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When a battery pays off
A battery earns money only when energy it stores is worth more later than when it was stored. That happens when:
- Your utility credits exports far below retail, as under California's Net Billing Tariff or Arizona's export rates. See net metering by state.
- Your rate plan has an expensive evening peak or a demand charge.
- A utility program pays you to let it use your battery, such as Austin Energy's Austin Energy Power Partner Battery - upfront rebate[1] or SMUD's SMUD My Energy Optimizer Partner+ battery enrollment incentive[2].
Under full retail net metering, as in Florida and most of New York, the grid already works like a free battery, so a battery is mainly for backup.
How to compare
- Usable energy (kWh): how much you can actually draw. Compare usable, not total, capacity.
- Continuous power (kW): how many appliances it can run at once. Central air and well pumps need more power.
- Peak or surge power: whether it can start motors such as an air conditioner compressor.
- Round-trip efficiency: the share of stored energy you get back. Measurement methods differ between datasheets.
- Warranty: the years covered and the energy throughput or capacity retention guaranteed.
- Built-in inverter: an all-in-one unit can be simpler to add to a new system; an AC-coupled battery may be easier to add to an existing one.
Home batteries compared, spec sheet by spec sheet
Figures are copied from each manufacturer's current datasheet for a single unit. Check the datasheet revision your installer quotes; models are updated often.
| Model | Usable energy (kWh) | Continuous power (kW) | Peak power (kW) | Round-trip efficiency | Chemistry | Built-in inverter | Warranty |
|---|---|---|---|---|---|---|---|
| Enphase IQ Battery 10C[3] | 10 | 7.08 kVA (MCDR 7.08 kW) @240 VAC | Peak output current 56 A (3 s), 44.8 A (10 s); Power Start up to 90 A LRA | AC 90% (at 50% power rating); DC 96% | Lithium iron phosphate (LFP) | Yes | Up to 15 years |
| Enphase IQ Battery 5P[4] | 5 | 3.84 kVA @240 VAC (3.33 kVA @208 VAC) | Up to 7.68 kVA peak; peak output current 32 A (3 s), 25.6 A (10 s) | AC 90% (at 50% power rating); DC 96% | Lithium iron phosphate (LFP) | Yes | 15-year limited |
| FranklinWH aPower 2[5] | 15 | Configurable 5 / 7.6 / 9.6 / 10 kW (10 kW / 11.5 kVA max continuous discharge);… | 15 kW for 10 s; 25 kW for 1 s; 185 A LRA (off-grid specs) | 90% (grid-battery-load, beginning of life, 3 kW, 77°F) | Lithium Iron Phosphate (LFP) | Yes | 15 years |
| Generac PWRcell 2[6] | 9 / 12 / 15 / 18 per cabinet (M3-M6, 3 kWh modules); 36 kWh with two M6 cabinets | 5.2 / 7 / 8.7 / 10.5 kW (M3-M6); 11.5 kW requires two cabinets with at least 7… | Max AC start capacity 65 / 87 / 108 / 130 A (M3-M6); inverter 130 LRA | 88% | Lithium Nickel Manganese Cobalt (NMC) (3.0 kWh PWRcell 2 DCB module) | No | Battery modules: 10 years or 7.56 MWh; Inverter, Cabinet, SDS: 10 years |
| LG Energy Solution RESU16H Prime[7] | 16 | Max charge/discharge power 7 kW | 11 kW for 10 sec (discharging only) | Not stated | Not stated | No | 10 years |
| SolarEdge Nexis Battery System[8] | 4.65 / 9.3 / 13.95 / 18.6 (1-4 Battery Blocks per stack; nominal 4.9-19.6 kWh) | Max charge/discharge 3.5 / 7 / 10.5 / 13 kW (1-4 blocks) | Load start 62 / 124 / 185 / 185 LRA | Peak DC roundtrip efficiency 93% | LiFePo4 | No | 10 Years |
| Tesla Powerwall 3[9] | 13.5 | 5.8 / 7.6 / 10 / 11.5 (configurable) | Load start capability 185 LRA; max output fault current 160 A (1 s) | Solar to Battery to Home/Grid 89% (typical solar shifting); Solar to Home/Grid… | Not stated | Yes | 10 years (datasheet) |
Questions to ask your installer
- Which circuits will the battery back up, and for how long at my typical evening use?
- What usable capacity does the quote include, and what does each extra unit cost?
- Which utility program or rate plan did you assume for the savings estimate?
- Who handles warranty claims if your company closes?
Panasonic has left the home solar and battery business; its existing warranties are being honored, but it is not in the table because it no longer sells new units.
FAQ
Frequently asked questions
Is a solar battery worth it?
It depends on your utility. Where exports earn much less than retail or evening power is expensive, a battery can pay back; under retail net metering it is mostly worth it for backup. Run your numbers in the calculator with and without exports.
How many batteries do I need for backup?
Add up the power of the appliances you want to run at the same time and the energy they use overnight, then compare with each model's continuous power and usable energy in the table.
Can I add a battery to my existing solar system?
Usually yes, with an AC-coupled battery or a hybrid inverter. Your utility will need a new interconnection approval before you switch it on.
sources
[ 9 ]Every number on this page links to one of these sources. Dates show when we last checked each one.
- Austin Energy - Power Partner Batteryaustinenergy.com · checked Nov 5, 2026
- SMUD - Battery storage for homeownerssmud.org · checked Nov 5, 2026
- IQ Battery 10C Data Sheet (DSH-00565-10.0-EN-2026-07-22)enphase.com · checked Nov 5, 2026
- IQ Battery 5P North America Data Sheet (DSH-00010-11.0-EN-2025-05-06)enphase.com · checked Nov 5, 2026
- FranklinWH aPower 2 Datasheetfranklinwh.com · checked Nov 5, 2026
- Generac PWRcell 2 Specification Sheet (A0008625505 REV C)generac.com · checked Nov 5, 2026
- LG Energy Solution 16H Prime Product Specification Ver 4.2 (linked from lgessbattery.com/m/us/home-battery/product-info.lg)lgessbattery.com · checked Nov 5, 2026
- SolarEdge Nexis Battery System For North America Preliminary Datasheet (DS-000263-NAM)marketing.solaredge.com · checked Nov 5, 2026
- 2025 Powerwall 3 Datasheet (North America)energylibrary.tesla.com · checked Nov 5, 2026