Calculators
All tools
Single-purpose calculators for each part of an off-grid solar system. Each runs live in your browser. For full system sizing, use the main calculator.
DIY battery pack & BMS
Build a custom 12V/24V/48V bank from prismatic LiFePO4 or cylindrical 18650/21700 cells — cell count, voltage range, BMS size.
Real vs nameplate capacity
What a “10 kWh” battery really delivers after DoD, temperature and round-trip losses.
Battery payback
Honest payback grounded in real delivered energy — your rate, no stored rebates or tariffs.
C-rate safety check
Can your bank deliver the current your loads draw? Continuous vs surge, by chemistry.
Array adequacy check
Will your solar array actually recharge the bank, or just match the load? Catches chronic undercharging.
Generator backup sizing
Size a backup generator to recharge the bank while running loads, with fuel-per-recharge estimate.
Convert watt-hours to amp-hours
Convert energy in watt-hours to battery capacity in amp-hours at a given system voltage.…
Convert amp-hours to watt-hours
Convert battery amp-hours to stored energy in watt-hours. Wh = Ah × V.…
Battery bank size for your daily load
Size the battery bank (Ah) needed to cover a daily energy use for a chosen number of bac…
How many days your battery bank lasts
Estimate how many days a battery bank can power your load with no charging, based on usa…
Usable capacity after depth-of-discharge
Find the usable capacity of a battery after applying the safe depth of discharge for its…
Series / parallel wiring configuration
Work out how many batteries to wire in series (for voltage) and parallel (for capacity) …
Solar array watts to recharge your load
Size the solar array (watts) needed to replace your daily energy use, given your locatio…
Charge controller amps & MPPT vs PWM
Size the solar charge controller current and see whether MPPT or PWM suits your array an…
Inverter continuous & surge watts
Size the inverter continuous and surge ratings for your simultaneous AC loads, with head…
Daily watt-hours for a device
Calculate the daily energy a device uses in watt-hours from its power draw, run time and…
How many panels for your array
Work out how many solar panels of a given wattage you need to reach a target array size.…
How long a battery runs a load
Estimate how long a battery can run a given load, based on usable capacity for the chemi…
Capacity loss by temperature
See how ambient temperature affects usable battery capacity. Lead-acid loses significant…
Energy out after storage losses
Find how much energy you get back out of a battery after round-trip charge/discharge los…
Daily grid-equivalent energy cost
Estimate the grid-equivalent cost of your daily energy use, to gauge potential savings f…
12V vs 24V vs 48V recommendation
Get a recommended system voltage (12V, 24V or 48V) for your system size. Higher voltage …