How Much Power Can You Actually Get From Solar Panels?

The average amount of electricity you can get out of your solar panels as a fraction of their rated generation capacity is called their capacity factor. The capacity factor is the figure you need to answer the question in the title of this article, and is what you would search for.

The capacity factor of solar panels is affected especially by cloudy weather, solar panel maintenance/replacement which may require the panels to be disconnected, and the fact that there is no sunlight at night.

Example: The capacity factor of a solar panel that generates as much as it’s rated generation capacity (100 watts, for example), all day, every day, and for the entire year is 100% (this is only realistic for solar panels deployed out in space (yes, this is a real initiative).

A solar panel of which the power generated averages out to be 50% of the rated capacity has a capacity factor of 50% and generates 50 watts on average.

Capacity factor is determined primarily by climate. Some climates experience 4 months of cloudy winter weather, such as most of the United States, and some experience no winter weather and are sunny for all 12 months of the year, such as tropical countries.

I will try to get more country-specific information.

United States: 4 months of winter (December to April), capacity factor is usually less than 25%.

Australia: 3 months of winter (June to August). Capacity factor data not found as yet.

What About the Rest of the World’s Climates?

Capacity factor varies widely from country to country, and even from state to state, if you are in the U.S, and you need to know what it is for your state or country to avoid buying an over sized or under sized solar setup.

If you are using a grid-tie setup, then this is not as important because if your setup is a little undersized, you will pay a little more for electricity, and if it is over sized, the power company usually pays you back for the surplus electricity generated (you have to contact your power company to confirm).

What is the Capacity Factor of Solar Panels?

The capacity factor of solar panels ranges from 15% to 50% [source]. To find the capacity factor for your location, search for this in Google: “Capacity factor of solar in [country name]“.

Additional Information