What battery capacity is best for a 50-watt solar panel?

The best battery capacity for a 50-watt solar panel depends on various factors such as the desired backup time, daily energy consumption, and efficiency losses in the system. To determine the appropriate battery size, you can follow these steps:

Estimate daily energy generation

Calculate the average number of peak sun hours in your location.

Multiply the solar panel wattage (50W) by the peak sun hours to estimate the daily energy generation.

For example, if your location gets an average of 5 peak sun hours, the energy generation would be 50W x 5h = 250 watt-hours (Wh) per day.

Estimate daily energy consumption

Determine the total energy consumption of the devices you want to power with the solar panel. Add up the wattage of each device and multiply by the number of hours each device will be used per day.

Calculate battery capacity

Divide the daily energy consumption by the depth of discharge (DoD) of the battery to account for the usable energy.

For example, if you have a lead-acid battery with a DoD of 50% and you need 200 Wh per day, the required battery capacity would be 200 Wh / 0.5 = 400 Wh.

You can convert this to amp-hours (Ah) by dividing the capacity by the battery voltage (usually 12V for small systems).

In this case, it would be 400 Wh / 12V = 33.3 Ah.

Keep in mind that this calculation is a rough estimate, and you should also consider factors like system efficiency, battery type, temperature, and potential power consumption variations.

It's always a good idea to consult with a solar professional to get a more accurate assessment of your specific situation.