Solar batteries and generators can both keep a home powered during an outage, but they solve the problem in very different ways. A battery stores electricity. A generator produces electricity from fuel.
Solar battery vs. generator at a glance
| Factor | Home battery | Generator |
|---|---|---|
| Energy source | Stored electricity, often rechargeable by solar | Fuel |
| Noise | Usually quiet | Engine noise |
| Runtime | Limited by usable battery capacity and recharge | Limited mainly by fuel supply and safe operation |
| Maintenance | Generally low routine maintenance | Regular engine maintenance required |
| Best fit | Short-to-medium outages and solar integration | Long outages and high sustained loads |
When is a solar battery better?
A battery can be attractive when you want quiet automatic backup, already have solar, experience shorter outages, or want to use stored electricity for reasons beyond emergencies. The system’s usable energy capacity and power output both matter.
When is a generator better?
A generator can make more sense when outages may last for days, when you need high continuous power, or when reliable fuel access is easier than installing enough battery capacity. Generators also require safe installation and operation because of fuel, exhaust, and carbon monoxide risks.
Battery capacity vs. power
One of the most common mistakes is looking only at kWh. Battery energy capacity, measured in kWh, describes how much energy is stored. Power capacity, measured in kW, describes how much power the system can deliver at a given time. The U.S. Department of Energy explains why both measurements matter.
How long will a battery run your home?
A simple planning formula is:
Backup time ≈ usable battery capacity (kWh) ÷ average load (kW)
For example, 10 kWh of usable energy supplying an average 2 kW load would theoretically provide about 5 hours. Real-world runtime will differ because of conversion losses, changing loads, battery operating limits, and system controls.
Which backup option should you choose?
Start with the loads you actually need during an outage. Refrigeration, lighting, internet, medical equipment, heating or cooling, pumps, and cooking equipment can have very different power requirements. Once you know your critical loads and likely outage duration, the choice becomes much easier.
Use our Home Batteries guide and battery sizing tools as you plan.