A 5 kW system is a common size for a family home. Here is what it produces and what it needs, using the same method as the system size calculator: 4.5 peak sun hours and 20 percent losses. Your own sun hours will change the result.
So a 5 kW system fits a home that uses roughly 550 kWh a month. An off-grid home with the same 18 kWh daily use needs about 15 percent more, around 5.75 kW, to cover battery losses.
| Panel size | Panels needed | Installed power |
|---|---|---|
| 400 W | 13 | 5.2 kW |
| 550 W | 10 | 5.5 kW |
| 700 W | 8 | 5.6 kW |
| 1000 W | 5 | 5.0 kW |
Plan on roughly 4.75 m² (51 ft²) per kW, so about 24 m² (256 ft²) of unshaded roof facing the equator.
For a grid-tied system, use a DC-to-AC ratio of 1.1 to 1.3. For 5 kW of panels that means an inverter of about 4 to 4.5 kW. For hybrid or off-grid systems, size the inverter to your loads and motor surge instead. See how to size a solar inverter.
If you want to cover 8 kWh of evening use, the nominal battery size is the useful energy divided by usable depth of discharge: LiFePO4 at 90 percent needs about 8.9 kWh, lead-acid at 50 percent needs 16 kWh. Compare them on the batteries page.
Next step: enter your own bill and sun hours, then compare panels.
