Storage
Solar Batteries
Sized in usable kilowatt-hours, against your critical loads and how many days of autonomy you want — not against your whole-home average, which overbuilds by roughly four times.
What to compare
- Usable capacity, not nominal — LiFePO4 gives 90-95%, lead-acid 50%
- Cycle life at a stated depth of discharge
- Low-temperature charge protection if it lives somewhere unheated
- System voltage — 48V for anything property-scale
How to size it
Size against critical loads, not against your whole house. Household consumption averages roughly 30 kWh a day in the United States; a critical-loads list — fridge, furnace fan, well pump, lights, internet, phone charging — is usually 4-8 kWh a day. Multiply your critical figure by the days of autonomy you want, then divide by the usable depth of discharge: about 0.95 for LiFePO4, about 0.5 for lead-acid. That last division is why a 10 kWh lithium bank replaces roughly a 20 kWh lead-acid one.
Mistakes that cost money
- Sizing from the whole-house average
- It is the single most common error in off-grid planning, and it inflates the bank by roughly four times. Deciding what actually has to stay on is the real work; the arithmetic afterwards is easy.
- Confusing rated capacity with usable capacity
- Rated capacity is gross. After depth-of-discharge limits and inverter conversion losses of 10-15%, usable energy is materially lower. Compare batteries on what comes out, not on what is printed on the case.
- Charging lithium below freezing
- Charging LiFePO4 below 0 C plates lithium onto the anode and permanently reduces capacity. Discharging in the cold is fine. If the bank lives somewhere that freezes, it needs a low-temperature cutoff or self-heating.
- Mixing old and new batteries
- Batteries in parallel share current according to their internal resistance. An old cell paired with a new one drags the pair down to the weaker one's behaviour, and mixing chemistries is worse still. Replace a bank as a unit.
Options
No solar batteries listed yet. We only list components we can price and specify accurately, and we are still onboarding retailers for this category.
The guides below cover how to choose one in the meantime — they are what we would tell you before recommending any specific product.