Home battery glossary
The terms a salesperson uses to make a quote sound better than it is, defined in plain language. We lead with the part that actually changes your decision, and we say when it does not matter.
Battery leases and PPAs: $0-down, but you don't own it
A battery lease or PPA lets a company own the battery while you pay monthly or per kWh. It is the only route with a federal credit pathway for a 2026 buyer, since the homeowner purchase credit expired at the end of 2025. The trade-off is that you never own the asset.
Depth of discharge (DoD): why usable capacity is not rated capacity
Depth of discharge is how much of a battery you can actually use. Usable kWh equals rated kWh times DoD, and on older or NMC packs that gap quietly cuts your real backup hours.
kWh vs kW: capacity vs power, explained
kWh is how much energy a battery stores. kW is how much it can deliver at once. Mixing them up is the single most common home-battery mistake, and it changes how many backup hours you actually get.
LFP vs NMC battery chemistry (and what LiFePO4 means)
Almost every 2026 home battery uses LFP (lithium iron phosphate). Here is why that chemistry beats NMC for a fixed home install, and what the LiFePO4 label on the spec sheet actually tells you.
NEM 3.0: why California solar now needs a battery
California's Net Energy Metering 3.0 sharply cut the credit new solar customers earn for exporting power. Storing your own solar is now where the value lives, which is why a battery is close to required for new California solar to pencil.
Round-trip efficiency: the energy you lose just by storing it
Round-trip efficiency is the share of energy you get back out of a battery versus what you put in. Modern home batteries land around 90 percent, so storing power quietly taxes every savings estimate you make.
SGIP: California's main home-battery rebate in 2026
The Self-Generation Incentive Program is California's main battery rebate in 2026. General Market pays $150 to $200 per usable kWh; the Equity Resiliency tier pays up to roughly $1,000 per kWh for qualifying homes. It matters more now because the federal homeowner purchase credit expired at the end of 2025.
Time-of-use (TOU) rates: why a battery is worthless on the wrong plan
Time-of-use plans price electricity by the hour, with expensive evening peaks. A battery profits by charging cheap and discharging at peak. On a flat-rate plan with no spread, that same battery barely dents your bill.
Virtual power plants (VPP): getting paid to share your battery
A VPP pays you to let your utility tap your home battery during grid stress. In California, programs can pay roughly $400 to $1,500 a year, which can meaningfully shorten payback. The catch is that availability and pay vary by utility.
Whole-home vs essential backup: what you actually need to keep running
Essential backup keeps your fridge, wifi, and lights alive for a long time on a modest battery. Whole-home backup runs everything, including AC and EV charging, but needs far more capacity and power, costs more, and drains faster. For most households, essentials are plenty.