Cheap battery vs cheap system
Battery cost per usable kWh
Put different battery routes on the same footing. Enter the prices and capacity evidence you actually have; the tool does not assume that one technology must win.
Estimated usable capacity = nominal capacity × state of health × chosen usable window. Complete cost includes the battery, controller or BMS, inverter and other entered costs. Figures stay in your browser and are not sent anywhere by this static page.
Reading the results
Battery-only £/nominal kWh
Useful for checking the headline purchase price, but it ignores degradation and operating limits.
Battery-only £/usable kWh
Adjusts the purchase price for estimated remaining capacity and your chosen working window.
Complete-system £/usable kWh
Adds the equipment needed to turn the battery into working storage. Do not add hardware already included in the pack.
What this does not calculate
Cycle life, efficiency, tariff savings, installation suitability or payback. Use the main calculator for household energy modelling.
Need the household answer?
Use the full calculator for solar generation, tariffs, battery shifting and payback.