What size battery do I need for 500 watt solar panel?

500watt 545watt solar panel

To determine what size battery are needed for a 500 watt solar panel, several factors need to be considered, including:

  1. How much power does a 500 watt solar panel produce in one day? 
  2. Electricity requirements at night
  3. Battery capacity

How much power does a 500 watt solar panel produce in one day? 

The amount of electricity generated by a monocrystalline 500 watt solar panel depends on a variety of factors, including location, weather conditions, and installation method.

Under ideal conditions, 500 Watt solar panels have module efficiency ratings of 21%.a monocrystalline 500 watt  solar panel will produce around 2-3 kWh daily and 731 -1096kWh of annual . However, the actual power output will vary depending on various factors:


In bad weather conditions, cloudy or rainy days can cause the output of the solar panel to drop.

Geographic location

The duration and intensity of sunlight varies from region to region, so the same solar panel will produce different amounts of electricity in different regions.

Installation method

Factors such as installation angle and direction will also affect the output power of solar panels.


In winter, when the sun’s rays are weak, the output power of the panel may drop. In summer, when the sun’s rays are stronger, the output function of solar panels increases, but when the temperature of solar panels is too high, their output power will decrease.

The amount of electricity generated by a solar panel can be calculated using the following formula:

Solar panel power generation = rated power of the solar panel  x   peak sun hours   x  conversion efficiency

Where insolation time is the amount of time in a day that the solar panel receives sunlight, usually measured in hours. Conversion efficiency is the efficiency of the solar panel in converting solar energy into electricity, usually around 80%.

For example, assuming you have a solar panel rated at 500 watts and there are 5 hours of sunlight in a day in a certain area with a conversion efficiency of 80%, the amount of electricity generated by the solar panel would be

500 watts x 5 hours x 0.8 = 2000 wh

So, the solar panel can generate 2000 wh of electricity in one day.

However, the above data and estimates are based on ideal conditions and the actual power generation may vary due to various factors. Therefore, in practical applications, it is recommended to conduct detailed field surveys and evaluations to determine the actual power generation capacity of a 500 Watt solar panel.


Electricity requirements at night

You need to consider how much power you will need for nighttime use when there is no power output from the solar panels.We cover the three ways to calculate your energy needs.

  1. Calculate your daily load manually
  2. Look at your electricity bill for average usage
  3. Ask a solar installation company to do it for you

Read this article to learn how to calculate electricity usage


Battery capacity

You will need to select a battery large enough to store the power generated by the solar panels during the day and provide nighttime use when needed.



In general, for a 500 watt solar panel system, a minimum of one set of 12 volt, 200 amp hour batteries is recommended. Of course, the actual number of batteries required will depend on your specific needs and the type of battery selected, so it is recommended to contact WinSeven SOLAR directly for more specific advice.

Then  you know that 500w solar panel is your best choice? Read more.