Tilted solar array on a steel ground-mount rack at golden hour over Arizona high desert

Off-grid solar sizing calculator

How many panels and batteries do you need to keep the lights on without the grid? Tell us your daily power use, your local sunlight, and how many cloudy days you want covered — we'll size the system.

Result

Solar array (W DC)
Battery bank
Usable battery
Nominal battery

How to read the result. The array wattage is the DC nameplate to buy after derating for inverter losses, soiling, and shading (default 0.75). The battery Ah figure is sized so the bank can supply your autonomy days without dropping below the depth-of-discharge limit (LiFePO4 → 0.85, AGM → 0.5).

Tip for AZ off-gridders. Generic high-desert peak-sun values are 5.5-6.5 in summer, 3.5-4.5 in December. Always design to the December figure if you don't have a generator — otherwise you'll be in the dark at Christmas. For exact numbers, look up your nearest NREL station.

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