Panels generate electricity. A battery moves some of that electricity to another time. Assess the extra cost and benefit separately.
Start with the panels
Ask for a generation estimate that reflects your roof, shading and location. Compare that estimate with your electricity use across the day and across the seasons. Annual totals alone cannot tell you how much solar electricity you will use directly.
Price the battery separately
Request two comparable quotes: the solar installation on its own and the same installation with a battery. The additional benefit must account for electricity that would otherwise have been exported, energy lost in storage and the battery’s usable capacity. Extra self-sufficiency does not automatically mean a faster return.
Compare three everyday scenarios
Consider your home as it is today, with flexible appliances shifted into daylight hours, and with storage added. Use realistic routines in every case. If backup power matters, ask exactly which circuits work during an outage; this is not a standard feature of every battery installation.
Match the system to an ordinary day
Sketch a weekday from breakfast to bedtime. A home office, a dishwasher after lunch and evening cooking create different opportunities to use solar electricity. Repeat the exercise for a weekend. The useful question is how much demand overlaps with production, not whether someone is technically at home. A small daytime load can still leave a large surplus, while vehicle charging can absorb it quickly.
Put a value on moving electricity
Consider a calculation example: 1 kWh that would earn €0.08 when exported is sent to storage instead. If 0.9 kWh comes back out and replaces electricity costing €0.30/kWh, the avoided purchase is €0.27. The extra benefit is €0.19 after subtracting the forgone export payment, before equipment costs. This is why multiplying every stored kilowatt-hour by the purchase price overstates the battery’s contribution.
Leave room for the next stage
If you might add storage later, ask for the proposed connection approach and compatible products in writing. “Battery ready” does not tell you which models will work, whether another inverter is needed or what extra labour will cost. Also check space, cable routes and monitoring. Compare the saving from a combined installation with the flexibility of waiting until your actual solar-use pattern is clear.
Your planning checklist
- A year of electricity use and a typical daily pattern.
- Separate solar-only and battery-inclusive installed prices.
- Usable storage capacity, losses and backup specification.
- One calculation with identical purchase and export prices.
Common questions
Can solar panels work without a battery?
Yes. A grid-connected installation can supply appliances while it generates and export surplus under the relevant connection and contract arrangements. The home imports electricity when solar output is insufficient. Storage is an additional choice.
Should I buy a battery before buying an electric car?
Model both possibilities separately. The car’s charging time matters: a vehicle away during daylight has a different demand pattern from one parked at home. Do not size today’s battery around an unconfirmed future routine.