Home battery backup without solar: when it makes sense

A home battery without solar panels can power chosen circuits during an outage if it charges from the grid and has equipment that isolates your home from the utility. It can’t recharge from your roof once the grid is down. Whether it also lowers your bill depends on your utility’s rate schedule.^1,2

Can a home battery work without solar panels?

Yes. A battery can charge from the grid and then power selected circuits when the grid goes down. To do that safely, the installer adds a transfer switch that disconnects your house from the grid while the battery runs. The backed-up circuits often sit on their own subpanel.¹

The inverter converts the battery’s direct current (DC) into the alternating current (AC) your circuits use. Charging from the grid isn’t enough on its own, because the system also has to disconnect from the utility and keep running by itself. The National Renewable Energy Laboratory (NREL), writing about solar systems, calls that safe disconnect “islanding” and says it takes additional power-management electronics. A battery-only system needs the same kind of isolation.^1,3

Soleil Energy’s battery storage page says the assessment starts by picking the circuits to keep running with you.⁴ For a closer look at designs, see our guide to whole-home battery backup.

How do you size a battery for the circuits you pick?

Start with two numbers. Power, in kilowatts (kW), is how much the battery can deliver at one moment. Energy, in kilowatt-hours (kWh), is how long it can keep delivering.² Then write the circuit list, because it tells you more than the phrase “whole-home backup” ever will.

For the exact equipment you’re quoted, get three figures:

• usable energy (kWh)
• continuous output (kW)
• the surge it can supply to start a motor, such as a well pump or compressor

The Pacific Northwest National Laboratory (PNNL) says a battery set up to run some but not all of a home’s circuits can last about a day before it needs recharging, and that the figure varies greatly with the size and type of system.¹

Here’s an example, not a real customer. A homeowner with a basement sump pump, a refrigerator, a few lights and the internet router puts those four on the backup subpanel. The battery has a modest job, and a day or so of coverage is plausible. Now add central air conditioning and an electric range to the same list. You’re asking for far more power and far more energy, so check the spec sheet before assuming the battery can carry them.

The kWh number on a brochure is the easiest thing to shop by and the least useful by itself. It tells you how long the battery can run, not whether it can start the motor on your well pump.

What happens when the battery runs out?

With no panels or generator feeding it, nothing refills the battery during a long outage. Once the usable energy is gone, the backed-up circuits lose power until the grid returns. Switching off loads stretches the supply, but it can’t replace a charging source.^1,3

Recovery matters too. PNNL notes that if a battery is completely depleted, some AC batteries need a signal from the grid before they will start charging again.¹ Find out from the designer what happens at zero and what has to be true for the system to restart when utility power returns.

Some hybrid designs add a backup generator that refills the battery when its charge drops. NREL describes that setup for solar-plus-storage systems.³ It’s a design choice made up front, not something to bolt on later. PNNL says backup power must not feed back into the grid and endanger line workers, and that backup systems must have automatic transfer switches that disconnect the house from the grid while they operate.¹ If you’re weighing a battery against a generator, our guide to home battery backup vs a generator lays out the tradeoffs.

If anyone in your home relies on medical equipment, don’t count on one backup source alone. Talk to your doctor, your utility and the equipment provider about a separate emergency plan.

A quick way to decide:

Can a battery without solar lower a Pepco or BGE bill?

It can shift when you buy grid power, charging in cheap hours and discharging in expensive ones. Whether that saves money depends on your rate schedule, usage, battery losses and the charge you hold back for outages. Pepco and Baltimore Gas and Electric (BGE) each publish a residential time-of-use (TOU) schedule, and other utilities publish their own.^5,6

Here are the two Maryland options as of October 25, 2026:

Each utility builds its supply total from different components, and delivery charges sit outside both columns, so don’t read one against the other.^7,8 BGE’s delivery charge under Schedule RD has its own peak split. For rate year 3, effective January 1, 2026, it is $0.08874 per kWh on-peak and $0.03736 off-peak.⁶ Pepco’s R-TOU-P delivery table lists rate periods only through October 31, 2026, so read the current tariff for the periods after that.⁵

Peak windows matter as much as prices. Weekends and holidays are off-peak on both schedules.

BGE’s electric-vehicle rate, Schedule EV, is a separate rate for Standard Offer Service customers who buy or lease a plug-in vehicle and charge it on a single whole-house time-of-use meter. A stationary battery alone doesn’t meet that condition.⁹

Two reality checks belong in any savings estimate. First, a battery returns less energy than it takes in. The National Laboratory of the Rockies (NLR, formerly NREL) 2025 Annual Technology Baseline, a national cost model and not a household quote, assumes 85 percent round-trip efficiency and a 15-year lifetime, which means a replacement may fall inside your ownership period.¹⁰

Does the price gap beat that loss? On supply charges alone, it does. The on-peak supply price sits 8.747 cents per kWh above off-peak on Pepco and 16.338 cents above it on BGE.¹¹ At 85 percent efficiency, off-peak energy only pays off if the on-peak price is at least the off-peak price divided by 0.85, which works out to about 15.0 cents for Pepco and 13.4 cents for BGE.¹¹ Both schedules clear that bar. That test leaves out the battery’s purchase price, delivery charges and the charge you keep in reserve, so treat it as a hurdle a quote has to clear, not a promise of savings.

Second, every kilowatt-hour you spend during an expensive afternoon is a kilowatt-hour that isn’t in the battery when an outage starts. Get two comparisons built on your own interval usage and the full current tariff, one that keeps an outage reserve and one that doesn’t.

Maryland is also working on utility virtual power plant (VPP) pilots, where a participating battery could be paid to support the grid. As of the Maryland Energy Administration’s September 2026 information sheet, those programs are under development and not yet open for enrollment. The sheet also says enrolling may change how much energy stays available for backup.¹²

Does the Maryland storage rebate require solar?

No. As of October 25, 2026, the Maryland Energy Administration (MEA) lists its fiscal year 2027 Residential and Commercial Energy Storage (RCES) program as open, and the announcement doesn’t require solar. The residential rebate is 30 percent of total project cost, up to $5,000, and you need an approved reservation before anything is installed.^13,14

The announcement treats solar as optional. It lists equipment that integrates storage with a solar system as one eligible cost among several, and it excludes the panels themselves.¹³ MEA decides each application, so confirm your equipment and ownership setup with MEA’s energy storage team before you sign a contract. For the full walkthrough, see our guide to the Maryland home battery rebate.

The process runs in four steps:

1. 1Reserve
2. 2Install
3. 3Permission to operate
4. 4Payment request

A reservation expires 180 calendar days after approval. Before then the system must be installed, have PTO, and have the payment request submitted. MEA may grant an extension for causes outside your control if you ask at least 30 days ahead, and none runs past May 1, 2028.¹³ Applications close at 3:00 p.m. Eastern Time on May 31, 2027, and the portal may close earlier if the budget is fully requested.¹⁴

MEA anticipates up to $4 million for rebates this year.¹⁴ Its budget table, last updated October 19, 2026, shows 20.90 percent of that requested and 4.15 percent reserved.¹⁴ The table is headed “Total FY26 RCES Grant Program Budget” even though it sits on the fiscal year 2027 page, but its $4,000,000 total matches the FY27 budget.¹⁴

A few other rules apply. MEA says a system is ineligible if funding was secured or reserved for that same system under another MEA energy program that offers an incentive to install storage. For a purchased system, MEA needs proof of full payment, or a fully executed financing agreement if you financed it, before it approves the rebate payment. You can apply yourself or authorize your prime contractor to apply for you, but not anyone else.¹³ When you compare contractors, ask each how they handle the reservation step and the timeline.

The federal homeowner credit is a separate question. The Internal Revenue Code says the Residential Clean Energy Credit does not apply to any expenditures made after December 31, 2025, and the Internal Revenue Service describes it as unavailable for property placed in service after that date. Don’t budget a newly installed battery around it.^15,16

Can you add solar to a standalone battery later?

You can, but raise the plan before you pick the battery. Future compatibility depends on the inverter, the controls, the connection design and utility approvals. Panels added later don’t automatically give you outage charging, and they may mean changes to the original equipment.³

Ordinary grid-tied solar shuts off during an outage so utility workers aren’t endangered. NREL explains that panels can supply backup loads or recharge a battery only if the system has the right isolation and controls.³ Our guide to whether solar panels work in a power outage covers that difference.

“Solar-ready” on a quote is a label, not an approved expansion plan. Get the future solar connection, the equipment changes and the utility review in writing. If you later go ahead with residential solar, you’ll need to revisit roof suitability and whichever rules apply by then.

How do you decide if a battery-only setup fits?

Start with your reason: outage coverage or a lower bill. If the purchase only works with savings you’ve assumed or a rebate you haven’t reserved, settle those questions first. Then work through these five steps in order, so the answer is clear before you sign anything.

1. Write a priority list of circuits and describe the outage you want to cover.
2. Get the supported loads, usable energy, starting power, reserve, and depletion and recovery behavior for the exact equipment.
3. Ask your utility to confirm your rate enrollment and the charging, parallel-operation and export settings.
4. If you want the RCES rebate, confirm eligibility with MEA and get reservation approval before installation.
5. Compare the full installed scope, including inspection, commissioning, monitoring and any future solar changes, and ask for separate outage and bill-only cases.

Permit rules depend on where you live. In Montgomery County, for example, the Department of Permitting Services lists electrical permits issued with and without a building permit.¹⁷ Call your local office to learn which permits and inspections apply to the battery, the inverter and the isolation equipment.

If backup is your priority, start with a circuit and site review. 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.

Sources (17)

1. Pacific Northwest National Laboratory, “PV Battery Storage for Power Outages,” basc.pnnl.gov, published September 29, 2021; read October 25, 2026. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

2. U.S. Department of Energy, “Solar Integration: Solar Energy and Storage Basics,” energy.gov, page modified March 31, 2025; read October 25, 2026. ↩ ↩²

3. National Renewable Energy Laboratory, “Will Solar Panels Help When the Power Goes Out?” (TP-7A40-75704), docs.nlr.gov, March 2020; read October 25, 2026. ↩ ↩² ↩³ ↩⁴ ↩⁵

4. Soleil Energy, “Battery Storage & Retrofits,” soleilenergycorp.com, current page, read October 25, 2026. ↩

5. Pepco, Maryland Electric Tariff, Schedule R-TOU-P (pages 24 and 24.1), pepco.com tariff PDF, tariff book issued September 28, 2026, effective October 1, 2026 (page 24 issued August 14, 2026); read October 25, 2026. ↩ ↩² ↩³ ↩⁴ ↩⁵

6. Baltimore Gas and Electric, Electric Tariff, Schedule RD (pages 37 and 38), BGE tariff PDF, page 37 filed April 16, 2026 and effective June 1, 2026; read October 25, 2026. ↩ ↩² ↩³ ↩⁴ ↩⁵

7. Pepco, Maryland Electric Tariff, Rider SOS, page 43.2, pepco.com tariff PDF, issued September 28, 2026, rates for October 1, 2026 through May 31, 2027; read October 25, 2026. ↩ ↩² ↩³

8. Baltimore Gas and Electric, Electric Tariff, Rider 1 Standard Offer Service, BGE tariff PDF, filed August 27, 2026, effective October 1, 2026; read October 25, 2026. ↩ ↩² ↩³

9. Baltimore Gas and Electric, Electric Tariff, Schedule EV (pages 39 and 40), BGE tariff PDF, page 39 effective January 1, 2024; read October 25, 2026. ↩

10. National Laboratory of the Rockies (formerly NREL), “Annual Technology Baseline: Residential Battery Storage,” atb.nlr.gov, 2025 edition; read October 25, 2026. ↩ ↩²

11. Illustrative calculation, run October 2026, with the inputs sourced at ⁷, ⁸ and ¹⁰. Supply gaps: Pepco 21.473 - 12.726 = 8.747 cents per kWh; BGE 27.734 - 11.396 = 16.338 cents per kWh. Break-even on-peak price = off-peak price / 0.85: Pepco 12.726 / 0.85 = 14.97 cents; BGE 11.396 / 0.85 = 13.41 cents. Supply charges only; delivery charges, battery cost and outage reserve are excluded. ↩ ↩²

12. Maryland Energy Administration, “Attachment C: Information about Virtual Power Plant (VPP) pilots under development in Maryland,” energy.maryland.gov, information sheet dated September 2026; read October 25, 2026. ↩

13. Maryland Energy Administration, “FY27 Residential and Commercial Energy Storage Program Funding Opportunity Announcement,” energy.maryland.gov, issued September 24, 2026; read October 25, 2026. ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

14. Maryland Energy Administration, “Residential and Commercial Energy Storage Program,” energy.maryland.gov, current page with budget table last updated October 19, 2026; read October 25, 2026. ↩ ↩² ↩³ ↩⁴ ↩⁵

15. Internal Revenue Service, “Residential Clean Energy Credit,” irs.gov, page last reviewed or updated July 4, 2026; read October 25, 2026. ↩

16. U.S. Code, Title 26, Section 25D(h), Termination, current text including Public Law 119-21 Section 70506(a); read October 25, 2026. ↩

17. Montgomery County Department of Permitting Services, “Electrical & Mechanical Codes, Licenses and Permits,” montgomerycountymd.gov, current page, read October 25, 2026. ↩