Germany has no net metering: exported solar power earns the EEG feed-in tariff of about 8 cents, while household electricity costs 30 – 40 cents. That gap is why batteries are popular, and why their size matters. Start with German values and enter your own tariff.
Starting values only. Your bill is the source of truth: enter your own import and export price in the simulator above.
| Typical import price | € 0.30 – 0.40 per kWh all-in |
|---|---|
| Export | EEG feed-in tariff, roughly € 0.08 per kWh for small roofs |
| Solar yield | about 950 – 1,100 kWh per kWp per year |
| Battery prices | about € 500 – 900 per usable kWh installed |
Because the spread between the feed-in tariff and the retail price is large. Every kWh you store instead of export saves you the difference, often 25 cents or more.
Not always. Once the battery covers your evening and night, extra kWh cycle less and pay back slower. Compare the sizes in the table above.
Since 2023 small systems can choose full export or self-consumption with export of the surplus. The simulator models self-consumption first, which is the common choice with a battery.
Other countries: NetherlandsBelgiumUnited KingdomIrelandFranceSpainItalyAustriaSwitzerlandAustraliaUnited StatesSouth Africa all countries
Change anything. Results update instantly. Pick a country for typical starting values, then type your own tariff from your bill.
Same roof and prices, only the battery changes. Bigger is not always better: once the battery covers your evenings, extra kWh sit idle.
| Battery | Battery saving / yr | Self-sufficient | Cycles / yr | Payback |
|---|
Every 15 minutes the simulator decides where each kilowatt-hour goes. Solar covers your use first, the surplus charges the battery, the battery covers your evening, the rest goes to or comes from the grid.
Your yearly kWh is spread over 365 days using a daily pattern for your profile: evening peaks for a home, daytime use for a business, more in winter than in summer.
Your panels produce a bell curve each day, long in summer and short in winter, scaled to the yield per kWp for your region. Nothing at night.
Every 15 minutes: solar covers your use first, the surplus charges the battery, the battery covers your evening, the rest is exported or imported. With 90% round-trip efficiency.
The same calculation runs on real smart-meter data in the WVE customer portal in the Netherlands: a virtual battery that follows a customer's measured 15-minute consumption for a month, with notifications and a report. Suppliers and installers can licence the engine for their own app, their own data and their own customers.
Free option: put the simulator on your own website in two minutes. Pricing for the engine starts with a pilot; software licence from € 995 per month including 100 simulations. We reply within two working days.