A home battery does one thing: it moves energy from a moment when electricity is cheap or free to a moment when it is expensive. Everything about whether it is worth buying follows from how big that price gap is where you live. The hardware is roughly the same everywhere. The economics are not, and they vary enough that the same battery is an obvious win in one household and a decade-long payback in another.
Start with the tariff, not the product.
What changed in 2026
- Time-of-use pricing spread further. More utilities moved residential customers onto tariffs with meaningful peak and off-peak differences, which is the condition that makes storage pay.
- Export rates kept falling. As solar penetration grew, the credit for sending power back to the grid declined in many markets, shifting the value case from export toward self-consumption.
- Chemistry options widened. Lithium iron phosphate remained the default while sodium-ion batteries began appearing in stationary products where weight is irrelevant.
- Backup became the leading motivation in some regions. In areas with unreliable supply or wildfire-related shutoffs, resilience rather than arbitrage drove most purchases.
Sizing without overbuying
| Household situation |
Sensible starting size |
Reasoning |
| Solar, high evening use, TOU tariff |
Covers evening peak load |
Shifts self-consumption; the strongest case |
| Solar, low evening use |
Small or none |
Little to shift; export may be better |
| No solar, wide TOU spread |
Covers peak-hour load |
Charge off-peak, discharge on-peak |
| No solar, flat tariff |
None |
Nothing to arbitrage |
| Frequent outages |
Sized to critical loads, not whole home |
Backup value is about duration on essentials |
The most common and expensive error is sizing to daily consumption. You do not need to store a full day. You need to cover the hours where power is expensive or unavailable, which for most households is a fraction of daily use. A smaller battery cycling fully every day earns more per unit of capacity than a large one cycling partially.
The numbers that decide the quote
Three specifications matter more than the headline capacity.
Usable capacity. Nameplate is what the cells hold; usable is what the system will let you take out. Depth-of-discharge limits protect cell life and reduce what you actually get. Compare quotes on usable kilowatt-hours.
Round-trip efficiency. Energy in is not energy out. Losses of a tenth or more are typical across the inverter and battery together. A system with meaningfully better efficiency delivers more from the same charge.
Continuous power output. Capacity determines how long; power output determines what you can run at once. A large battery with modest output cannot start a heat pump or run an oven, which matters enormously for backup.
For backup specifically, understand that grid-tied batteries do not automatically power your home during an outage. Islanding requires a transfer switch and specific inverter capability, and whole-home backup requires panel work. Confirm what a quote includes rather than assuming. Our guide to home battery backup systems covers the equipment side.
Common mistakes
- Sizing to daily kilowatt-hours. Size to the expensive window.
- Comparing nameplate capacity across quotes. Usable capacity and efficiency change the real number substantially.
- Assuming backup is included. It is a separate capability with separate cost and wiring.
- Ignoring cycle warranty terms. A warranty stated in cycles at a given depth of discharge tells you more than one stated in years.
- Buying before checking tariff options. Switching to a time-of-use plan sometimes improves the case dramatically, and sometimes reveals there is no case.
FAQ
How long do home batteries last?
Warranties commonly run around a decade or a stated cycle count, with capacity retention guarantees. Real life depends on cycling depth and thermal conditions.
Does a battery let me disconnect from the grid?
Almost never economically. Off-grid requires large generation and storage overprovisioning for the worst week of the year, which costs far more than staying connected.
Should I add a battery to existing solar?
Often yes if you have a time-of-use tariff and low export rates, because self-consumption becomes more valuable than export. Run the numbers on your actual usage pattern.
Is sodium-ion worth considering?
For stationary storage, increasingly yes — the weight penalty is irrelevant and the material costs are lower. Ask installers whether they offer it and compare on cycle life.
Where to go next
For chemistry choices, read sodium-ion batteries explained and solid-state batteries. For equipment selection, best home battery backup systems, and for cutting the bill before you buy hardware, energy bill optimization.