The moment you drive home a new EV in Switzerland, your relationship with electricity changes permanently. Petrol costs are replaced by kilowatt-hours, and suddenly the case for solar with battery storage becomes dramatically stronger. With Swiss retail electricity prices between 28 and 38 Rp/kWh depending on your canton and tariff, charging an EV at home from the grid costs roughly CHF 1,500–2,000 per year for a typical 15,000 km driver.
Solar covers that cost — but only if the system is sized correctly.
Step 1 — Quantify Your EV Electricity Demand
The first step is calculating your EV's annual electricity consumption. Swiss road conditions and speed limits mean real-world consumption typically runs 17–23 kWh per 100 km.
Example:
- Distance driven per year: 15,000 km
- Vehicle: Tesla Model Y Long Range (18 kWh/100 km real-world)
- Annual EV electricity: 15,000 × 0.18 = 2,700 kWh
Add this to your existing household consumption before sizing the solar system.
→ Before you read on — see what payback looks like for your roof in under a minute.
| Household type | Base consumption | EV added | Total |
|---|---|---|---|
| 2 people, no EV | 3,500 kWh | — | 3,500 kWh |
| 2 people + 1 EV | 3,500 kWh | 2,700 kWh | 6,200 kWh |
| 4 people + 1 EV | 5,000 kWh | 2,700 kWh | 7,700 kWh |
| 4 people + 2 EVs | 5,000 kWh | 5,400 kWh | 10,400 kWh |
Step 2 — Size the Solar Array
Using Zürich as the reference point (specific yield ~1,000 kWh/kWp):
Required kWp = (Total annual kWh × 0.70 target coverage) ÷ 1,000
For a 4-person household with one EV (7,700 kWh total):
(7,700 × 0.70) ÷ 1,000 = 5.39 kWp minimum
In practice, accounting for seasonal variation and roof losses, a 9–12 kWp system is appropriate for this household in the Zürich region.
Step 3 — The EV Charging Problem Solar Alone Cannot Solve
Here is the core challenge: solar produces electricity mainly between 9am and 5pm. Most Swiss EV drivers charge at home overnight or in the evening. Without a battery, you cannot directly charge your EV from solar surplus — you export midday solar at low feed-in rates and import expensive grid electricity overnight.
A 10 kWh battery (e.g. BYD HVM or Fronius GEN24 + BYD stack) captures midday surplus and releases it in the evening, raising self-consumption from ~30% to ~65–70% for a typical Swiss household. For EV charging, this means a significant portion of your EV electricity need is met by your own solar.
Step 4 — Smart Charging Integration
For maximum solar-to-EV efficiency, your charger should support surplus solar charging — adjusting charge rate dynamically based on real-time solar output. Chargers with this capability in Switzerland include:
- Zaptec Go (via Zaptec Portal API + inverter integration)
- easee Home (via easee Equalizer)
- Fronius Wattpilot (natively integrated with Fronius GEN24 inverters — the most seamless Swiss option)
The Fronius Wattpilot is worth highlighting: it is the only charger in the Swiss market with native, no-API-configuration integration with Fronius inverters, automatically throttling charge rate to match real-time solar surplus to the nearest 100W.
Winter Charging — The Swiss Season Challenge
In December and January, a 10 kWp system in Zürich produces roughly 350–450 kWh total — versus 1,200–1,400 kWh in June and July. An EV driving 15,000 km/year needs roughly 225 kWh per month (constant). Winter solar will cover perhaps 30–40% of EV charging needs from November to February.
→ Numbers speak louder: calculate your annual solar return and take the guesswork out.
The honest answer: full solar coverage of EV charging year-round is not achievable in Switzerland without a very large system (15+ kWp) or significant battery storage (20+ kWh). Design for 70–80% annual solar coverage and accept grid top-ups in winter — this still represents a very strong economic and environmental result.