Should You Add Battery Storage to a Multifamily Solar Project?

The three questions

1. Does your utility have time-of-use rates with a wide peak-to-off-peak spread? If peak rates are 2.5×+ off-peak, storage arbitrage works. If your utility is flat-rate, storage is decorative.
2. Do you have a demand charge? Rare on residential; common on mixed-use. If yes, storage pays back fast through demand shaving.
3. Is resilience part of the value proposition? In hurricane and wildfire markets, backup power is a real leasing feature. Whether it supports a rent premium depends on the local market.

Cost delta

Adding storage roughly doubles the per-unit installed cost vs. solar alone. A federal credit can apply to qualifying storage, on its own rules and its own timeline, and bonuses may apply in some census tracts. Rate and eligibility are project-specific.

When it works

• California multifamily with NEM 3.0 (storage recovers most of the export-rate loss).
• Texas properties in ERCOT with wholesale-indexed billing.
• Any hurricane-zone Class A property using resilience as an amenity.

When it doesn't

• Flat-rate utility markets with no demand charges.
• Properties under 20 units — the fixed cost of a battery cabinet doesn't amortize.

Default recommendation: start with solar-only, wire in a storage-ready inverter, add batteries in year 3 if TOU spreads widen.

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