Solar Array Size
Calculator
Results
- Required array size (kW)
- 6.944444
- Required array size (W)
- 6,944.444444
- Panels needed
- 17.361111
Energy results
| Required array size (kW) | 6.944444 |
| Required array size (W) | 6,944.444444 |
| Panels needed | 17.361111 |
formula-map diagram
- Required array size (kW)
- 6.944444
- Required array size (W)
- 6,944.444444
- Panels needed
- 17.361111
Energy relationship
Formula
kW = daily kWh ÷ (PSH × derate)= 6.9444444444444
Note
This is a simplified model: it applies the standard equation to the numbers you entered and ignores real-world losses, weather variation, tariff structures and equipment tolerances. Wind power assumes air density 1.225 kg/m³ at ISA sea level and the power coefficient you enter (Betz limit 0.593). Verify with measured data or a professional energy audit before making purchasing decisions.
More in Energy and environment
See all →Frequently asked questions
How does my electricity usage translate into array size?+
The calculator divides your target daily or annual energy consumption by the expected output per unit of installed capacity for your location, based on peak sun hours and system losses. The result is the total kW of panels needed to offset that usage over a year.
Should I size the array to cover 100% of my usage?+
That depends on your goals and net metering policy. Sizing for 100% offset assumes ideal production and no other changes; many homeowners size slightly under 100% to avoid over-generating in months when the utility doesn't fully credit excess power.
Why do two homes with the same usage need different array sizes?+
Peak sun hours vary significantly by geographic location and local climate, so a home in a sunnier region needs less installed capacity to produce the same annual energy as one in a cloudier region. Roof orientation, shading, and tilt also shift the required size.
What happens if my roof can't fit the calculated array size?+
You can use higher-efficiency panels to fit more wattage in the same roof area, add a ground-mounted array if space allows, or accept a partial offset and cover the remainder from the grid. The calculator gives the ideal size assuming no space constraints.
Does this account for seasonal variation in production?+
The calculation typically uses annual average peak sun hours, which smooths out the fact that a system produces far more in summer than winter. Actual monthly output will swing above and below the average even though the yearly total lines up.