How much do solar panels produce?
How much electricity do solar panels produce?
kW hours per day
Choose your state to see the complete guide to installing solar panels
Please also note when using the map above that the estimates assume a perfect installation facing due south, at an optimal tilt angle, and unshaded between 9am and 3pm. Click on your state in this map to see our complete guide to installing solar panels in your state.
Geography and Location
Here is a map that shows the average amount of kWh produced by a 1 kilowatt solar power system each day in each state of the USA.
As you can see across the USA daily production per kilowatt installed varies from as little as 2.9 kWh per kw per day to close to 4.7 kWh in very sunny locations. This is because of different levels of solar irradiation available in different locations and is measured in Sun Hours.
Please also note that in some states different parts of the state have very different climatic conditions and so whilst the amount quoted above may be true for some parts of the state it may not necessarily be the case where you live. To see a more accurate estimate for your exact location, our solar production calculator will show you the amount of kWh of production you will get for a certain sized array of solar panels in your zip code. Our database has solar irradiation data for each zip code in America.
The seasons have a significant effect on solar power production and the numbers quoted above as state averages are the averages across all days of the year. Average production would typically be much lower than this is winter and much higher than this average figure in summer. Here are the results for a 6kw array in Los Angeles demonstrating this:
(kWh / m2 / day)
The tilt and direction of your roof
Because we live in the Northern Hemisphere the optimal direction for your array to tilt towards is south. As most residential systems are installed on an existing roof the roof orientation and the pitch (or tilt) are generally something you have to take as a given when designing a solar system.
However to the extent this orientation is away from south there will be some system losses. Here is the same data from above but this time the direction of the roof was southwest (45% off south):
(kWh / m2 / day)
You can see from this that the change of roof direction from South to South West reduced solar electricity production by 2.2% over the year. If we change the direction of the roof to have the array facing directly west then there is an output loss of 10.9% when compared to a true south facing roof.
To see how this would affect your economics enter your details into the solar calculator below.
The amount of electricity produced by each kW of solar you install is primarily a function of the solar irradiation that falls on your home or business. Solar irradiation is often measured in Sun Hours. To work out how many Sun Hours falls on each area, meteorologists measure the total amount of irradiation that falls on a place in a day (in mega joules). They then work out what this is equivalent to if it were converted to complete hours when there was 1000 mega joules per square meter of solar irradiation falling on an area, so if there was 500 mega joules falling on average over a 12 hour day then the Sun Hours would be 6. The reason this ties back into the output of solar panels is that solar panels are rated based on the power they produce with 1000 mega joules per square meter of irradiation falling on them.