Many people assume solar means a battery. In Kerala, with net metering, it usually does not: but sometimes it should.
When grid-tied solar is enough
A grid-tied system with net metering already takes your energy charges to zero where the roof is large enough to cover your consumption. Surplus units you export are credited against what you draw at night and in monsoon months. It costs less and pays back fastest.
When a hybrid system makes sense
- Power cuts affect your work, medical equipment or comfort.
- You want to use your own solar after sunset instead of exporting it and drawing it back.
- You plan to charge an EV overnight.
A hybrid system adds a LiFePO₄ battery and a hybrid inverter. When the grid fails, it switches to battery and keeps an essential-load circuit running.
How long will a battery last?
Backup time is usable energy divided by your load. A 10 kWh battery gives about 9 kWh usable (90% depth of discharge). At a 0.4 kW essentials load (lights, fans, fridge, router) that is roughly 22 hours. Add a 1.5 kW air conditioner and it falls to under 5 hours.
A note on subsidy
The PM Surya Ghar subsidy applies to the solar portion of a residential system, not the battery. Battery incentives are shown only once verified.
Not sure? Try the battery duration tool with your own appliances, or take the 60-second quiz.