Calculator

Solar Charge Controller Calculator

By NerdVolt Editorial TeamJune 16, 2026Estimate tool

Accuracy note: The arithmetic on this page is deterministic from your inputs. Solar production, code, utility, incentive, and savings outputs are estimates unless you supply exact equipment specs, tariffs, shade data, and local requirements.

Inputs

PV array wattsBattery voltage (V)Controller max PV voltage (V)Modules in seriesPanel Voc at STC (V)Voc temp coefficient (%/°C, absolute)Lowest cell temp (°C)Safety margin (%)

Result

How this is calculated

Controller amps ≥ PV watts ÷ battery volts × safety margin. Cold Voc = STC Voc × [1 + coefficient × (25°C − lowest cell temperature)]. String Voc = modules in series × cold Voc.

Sources

NREL: standard PV test/reporting conditions