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How many units will your solar panels actually make?

Pick your city and the system size you are being quoted. This shows the output month by month for a normal year, and tells you whether a number a salesman has given you is physically possible where you live.

Your city

Nearest of 25 cities is close enough. Sunlight varies slowly across a region.

System size in kW

The number on the quote. A common home system is 2 to 5 kW.

Units per day you were promised (optional)

Leave blank if nobody has quoted you a figure. Fill it in and we will check it against the sunlight your roof can actually receive.

Why this question is worth asking before you buy

The most common complaint about a rooftop system is that it makes less than the buyer was told it would. Sometimes the system is faulty. Often the promise was never possible, because there is a hard limit on how much sunlight falls on a given roof in a given city, and no panel brand, inverter or warranty moves it.

That limit is public data. This page applies it to your city and your quoted size, so an unreachable number can be spotted while it is still a conversation rather than a dispute.