Guide · Battery vs. Generator
Two very different answers to the same question.
Both a home battery and a standby generator answer "what happens when the grid goes down?" — but they get there through opposite engineering tradeoffs, and the numbers changed materially for 2026. Here's what actually differs, with sources.
The hardware
What each product actually is.
"Typical cost" below is equipment-only at the specific configuration noted — not an installed price. Real installs typically add several thousand dollars for electrical work, permitting, and labor. Capacity, efficiency, and warranty terms come directly from manufacturer datasheets.
Home batteries
| Model | Capacity | Continuous power | Round-trip efficiency | Warranty | Coupling | Typical cost‡ |
|---|---|---|---|---|---|---|
| Tesla Powerwall 3 | 13.5 kWh | 11.5 kW | 89–97.5% | 10 yr / 70% retention | DC-coupled | $13,500 (1 unit) |
| Tesla Powerwall 2 | 13.5 kWh | 5.0 kW | 90% | 10 yr | AC-coupled | $12,000 (1 unit) |
| Enphase IQ Battery 5P | 5.0 kWh | 3.84 kW | ~90%† | 15 yr / 6,000 cycles | AC-coupled | $8,500 (1 unit + backup controls) |
| Generac PWRcell 2 | 9–36 kWh (stacked) | 5.2–11.5 kW | 88% | 10 yr / 7.56 MWh throughput | DC-coupled | $21,500 (15 kWh M5 config) |
| FranklinWH aPower 2 | 15–225 kWh (stacked) | 10 kW | 90% | 15 yr / 60 MWh throughput | AC-coupled | $17,700 (1 unit + aGate) |
| LG Energy Solution Enblock S | 10.6–17.7 kWh | n.a. | n.a. | n.a. | n.a. | $12,500 (14.1 kWh S14 config) |
† Enphase efficiency figure is sourced from an Enphase India-market datasheet; we could not confirm it matches the U.S.-market IQ Battery 5P spec and flag it as provisional. LG Enblock S mostly lacks published consumer-facing specs — most fields above are not available (n.a.). ‡ Typical cost is equipment-only at the specific unit/configuration noted in parentheses, which may differ from the capacity figure shown in the Capacity column when that column reflects the full stackable range.
Standby generators
| Model / tier | Output (LP / NG) | Noise @ 23 ft | Warranty | Equipment MSRP |
|---|---|---|---|---|
| Generac 14 kW | 14 / 12.5 kW | ~65 dB | 5 yr / 2,000 hr | $4,569 |
| Generac 22 kW | 22 / 19.5 kW | 61–69 dB | 5 yr / 2,000 hr | $6,119 ($6,979 w/ transfer switch) |
| Kohler 20RCAL | 20 / 18 kW | 64–69 dB | 5 yr / 2,000 hr | $6,782 |
| Briggs & Stratton 20 kW | 20 / 18 kW | ~64 dB | 5–6 yr | n.a. |
Generac has no 11–12 kW tier — the lineup jumps from 10 kW to 14 kW. Annual service cost and typical equipment lifespan in years are not consistently published by any manufacturer in this table; treat any number you see elsewhere for those two figures with caution unless it cites a source.
Beyond the price tag
Where they actually differ.
Runtime
This is the sharpest structural difference. A battery's runtime is fixed by its stored kWh — once it's empty, it's empty, unless paired with solar. A generator's runtime is limited only by its fuel supply, which for a home on a natural gas line is effectively unlimited, and for LP/propane is limited only by tank size. For a multi-day outage, a properly fueled generator simply keeps going in a way no standalone battery can. Use the Backup Runtime Calculator to see the actual hours a given battery size buys for your specific load.
Noise & maintenance
Not close. Batteries run under 50 dB — essentially silent from a normal conversational distance. Standby generators run 61–69 dB at 23 feet, comparable to a loud conversation or a vacuum cleaner, and require periodic oil changes, filter replacement, and an annual service visit. A battery has no combustion engine and no scheduled maintenance beyond a firmware check.
Warranty
Batteries carry 10–15 year warranties. Generators typically carry 5-year or 2,000-run-hour warranties, whichever comes first — and a generator that runs frequently during outages, or gets exercised weekly per manufacturer recommendation, can burn through those hours well before five years is up.
Recurring income
A battery can earn money while it isn't backing up your home, by enrolling in a utility VPP or demand-response program — Tesla + utility partnerships, ConnectedSolutions, GMP BYOD, and others pay per kW of dispatchable capacity or per event. A generator has no equivalent revenue path; it only ever costs money to own. See the VPP Earnings Calculator for what this could look like in your area.
See what applies to you
Federal incentives are largely off the table for 2026, which makes state, utility, and VPP programs the whole story. Look up what's active in your state, then size a system with the calculators.
Specifications above are drawn from manufacturer datasheets and product pages as of August 2026 and may change with new product revisions. No manufacturer publishes a fully installed cost — the MSRP and capacity figures shown are equipment-only; installation, permitting, and electrical work typically add several thousand dollars for either product and vary enormously by home and region. This is not engineering or financial advice. See the methodology page for full sourcing.