Short answer
An economic solar array does not automatically make a battery economic. Storage pays only through incremental benefit versus solar alone: more self-consumption less foregone export, losses, degradation and investment.
Important variables
- Additional self-consumed kWh
- Difference between retail and export price
- Efficiency and degradation
- Battery price and useful life
RATIOXA TOOLRun your own numbersDoes solar pay? →
Worked example
If a battery shifts 1,800 kWh yearly and each kWh is worth €0.22 after losses, annual benefit is about €396 before maintenance. An €8,000 investment therefore needs a long useful life.
Break-even: What changes the result?
A wider price spread and many usable cycles strengthen storage. Oversizing, low evening demand and rapid degradation weaken it.
Common mistakes
- Double-counting solar and battery benefit
- Using all nominal capacity
- Assuming zero export revenue
Terms in this guide
Self-consumptionShare of PV generation used on site at the same time, replacing grid purchases.PVAbbreviation for photovoltaic conversion of light directly into electricity.Battery storageSystem that shifts electrical energy from one time to another.Self-consumption valueAvoided grid purchase per self-consumed kilowatt-hour.
Sources & assumptions
- IEA PVPS — Photovoltaic Power Systems Programme (2026-08-17)
- RATIOXA — Methodology and formulas (2026-08-17)
Continue learning
Continue with your numbers
Was this guide helpful?