How to produce environmentally friendly solar electricity

How does a solar energy system work?

A solar energy system – also known as a photovoltaic system, or PV system for short – converts the sun’s rays into useful electricity. Solar modules capture the sun’s rays with solar cells and use them to produce direct current. The inverter converts the direct current into alternating current. This current, known as electric current, is used, for example, to power domestic appliances. This means that solar electricity is, by definition, the electricity generated by the photovoltaic effect within solar cells. Producing electricity this way does not generate any exhaust emissions. This makes solar electricity particularly environmentally friendly. In addition, solar electricity is classed as a renewable energy, as the sun is an infinite source of power.

Unlike photovoltaics, thermal solar systems (also called solar thermal systems) convert solar radiation into heat. This can be used to heat rooms or water.

How much power can you generate with solar cells?

The most powerful solar cells currently on the market are gallium arsenide cells. They achieve an efficiency of up to 25%. Classic photovoltaic modules consist of monocrystalline cells (up to 22% efficiency) or polycrystalline cells (20% efficiency).

Electricians and solar installation technicians can calculate your expected electricity output accurately using computer simulation.

Which solar cells are profitable for your house?

This varies from house to house. The decisive factor is a good cost-benefit ratio – solar systems with monocrystalline cells are more expensive than solar systems with polycrystalline cells. In building practice, solar panel installations with monocrystalline cells are the most popular choice for smaller roofs. Those who have more space available increasingly opt for the more inefficient, but cheaper polycrystalline cells.

What should you bear in mind when installing a solar energy system?

Proper installation is a precondition of a legally compliant solar energy system:

• Solar panels are usually mounted on the roof or on the façade. This means that special safety precautions are required when installing a solar energy system.

• Installing and operating a solar system are both subject to the Electricity Supply Act (StromVG) and the Energy Act (EnG).

• A permit is required in order to commission a photovoltaic system.

When installing solar panels, you should also pay attention to their alignment. Orienting the photovoltaic modules to face south, at an inclination of approx. 30° is ideal. Shade from neighbouring buildings and trees, for example, should be avoided.

A photovoltaic system can also be installed on a flat roof. The solar system is optimally aligned with the help of an elevation.

What are your installation options?

The following two installation options are available for photovoltaic roof systems:

Option 1: On-roof mounting

The on-roof installation of a solar system is particularly suitable for pre-existing houses.
The photovoltaic modules are mounted on the existing roof. They have no sealing properties - the roof itself continues to protect against sun, rain, snow, wind and hail.

Option 2: In-roof mounting

In-roof mounting is attractive for new buildings or roofs in need of renovation. Solar cells take over the function of roofing and are aesthetically pleasing - new solar modules look deceptively similar to tiles and shingles.

Who carries out a solar installation?

An electrician or solar installation technician will install and set up your photovoltaic system.

Is storing solar energy worthwhile?

In a solar system with electricity storage, the surplus solar electricity is temporarily stored locally in a chemical battery storage system (battery for short). In this way, you ensure a supply of solar energy, even if the weather is bad. With a battery storage system, you increase the proportion of solar electricity that you consume and generate yourself. In a single-family home, self-consumption rates of up to 90% can be achieved.

Lithium-ion batteries are currently particularly attractive due to their cycle stability and steadily falling prices. A photovoltaic system can also be retrofitted with a battery storage system.

Can you receive subsidies for solar energy systems?

The Swiss government subsidises the installation of a solar system as an important component of energy-efficient renovation. The government supports small-scale photovoltaic systems for single-family homes with a one-off payment. This covers a maximum of 30% of the installation costs. The exact subsidy amount is made up of a basic contribution and a performance contribution per installed kilowatt and varies according to the type of installation (attached, free-standing or integrated). Owners of solar systems with an output of less than 100 kilowatts receive the subsidies only after commissioning.

© This input for this content was provided by Raiffeisen Casa.