Base Power and Energywell: what a nearly free home battery really costs

How a hosted battery works

In Case Study 01, we found that a homeowner who buys a battery rarely earns it back from time-of-use (TOU) bill savings alone. Hosted-battery companies flip the arrangement. They own the battery, and they earn money from the grid, not your bill.

The company is also your electricity supplier. In Texas, Base Power is a licensed retail electric provider (REP), and it says its revenue comes from the power grid rather than from homeowners (Base Power). In Illinois, both companies are paid through the state's Clean and Reliable Grid Affordability (CRGA) Act, which rewards batteries that help balance the grid. They charge customer batteries when power is cheap and send stored energy back during peak demand, according to the Citizens Utility Board (CUB). That grid revenue is what pays for the free or low-cost installation.

The monthly fee is not the business. An analysis of Base by Sacra notes that its $19–$29 fees alone would take more than 20 years to pay back the battery. Investors are betting on the grid revenue: Base raised another $1 billion in August 2026 at a $13 billion valuation (Canary Media).

The three offers, side by side

Base Power operates in Texas and, since mid-2026, in parts of ComEd's northern Illinois territory. Energywell, affiliated with the Illinois supplier Think Energy, is available only in select ComEd neighborhoods (CUB). Neither offer is available in Ameren Illinois territory.

The test homes

We use average-sized homes in each market and compare the hosted offer with what the same household would pay without it. Everything else, including utility delivery charges, is the same either way.

Texas: the battery is cheap, not free

Base's Texas pitch is a fixed energy rate that it says is below market and stays below market at renewal. With Oncor's delivery charges added, our test home pays about 14.16¢ per kWh all-in, or about $2,039 a year. Add $228 a year in membership fees and the $695 installation spread over 12 years, and the Base household spends about $2,325 a year.

That makes one number decisive: the all-in price of the plan you'd choose without Base. If it's above about 16.1¢, the battery pays for itself through lower energy costs. Below that, you're paying for backup.

Against the average Texas price, the Base household spends only about $29 a year more. That works out to about $352 over 12 years for 39 kWh of whole-home backup, which is close to free. Against a household that shops well and renews carefully, Base costs about $496 a year more, or roughly $5,951 over 12 years. That's still a fraction of the cost of owning the equipment, but it's a real cost, and Base's comparison marketing sets its rate against incumbent plans that most careful shoppers wouldn't choose.

Renewal is the other unknown. The energy rate is fixed for 36 months; the battery agreement runs 12 years. At renewal, Base's terms promise a "competitive" price. If it's higher than the average comparable plan on Power to Choose and Base can't match it, you can leave without owing a cancellation charge (Energy Choice Matters). That protection is meaningful, but it's tied to the market average, not the best price available.

Illinois: you get paid to host

The Illinois offers are more generous because the savings are guaranteed against a published benchmark. Both undercut ComEd's Price to Compare by at least 25% (CUB). For our 8,000 kWh home, that's about $212 a year with Base and $208 with Energywell. Energywell's cheapest hours are only 11 p.m.–5 a.m., so fewer kWh get its deeper 28% discount. Neither offer charges a monthly fee.

That guarantee stands out. In the year to May 2026, the roughly 716,000 ComEd households buying from alternative suppliers paid about 1.28¢ per kWh more than ComEd's price, even after adjustments, according to the Illinois Commerce Commission. These are among the few supply offers built to beat the default.

What happens after the initial term matters most. Base guarantees the full discount for two years and after that promises only to "meet or beat" ComEd's price, which could mean a discount of zero (CUB). Energywell's first term runs five years, and at renewal its rate must beat ComEd's price. If you find a lower comparable offer, it will match it or let you cancel with no fee (Energywell).

One billing detail also matters. When the company charges your battery from the grid, that energy can appear as extra ComEd distribution charges on your bill. Both companies credit it back on the supply portion of the bill. Base's credit was 3.48¢/kWh in June 2026; CUB couldn't confirm Energywell's amount (CUB). Check that the credit appears on your first few bills.

Compared with buying backup yourself

A hosted battery makes the most sense as a backup purchase. If you'd otherwise pay for a generator or a large battery, the comparison looks very different from the bill-savings view.

Even the most expensive hosted case, Base in Texas against a well-shopped plan at about $496 a year, costs roughly a third of owning a battery in Texas. In Illinois, the hosted offers pay you while an owned battery still costs $500 to $1,500 a year after the new rebate. The rebate helps owners, but it doesn't close the gap.

What you give up

1. Control of the battery

The company owns the battery and decides when it charges and discharges. Base's help center says backup energy can't be guaranteed and shouldn't be used for life-critical devices (Base Power). CUB notes that neither company guarantees a full charge when an outage starts (CUB). A battery you own can be set to hold a reserve before a storm; a hosted one may be partly drained after supporting the grid.

2. Flexibility for 12 to 15 years

You're tied to one supplier and one battery through at least two or three rate cycles. When new programs arrive, such as ComEd's residential virtual power plant tariff, expected in spring 2027 (CUB), or cheaper batteries, joining may mean paying to leave.

3. Rooftop solar

Energywell's agreement excludes homes with solar or other on-site generation during the 15-year term. Base warns that Illinois solar owners may pay more than they would with ComEd, which offers net metering and hourly pricing (CUB). In Texas, Base buys back excess solar at a flat rate (Base Power). If solar is in your plans, price it before you sign.

4. Moving is a negotiation

Both companies let you transfer the agreement to a buyer. If the buyer doesn't want it, you owe the exit fee (CUB). A battery contract becomes one more item in the home sale.

Who this fits

• A good fit: homeowners who want whole-home backup, plan to stay 12 years or more, don't have and don't plan to add solar, and would otherwise buy a generator or leave the default supply rate untouched.
• A weaker fit: Texas households who already shop for plans in the 12–13¢ range. For them, Base's energy rate may be higher than the plan they have, so the battery costs them several hundred dollars a year.
• Not a fit: renters and condo owners (both Illinois offers require an owned single-family home), solar owners, anyone who needs guaranteed backup for medical equipment, and anyone likely to move soon.

Questions to ask before signing

• What is my all-in price per kWh at my usage, including delivery, and how does it compare with my current plan?
• Exactly how is the renewal price set, and what are my options if it isn't competitive?
• What minimum charge will the battery keep for backup, and can I raise it before a storm?
• What do I owe if I move, add solar, switch suppliers, or cancel? Get each figure in writing.
• Who claims any incentives on the battery, such as Illinois' storage rebate?