his guide shows you the best home battery options, how the systems work with grid and solar, what specs actually matter, and how to size a system for your house. You’ll also see a simple calculator, side-by-side comparison tables, and an FAQ that answers the questions homeowners ask most.
Quick picks for home backup scenarios
| Scenario | Recommended choice | Why it fits | Typical system size |
|---|---|---|---|
| Whole-home backup with central AC | High-power, stackable LiFePO4 packs paired with a compatible hybrid inverter | Higher continuous/peak kW, scalable kWh | 20–40+ kWh total, 10+ kW output |
| Essential loads backup only | One powerwall-style 51.2 V LFP unit with critical loads sub-panel | Keeps fridge, lights, Wi-Fi, sump pump running | 10–15 kWh, 3–5 kW output |
| Budget install with room to grow | Rack-mount 51.2 V modules that add capacity in steps | Lowest $/kWh, easy expansion | Start 10 kWh → add as needed |
| Cold-climate reliability | LFP batteries with low-temp charging protection | Safer chemistry, stable in cold | 10–30 kWh depending on loads |
| Off-grid cabin or RV | Modular LFP with solar charge controller | Simple, robust, long cycle life | 5–15 kWh, 2–5 kW output |
How a home battery backup works with grid and solar
A home battery sits between your main service panel and your solar inverter (or pairs with an all-in-one hybrid inverter). When the grid fails, the battery and inverter form a protected island so your critical circuits keep running. During normal days the system can:
- Store daytime solar for evening use (self-consumption).
- erform time-of-use arbitrage (charge off-peak, discharge on-peak).
- Provide backup power during outages.
Key parts: battery pack (kWh), inverter/charger (kW), battery management system (BMS), transfer/islanding device, and a critical loads panel if you’re not doing whole-home backup.
How to choose a solar battery for home backup
- Usable capacity (kWh) — How long you can run. Most homes use 8–30 kWh/day.
- Continuous and peak power (kW) — What you can run at once and start surges (AC, well pump).
- Chemistry — LiFePO4 (LFP) is the ESS favorite: long cycle life, stable, wide safety margin. NMC/NCA are higher energy density, common in some brand packs.
- Scalability — Can you stack more units later? Check min/max kWh.
- Coupling method — AC-coupled is easiest for retrofits; DC-coupled can be more efficient in new installs.
- Warranty and throughput — Years (often 10–15) and MWh throughput or cycle count.
- Efficiency and temperature — Round-trip efficiency and low-temp charging support matter.
- Compatibility — Inverter brand, grid code compliance, UL9540/9540A certifications.
- Budget — Equipment + installation. See the cost section below.
AC coupled vs DC coupled home battery
AC-coupled systems
- Perfect for adding a battery to an existing PV system.
- Simple wiring; each unit has its own inverter.
- Slightly lower round-trip efficiency than DC in some cases.
DC-coupled systems
- Best for new builds with hybrid inverters.
- Fewer conversions, potentially higher efficiency.
- Tighter integration and often lower BOS cost.
Rule of thumb: Retrofits → AC-coupled. New installations or full re-work → DC-coupled. Always confirm compatibility with your installer.
Compare top home battery systems in 2025
Values are typical bands to keep this page evergreen; check the latest datasheets before purchase.
| System | Chemistry | Usable kWh per unit | Continuous / Peak kW | Coupling | Scaling range | Warranty notes | Best for |
|---|---|---|---|---|---|---|---|
| Tesla Powerwall | NMC/LFP generations | ~13–14 | ~5 / higher peak | AC | 1 → 40+ kWh | 10 yrs, throughput-based | Whole-home with multiple units |
| Enphase IQ Battery | LFP | ~10–15 | ~3–5 / higher peak | AC (micro-based) | 1 → 40+ kWh | 10 yrs | Micro-PV retrofits |
| FranklinWH aPower | LFP | ~13–14 | ~5 / higher peak | AC | 1 → 30+ kWh | 12 yrs typical | High-power essential loads |
| Generac PWRcell | NMC/LFP by batch | 9–18 (modular) | ~3–6 / higher peak | DC (hybrid) | 9 → 36 kWh | 10 yrs | New installs with Generac hybrid |
| SAFTEC 51.2 V Powerwall LFP | LFP | 10–15 | 3–5 | AC/DC via hybrid | 10 → 40+ kWh | 10–15 yrs options | Essential loads backup |
| SAFTEC 51.2 V Rack Module | LFP | 5–10 | Inverter-dependent | DC with hybrid | 10 → 100+ kWh | 10–15 yrs options | Budget and scalable |
| SAFTEC Stackable ESS | LFP | 10–20 each | 5–10 with inverter | AC/DC | 20 → 60+ kWh | 10–15 yrs options | Whole-home expansion |
How many batteries do I need for whole home backup
Estimate daily energy use (kWh).
- Light use apartment: 8–12 kWh/day
- Typical family home: 15–25 kWh/day
- Large home with electric cooking/EV: 25–40+ kWh/day
Decide backup hours or days.
- Storm-day essential loads: 12–24 hours
- Whole-home overnight: 10–16 hours
- Multi-day resilience: 1–3 days (with solar recharge)
Do the math.
Required capacity ≈ daily kWh × backup days × 1.15 (losses headroom)
Examples
- Essentials only, 12 kWh/day × 1 day → ~14 kWh ⇒ one 10–15 kWh unit
- Whole-home, 24 kWh/day × 1 day → ~28 kWh ⇒ two 13–15 kWh units
- Two-day outage, 20 kWh/day × 2 → ~46 kWh ⇒ three to four units or a rack stack
Power limit matters: Even with enough kWh, you need sufficient continuous/peak kW to start AC compressors or well pumps.
Can a battery backup run air conditioner at home
Yes—if the system has enough kW. Central ACs can need 3–6 kW running and 2–3× surge for a few seconds. Options:
- For whole-home with AC, size for 10+ kW continuous (multiple units or higher-power inverter).
- Or move AC off the critical loads panel and back up only the essentials.
Soft-start kits and inverter-driven heat pumps reduce surge and help battery systems.
Solar battery price and installation cost explained
Pricing varies by brand, region, and labor scope. Typical installed ranges (equipment + BOS + labor):
- Essential-loads single unit 10–15 kWh: $8k–$15k
- Whole-home multi-unit 20–30 kWh: $15k–$30k+
- Adders: service upgrades, sub-panel work, generator integration, roof-mounted PV retrofits.
Incentives: federal tax credits in some markets, state programs, utility rebates, and demand-response payouts. Check local rules.
Home battery warranty cycle life and safety basics
- Warranty length: commonly 10–15 years with energy throughput caps.
- Cycle life: LFP often reaches 3000–6000+ cycles under typical DoD and temperature.
- Safety: Look for UL9540/9540A, thermal protections, and an active BMS that monitors cell voltage, current, and temperature.
- Environment: Avoid charging below manufacturer low-temp limits; ensure ventilation clearances per installer guidance.
Frequently asked questions on home battery backup
What is the best solar battery backup for home use?
For most homes a LiFePO4 system with 10–15 kWh per unit, stackable capacity, and a compatible hybrid inverter covers essentials with room to expand.
How long will a 10 kWh or 13.5 kWh battery last?
Essentials around 500–800 W average → 10 kWh ≈ 10–15 hours; 13.5 kWh ≈ 13–20 hours. Real time depends on loads and inverter efficiency.
How many batteries do I need for a 3-day storm?
Daily 20 kWh × 3 × 1.15 ≈ 69 kWh usable. That’s five 13–15 kWh units or a larger rack bank, assuming limited solar recharge.
Can I charge a home battery from the grid?
Yes. Many systems support grid charging for time-of-use savings and pre-storm top-up.
Is AC-coupled or DC-coupled better for me?
Retrofit PV → AC-coupled is simplest. New hybrid inverter → DC-coupled can be more efficient.
What is the difference between LFP and NMC in home batteries?
LFP prioritizes cycle life and thermal stability. NMC emphasizes higher energy density. For stationary storage, LFP is widely favored.
Can a home battery run central air conditioning?
Yes with adequate kW. Many homes need multiple units or a higher-power inverter for whole-home with AC.
What maintenance do home batteries need?
Very little: keep clearances, update firmware when advised, and follow the installer’s health checks.
Battery size and runtime quick reference
Battery size chart you’ll see in residential systems:
- 10–15 kWh single unit for essential loads
- 20–30 kWh stacked for whole-home overnight
- 40 kWh and above for large homes or multi-day goals
Rule of thumb: start with essentials, monitor usage, and add modules as needs grow.