EV Charger & Solar Panel Integration: Getting the Most from Both
Pairing a smart EV charger with solar panels means your car can charge for free during the day. Using a solar-matched charger like the myenergi Zappi, you can divert excess solar generation directly to your vehicle rather than exporting it at a low SEG rate. This guide explains how the integration works and what to expect.
The Opportunity
Electricity costs approximately 24p/kWh at standard daytime rates. Using solar-generated electricity to charge your EV instead of paying grid rates effectively gives you free fuel. In Cornwall, with 1,298 kWh/m²/year of solar irradiance, a well-sized solar system can provide 60–80% of an average EV driver's annual charging needs in summer months, and 15–25% in winter.
How Solar EV Charging Works
A standard 7kW EV charger draws power at a fixed rate. If your solar panels are generating 3kW and you start a 7kW charge, you're drawing 4kW from the grid. A solar-divert charger like the myenergi Zappi monitors the generation vs consumption balance in real time and throttles the charge rate to match the surplus — keeping the entire charge within your solar surplus at zero grid import cost.
The tradeoff is speed: solar divert charging is slower. But for an EV parked at home most of the day while solar generates, this is ideal.
Smart Charger Options
- myenergi Zappi (7.4kW): Market leader for solar integration. Three modes: fast, eco (top-up from grid + solar), eco+ (solar surplus only). Compatible with most inverters via CT clamp. £780–950 installed.
- Ohme Home Pro (7.4kW): Strong smart tariff integration with Octopus Energy. £700–850 installed.
- Easee One (7.4kW): Sleek design, good app, smart scheduling. £750–900 installed.
For solar integration, the Zappi is our most-recommended option due to its inverter-agnostic CT clamp monitoring. See our EV charger installation page.
How Many Free Miles Can You Expect?
Using a 4kWp Cornwall solar system with solar divert charger, EV consuming 3.5 miles/kWh, 35% of solar surplus available for EV:
- Annual EV-available surplus: ~1,785 kWh
- Free miles: ~6,250 miles/year
- Value at 24p/kWh: ~£429/year saved
For a household driving 8,000–10,000 miles per year, this represents 60–75% of annual mileage charged for free. See: Charging Your EV with Solar Panels.
Adding a Battery for Even More Value
A battery stores solar surplus during the day for EV charging in the evening, increasing free EV miles by a further 20–30%. The optimal setup: solar panels → battery storage → Zappi charger. The battery fills from solar surplus during the day; the Zappi draws from the battery in the evening. On days when neither solar nor battery suffices, the Zappi can automatically switch to cheap overnight grid rates. See: Is a Solar Battery Worth It?
Get a Quoted System
CCS Heating & Renewables can design and install a complete solar + battery + EV charger system, sized to your home and driving habits. Book a free survey and we'll model the system output and payback for your specific property.
Need personalised advice?
Our MCS certified engineers can answer your questions and provide a free, no-obligation assessment for your property.