Battery storage went from "nice but unaffordable" in 2018 to "mandatory in some states" in 2026. The deciding factors are simpler than the marketing suggests.
The 3 questions that decide it
1. What does your utility pay you for exports?
If it's full retail rate, you don't need a battery for economics. If it's less than 50% of retail (most successor tariffs), a battery often pays back through self-consumption.
2. Do you lose power more than 3 times a year?
If yes, the backup value of a battery is real — even hard to monetize, it's worth $500–$1,500/year in convenience. If you've never lost power for more than an hour, this value is closer to $0.
3. Are you on a time-of-use rate plan with steep peak pricing?
If on-peak rates are 2x off-peak (common in CA, MA, NY, parts of TX), batteries can arbitrage by storing cheap off-peak energy and discharging during peak. The math gets attractive when the spread is wider than 12¢/kWh.
The actual cost in 2026
- Tesla Powerwall 3 (13.5 kWh): $11,500–$13,500 installed
- Enphase IQ Battery 10C: $13,000–$15,500 installed (10 kWh)
- FranklinWH aPower (13.6 kWh): $11,000–$13,000 installed
The 30% federal tax credit applies. Net cost after credit: $7,700–$10,800.
Don't add a battery just because…
- "To go off-grid." A single residential battery doesn't get you off-grid. Real off-grid requires 3–4 batteries plus a generator backup.
- "To sell electricity back." Most states don't let you arbitrage retail rates with stored grid energy.
- "It's the future." Future-proofing is rarely worth $10,000 in present-day dollars.
Do add a battery when…
- You live in California, Arizona, Nevada, or another successor-tariff state.
- You have frequent outages and need to keep critical loads (refrigerator, well pump, medical equipment) running.
- You're on a TOU rate with at least a 12¢/kWh peak/off-peak spread.
- You're planning an EV purchase within 3 years (battery + solar + EV charging is a strong combo).