A standard grid-tied system usually switches off during a power cut. A battery alone does not mean whole-home backup.
Watts, watt-hours and capacity
- Watts (W) measure what runs at once. The inverter must handle the total and any surge when motors start.
- Watt-hours (Wh) measure energy over time. A 200 W load running for five hours needs 1,000 Wh before losses.
- Usable battery capacity is lower than the nameplate rating. Inverter losses and reserve limits reduce it.
Backup in a power cut
Your quote should list the backed-up circuits, continuous output and surge rating. The quote should also say whether solar recharges the battery during a cut.
Battery size for a power cut
These figures assume two fans, four lights, a Wi-Fi router and a fridge.
| Example | Battery size |
|---|---|
| 2-hour power cut | About 1 kWh |
| 4-hour power cut | About 2 kWh |
| 8-hour power cut | About 3.5 kWh |
Portable power stations
A “solar generator” is usually a power station paired with compatible solar panels.
- Battery capacity (Wh) is how much energy the station stores.
- AC output (W) is what the station can run at once. Compare its surge limit too.
- Solar input sets the allowed voltage, current, connector and maximum input power.
- Runtime is the usable watt-hours divided by the load in watts.
- Charging and portability cover recharge time, weight, warranty and service.
For India, look for 230 V, 50 Hz AC output and suitable sockets.
Never connect a power station to a wall socket to power the house. Linking a station to home wiring needs proper equipment and a qualified electrician.