Generator vs battery backup

Both keep the lights on when the grid goes down. They fail in different ways. A generator fails when the fuel runs out. A battery fails when it is empty and the sun is not recharging it. Start with the outage you plan for.

Which outage are you planning for?

• A few hours a few times a year: a battery covers it quietly. A small generator works too.
• A shutoff for one to three days in wildfire weather: a battery with solar can ride it out if you limit loads. A generator with fuel on hand can cover heavier loads. See the shutoff prep checklist.
• Medical equipment: talk to the equipment supplier and your utility about backup. Do not rely on a plan you have not tested.

Runtime, in plain math

For a battery, runtime is usable kilowatt-hours divided by the kilowatts you run. A 13 kWh battery at 1 kW lasts about 13 hours. At 5 kW it lasts about 2.6 hours. A refrigerator, lights, internet and phones can come in near 1 kW. A central air conditioner or electric range can use several kilowatts alone.

For a generator, runtime is the fuel in the tank divided by the burn rate. A portable gasoline unit needs refueling and gas on hand. A standby unit on natural gas or propane can run for days if the fuel supply holds, but it depends on the gas supply and the unit size.

Typical SoCal cost ranges

These are typical SoCal ranges as of October 2026, from the cost pages. Hardware and permit rules vary.

Option	Electrical work, typical range	Notes
Interlock kit and inlet	$400 to $1,800	Interlock $400 to $850; inlet box and cord raise it. The generator is extra
Manual transfer switch	$400 to $1,300	Powers chosen circuits from a portable generator
Automatic transfer switch	$600 to $2,500	For a standby generator
Standby generator hookup	$1,500 to $3,000	Electrical labor only. The generator is extra
Home battery, electrical side	$1,500 to $4,000	Desk estimate. The battery is priced separately by capacity and brand

The pattern is clear. A portable generator with an interlock is the lowest cost to start. A battery costs more but has no fuel to buy, store or smell.

Fuel and safety

A portable generator burns gasoline that goes stale and that you must store safely. In a wildfire zone, storing fuel near the house and fueling a hot engine in dry weather carry real risk. See wildfire zones and electrical work. A standby unit uses a gas line and a shutoff valve, so it depends on gas service continuing. A battery has no exhaust.

Never run any fuel engine in a garage, basement or near a window. Carbon monoxide kills. Install carbon monoxide alarms either way.

Permits and inspection

Anything that ties into the panel needs an electrical permit. That covers an interlock kit, a transfer switch and a battery system. A backfeed through a dryer outlet or a “suicide cord” is unsafe and not allowed. It sends power onto the utility lines and can hurt lineworkers. Batteries tied to solar also need the utility’s interconnection approval. A critical loads subpanel is a common way to choose what stays on and keep the equipment smaller.

Noise and neighbors

Portable and standby generators make engine noise. Cities set their own noise limits and setbacks for standby units, so ask your building department before you site one. A battery’s fan is quiet by comparison. Engines in the South Coast region can also fall under air-district rules, so check with your city or the air district before buying a standby unit.

Incentives

• State: the CPUC’s Self-Generation Incentive Program ratepayer budgets closed to new submissions on December 31, 2025. The income-qualified equity budget was on a waitlist in most areas as of October 29, 2026. Check the program page.
• Federal: the residential clean energy credit (25D) stopped for property placed in service after December 31, 2025. See federal tax credits in 2026.

A simple rule

Choose a battery if you want quiet, low-effort cover for the essentials and may add solar. Choose a generator if you need to run big loads for days and can store fuel safely. Some homes do both, with a small battery for daily outages and an inlet for a rented generator in a long one. The backup power hub lists every option.