Lightning protection systems in photovoltaic power plants
Photovoltaic power plants are always located in huge and isolated areas or on roofs due to their functions. They are high-cost equipment and when damaged can cause losses to energy supply, especially if they are connected to the distribution network. Its operation is controlled by sensitive electronic devices that can be highly damaged by transient surges. Therefore, from the point of view of lightning protection they are high-risks installations.
Aplicaciones Tecnológicas S.A. has all the elements available to achieve the best protection for solar plants: effective lightning rods for capturing lightning, special grounding electrodes for high resistivity soils and a wide range of surge protection devices (SPD) that are able of protecting from data lines connected to electronic devices to the output of transformation centres. Protection must be carefully designed by an expert team as a large number of parameters are involved. Our experience of over 30 years in lightning protection allows us to determine the most convenient solution for each facility.
ESE Lightning air terminals DAT CONTROLER® REMOTE
An ESE lightning rod is characterized by its response to the approach of lightning, overtaking other elements in its capture within its protection zone and leading it to land safely.
DAT CONTROLER® REMOTE lightning rod uses the environmental electric field as the only power source. It is totally autonomous, maintenance-free and its functioning can be checked at any time. For a greater guarantee, DAT CONTROLER® REMOTE lightning rods have been subjected to all necessary tests in official and independent laboratories.
DAT CONTROLER® REMOTE lightning rods installation must be carried out following the 21186 UNE standard: “Lightning Protection with Early Streamer Emission Air Terminals”. With only one single lightning rod it is possible to protect a surface of almost 20.000m2 considering Level of Protection 1, which is the most demanding. However, to achieve this protection, lightning rods must be installed at least 6 meters above the solar panels, which can cause a problem with shadows. To minimize it, it is recommended to place the installation in the perimeter of the solar farm. This way shadows on photovoltaic panels are avoided as much as possible.
To reduce these shadows, it is recommended to set up the lightning rod on a 10m free standing mast (AT-092C) so it rises above the solar panels.
Protection radius (in meters) at different heights from the lightning rod over the element to be protected are calculated for each of the four levels of protection according to standards UNE 21186:2011, NF C 17-102:2011 and NP 4426:2013.
Self-diagnosis and connectivity (IoT)
The REMOTE device allows daily self-test of lightning rod condition without the need to dismantle the lightning rod or the auxiliary lifting equipment.
The result of its self-test is sent to a receiving device (mobile, tablet, computer) by M2M communication. The information can be seen on the portal web along with other personalized notifications, thus facilitating the right preventive and corrective maintenance of the installation and reducing associated costs.
Intelligent lightning event counter:
- It registers the passage of lightning current, amplitude, polarity, date and time of the discharge.
- Information can be collected on a specific device with USB connection.
- It stores information of up to 40 events.
- Data management software is intuitive and easy.
- Easy installation: does not need interruption of downconductor.
Equipotentialization and earth systems
The earth termination system is important because it serves to stabilize the voltage relative to earth during its normal operation. Therefore, it is common that photovoltaic panels have an adequate earth termination system. It is highly recommended that all earthing systems are united, i.e. there is a general earth network to which each solar panel is connected to. Besides, metal masses (metal fences, enclosures, brackets and equipment cover) should be connected to the ground as established in UNE-EN 61173 standard to achieve equipotentialization of all elements avoiding potential differences and dangerous sparks as much as possible.
The lightning protection system has its own earthing system that will be unified to the general one with a spark gap for earth bonding to keep them separate during the normal functioning of the equipment, eliminating the possibility of causing problems such as electromagnetic noise or corrosion. For the grounding of lightning rods it is preferable to use vertical electrodes about two or three meters long which form a triangle. This is the most suitable configuration for rapidly dissipating lightning, which is pulse current.
Preventive protection is complementary to external and surge protection. Having information about the proximity of a storm and taking the adequate measures can avoid special risk situations, but cannot avoid device damage if there is not a good protection system. Early detection in thunderstorms is interesting for avoiding maintenance operations and placing mobile panels in less risky positions. It is also interesting for connecting autonomous supply systems to avoid lightning striking on electric lines where connected devices could be damaged.
The ATSTORM® thunderstorm detector is the ideal tool for preventive protection for storm effects and atmospheric discharge since it allows to take specific measures with an anticipation of several tens of minutes before imminent risk of a thunderstorm. It safeguards people and equipment from its destructive effects.
The objective of a local thunderstorm detector is to identify the risk of formation or proximity of a thunderstorm with as much anticipation as possible.
Electromagnetic fields caused by lightning can affect the lines and the equipment, even if there is a lightning protection system that intercepts direct strikes. Cloud-to-cloud lightning and nearby lightning strikes (up to 1 km distance) cause transitory surges capable of damaging equipment. Protection against surges of photovoltaic plants is custom-designed for every installation in order to protect photovoltaic cells and all the integrated elements as much as possible.
If the photovoltaic plant is protected with lightning rods, panels are in an external zone but safe from direct strikes. If there is no external lightning protection it will be necessary to install surge protectors capable to support direct strike effects. Therefore, protectors will be different for each case.
On the other hand, for the protection of electric installations we must distinguish the cases in which generated energy is for self-consumption from those in which it is used for selling to an electric company through a transformation center.
Components used for surge protection
- ATPV series
Custom-designed protective enclosure of photovoltaic plant with the most adequate protectors for photovoltaic cells and invertors of each installation.
- ATVOLT Series
Protection for DC supply lines in modules with coordinated protection for a pair of wires. Capable of withstanding a peak current of 20kA per pole with a 8/20 μs wave and a residual voltage of less than twice the rated nominal voltage.
- ATSUB Series
Single-phase protector capable of withstanding currents of tens of kiloamperes with 8/20μs wave and with residual voltages between 1 and 2kV. Different models available.
- ATSHOCK Series
Single-phase protector capable of withstanding a peak current of 50kA per pole and 10/350 μs wave with a residual voltage under 4kV.
- ATCOVER Series
Protector both in common mode and differential mode. Capable of withstanding a peak current of 30kA per pole and 8/20 μs wave with a residual voltage under 900V. Includes visual warning and connection for remote warning.
For more information about lightning protection systems in photovoltaic installations you can refer to our technical specialists here.