Is that a bug in my system?

PV system: The 7 most common mistakes when installing a solar system

In order for a PV system to really work economically, precise planning is important before it is set up. A lot can go wrong, especially during assembly. So that this does not happen and you can enjoy the solar yields of your photovoltaic system for as long as possible, we list the seven most common mistakes that you should avoid during installation.

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Error 1: The available roof area for the PV system was incorrectly calculated

Sounds a little ridiculous, but it happens every now and then: Due to incorrect dimensions, the number of photovoltaic modules required is suddenly oversized or undersized. Neither the "thumbs up" method and old blueprints are really helpful.

To really be on the safe side, only one thing helps: You should re-measure the roof area. This is the absolute basis for all further steps and only in this way can you really be sure that all subsequent calculations are correct.

Error 2: Roof statics not checked

The collectors, the substructure, the fastening material - seen individually, the components of a PV system are not heavy. Together, however, they matter in the truest sense of the word.

Therefore, a roof has to bear a lot when installing a photovoltaic system. It is not always certain whether it will hold up. It becomes particularly critical when there are additional loads from wind or snow. Therefore, have the statics of the roof checked before installation. And take this opportunity to see whether it is worthwhile to carry out minor repairs on the roof before installation.

Error 3: Insufficient needs assessment

Although this has nothing to do with assembly, it is still important. Before the first module comes on the roof, you should know exactly how much solar power your PV system should actually produce. Or to put it another way: How much solar energy yield is possible with you?

The maximum yield of a photovoltaic system results from the following factors:

  • the individual sun exposure
  • the roof size
  • the roof orientation

The maximum output of your photovoltaic system can be calculated from these individual values. In contrast, there is your electricity consumption (if you want to use the electricity produced yourself). And you may need a memory. The PV system should therefore be dimensioned in such a way that it covers your electricity needs as precisely as possible.

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Error 4: Incorrect substructure of the PV system

The solar modules are usually attached to a support structure. This in turn is connected to the rafters via roof anchors or roof hooks.

In numerous specialist portals it is pointed out again and again that one should definitely not save on the number of roof hooks. The manufacturers of the PV system usually specify how many roof hooks are to be used in order to ensure optimal relief of the roof. In addition, the roof hooks should compensate for the unevenness of the roof. Otherwise there will be unwanted shading - and thus a loss of performance of the PV system.

In addition, there are always mistakes when fastening the roof hooks. They must not lie directly on the roof tiles or roof tiles - otherwise they would be damaged. There are precise specifications for the distances between the roof hooks and the tiles, and the same applies to the tightening torque of the screws.

Error 5: Incorrect laying of the solar cables in a PV system

In principle, the structure of a photovoltaic system is always the same. It consists of three components:

  • Solar modules convert sunlight into electricity
  • the electricity generated is transported further into the house by means of solar cables
  • the generated direct current is converted into (grid-compatible) alternating current by an inverter

So there are some electrical components here that are quite delicate. The modules and the inverter usually get more attention during assembly than the solar cables. Poorly laid solar cables can quickly break if, for example, they get stuck between the roof tiles or are even laid through the rain gutter. And if the cable bundle is too thick, this reduces the current-carrying capacity.

Error 6: Unsuitable location for the inverter

The inverter converts the solar power generated by the solar modules from direct to alternating current. When installing the PV system for the inverter, you should find a place that is as protected and dust-free as possible.

Dust can ensure that the inverter can only dissipate heat poorly and, in the worst case, overheat. You should also protect the device from other weather conditions. You also have to consider the IP protection class during assembly.

Error 7: Missing documentation for the PV system

Good documentation pays off for maintenance and inspection, but also in the event of errors in the PV system. The specialist will find all relevant information in the, in order to correctly maintain or repair the system.

Sounds like paperwork. It is. But one that is important - and above all precisely regulated. The DIN 62446 specifies exactly what belongs to a system documentation. That would be:

  • Measurement protocols
  • Addresses of the system planners and executing companies
  • Serial numbers of the installed system components
  • Data sheets and guarantee certificates for the components
  • String and circuit diagrams

As I said: That means some bureaucratic effort. If the first problem arises with your PV system, you will certainly be happy if you have such a well-kept documentation of the system.