How the calculation works
The rules from 2027
From 1 January 2027 the feed-in payment follows the spot market price at the moment of export, unless you have agreed something else with your grid operator. The price is set every quarter of an hour on the day-ahead market for the Swiss market area.
| Base payment | Spot price of the quarter-hour in which the electricity flows. It can turn negative. |
|---|---|
| Minimum premium | For installations up to 150 kW. If the quarterly reference market price falls below the minimum remuneration, the difference is paid afterwards per kilowatt-hour exported. The minimum is 6 Rappen up to 30 kW. |
| Guarantees of origin | Many operators additionally pay a low single-digit Rappen amount, more in winter than in summer. Nothing is paid at negative prices. |
| Transition period | Installations without a smart meter may continue to be settled at the reference market price until the end of 2027. Operators must fit smart meters by then. |
Data
- Measured global radiation and air temperature from the automatic MeteoSwiss stations, hourly, for the year shown.
- Day-ahead prices for the Swiss market area, from the same year as the weather. This matters: it is the only way the link between sunshine and low prices survives. Euro prices are converted to francs at each day's reference rate.
- Reference market price for solar: the official quarterly figures where published, otherwise computed from the prices by the same definition, weighted by the feed-in of the Swiss solar fleet.
- Household tariffs and grid operators by municipality. Where operator-level data is not yet loaded, the Swiss median is used and this is shown.
Data as of:
The model
From the measured horizontal radiation, the direct and diffuse shares are found with the Erbs correlation, transposed onto your roof plane with the Hay and Davies model, and converted to alternating current through a cell temperature, a temperature coefficient of minus 0.35 per cent per kelvin and 14 per cent system losses. Household consumption follows a standard day curve with a seasonal tilt; heat pump, water heater and car charging are tracked separately so that shifting them into the midday hours can be calculated. Batteries charge and discharge hourly, at 90 per cent round-trip efficiency and a 5 per cent minimum state of charge.
Limits
- The calculation is hourly. The Swiss day-ahead market only moves to quarter-hour products on 3 November 2026, so historical prices exist only by the hour. An hourly calculation typically overstates self-consumption by a few per cent; with a battery the effect is smaller.
- The radiation comes from the measuring station nearest to your postcode, not from your roof. Shading, snow and soiling are not in the model. If you enter your installation's yearly production, the site uses that figure and keeps only the hour-by-hour pattern from the model.
- Your consumption profile is estimated from a standard curve. Downloading your quarter-hour values from your operator and loading them here gives a much more accurate result.
- Your grid operator's own figures are what count. Some pay more than the law requires, or keep fixed prices.
- At negative market prices the site assumes by default that you pay the negative price and keep receiving the minimum premium. Each grid company decides this itself, though; some simply pay nothing. You can choose that case in the calculator under "Optional".
- The calculation uses past years' prices: the latest year in detail, the years before it one by one in a table, never averaged. Future prices will differ; the more solar is built, the lower midday prices are likely to fall.