Solar yield estimator
Pick a city, a system size and one of six panel layouts to see how many kilowatt-hours the panels make each year and each month, how the city ranks and how a second city compares.
Result
9,610 kWh a year
6 kW of panels in Denver, CO, south-facing at a 20° tilt.
- Per kW of panels
- 1,602.0 kWh
- Average day
- 26.3 kWh
- Rank, this layout
- 27th of 100
- Best · weakest month
- May · Dec
The same system in Seattle, WA makes 6,530 kWh a year: −32.1% against Denver (99th of 100 for this layout).
| Month | Denver, kWh | Seattle, kWh | Difference |
|---|---|---|---|
| January | 592 | 238 | −59.7% |
| February | 685 | 329 | −52.0% |
| March | 856 | 490 | −42.8% |
| April | 905 | 694 | −23.3% |
| May | 983 | 825 | −16.1% |
| June | 971 | 786 | −19.0% |
| July | 977 | 860 | −11.9% |
| August | 905 | 854 | −5.6% |
| September | 844 | 613 | −27.4% |
| October | 721 | 410 | −43.1% |
| November | 624 | 230 | −63.2% |
| December | 550 | 199 | −63.9% |
| Year | 9,610 | 6,530 | −32.1% |
PVWatts® v8 model, typical-year weather, 14% system losses, no shading. The size multiplies the 1 kW result for the city and layout. Yearly totals are rounded to 10 kWh and months to 1 kWh, so the months may not add up exactly. Rank compares all 100 cities with the same layout (1 = most output).
How to use it
- City. Choose one of the 100 cities. If yours is not listed, pick the nearest one, or one with similar weather from the list of cities.
- Size. Type the rated power of the panels in kW (the sum of the panel wattages ÷ 1,000).
- Layout. Choose the direction and tilt closest to your roof. Only the six layouts in the data are offered: south at 20°, south at the city's latitude, flat, east at 20°, west at 20° and a 1-axis tracker.
- Second city (optional). The same system is placed there, so the difference shows the effect of location alone.
The example above, before you change anything, is 6 kW in Denver, CO facing south at 20°: 9,610 kWh a year, 27th of 100 cities.
What the numbers mean
kWh a year is the electricity the system delivers in a typical year, after inverter and wiring losses. Per kW is the same figure for 1 kW of panels, the number used to rank cities. Average day is the yearly total ÷ 365.
The monthly bars and table show how output moves through the year. A second city's column shows its own monthly kWh for the same size and layout; the difference is its output against the first city, month by month.
More on reading these figures: how to use the estimator, what kWh per kW means and how direction and tilt change output.