the battery will be fully discharged. You can recharge it with solar panels, a generator or any other power source. You will need a bigger battery bank to keep the refrigerator going for a few days.
here is scenario: in case of power outage you want to be able to keep the refrigerator going for 3 days. How many batteries and solar panels will you need?
Assume the fridge has a 0.5 duty cycle and the motor needs 2 times the running watts. The fridge consumes 500 watts an hour so the surge capacity is 1500 watts.
Watts / volts = amps
1650 12V = 125
You need a 12V 125ah battery to run the fridge for 24 hours. So for three days that would be 375ah.
A 125ah battery is the minimum requirement,, but you should always have reserve power in case of a power surge. You can get a 200ah 12V lithium battery for the bet results. We recommend the Ampere Time LiFePO4 12V as t runs heavy duty appliances without problems.
With three 300ah lithium batteries you can run the refrigerator for 3 days straight. You do not have to worry about the rain or lack of power during night time.
How Many Solar Panels Do I Need to Charge the Batteries?
Suppose you have used up one 200ah battery and running the fridge on the second. You want to recharge the first battery so you have two in reserve in case you need to keep the refrigerator going for more than 3 days. How many will you need?
Amps x volts = watts
200 x 12 = 2400 watts
You need 2400 watts of solar power to charge a 200ah battery. With five 100 watt solar panels you can charge the battery in 5 hours. This presumes there are 5 hours of sunshine and the panels produce 100 watts an hour each.
To compensate for weather fluctuations you should get at least six 100 watt solar panels . Actually the more panels you can buy, the faster you can charge the battery.
We have been using lithium battery in our examples because of its efficiency. But i you want to use AGM or gel you can do so. But they do have a 50% depth discharge, so you have to either double the capacity to 400ah or reduce the refrigerator running time. Check this out for a detailed comparison of these batteries.
12V Camping Fridge Solar Panel Buying Guide
There are several factors that you have to go over before buying a solar panel. The type of solar panel you buy depends on what type of camping fridge you have.
Usage. How will you use the refrigerator? Will it be just a fridge or will it double up as a freezer? If you are only going to store cans and snacks there, a portable fridge will do. For other types of foods you will need a freezer. The bigger the appliance, the more solar power is required.
Are you planning for a prolonged power outage/ Or are you content to be able to run the fridge for just a day? Decide now so you can determine how many solar panels and batteries you will need.
Warranty. Solar panels have good warranties, but do check the coverage. Camping out may lead to a few bumps here and there and you want to make sure there is warranty coverage in case of damage.
Power source. Do you have access to electric power or a generator? Or is your only source a battery inverter or solar panel? Access to another power source provides you with more flexibility. if you have another power source to connect the fridge, a few solar panels may be enough to top off the battery.
Duration. How long do you plan to use the fridge? 1 day? 3 days? This is directly related to the system you will need. The longer you intend to use the refrigerator, the more likely a few 100 watt solar panels will be insufficient. Having a good sized battery or even a portable solar generator will come in handy here.
The rule of thumb is the higher the refrigerator amp draw, the more power it requires. You can get an idea from the refrigerator specs, but it is best to overestimate the amount you need.
There are a lot of factors that come into play, but the bottom line is this. It is possible to use a 100W solar panel to run a refrigerator, but it is not practical due to how solar power works. It is more practical to use the solar panel to charge a battery and let the battery operate your fridge.