Inverter and Battery Calculator
The inverter VA, battery Ah and battery count for the backup you want, and the solar panels that would refill it each day.
SolarOpen Calculator
Solar Calculators
Rooftop system size, subsidy and payback; inverter and battery backup.
Quick Answer
The rooftop planner sizes a system in kW from your monthly units, then works out the PM Surya Ghar subsidy and payback. The inverter calculator gives the VA rating, battery Ah and backup hours. Both use factors from MNRE guidelines.
Source: MNRE: Guidelines for PM-Surya Ghar: Muft Bijli Yojana, CFA to Residential Consumers, checked Oct 2026.
About our solar calculators
Rooftop solar comes down to a few numbers: what you use each month, how much open roof you have, the subsidy you qualify for and what you pay per unit. The rooftop planner works through those for a grid-connected system. The inverter and battery calculator sizes backup for power cuts and the panels needed to recharge it. Both print every step, so you can check an installer's quote against them.