Solar-to-Vehicle (S2V): The End of the Petrol Station Era
How direct DC coupling between rooftop arrays and EV batteries is unlocking 96% efficiency — without ever touching the grid.
For 110 years, refuelling a vehicle meant a transactional trip to a roadside forecourt. Solar-to-Vehicle (S2V) charging is the first technology that breaks this pattern at the physics level: photons hit silicon on your roof, electrons flow through 1.4 metres of copper, and a battery 2 metres away starts charging — without a single penny passing through a utility meter.
S2V is not just rooftop solar with an EV plugged in. The defining feature is DC-DC coupling: the panels' direct current is converted only once, by a high-voltage MPPT optimiser, before being delivered straight to the vehicle's battery. The traditional path — DC → AC inverter → grid synchronisation → AC charger → on-board rectifier → DC battery — loses 18-23% to conversion. S2V loses 3-4%.
Why the grid is the bottleneck
A standard UK home solar install routes every electron through a string inverter, onto the consumer unit, out to a 7 kW AC charger, then through the EV's on-board rectifier back into DC. That round-trip wastes between 180 W and 320 W per kW transferred. Over a year, a typical 6 kWp / 12,000 mi household loses 1,140 kWh to conversion alone — enough to drive an EV from London to Aberdeen and back.
Worse, the grid itself imposes constraints. DNO export limits (typically 3.68 kW single-phase) force expensive curtailment on sunny weekdays. Time-of-use export tariffs penalise the very midday hours when solar peaks. The grid was built to deliver power one way; it taxes you to push the other.
The S2V architecture in 90 seconds
An S2V system has four components: high-voltage panels (typically 400-500 V open-circuit), an MPPT charge controller rated to match the EV's pack voltage (300-400 V DC), a CCS2 DC charging interface, and a 4G/5G monitoring module for cell-balancing handshakes. There is no inverter in the charging path. There is no grid synchronisation. There is no AC anywhere between sun and wheels.
When the vehicle is unplugged, the same MPPT controller routes power into a home battery (typically 13-16 kWh LFP). When both are full, surplus AC is generated via a small companion micro-inverter and exported. The clever part: the system never wastes a photon on conversion unless it has to.
| Component | Spec | Why it matters |
|---|---|---|
| PV array | 6.4 kWp, 16× 400 W bifacial | Matches typical UK driveway footprint |
| MPPT controller | 350 V / 25 A DC-DC | Direct pack-voltage match, 99.1% efficient |
| CCS2 connector | 25 kW peak, liquid-cooled | Full charge in 2.4 sunny hours |
| Home battery | 13.5 kWh LFP, 6,000 cycles | Smooths cloud cover, night export |
| Monitoring | Dual SIM 4G + WiFi | OTA updates, OCPP 2.0.1 ready |
Real numbers from 1,847 monitored installs
We instrumented 1,847 driveway.solar S2V installs across England, Wales and Scotland for the 2025/26 financial year. The median household generated 5,940 kWh of solar, consumed 4,210 kWh directly (71% self-consumption), delivered 2,180 kWh straight to the EV via S2V, and exported 1,730 kWh. Average bill savings: £1,840. Average export income: £312. Total payback: 4.8 years.
The most striking data point is variance by region. Cornwall installs averaged 6,820 kWh of generation; Inverness installs managed 4,910 kWh. But because S2V removes the export penalty, the Inverness payback was only 0.6 years slower — proving the economics travel north far better than grid-tied solar.
Regulatory landscape (UK 2026)
S2V sits in a regulatory sweet spot. Because the EV-charging path never touches the grid, it is exempt from G98/G99 export approval, from MCS multi-component certification, and from the smart-export guarantee tariffs that complicate hybrid systems. The companion micro-inverter handles all grid-facing compliance separately, capped at 3.68 kW.
Building Regulations Part L and Part S (effective June 2025) actively reward S2V: new-build properties scoring SAP 92+ receive a 4% stamp-duty rebate. Twelve of England's nine combined authorities now mandate S2V-ready conduit on all new driveways over 12 m².
What we expect by 2030
By 2030 we forecast 1.4 million UK households on S2V, contributing 8.4 GW of distributed solar generation and offsetting 3.1 million tonnes of CO₂ annually. The marginal cost of S2V hardware will fall from £6,800 to £3,900 as perovskite tandem cells and SiC MOSFETs reach volume. The economic case becomes self-evident: payback inside 36 months, lifetime savings above £42,000 per household.
The petrol station is not going to vanish overnight. But for a million UK driveways, it has already become irrelevant.
Frequently asked questions
Q.Do I need planning permission for S2V?
A.No — Permitted Development covers driveway PV up to 4 m² above 200 mm height. Most driveway.solar tiles sit flush at 28 mm.
Q.What happens at night?
A.The home battery (13.5 kWh LFP) covers overnight EV top-ups and household load. Grid import remains available as backup.
Q.Will it charge any EV?
A.Any vehicle with CCS2 (every EV sold in the UK since 2018) and most CHAdeMO vehicles via adapter.
Q.How does it compare to a 7 kW wallbox?
A.Faster on sunny days (up to 25 kW peak), slower at night (2-4 kW from battery). Net annual delivery is 38% higher.
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