The photovoltaic effect (or photoelectric), the conversion of light into electricity, was discovered by Becquerel in 1839. However, its industrial application was only in 1954, specifically in the aerospace industry.
The term “photovoltaic” means transformation of solar radiation (photons) into electric current (Volts). Solar panels produce continuous electric current that is converted into alternative current through an inverter and that is then injected into a home’s power grid.
If solar energy produced isn’t being used directly (during the holidays for example), the energy is stored free of charge on the grid and is taken when needed at night. Like that all the energy produced is deducted from your invoice. Photovoltaic cells are made up of 2 fine layers of silicon to which boron (B) and phosphorus (P) are added. The light received by the photovoltaic cell diffuses into the silicon and liberates electron-hole pairs producing electric current. 8 m2 of photovoltaic panels = 1KWc producing annually 1000kWh, that is to say 25% of the consumption for a 4-person household.
In case of solar power production without immediate use (periods of holidays for example), all the not used energy is resold to your network manager and so deducted from the invoice. However, it is also possible to store this energy in batteries.
Self-consumption of current, produced locally, is authorized in all of Switzerland. This means that it is possible to consume directly one’s own photovoltaic electricity production and to compensate immediately for the energy necessary for the proper functioning of domestic appliances, heat pumps and whatnot.
And the profitability in all this?
The optimization of self-consumption consists in minimising the unprofitable injection of current into the network which is taken back for 9 ¢ / kWh on average. If photovoltaic current is consumed directly, your electricity bill can be reduced by about 70%. As of 35% self-consumption, photovoltaic electricity is more advantageous than that supplied by the grid.
How to increase one’s self-consumption?
Without optimization and without storage, an average home in Switzerland (villa of 4 people) will consume approximately between 30 and 50% of its photovoltaic production directly. By optimizing and synchronizing your production with your consumption, by means of a control system, your self-consumption can reach 80%. So, for example, an electric boiler and a heat pump, can be operated when solar production is self-sufficient. In this case, the supplied energy is "free" since the grid will not be solicited. On the other hand, it is possible to start up your electric boiler during the day (when solar production is active) and will allow you to save, with the night rate, 9¢ / kWh charged by your grid provider.