The demands placed on cables for photovoltaic systems are significantly higher than those made on conventional installations for AC devices. Particularly high safety regulations apply to PV system installations since the generation of electricity (solar power) is direct current.
Cables are prescribed that are double insulated and have only one wire. Since photovoltaic systems are installed outdoors, the cables must also be able to withstand extreme weather conditions. Protection against moisture and UV resistance plays a major role here. If you are planning to install a photovoltaic system, you should, therefore, make sure that you only use these special ZW 4mm solar cables, because if you save on the cables, you may experience unpleasant surprises.
Requirements for solar cables
Experience shows that sooner or later solar cables that do not meet the requirements mentioned can be responsible for damage and faults in the photovoltaic system. If you have an offer for a photovoltaic installation prepared, you should, for example, make sure that the solar cables meet these criteria.
When choosing the cross-section of the cable, care should be taken that the energy losses are less than one percent. In most cases, a cable cross-section of 4 square millimeters should be used. Smaller cross-sections often make no sense.
Use only tested solar cables
Since the cables of a solar power system are exposed to extreme weather conditions such as wind, frost, and heat, they have to meet particularly high demands. Sunlight and its UV radiation can also clog the insulation of the solar cables and cause the sheathing to age. Since damage to the cabling of the solar modules can only be located with great effort afterward, the operators of a PV system incur high costs.
It is therefore of fundamental importance that the photovoltaic system is designed and implemented in such a way that no exchange of solar modules and their cabling is necessary for at least the next 30 years.
Cross-section of solar cable
If you bear in mind that the solar cable plays a subordinate role in terms of costs compared to all other components of the photovoltaic system, it is not worth saving at this point. Therefore, the future PV system operator should put special emphasis on using only tested and high-quality solar cables.
Cross-section of solar cable tested cables for solar power systems can be recognized by the “PV1-F” label. These have double insulation of the conductive wire. If you want to be sure that the cabling of the photovoltaic system will last for the next 30 years, make sure that it complies with the VDE or TÜV standards. These lines are marked accordingly.
If you look at a solar cable inside, you can see that the copper wire (also known as a strand) is surrounded by an additional tin sheath from the outside. During long-term tests, it was found that insulation made from the cross-linked polymer is more resistant than insulation made from rubber.
Connection technology for photovoltaic systems
Plugs specially developed for the connection of the individual solar modules ensure a firm hold for years. Photovoltaic plugs for solar cables
When selecting suitable connectors, it must be ensured that only those that are approved by the solar cable manufacturer are used. Time and again mistakes are made during installation or costs are saved, which in retrospect are expensive for the operator.
Photovoltaic plugs & connectors again, the rule applies: “Only the best is good enough”. An experienced electrician knows which connectors to use for the installation. A requirement that a solar connector must meet in any case is that it must be non-contact. Furthermore, they must be watertight or prevent the ingress of moisture.
However, cheap products often do not meet these requirements. It is therefore advisable to only use brand manufacturers.
In addition to the optimal connection of the solar modules via a connector, it is possible to use further connection technologies:
Connection with screw terminals
If the modules of the solar generator are connected using screw terminals, it is important to ensure that an end sleeve is crimped at the end of the cables. This holds the fine wires of the wire together.
Connection with screw connection
Similar to a screw terminal, a so-called cable lug must be pressed onto the end of the wire instead of the end sleeve. This connects the solar cable to the component.
Use of spring clamps
This form of connection technology also offers a very good connection between the solar cable and the solar module. The cable is securely fixed in the clamping point using a spring.
Protect the solar cable additionally
Since the cables of a solar system can also be exposed to other influences, such as the marten bite, it can make sense to take special precautions. For example, the cables can be routed in cable ducts or protective lines and, in addition to protecting against martens, the solar cables can also be protected from the weather.
If possible, the cables can also be laid inside the roof. To protect existing lines against marten bite, you can also use marten repellents that are available for the automotive sector.