Family decision brief on the Base Power whole-home battery offer for 134 Willow — plus a setup tracker for the house's utilities. Prepared September 26, 2026; updated the same day with findings from Base Power's actual contract documents (read in full). Pricing and terms can change; the final agreements control.
Base owns and controls the battery. It earns money by operating a fleet of home batteries to support the grid. In exchange, we get low-cost backup and buy electricity supply from Base at published rates currently at least 25% below ComEd’s Price to Compare. ComEd still delivers the power and sends the bill.
$3,600 is valid math — but it is the optimistic 12-year case.
The catch: $25 for 144 straight months is an assumption. The published 25% comparison applies to electricity supply, not the entire ComEd bill, and the separate electricity agreement — not the 12-year battery agreement — governs how long a particular supply price lasts. The 25% discount is only guaranteed for the first 2-year supply term; after that Base promises to meet or beat ComEd’s price to compare by an amount set at renewal.
If the 25% protection lasts only for the first two-year supply term, $25 a month produces $600 gross, or $505 after a $95 install. Later savings are unknown until renewal terms arrive.
If $25 average savings continues for all 12 years, gross savings reach $3,600 and net savings are $3,505 after the $95 install. If ComEd’s price to compare keeps climbing (it rose from 9.66¢ to 10.399¢/kWh in June), dollar savings could grow — but only while the discount holds.
It is the published promotional charge for a standard installation (limited to the first 2,000 Illinois customers — $295 after that), with no ongoing battery fee advertised. It is not a cap on nonstandard site work, electricity charges, late/rescheduling fees, early cancellation ($500 if Base recovers the equipment), damage, or failure to surrender the battery.
The part most people miss: the battery deal and the electricity deal are separate contracts with opposite renewal mechanics.
The benefits are practical; the costs are mostly loss of control.
Base advertises the 39.2 kWh Core in Illinois for $95, with no monthly battery fee. Comparable backup normally requires a large capital purchase.
Up to 36 hours at reduced consumption. Practically: prioritize heat controls, refrigeration, lights, internet, and the sump pump — not central A/C, dryer, oven, and EV charger as usual.
Published time-of-use supply rates at least 25% below ComEd’s Price to Compare (currently 7.8¢ on-peak, 7.6¢ off-peak).
Base owns the system and is responsible for maintenance, warranty support, repairs, and replacements.
Quiet and automatic — no fuel logistics, emissions, or routine servicing of a standby generator.
Cancelling in year 5 normally means a $500 removal charge if Base recovers the equipment. Damage is charged at repair cost; blocking recovery can trigger fair-market-value damages.
Base controls charging and dispatch and only endeavors to preserve at least 5 kWh. Keep a separate plan for medical equipment and long winter outages.
Base controls when energy goes to the house, grid, or battery, and keeps the tax credits, rebates, demand-response payments, and other program value.
Base may record evidence of its ownership or make UCC filings. Disputes go to individual arbitration, generally in Austin, under Texas law; liability is limited.
Twelve years is a long time for a 2023-founded company — though Base raised $1B in August 2026 at a $13B valuation and shows no distress signals. The agreement can still be assigned to another service provider without our consent, and Illinois operations only began in June 2026 (BBB B+, 6 complaints; no independent reviews yet).
A roof or solar project in 5–7 years does not undo the case.
The battery is ground-mounted, so a normal reroof should not require removing equipment. Solar is technically compatible — Base says Core can connect to solar, and the Illinois battery agreement already requires a Net Metering Addendum. During an outage, solar may extend backup by recharging the battery. But read the addendum's economics: Base pays only $0.0348/kWh for solar exported to the grid and nothing when it dispatches the battery to the grid — compare that against ComEd's Smart Solar Billing export values before assuming solar + Base is the best pairing.
The limitation is control: Base — not us — operates the battery and keeps grid-program compensation. A future solar installer will need to design around Base’s equipment and ComEd interconnection requirements. The contract requires 90 days’ notice for improvements that may affect the battery, so get Base’s written coordination requirements before any future roof, panel, service, or electrical project.
Interpretation: Base is a good low-cost resilience decision now, even if solar is likely later. It is less attractive only if owning and personally optimizing a solar battery is already a near-term priority.
Updated with findings from the contract documents — items marked confirmed are resolved; the rest need action.
The five biggest risks, straight from the contract documents.
In 2038, renewal is opt-in — not automatic.
About 30 days before the renewal date, Base must provide notice and an opportunity to renew under the terms available at that time. To continue, we must notify Base in writing during that 30-day opt-in period — the new price, battery arrangement, and terms could differ from today’s deal. If we do nothing, the agreement ends; there is no automatic 12-year renewal. If service ends, Base may immediately render the battery inoperable, notify us in writing, coordinate a removal time, and remove the battery.
Base rates Core for operation from −22°F to 122°F, which covers normal Deerfield winter temperatures. But the ComEd rollout is new, and Base has not published Illinois-specific field results covering a full local winter. Two specs are still unpublished: the Core's continuous/peak AC output (kW) — needed to judge whole-home surge capability — and a cold-derating curve showing actual capacity at −22°F. Note the marketed "12–18 hour typical" backup figure is based on an average Texas household, not an Illinois winter home.
Lithium iron phosphate (LFP) batteries can discharge in the cold, but usable capacity can temporarily fall by roughly 20–30% in subfreezing conditions. Charging cold cells below 32°F can cause permanent damage, so an outdoor system must rely on thermal management and a battery-management low-temperature cutoff. In a deep-cold outage, expect less runtime than a 12–18 hour real-world planning estimate; capacity recovers as the cells warm.
Say yes unless one of these issues changes the deal: the installed price stays near $95 with no material site charges; the supply terms match the pitch; the equipment location works for the property; future solar is confirmed in writing. Pause if: site costs materially increase, we expect to sell soon, owned solar storage is a near-term goal, or the lender/trust structure creates friction.
Bottom line: a qualified yes. The everyday downside is small relative to the value: low-cost backup plus supply savings. The meaningful catch is accepting a 12-year relationship in which Base owns and controls equipment attached to the property. If the confirmations are clean, proceed.
Download the PDF briefThe PDF is the September 26 morning version — this page has the latest contract-document findings.
Setup tracker for 134 Willow — placeholders until accounts are opened around closing. Nothing here is active yet.
Delivery account must be in our name at or before the October 15 closing. ComEd keeps delivering power and sending the bill no matter who supplies the electricity.
The offer evaluated in this brief. Decision after closing; the October 16 calendar reminder covers the $95 price check. If we pass, supply stays with ComEd.
Nicor Gas serves most of the northern third of Illinois outside Chicago, so it is the expected provider for Deerfield — confirm when opening the account. Set up before move-in; the furnace is gas (Roberts Heating check November 3).
Seller notifies Finance by October 8 for the final meter reading; we set up our account at or before closing. Trash day is Wednesday — confirm with the village at move-in.
Provider to be chosen before move-in. Placeholder for now.
Revisit in roughly 5–7 years. See the future-proofing notes above for how it interacts with the Base battery.