Home battery backup vs generator for a Maryland home

Home battery backup vs a generator comes down to how long your outages run and what has to stay on. A battery delivers stored electricity until it needs a recharge. A standby generator makes power as long as it has fuel and works. Choose a battery for quiet backup on a set energy budget; consider fuel for long outages.^1,2

The comparison below covers permanently installed home batteries and fixed standby generators. A portable power station sold as a “solar generator” is a different product.

Which backup option fits your outages?

A home battery suits a household that can limit what it backs up and recharge before the stored energy runs out. A standby generator deserves a look when outages run long and loads are heavy. Fuel delivery, outdoor space, and noise can tip the choice either way.^1,2,3

Start from your own outage history. Write down what stopped working, how long the power stayed off, and what you missed most. A refrigerator, phone charging, a sump pump, and the controls on a heating system matter more to most households than the dryer. Have a qualified professional measure the real electrical demand before you buy anything.

“Whole home” is a label, not a circuit list. Two proposals using the phrase can leave different circuits on and shut off different appliances. Compare the actual circuit lists against your own priorities. Our guide to whole-home battery backup goes deeper on that question.

How long can each option carry the house through an outage?

Battery runtime is usable energy divided by the average load, and appliance start-up surges add a separate limit. A generator keeps running while fuel lasts, within service and equipment limits. Solar can recharge a compatible battery in an outage, but weather and restart behavior after a full drain matter.^2,3,4

Two units do most of the work. Energy, measured in kilowatt-hours (kWh), is the battery’s stored supply. Power, measured in kilowatts (kW), is how much equipment can run at once. The U.S. Department of Energy draws the same line on its storage basics page.³

nominal 15.0 kWh x usable 80% = 12.00 kWh usable
round-trip efficiency 85%: delivering 12.00 kWh takes about 14.12 kWh in; ~2.12 kWh lost as heat/conversion
runtime = 12.00 kWh / 0.50 kW = 24.0 h (no solar recharge; average load; energy limit only)
runtime = 12.00 kWh / 1.50 kW = 8.0 h (no solar recharge; average load; energy limit only)

The usable share and the efficiency are separate assumptions, and “usable” here means the energy that reaches your loads. Triple the load and the runtime drops to a third, so a runtime claim means little without a load list. The math leaves out changing appliance cycles, temperature effects, and capacity loss over time. It also can’t predict whether a particular motor will start: clearing an average-power check is a different test from handling a start-up surge.

For a real-world yardstick, Pacific Northwest National Laboratory (PNNL) says battery backup systems can last about a day when set up to run some, but not all, of a home’s circuits before the battery needs a recharge, and that this varies greatly with the size and type of system.⁴

Comparing solar with a generator? Look at the controls. The National Renewable Energy Laboratory (now the National Laboratory of the Rockies) explains in its March 2020 resilience report that ordinary grid-connected solar shuts down during an outage. Backup operation needs equipment that safely isolates your home from the grid.² For the longer version, read do solar panels work in a power outage.

Restart after a full drain is another difference. PNNL notes that most, if not all, AC-coupled batteries (the type wired in on the home’s AC side) need to see a grid signal before they can charge again, while most DC-coupled batteries have a black-start capability that lets them restart from solar alone.⁴ The installer should be able to tell you which type is on the proposal and point to the datasheet line that says so.

What does each option cost to buy, fuel, and maintain?

Compare complete installed proposals first, then separate the energy you buy from maintenance and eventual replacement. A battery draws charging electricity and loses some in storage. A generator burns fuel and needs engine service. Model, load, tariff, and service scope drive the totals.^3,6,4

A generator’s equipment price can leave out the transfer equipment, fuel piping, a tank, site work, permits, and electrical work. A battery proposal should name the usable energy, the inverter and backup controls, panel work, installation, approvals, and whether solar is included. Line those fields up side by side when you compare quotes.

Running costs: useful inputs and their limits

Two federal price series give a rough check on energy costs. Neither is your bill.

The electricity number is a statewide average that spreads fixed charges across all usage. Charging a battery costs whatever your own tariff says. The gas number is a statewide average as well, so it won’t match your marginal gas rate, and it says nothing about delivered propane.

Fuel burn varies by generator model and load. A spec sheet lists consumption at half and full load for natural gas and propane. Pull the sheet for the exact unit you’re quoted, then price it with a dated local fuel quote.

Upkeep: where the two part ways

PNNL’s home-backup guidance, last updated September 29, 2021, lists generator maintenance as periodic: coolant and oil level checks and replacements, starter-battery checks and replacements, and load tests, with monthly and annual chores. It adds that battery-based backup avoids those chores.⁴ That guidance dates from 2021 and service intervals differ by model, so ask for the written schedule for the exact equipment, and settle who handles service during a long outage.

A battery skips the combustion engine but still needs a support and replacement plan. The 2025 Annual Technology Baseline puts fixed operation and maintenance at four percent of capital cost, the amount it says is needed to offset degradation over a modeled 15-year life.⁶ Treat that as a research assumption. A written service price is what you’d budget from.

Will your property and county allow a generator or a battery?

A standby generator needs an outdoor spot, a fuel supply, and a local permit. A battery needs an approved location and an electrical design. County rules can settle the choice before price does, so check your lot, the neighbors’ windows, and your utility’s requirements.^1,9,10,11

Exhaust is the safety issue to take seriously. In a June 2025 report on stationary generators, staff at the U.S. Consumer Product Safety Commission (CPSC) described what followed Hurricane Ida in 2021. CPSC received information on 256 homes that reported carbon monoxide exposure, and a stationary generator was the source in at least 105 of them. Field investigators gathered detail from residents of 57 affected homes and found incidents where exhaust traveled at least 25 feet from the enclosure. Staff recommended that the technical committee for NFPA 37, the National Fire Protection Association standard covering stationary combustion engines, raise the required separation between a generator and openings into a structure from the current 5 feet to at least 25 feet.¹ The report is a staff document, and the Commission has not adopted it as a rule. Your installer should follow the manufacturer’s instructions and local code, and explain in plain words how the siting handles windows, vents, and doors.

Permit rules are local. Montgomery County is the example below, and it doesn’t speak for the other counties we serve.

A sound rating measured at some other distance doesn’t show compliance at the property line, so compare the spec sheet with the line that counts. The county’s electrical-permit staff can say how a battery-only retrofit is handled.

For fuel, find out whether your gas service can support a generator alongside your existing appliances. A propane design needs a tank and a delivery plan. And a gas connection can still be interrupted.

Utilities set their own rules for storage that can send power to the grid. Baltimore Gas and Electric (BGE), which serves Howard County, says in its June 2024 technical interconnection guide that storage capable of exporting electricity counts as a distributed energy resource.¹¹ Customers in most of Montgomery and Prince George’s counties are served by Pepco, which has its own process, so ask your utility for the current one. A battery set not to export may still need approvals.

Already have solar? Maryland’s Utility RELIEF (Reducing Energy Load Inflation for Everyday Families) Act, Chapter 353 of 2026, says a customer-generator under a net energy metering contract or tariff on July 1, 2027, remains eligible until the earliest of four events: decommissioning, a modification that increases net power flow (by adding solar modules) or the system’s alternating current output capacity, a new interconnection agreement, or repowering.¹³ Whether your battery design triggers any of those is a question for your utility before you sign. Our guide on adding a battery to existing solar covers the retrofit side.

Do current incentives change the comparison?

Yes, in favor of the battery. Maryland’s storage rebate covers energy storage systems, not generators, but it needs an approved reservation before installation and funding is limited. The federal residential clean energy credit does not apply to expenditures made after December 31, 2025. Compare prices before incentives.^14,15,16,17

Here is where each program stood on October 25, 2026.

MEA’s table heading says FY26 even though the page contains FY27 documents. Confirm with MEA which year the requested and reserved figures track.¹⁹

Several conditions in the funding opportunity announcement (FOA) bear on this comparison:¹⁸

• The system has to be grid connected, permanently installed, and installed by an entity holding the required certifications and licenses. Portable power stations and removable batteries are ineligible.
• The eligible-cost list names batteries, inverters, controls, permitting fees, electrical work, and interconnection fees tied to the storage system. It doesn’t list generators.
• The customer can authorize only the prime contractor to apply on their behalf or to receive the payment.

Program rules decide who qualifies, and a tax professional can check any tax credit before you subtract it from a quote. The Maryland battery rebate guide walks through the reservation steps.

Can a battery and a generator work together?

A professionally designed hybrid can pair stored electricity with fuel-backed generation. The battery covers loads between generator runs, and compatible generation can refill the battery when needed. The equipment and controls must support that arrangement; owning both devices isn’t enough.²⁰

The national laboratory’s March 2020 resilience report describes a hybrid in which a generator refills depleted storage. It names diesel as the common choice in that example.²⁰ Treat that as a concept rather than a wiring plan. A designer should document the permitted operating modes, charging limits, transfer behavior, and what happens after the battery empties.

One Maryland-specific wrinkle: MEA’s Fossil Fuel Policy, revised effective July 1, 2026, says MEA programs won’t support projects that expand fossil fuel use, including installing new fossil fuel equipment. The FOA lists the ability to comply with that policy as a minimum requirement, “if applicable.”^21,18 The documents don’t say how a generator installed beside a rebated battery is treated. If you’re weighing both, put that question to MEA’s energy storage team before you install either one.

How do you choose between them?

Picture a hypothetical household. Its must-run list is a refrigerator, a sump pump, internet, and a few lights, and outages last hours, sometimes a day. A neighbor’s bedroom window faces the equipment spot, so quiet matters. That points to a battery sized to the must-run list, plus a written plan for an outage that outlasts the stored energy.

Now change one fact. The same household adds electric heating that has to run through a multi-day winter outage. The load list grows, the energy budget grows with it, and a fuel-backed source or a hybrid moves up the list. The longest outage and the biggest load made the call, whatever the brand.

What to get in writing

Give each provider the same loads and the same outage scenario, then collect the same documents from all of them:

1. A load list: the appliances that must keep running and the longest outage you want to plan for. A qualified professional verifies demand and motor-starting needs.
2. Product datasheets showing usable energy, continuous power, and surge or starting power for a battery, or rated output and fuel consumption at half and full load for a generator.
3. A written scope listing exclusions, service prices, and who handles permits and inspections.
4. For a battery rebate, the MEA Step 1 approval notice before any equipment goes in. For the county permit, the permit number and the final inspection record.
5. A description of what the system does when fuel, stored energy, communications, or solar recharge is unavailable.

A battery without solar has no rooftop production to recharge it in an outage. A solar-and-battery system can still run short in poor weather. A generator can stop for lack of fuel or maintenance. None of these should be your only plan for medical equipment; talk to your doctor and your utility about a separate emergency plan, and check with the equipment provider too.

Start with your longest outage and your must-run list

Decide on your longest realistic outage and your must-run list before you look at products. If both are modest, a battery is the quieter, simpler fit, and the Maryland rebate may apply if funding remains and an approved reservation comes first. If both are large, price a fuel-backed option or a hybrid and read the siting and noise rules first. Either way, compare proposals on the same load list.

For batteries, Soleil’s battery storage page describes backup for the circuits you choose, either whole-home or essentials only.²² If solar recharge is part of your plan, ask about residential solar alongside the backup design.

Book a free assessment or call (301) 953-4140.

Solar savings and incentive eligibility depend on your roof, your usage, your utility, and your tax situation. Incentive programs change and some have limited funding. We are not tax advisors — we will review your bill with you and tell you what you may qualify for. Confirm any tax credit with a qualified tax professional.

Program rules decide who qualifies. Ask any installer whether it is on the program’s contractor list.