Building a solar plant

There are different ways to mount a photovoltaic system to the roof. The most common ones are the rooftop or the in-roof installation. In the former the solar modules are installed with a rack above the roof and in the in-roof installation the modules are integrated into the roof area. Photovoltaic systems can also be mounted on facades or to the ground.

Photovoltaic systems can be installed in all locations with sufficient solar radiation. Accordingly, many roof areas can be used. The ideal conditions for in Central Europe, e. g. Germany, are an inclination of 30 ° and south orientation without shading. A horizontal deviation to the southwest / southeast or slopes between 25° and 60° reduce the energy yield slightly. Stronger shading through trees or neighboring houses should be avoided. In order to achieve the highest possible self-consumption rates, depending on the consumption patterns, east and west orientations may also make sense, as here the production maximum is generated before and in the afternoon.  

Since self-generated solar power is cheaper than electricity to the typical household customer tariff, the highest possible self-consumption rate is decisive for most operators. In practice, this depends on a large number of factors. The most important are the ratio of the amount of energy produced and consumed and the consumption profile (i.e. when and how much electricity is used in a day). A PV system in Central Europe annually produces between 850 and 1,100 kilowatt hours per kWp of installed capacity. A plant with 5 kWp generates approximately the amount of electricity that is consumed by a family of four on average. However, generation and consumption do not always take place at the same time. The typical self-consumption rate without further measures in this case is only about 30 percent. With intelligent energy management systems for consumer control and temporary storage of solar power, this proportion can be significantly increased. The alternative is a comparatively smaller PV system, where the absolute amount of self-generated and used solar power is smaller.

As experience has shown, a photovoltaic system generates between 850 and 1,100 kWh of electricity per kWp per year in Central Europe, e. g. in Germany, depending on the region (Northern / Southern Germany), the orientation, the weather conditions and the plant technology. In good years and at optimal locations, more than 1,100 kWh can be achieved.

Since a roof-parallel photovoltaic system does not increase the likelihood of lightning strikes, the solar modules themselves are not at a higher risk than the inverter or other devices connected to the grid. However, in the rare event of a direct lightning strike into the solar generator, considerable damage to the modules is to be expected. The integration into a lightning protection system can help (external lightning protection).

Indirect or near lightning strikes, in which a partial lightning current flows through the electrical installation or rather an overvoltage is induced there, are much more common. In this case, staggered surge protection at the feed-in point or at the PV generator can greatly reduce the risk of damage (internal lightning protection). Modern inverters are also protected against atmospheric disturbances by thermally monitored varistors.

The grounding of the module frame and the substructure is not mandatory, but recommended. If a lightning protection system is installed on the building, the solar modules and the substructure may need to be integrated there.
In any case, it is recommended to develop a suitable protection concept, particularly with regard to the insurance premiums. Due to the complexity of the topic, you should always consult a lightning protection expert.

Yes. As the building fire insurance also has to replace the solar power system in case of damage, you are obliged to report its installation. However, the premium increases are very low.

A photovoltaic system usually requires little maintenance and is very reliable because the photovoltaic effect works without moving parts. The guaranteed lifetime of solar modules differs from manufacturer to manufacturer and is about 20 to 30 years. Depending on the quality of the single components, a service life of more than 30 years is possible. However, the performance of the solar modules after about 20 years is only about 80 percent of the original power output.

Modern inverters usually reach a service life of approx. 20 years. Manufacturers offer warranties of five to ten years today, which can be extended to up to 25 years.

The installation of a photovoltaic system usually takes only a few days.

No, the electricity can be fully consumed in your home. Since solar power from your own photovoltaic system already is much cheaper than the electricity from the power supplier, it pays off to aim at a high level of self-consumption.