It depends on your state. With full net metering a battery adds little; under net billing such as California's NEM 3.0, exported power earns a fraction of the retail rate and a battery becomes the main lever. Pick the export rule that matches your utility.
Starting values only. Your bill is the source of truth: enter your own import and export price in the simulator above.
| Typical import price | $ 0.12 – 0.35 per kWh, by state |
|---|---|
| Export | Net metering in many states; net billing at $ 0.03 – 0.08 per kWh in others (e.g. California NEM 3.0) |
| Solar yield | about 1,200 – 1,700 kWh per kWp per year |
| Battery prices | about $ 700 – 1,100 per usable kWh installed, before the federal tax credit |
Check your utility. Choose "Net metering (yearly)" if exports are credited at the retail rate, otherwise "Paid per kWh" with your export rate.
Enter your net cost after the Investment Tax Credit in the advanced fields.
Not yet. Both can make a battery more valuable than shown.
Other countries: NetherlandsGermanyBelgiumUnited KingdomIrelandFranceSpainItalyAustriaSwitzerlandAustraliaSouth 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.