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Solar Array and Battery Bank Sizer: How Much Solar Do You Need Where You Actually Camp?

What array and bank does that require, in my location, in my worst season?

This calculator needs JavaScript to run the arithmetic in your browser. Nothing you enter is sent anywhere — the calculation happens entirely on this page — but it does need scripting enabled. The method it uses is written out in full below the form.

1 · Consumption and placeGlobal inputs

Daily energy requirement Wh/day

Required. The load calculator produces this figure and passes it here.

Location state

Usage window

Sets the design month. The most consequential field on this form.

2 · The installationDerate inputs

Mounting

Shading

Charge controller

Battery chemistry

Days of autonomy days

Higher than T1’s default. This tool sizes for weather, and weather does not arrive in 1.5-day units.

System voltage V

Cold, existing hardware and roof area coldest night 32°F · no existing array

Coldest overnight temperature °F

Not optional in the calculation — it derates usable capacity.

Existing array W

If non-zero, the shortfall case runs against it.

Existing battery bank Ah

At your system voltage. Needed for the days-to-floor figure.

Available roof area ft²

Optional. Triggers the feasibility check.

Override peak sun hours h

Zero uses the zone table. A year of logged controller data beats any model — enter it and the tool uses it unmodified.

Result

Array required

Battery bank

Charge controller

Derate applied

Show your working

Peak sun hour data: seed values, not production data The figures behind this tool are the six-zone seed table from the specification, resolved from your state's population-weighted centroid. They are placeholders. Production requires per-ZIP monthly values derived from NREL PVWatts / NSRDB, and until those are loaded this result carries a real accuracy penalty rather than an implied precision — particularly in the eight states flagged for high intra-state variance. If you have a year of logged controller data, use the override field: it will beat this table.

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