What Size Solar Panel to Charge 100ah Battery

Calculating the right size solar panel is not that difficult if you know the solar size calculating method. But It’s not also easy for a person who just planning to buy solar panels for the first time. Basically, when we buy solar panels we buy it on the basis of battery power. If the solar panel is not compatible with the power of the battery then it will fail to provide the exact amount of charge that the battery needed.

So, at first, we should calculate the total amount of power we need and buy the battery on the basis of this amount and choose the solar panel according to the battery power. Most of the people have a common question about the solar panels that what size solar panel to charge 100ah battery? So here will try to figure out the answer to this common question and some other factors that we should know about solar panels.

Solar Panel Ratings

Normally the production house constructs each solar panel with a power rating of 250 watts. And the cells on each panel determined how much power it can generate from the sunlight. The panels we see on the rooftop either for the residential or commercial area are made of 62 to 72 cells. And the number of cells in a solar panel is increasing.

So, if you have four solar panels installed on your rooftop it can generate 250 watts×4 cells = 1000 kilowatts in an hour of full sunlight. So, this solar power rating will tell you how many panels do you need for your 100ah battery.

Calculating the Solar Panel Size

Calculating Your Solar Power Requirements

Think, you have a 12volt 100ah (AmpHr) battery Which is really small size for your home appliance. Multiply the 12 volts with 100Ah and the result is 1200-amp hours. So how much power does your battery need from a solar panel? As you have four solar panels which are in total 1000 kilowatts. So, it can produce 1 kilowatts of power at an hour. But your 12-volt battery requires 1200 KW to get the full charge. So, you need more power-generating solar panels to charge the rest of the 200Ah. Therefore, you need solar panels that can produce in total 1.2 KW.

But your solar panels are not generating the power for only 1 hour in a day. If your solar panels get a good amount of power from the total 5 hours of sunlight then it can produce 5 kilowatts a day. So, calculate the number of kilowatts your appliances need daily. If your daily needs are below 5 KW then a series of solar panel (4 panels) is enough to produce the full battery charge. Even It is possible to charge a 2400AH battery with a 1000 KW solar panels. Because the solar panels produce the power for the whole day. But it's not recommended to use 1000KW solar panels for 24 volts 100AH battery which means 2400Ah battery.

Why we are talking about the 5 hours because it’s the peak hour when the solar panels get the proper sunlight. But if we are using a 2400Ah battery with 1000KW solar panels it is not possible to get enough power for the same 5 hours of sunlight. It may be possible if our appliances consume less than 2 or 3 KW a day. But we buy our barriers based on the power consumption rate of our appliances. So, for 2400Ah battery we should buy 2500KW solar panels.

Mistakes We Do After Calculation

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When we are done with the calculation we think 2500KW solar panels is enough for 2400Ah battery. Our calculation is right if our appliances consume less KW a day then the KW produces by the solar panels. For instance, if our solar panels produce 20 KW a day and our appliances consume 5 KW a day then It is a good sign for the battery life. Because If we discharge our battery more than 50 percent daily then the battery will not last long.

But if our appliances consume 15KW a day then we should use the double size solar panel which is 5000KW. It will help to get the fast charge and produce more power even the consuming rate is more than 15 KW.

So here we got the answer for the total solar panels normally we need for 100Ah battery. For the 24volt battery, we need 2500KW solar panels and for the 12-volt battery, we need 1205 KW solar panels.

Last Updated on February 5, 2021 by Leo Evans

1 thought on “What Size Solar Panel to Charge 100ah Battery”

  1. Evening,
    We have terrible power interruptions in South Africa. Some days three times per day for two hours at a time.
    I thus need to fit one of my boreholes with a solar system for household water usage.
    I bought a 0.375 Kw submersible pump and it is hanging 30 meters deep in the borehole, the water surface is at 16 meters, thus the pump is submersed 14 meters deep in the water. Currently this pump is connected to electricity and fitted with a 18mm pipe on the surface and is working fine but I need to convert it to solar as back- up.
    I also bought a Booster pump of 0.37Kw to connect to a water storage tank of 2500 liter.
    I must pump the water vertical to the surface, 30 meters, then pump the water horizontal to the tank about 50 meters away and then again 2 meters vertical to the tank inlet pipe.
    Can you please assist me in order to allow me to buy the right Solar panels, Inverter, Regulator and batteries. I pump water between 15 minutes and 25 minutes every day to fill the tank. The booster pump is used when we need water in the house.
    Will it be possible to connect two freezers and two deep freezes to this system?

    Please assist with your knowledge.



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