A house with a solar roof in the foreground and another house with a PV system behind it. A snow-covered mountain can be seen in the background.
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Building and buying

Photovoltaic systems: functioning, costs and subsidies

Thomas Bott

More and more homeowners are opting for photovoltaic systems. There are good reasons for this, because a photovoltaic system allows you to save on energy costs – and help protect the environment. Find out here how the systems work, what options are available when planning or modernizing a house, and when it’s worth installing a photovoltaic system.

Photovoltaic systems: structure and functioning

The construction of a photovoltaic system is not particularly complicated. In principle, the system consists of three important main components, which each serve a different purpose:

1. Solar modules

The photovoltaic modules (PV modules) are usually placed on the roof to capture sunlight. They generate electricity from this solar energy. To do so, multiple solar cells are interconnected. They are available in different colors, which result from the composition of the substances they contain. Monocrystalline models contain pure crystalline silicon and are usually black. Polycrystalline versions are composed of several silicon crystals and tend to be blue or purple. The difference therefore basically depends on the production method. This changes not only the color, but also other properties. For example, monocrystalline modules are more efficient, but also more expensive.

View of a bungalow with a large number of photovoltaic modules. An e-bike can be seen in the foreground.

Solar modules are available in different designs and sizes.

2. Inverter

This very compact device is placed behind the solar modules and plays a very important role, because it converts the electricity that has been generated. PV modules are only able to produce direct current, whereas the power network in buildings runs on alternating current. The inverter is also responsible for controlling the entire photovoltaic system. Without it, the solar power cannot be used.

3. Electricity meter

The electricity meter in any household measures the electricity drawn from the grid. If you rely on a photovoltaic system to produce energy, the electricity emitted must be recorded as well. A photovoltaic system not only produces electricity for your own consumption. If your production exceeds your requirements, the surplus will be fed into the public grid. Consequently, the electricity you generate can help to ensure that other households also receive solar energy. You will receive a refund for this (see below).

Planning the system: what you need to consider in advance

First of all, it’s important to find out whether your house is suitable for the installation of a photovoltaic system. A large enough area must be available on the roof. It doesn’t matter whether you have a flat roof or a pitched roof – appropriate solutions are available for both types. More important, however, is whether the roof is strong enough to bear the additional weight. The age of the roof also matters: as a rule, the modules of a PV system have a service life of around 30 years. The roof should also last this long without requiring any repair work, otherwise the photovoltaic system may require costly disassembly during the course of the renovation.

If you have a flat roof in good condition, it is usually worth having a photovoltaic system mounted on the roof. This will be fitted on a framework above the tiles. However, if you are planning to build a new house or want to replace the roof, it’s better to opt for an in-roof solution. This will fit better into the overall concept of the building.

Once you’ve decided on the right type of system, the orientation is a key factor. A system facing south or south-west is ideal, as this is where the sun will shine for the most hours of the day. The north is unsuitable as a direction for a photovoltaic system as there is too much shade.

A house with a large PV system on the roof.

Whether old or new: a PV system fits on almost every house. But good advance planning is essential.

Photovoltaic systems: energy amortization and carbon footprint

Environmental considerations are often also taken into account in the decision to install a photovoltaic system. The first point to note is that the actual manufacturing of the solar system itself requires a lot of energy. You can actually soon recover this once the system is in operation. On average, the system will have paid for itself in terms of energy after about two or three years. Every kilowatt hour (kWh) produced from this point on will contribute to a positive energy footprint.

Photovoltaic systems are not yet completely CO2 neutral. The reason for this is that the modules are made of silicon. Even so, their carbon footprint is much better than that of some other types of electricity generation: according to the Swiss Energy Foundation, less than 100 grams of CO2 are given off per kilowatt hour. CO2 levels with this technology are thus significantly lower than for biomass (241g/kWh), natural gas (478g/kWh), oil (1,041g/kWh) and coal (1,335g/kWh).

Costs: the purchase soon pays off

Many people who are interested in purchasing a photovoltaic system are put off by the price. The panels, technology, material and installation can be expensive. The costs depend on your own consumption and the performance of the system. As an example: a family of four consumes 4,500 kilowatt hours per year on average. To generate this energy with a PV system, a maximum output (power at peak times) of five kilowatts peak (kWp) is required. You should expect to pay around 7,500 francs to purchase a system of this capacity.

A specialist and several colleagues install solar modules on a flat roof.

The cost of a photovoltaic system is often lower than expected. However, the installation should be carried out by professionals.

You must also factor in the savings you will make on electricity. According to Statista, the average price per kilowatt hour in Switzerland is 20.7 centimes. That results in annual electricity costs of around 930 francs. If you no longer have to pay any of this amount, the system from the example above would have paid for itself after a good eight years. However, since a PV system does not cover demand for electricity 24 hours a day, and additional costs such as insurance and maintenance have to be taken into account, it is more likely to take ten to twelve years to break even.

On the other hand, money can be earned by selling electricity. Energy providers pay per kilowatt hour and for the certificate of origin. This ensures that the consumer knows how the electricity is generated. Prices per kilowatt hour fluctuate depending on the power company and market trends – but you can expect around 10 centimes per kWh on average.

Photovoltaic systems: attractive subsidies in Switzerland

At federal level, Switzerland grants a one-off payment to subsidize photovoltaic systems. This represents up to 30 percent of the investment costs. Taking the figures from the above example, you would receive about 2,700 francs in subsidies for a five kWp system. This comprises a basic amount of 1,000 francs and a variable amount calculated on the basis of performance. The subsidy means that the PV system will pay for itself faster and be even more worthwhile.

Conclusion: an investment in the future

A PV system pays for itself after around ten years and is also quickly amortized in terms of energy. The initial hurdle, which appears considerable at first sight, is therefore actually much easier to overcome than you might think. In return, you can access modern technology which requires little maintenance, help protect the environment – and make yourself much less dependent on the local power company.

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