EV from Solar Calculator
How much of your EV charging your solar covers, and the remaining grid cost.
About
Combines your driving distance, EV efficiency and solar system size to estimate how much of your annual EV charging comes from your own roof and how much you still buy from the grid.
How it works
- Daily EV demand = (kWh/100 km × daily km) ÷ 100.
- Annual solar production = system kWp × annual yield (kWh/kWp).
- Default: 50% of production overlaps with charging windows. Smart charging or a battery raises this to 70–80%.
Frequently asked questions
How much solar do I need to fully cover my EV?+
For a typical 15,000 km/year driver consuming ~2,500 kWh/year for charging, you need 2.5–3 kWp of dedicated solar in a sunny region (1,300 kWh/kWp), or 3.5–4 kWp in a cloudy region. Add 30% if you can't time-shift charging to midday.
Should I install a battery to charge my EV from solar?+
Only if your tariff spread (retail minus feed-in) is large. In Germany, NEM 3.0 California, and Octopus UK, a battery raises EV solar coverage from 30–50% to 70–90% and pays back in 8–10 years. In flat-rate utility regions, daytime charging via smart EVSE is cheaper.
Is it cheaper to charge an EV at home or at public chargers?+
Home charging costs $0.05–0.30/kWh depending on tariff. DC fast chargers cost $0.40–0.60/kWh. Even without solar, home charging is 2–4× cheaper. With solar, marginal cost approaches zero on sunny days.
Can I charge my EV directly from solar without a grid connection?+
Yes via DC-coupled EV charging (Sigenergy SigenStor, Tesla Powershare with hybrid inverter). Off-grid only EV charging requires substantial battery + array (10+ kWp + 30 kWh battery for daily commuting). For most users, grid-tied is far more economical.