Solar Panel Calculator

How output and savings are worked out

Annual output is the system size in kilowatt-peak multiplied by the yearly yield per kilowatt-peak. The monetary saving then comes from multiplying the generated electricity by the price you pay for power.

For example, a 5 kWp system with a yield of 900 kWh/kWp produces about 4,500 kWh a year. At an electricity price of 15 cents per kilowatt-hour, that is roughly 675 dollars of savings annually.

What you enter and what you get

You enter the system size, the annual yield per kilowatt-peak and the electricity price. The calculator returns the estimated annual output in kilowatt-hours plus the savings per year and on average per month.

In the US a south-facing array typically yields around 1,200 to 1,700 kWh/kWp depending on the region. Further north or on shaded roofs the figure is lower.

Who it suits

It serves homeowners weighing up a solar investment, as well as anyone who wants to compare the output of different system sizes before requesting quotes from installers.

Good to know

Savings depend heavily on the self-consumption rate, that is how much of your production you use yourself. Self-used electricity saves the full retail price, while power sold to the grid usually fetches less. Treat the figures as a guideline.