Solar battery storage
Powerwall, Enphase, LG — backup + time-of-use savings. We match you with up to 4 vetted local contractors who verify their license and insurance with our network.
Solar battery storage is the home-services category with the steepest learning curve. The technology is good and improving fast, but the install variables matter enormously: which battery brand fits your existing inverter, how much backup capacity you actually need, whether to do whole-home or essentials backup, and what your local utility's time-of-use rate structure does to the math.
This page covers what you need to know before scheduling: when battery storage actually makes sense (and when solar alone is enough), how to size your battery to your daily kWh use, brand decisions (Powerwall vs Enphase IQ vs LG vs FranklinWH), and whole-home vs essentials-only backup. We connect homeowners with NABCEP-certified solar installers and vetted battery specialists.
When battery storage is the right call
Solar battery storage makes sense in three distinct situations, and the right answer for your home depends on which one applies.
Grid-instability backup: regions with frequent or extended outages (PSPS shutoffs in California, hurricane-belt Florida and Gulf Coast, ice-storm Texas and Tennessee, derecho-prone Midwest). The value here is reliability — keeping critical loads running through outages of hours to days. Battery sizing follows your essentials profile: refrigerator, internet, lighting, well pump, medical equipment, possibly HVAC.
Time-of-use rate optimization: regions with utility tariffs that charge more during peak hours (California IOUs, parts of New England, Hawaii, Arizona). Battery charges during off-peak (often midday solar production) and discharges during peak (evening). The savings come from rate arbitrage; they only work in markets with significant peak/off-peak rate spreads (typically 2x or more).
Solar self-consumption maximization: states with poor net-metering buyback rates or "net billing" structures that pay you less than retail for exported solar. Battery captures excess solar production for later use rather than sending it to the grid at low value. Particularly relevant in California post-NEM 3.0, which significantly reduced solar export compensation.
Battery storage is NOT typically the right call in: stable-grid markets with full retail net metering, homes without solar (a battery alone is just a backup generator with worse economics), or homes where the existing solar inverter is incompatible with the available battery options without expensive replacement.
Sizing the battery to your home
Battery sizing follows two different math depending on your goal. Both start with measurement, not estimation.
For backup-during-outages sizing: identify your essential loads and how long you want them to run. A standard refrigerator draws ~150-200 W continuous, ~1.5-2 kWh per day. A well pump cycles ~1-3 kWh per day. Internet equipment ~0.5 kWh. Add LED lighting at 0.2-1 kWh per day depending on usage. The total essentials profile is usually 4-8 kWh per day. A 13.5 kWh Powerwall covers essentials for ~2-3 days; two Powerwalls take you to 4-6 days.
For whole-home backup including HVAC: the math gets harder fast. Central air running 6-8 hours per day in summer can draw 30-50 kWh on its own. Heat pumps in winter, similar. Whole-home backup typically requires 2-4 batteries plus careful load management — hardware that automatically sheds non-essential loads when battery state of charge drops.
For time-of-use arbitrage sizing: match the battery capacity to your peak-rate consumption window. A typical California peak window (4-9 PM) might consume 8-12 kWh. A 13.5 kWh Powerwall covers that with margin. Larger homes or higher peak consumption argue for 2 batteries.
The right install starts with a current load profile from your utility (most utilities provide 12 months of hourly usage data on request). The contractor's software uses this to model battery sizing. Anyone proposing battery sizing without your actual usage data is sizing by rule of thumb.
The major brand decisions
Battery brand fit depends mostly on your existing solar inverter and backup architecture goals:
- Tesla Powerwall 3 — fully integrated solar + battery + inverter in one box. Strong app, mature install ecosystem, the default for new solar+battery installs. 13.5 kWh per unit, stackable. Lower install complexity but locks you into Tesla's integration path.
- Enphase IQ Battery (5P, 10C, 20C) — integrates with Enphase microinverter solar systems (a large share of new residential solar). Modular sizing, AC-coupled, robust monitoring. Best fit if your solar is already Enphase or you're installing solar + battery together.
- LG Energy Solution (Home 8, Home 16) — competitive on price-per-kWh, AC-coupled architecture, works with most existing inverters. Less integrated than Tesla or Enphase but more flexible across solar systems.
- FranklinWH aPower 2 — newer entrant focused on whole-home backup. AC-coupled, large capacity (15 kWh per unit), smart load management built in. Strong choice for whole-home backup with managed loads.
- Generac PWRcell — battery + automatic transfer switch + load management as integrated system. Common in markets where Generac's standby generator dealer network already operates.
Whole-home vs essentials backup
The whole-home vs essentials backup decision is one of the biggest cost variables in a battery install — and one of the most over-sold.
Essentials backup architecture: a critical-loads subpanel handles refrigerator, internet, lighting, well pump, medical equipment, and one or two outlets per room. The battery and inverter are sized to support this subpanel during outages. Lower battery capacity required (often single-battery), lower total install cost, simpler architecture. The tradeoff: when the grid is out, your AC and large appliances stop working.
Whole-home backup architecture: the battery + inverter system supports the entire main panel during outages, often with a smart load-management controller that automatically sheds non-essential loads when state of charge drops. Higher battery capacity required (typically 2-4 batteries), higher install cost, more complex architecture. The benefit: AC, electric oven, and other large appliances continue working through outages.
The deciding question is usually: how long does the outage last in your area, and what loads matter? In a region with 4-12 hour outages, whole-home backup is overkill — you can run AC for that duration on essentials backup if you size the battery up. In a region with 2-5 day extended outages (hurricane recovery, PSPS), whole-home backup matters because AC for days vs hours is a quality-of-life difference.
A hybrid architecture exists: install the larger battery for whole-home capability but configure with a smart load controller that initially supports the whole home, then automatically reduces to essentials as battery state of charge drops. This preserves comfort during short outages while extending coverage for long ones.
Common solar battery install failures
Patterns that show up in 3-5 year follow-ups:
- Battery sized to a rule-of-thumb (13.5 kWh "because that's a Powerwall") rather than to actual usage — under-performs in real outages
- Critical-loads panel not properly isolated from main panel — backup feeds the wrong circuits
- Inverter compatibility mismatch — DC-coupled battery wired to existing AC-only solar inverter, or vice versa
- Generation interconnect agreement not filed with utility — the system is technically illegal until paperwork lands
- Permit not pulled or final inspection not completed — bigger problem than it sounds for resale
- Outdoor battery installations in environments outside the manufacturer's temperature spec — capacity degrades faster than warrantied
- Smart load management not commissioned correctly — whole-home system that turns off the wrong things during outages
Frequently asked questions
Do I need solar to install a battery?▾
No, you can install a battery without solar — but the economics are usually worse. A battery without solar is essentially a quiet backup generator: it provides backup during outages and possibly time-of-use arbitrage, but you have no source of free daytime energy to charge it (you're paying full retail electric rates to charge from the grid). The math is most favorable when you have or are installing solar at the same time. A standalone battery makes sense in markets with very high time-of-use rate spreads or for homeowners specifically buying backup capability without solar interest.
How long does a battery last during an outage?▾
Depends on the battery capacity and your loads. A single 13.5 kWh battery covering essentials (~5 kWh per day) lasts 2-3 days. The same battery powering whole-home loads including AC may last 4-12 hours. The math is straightforward: divide battery capacity by your hourly load. The variable that matters most is what you're running — AC and electric stoves are the big draws. A battery covering only refrigerator, internet, and lighting can run for days; the same battery powering AC runs for hours.
Which battery is best — Powerwall, Enphase, LG, or FranklinWH?▾
There's no universal best. Tesla Powerwall 3 is the default for most new solar+battery installs because of its integrated solar/battery/inverter package. Enphase IQ is the best fit if you already have Enphase microinverter solar. LG is competitive on price-per-kWh and works with most existing inverters. FranklinWH is strong for whole-home backup with smart load management. The right answer depends on your existing solar (or lack of it), your backup architecture goals, and your utility rate structure. A good installer walks through all four options based on your specific situation.
Can I get whole-home backup with one battery?▾
Usually no. A single 13.5-15 kWh battery handles essentials backup or short-duration whole-home backup, but sustained whole-home operation including AC typically requires 2-4 batteries plus a smart load-management controller. The exception is small homes with low daily kWh (under 25 kWh/day) where careful load management can stretch a single battery to whole-home backup for multi-hour outages.
How long does a solar battery install take?▾
1-2 days for a battery added to an existing solar system, depending on inverter compatibility and panel work. 3-5 days for solar + battery installed together (the solar part is the bigger time variable). Permits and utility interconnect can add 4-12 weeks of calendar time before commissioning, depending on local AHJ and utility process.
What rebates and incentives apply?▾
Federal: the 30% Investment Tax Credit (ITC) under the Inflation Reduction Act applies to solar + battery installs. The battery alone qualifies if it's charged primarily from solar. Various state and utility programs add layered incentives — Self-Generation Incentive Program (SGIP) in California, Massachusetts SMART, NY-Sun, and others. The contractor should pull current rates from your utility and state at proposal time. Federal credit changes occasionally; verify current eligibility before assuming.
How long do batteries last?▾
Modern lithium-ion home batteries typically warranty 10 years with 70% capacity retention at end of warranty. Real-world results vary by climate (heat is harder on batteries), cycle count (deeper daily cycling wears them faster), and brand. Tesla and Enphase both have longer-term operational data showing batteries hitting their warranted capacity. Plan for a 10-15 year useful life, with some replacement consideration around year 10-12.
How do I find a vetted battery installer?▾
Use the form on this page. We match you with NABCEP-certified solar installers and vetted battery specialists licensed in your state with current insurance verified at network admission.