Start with Your Annual Electricity Consumption
Before thinking about panel count or system size, you need your household's annual electricity consumption in kilowatt-hours (kWh). The best source is your electricity bill — Swiss grid operators provide an annual summary (Jahresabrechnung) that shows total kWh consumed per year.
Typical annual consumption benchmarks for Swiss homes:
| Household type | Annual consumption |
|---|---|
| 2-person flat, no EV | 3,500–4,500 kWh |
| 4-person house, no EV | 5,000–7,000 kWh |
| 4-person house + heat pump | 8,000–12,000 kWh |
| 4-person house + heat pump + EV | 12,000–18,000 kWh |
At CHF 0.27/kWh average grid electricity in 2025/2026, a 12,000 kWh/year household spends roughly CHF 3,240 per year on electricity — and every kWh generated from solar offsets that.
Irradiance by Region
Solar yield depends on local irradiance, expressed as peak sun hours per day (or annual kilowatt-hours per kWp installed). Switzerland's three main population centres differ noticeably:
| City | Annual irradiance (kWh/m²/year) | Yield per kWp installed (south-facing, 30° tilt) |
|---|---|---|
| Zurich | ~1,100 | ~980–1,050 kWh/kWp |
| Bern | ~1,120 | ~1,000–1,080 kWh/kWp |
| Geneva | ~1,280 | ~1,150–1,220 kWh/kWp |
Geneva's superior irradiance — driven by its climate near the French Alps and fewer overcast days — gives it a meaningful yield advantage. A 10 kWp system in Geneva produces roughly 15–20% more than the same system in Zurich.
→ Before you read on — see what payback looks like for your roof in under a minute.
System Sizing Rules of Thumb
The self-consumption target
For most Swiss homes without battery storage, targeting 75–90% of annual consumption from a solar system is a practical starting point. Going beyond that generates significant surplus that earns only CHF 0.07–0.12/kWh in feed-in remuneration — far below the value of avoided consumption.
With battery storage
Adding a battery shifts the optimal system size upward. You can increase the array size knowing that midday surplus charges the battery for evening use rather than being exported at low rates.
Worked examples
Zurich, 4-person home, heat pump, no EV
- Annual consumption: 9,500 kWh
- Target self-supply: 80% = 7,600 kWh/year
- Required system at ~1,010 kWh/kWp yield: 7.5 kWp
- Typical panel count at 410W: 18–19 panels
- Required roof area: ~35–38 m²
Bern, 4-person home, gas heating (standard), no EV
- Annual consumption: 5,500 kWh
- Target self-supply: 80% = 4,400 kWh/year
- Required at ~1,040 kWh/kWp: 4.2 kWp
- Panel count at 400W: 10–11 panels
- Required roof area: ~20–22 m²
Geneva, 4-person home, heat pump + EV
- Annual consumption: 15,000 kWh
- Target self-supply: 75% = 11,250 kWh/year
- Required at ~1,180 kWh/kWp: 9.5 kWp
- Panel count at 430W: 22 panels
- Required roof area: ~44 m²
Roof Orientation and Shading
Due south at 30–35° tilt is optimal, but Swiss homes with east-west split roofs can still install effectively. An east-west configuration typically yields 15–20% less than due south but spreads production more evenly through the day — sometimes increasing self-consumption without a battery.
Always have your installer produce a shading analysis using tools like PVsyst or Helios3D. Even small shading from a chimney or neighbouring tree can significantly reduce output if string inverters are used. If shading is unavoidable, specify a power optimiser (SolarEdge) or microinverter solution to mitigate losses.
→ Numbers speak louder: calculate your annual solar return and take the guesswork out.
Getting Comparable Quotes
When comparing installer quotes on Comparisun, ensure each quote specifies the same system parameters: kWp, panel model, inverter model, and estimated annual yield in kWh. A cheaper quote delivering 20% less annual yield is rarely the better choice at CHF 0.27/kWh. Get instant solar offers for your Swiss address to compare quotes with regional irradiance already calculated.