How to Protect Solar Panels from Lightning?
Photovoltaic systems are becoming very common in our country with the recent efforts. The volume of the sector is growing day by day; Dozens of new companies and investors are added to the economic cycle.
The growth in Solar Energy Systems is seen as a very positive development for our country and our future. At this stage, we should point out that, in parallel with the developments in this field, current standards on basic issues such as project design, implementation, commissioning and material selection have not yet been fully established in our country. In order to overcome this situation, we have to constantly research and be open to innovations in order to establish correct and feasible systems.
Considering the investment dimensions of photovoltaic systems, system continuity should be ensured for many years. For this reason, at every stage from the project planning stage to the acceptance of the system, the technically correct product that complies with the standards must be selected and system security must be ensured.
Photovoltaic systems are becoming very common in our country with the recent efforts. The volume of the sector is growing day by day; Dozens of new companies and investors are added to the economic cycle.
The growth in Solar Energy Systems is seen as a very positive development for our country and our future. At this stage, we should point out that, in parallel with the developments in this field, current standards on basic issues such as project design, implementation, commissioning and material selection have not yet been fully established in our country. In order to overcome this situation, we have to constantly research and be open to innovations in order to establish correct and feasible systems.
Considering the investment dimensions of photovoltaic systems, system continuity should be ensured for many years. For this reason, at every stage from the project planning stage to the acceptance of the system, the technically correct product that complies with the standards must be selected and system security must be ensured.
Considering the investment dimensions of photovoltaic systems, system continuity must be ensured for many years. For this reason, at every stage from the project planning stage to the acceptance of the system, the technically correct product that complies with the standards must be selected and system security must be ensured.
The lands where solar energy investments take place are generally open areas where lightning strikes can easily reach. The risk reaches more serious levels in umbrella institutions. A lightning strike at a nearby location also poses a risk for our facility.
Sudden voltage changes caused by grid returns other than lightning damage photovoltaic cells and inverters. Since the panels and all other elements of the system are very close to each other in solar power projects, a lightning strike to the facility can spread very quickly to the entire system due to small resistance differences. In light of the information we have gained from our field experiences, an investment worth millions of liras can suddenly become disabled and completely damaged.
Lightning strike is a natural disaster that can reach a maximum value of 200 kA, travel through the system in nanoseconds, and reach temperatures up to 28,000°C. We must protect our project, which we created with an investment of millions of lira, against the damages of such a coup. For this reason, protection systems against Lightning and Sudden Overvoltages in Solar Power Plants must be properly designed; With the right product and system selection, protection should be achieved at the maximum level in the light of VDE IEC 62305 -5, DIN VDE 0100 Part 712/E and DIN IEC 64/1123/CD Standards.
In AC and DC lines before and after the inverter; Installing a surge arrester system in the main distribution panel, data lines and before each panel will ensure the continuity and reliability of the facility. We can use a D product at the inverter input and an AC product at the inverter outputs of serially connected panels.
How Should We Create Our "Lightning and Sudden Overvoltage Protection" Project in Solar Panels?
The project planning phase of Solar Power Plants is of great importance in terms of protection from overvoltage and lightning. The system should be considered as a whole and "grounding, equipotential system, external lightning system and internal lightning system" should be designed in an integrated manner. In this article, we will primarily present findings on the design of internal lightning systems and external lightning systems.
If we want our project to be protected from lightning and sudden overvoltage impacts, we have to use internal lightning arrester system in energy and data lines without exception. Installing a surge arrester system at the inverter energy input and output ports (AC output and DC input), main distribution panel, data lines and even before each panel will ensure the continuity and safety of the facility.
The first of the most important points we should pay attention to when choosing internal lightning systems is the protection class of the product. While class B provides protection against lightning strikes in surge arrester systems, class C products only provide protection against mains strikes. For this reason, it is important to choose B+C class products for both AC and DC lines. DC product should be used at the inverter input of serially connected panels and AC product should be used at the inverter outputs.
The second thing we need to pay attention to is the maximum continuous voltage that the product can withstand. In DC, the continuous voltage of the panels can reach up to 1000 V. If a 600 V tested product is used in a system with a voltage value of 1000 V, we will damage the surge arrester at this point.
Therefore, continuous test voltage is important. Another issue we need to focus on is the protection value of the surge arrester. Although this generally varies regionally and according to the physical condition of the facility, on average a product with a protection level of 50 kA is suitable for before and after the inverter. The use of class B products with spark gap technology with a protection value of 150 kA in the main panel at the point of transferring energy to the system maximizes system security.
The lands where Solar Energy investments take place are generally open areas where lightning strikes can easily reach, the risk reaches even more serious levels in roof systems.
If the energy produced in the facility is monitored remotely and communication modules are used, class D products can be used at this point. Communication module protections ranging from 24V, 48V, 120V can be selected by expert engineers according to the system characteristics. The installation of surge arresters is carried out in B + C classes, parallel to the system, with a cable with a cross section of 16 square millimeters.
For D classes, a serial connection is suitable. Installation is as important for system continuity as product selection. With the design of internal lightning systems, we absorb any shocks to our solar power plant and equipment before they reach the system.
In accordance with design standards; There must be a certain angle between the collector rod and the solar panels, the angle must be calculated according to appropriate criteria.
For the physical security of the facility, we need external lightning systems to control lightning strikes directed to our Solar Power Plant project and to ensure human and environmental safety. The use of passive lightning protection systems in systems to be designed based on the rolling sphere method should be preferred within the scope of the IEC 62305 standard.
Lightning rod systems will also attract lightning that may strike around our facility to our site. For this reason, protection by creating a protection angle with passive catch rods that are activated only if lightning strikes the facility is of great importance.
This way we can create 3 different types of protection:
1-) Faraday cage method by creating a protection angle with long catch ends behind the panel: A mesh method is created on the facility surface.
2-) Creating a protection angle with short catch leads on the panel: In this method, each panel must be included in the equipotential system.
3-) Field area protection: Field protection with long insulated lightning arresting poles - ring line and equipotential system is of great importance.
With an appropriate survey based on the size and physical condition of the facility, the protection system can be selected in accordance with the facility characteristics. Our aim is to ensure that the lightning strike falls on the system designed by calculating the angles and that no impact reaches the panel. In order to avoid shadow problems in the 1st and 2nd systems, the distance between the panels must be at least 2 times the panel length. This is also done in classical systems because it provides more comfortable operation.
It is also an important point that the lightning strike and ground damping conductors are isolated. Otherwise, the magnetic field created by the lightning strike may cause damage to the equipment. For this reason, internal lightning systems must be used. If an insulated conductor is not used for connections between panels, lightning strike and grounding, the "s" protection gap distance must be observed. In this context, the distance of the conductor from the equipment is calculated with the following formula in the light of the IEC 62305 standard:
The system appropriate to the facility characteristics should be designed and implemented by expert engineers. Each product to be selected must have a lifespan of at least 25 years, and all precautions must be taken against the risk of corrosion.
In systems where area protection will be provided, lightning capture terminals up to 8 meters are included in the equipotential system with ring lines and panels, and any lightning that will strike the environment is not reflected to the facility with area defense. Each system has its own arguments.
The issue of lightning protection of solar power plants is ignored in our country (especially the use of internal lightning systems). Investments worth millions of lira are disabled just for this reason and serious damage occurs. As renewable energy investments increase in our country, we have no doubt that all systems will reach a perfect structure in the shortest time as a result of TEDAŞ's superior work on this subject.