Performance and output
Enter your system size and region. Get an instant annual output estimate with no detailed inputs required.
How it works
Step 1
Just the rated kW capacity of your panels. No wattage, panel count, or tilt needed here, unlike the annual output estimator.
Step 2
Choose the closest match from four broad regional bands, then get your estimate instantly. If you want to compare against your actual usage, try the output vs usage gap analyzer next.
A quick estimate is meant to get you in the right ballpark fast, typically within 10 to 15% of a detailed estimate, since it skips factors like roof angle, shading, and equipment losses that a fuller calculation accounts for. That's a reasonable trade-off when you just need a number in seconds. A DOE federal PV performance study found real-world energy ratios averaging around 75%, a helpful reality check for any quick estimate.
The annual output estimator asks for panel wattage, count, tilt, and derating factors to build a detailed figure, while this tool uses just your system size and region to give you a fast number in seconds. Use whichever fits the moment, quick for a gut check and detailed for real planning. The solar panel calculator turns the same quick estimate into a panel count.
Regional sun exposure is the single biggest driver of output per kW installed, so even a bare-minimum estimate needs to account for it to be useful at all. That's why this tool asks for region even though it skips almost everything else. National Solar Radiation Database show just how much that regional swing actually looks like across the country, with the sunniest states seeing roughly 40% more annual irradiance than the cloudiest ones. If you already have monthly usage figures, the monthly output estimator can refine things further.
A quick output estimate is really the first step toward two bigger questions: whether the system covers your usage, and how long it takes to pay for itself. Once you have a ballpark output figure, the payback period calculator can turn it into a rough timeline for when the system starts saving you money outright.
Use it to sanity-check a quote or a rough plan rather than to finalize sizing, since it doesn't account for your specific roof, shading, or equipment. Once you have a rough number, size things properly with the household output calculator or check the performance and output hub for a more detailed tool.
Questions
A quick estimate is meant to get you in the right ballpark fast, typically within 10 to 15% of a detailed estimate, since it skips factors like roof angle, shading, and equipment losses that a fuller calculation accounts for.
The annual output estimator asks for panel wattage, count, tilt, and derating factors to build a detailed figure, while this tool uses just your system size and region to give you a fast number in seconds.
Regional sun exposure is the single biggest driver of output per kW installed, so even a bare-minimum estimate needs to account for it to be useful at all.
Use it to sanity-check a quote or a rough plan rather than to finalize sizing, since it doesn't account for your specific roof, shading, or equipment.