PV applications

PV systems can either be connected to the public power grid (grid-connected systems) or operated independently (stand-alone systems).

Grid-connected systems

Most photovoltaic systems feed the generated power into the public grid. This is called grid operation. By connecting the solar installation to a large grid (usually the public power grid), you can make sure that there are always enough consumers using the solar energy directly. There is no need for intermediate storage. Power supply is guaranteed at all times and normal alternating current appliances can be used.

Today, the self-consumption of solar electricity is often key for a PV system’s profitability (for more information, please visit SwissEnergy). What does this mean? The more solar power is used directly at the system’s production site right as soon as it is generated, the quicker a PV plant will pay off financially.

Without battery technology, a single family home needs approximately 20 m2 of PV modules to achieve a simultaneous self-consumption rate ranging between 20% and 30%. A high self-consumption rate can also be achieved by commerce and industry buildings with PV systems, since most of their electricity is used during the daytime.

The electricity surpluses are fed into the public power grid and refunded by the local grid operator. According to Art. 11 § 1 of the Swiss Energy Ordinance (EnV), grid operators are obligated to acquire the extra power produced. Art. 12 § 1 EnV defines the remuneration as being based on the costs the grid operators would incur when acquiring equivalent third-party electricity, as well as on the initial cost of their own production plants. There are very large differences in the redelivery refunds paid: see www.pvtarif.ch.

Solar power can be used to produce thermal energy or heat that is easy to store. This helps to increase the self-consumption rate. From an energy efficiency perspective, the best solution is using solar power to operate heat pumps. In order to achieve optimum integration, the heat pump’s control must be coupled to the PV system. This job is best done with the support of plumbers.

Private consumption communities (ZEV) enable several apartments or adjoining plots of land to jointly use the power produced by one PV system; this also helps to achieve a higher self-consumption rate. More information

Stand-alone systems

Remote objects, such as mountain cabins, holiday homes, SOS phones and parking meters, can use power provided by stand-alone solar installations with batteries (power storage). This is called isolated operation.

These are the features of a stand-alone system:  

  • a cost-saving alternative to connecting remote consumers to the grid;

  • operation is generally based on continuous current with a 12 V or 24 V voltage; this operation requires special devices and lamps if no inverter is used;
  • this type of PV system generally consists of three components: the solar generator, the charge controllers and the batteries.