The best direction is not always what we think
Many owners start with a simple idea: due south = best installation. This is true if the objective is to push the maximum annual production on a given area. But in Switzerland, the good question is often different: when do you consume your electricity, how steep your roof is, and how much of your production will you really be able to keep for yourself?
On a house occupied early in the morning and at the end of the day, an installation east-west can produce a little less in total, but better distribute the production curve. This can improve self-consumption without battery and reduce the quantity resold at low prices to the network.
The method in 5 steps
Map your consumption on a normal day
Start by identifying your real usage peaks: breakfast, evening cooking, heat pump, charging an electric vehicle, hot water tank. If your house consumes mainly in the morning and evening, more spread out production can be worth more than a peak massive at midday.
The right indicator is not only the annual kWh, but the useful kWh at the right time.
Evaluate the actual roof geometry, not the ideal roof
Orientation, slope, dormer windows, chimneys, windows roof, seasonal shading: the decision depends on the roof that you have, not the perfect diagram on a brochure.
On many Swiss houses, two east and west sides clean results in a simpler, more homogeneous and sometimes more profitable than a small area facing south cluttered.
Compare gross production and recoverable production
Ask for two simulations: scenario due south, scenario B east-west. Then compare not only annual production, but also self-consumption expected and the share injected into the network.
A scenario that produces 5 to 10% less can remain better if the economic value of each kWh consumed on site is significantly higher than the resale price.
Check the impact on electrical sizing
An east-west configuration often smoothes the tip of midday production. This can make the work of the inverter, reduce some clipping and better distribute the energy available for a heat pump, a terminal or a piloted balloon.
If you are planning a battery later, also look how each orientation fills this battery on a typical mid-season day.
Decide according to your main objective
If your priority is maximum production per m², the due south often keeps the advantage. If your priority is self-consumption, daily stability and a residential logic, east-west may be best compromise.
The right decision in Switzerland is therefore rarely ideological : it must come from a numerical comparison of two concrete scenarios.
When east-west often wins
East-west becomes particularly interesting on houses with a strong presence in the morning and evening, homes equipped with a water pump heat, or roofs which have two clean sides but not one large free southern area. It is also a good choice when you want a curve of more regular production and less dependent on a single peak around noon.