India rooftop solar guide

Solar batteries and backup

A battery solves a backup problem, not a solar-generation problem. Size it from the appliances and hours you need during a cut, then check whether the extra cost is worth it.

7 min readLast reviewed 3 September 2026
In brief A battery solves a backup problem, not a solar-generation problem. Size it from the appliances and hours you need during a cut, then check whether the extra cost is worth it.

Grid solar and backup are different jobs

A standard on-grid inverter switches off during a power cut. This anti-islanding protection helps keep utility workers safe. Solar panels on the roof do not mean your home stays powered in an outage.

If cuts are rare, an on-grid system is usually the simpler financial choice. If you need fans, lights, internet, a fridge or medical equipment during cuts, compare a hybrid inverter and battery. Existing home inverters can sometimes remain separate from the solar system.

Size the essential-load circuit

Add the watts of appliances that must run together, then multiply by backup hours. A 100 W fan, 15 W light, 15 W router and 150 W average fridge load total about 280 W. Four hours needs 1.12 kWh before conversion losses and reserve capacity.

Simple rule Battery energy in kWh is not the same as inverter power in kW. Energy controls how long the backup lasts. Power controls what can run at once.

Air conditioners, geysers, pumps and induction cooktops can make a backup system much larger. Ask for both continuous and surge ratings.

Plan for ₹20,000 to ₹30,000 per usable kWh

As a broad 2026 planning range, a residential lithium battery package can cost about ₹1.0 to ₹1.5 lakh for 5 kWh before changes to the inverter or wiring. Quotes vary by chemistry, usable depth of discharge, power rating, enclosure, brand and warranty.

Compare warranted years and warranted energy throughput. A ten-year label with strict cycle or usage limits is not an unlimited promise. Ask what capacity remains at the end of warranty.

Give the battery a safe, serviceable place

Follow the manufacturer’s temperature, ventilation and clearance rules. Keep the unit away from living-room escape paths, direct sun, rain and flood risk. Use compatible protection devices and a trained installer. Do not mix unmatched batteries or alter a battery management system.

PM Surya Ghar assistance is calculated from eligible solar module capacity. Adding a battery does not raise the central subsidy. Read the scheme guide before choosing a hybrid design.

Common questions

Will solar run during a power cut without a battery?

A normal on-grid system will not. Some hybrid or backup-capable designs can supply selected loads, but the system must be designed for that use.

How large a battery does a 3 kW solar system need?

There is no fixed match. Size the battery from essential appliance load and required backup hours, not only from panel capacity.

Official sources

Rules and portal processes can change. Check these sources before committing money.

  1. Central Electricity Authority regulations and safety resources
  2. MNRE PM Surya Ghar guidelines
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