Off-Grid PV Calculator

The following is a calculator designed to provide a rough approximation of the system components needed for an off-grid PV system. It requires you to input your individual AC and/or DC loads, the solar irradiation at your location, and a few module and battery parameters. The output data will give you an estimate for how many PV modules and batteries are needed, as well as minimum inverter and charge controller sizes required. See the help page for more information.

Note that the results on this page are generalizations and do not take into account shading effects, available space for modules, and wire and circuit breaker size requirements.

STEP 1: Calculate Average Daily Loads
AC Load Description Power (Watts) Usage (Hours/Day) Usage (Days/Week)

Minimum Inverter Size (W):

DC Load Description Power (Watts) Usage (Hours/Day) Usage (Days/Week)

STEP 2: Calculate Number of PV Panels and Charge Controller Size:
Average Peak Sun Hours Per Day (h/day):
Nominal System Voltage (V):
Inverter Effeciency:
Battery Effeciency:
Wire Losses (%)
Module Power (W):


Required System Size (W):
Number of modules in series:
Number of modules in parallel:
Number of modules required:
Min. controller charge current (A):


STEP 3: Calculate Battery Size
Battery Autonomy (days):
Battery Depth of Discharge Limit (%):
Individual Battery Voltage (V):
Individual Battery Capacity (Ah):
Min. Battery Storage Temperature (° C):
Total Battery Capacity Needed (Ah):
Number of Batteries in Series:
Number of Batteries in Parallel:
Total Number of Batteries Needed: