The UK government has set targets to reach net zero by 2050, with a strategy for all electricity to be supplied by 100% zero-carbon generation by 2035. To achieve this target, the development of renewable energy infrastructure, such as wind farms and solar farms, has increased significantly in the last three years, with renewable generation increasing by 10 percent compared to 2022[1]. Battery energy storage systems (BESS) also have a vital role to play alongside renewable generation, by capturing the green energy and releasing it to the electricity network at times of high demand. Given the importance of renewable generation and battery storage systems to the future UK electricity network, it is important to consider the impact of lightning and the potential damage it could cause to this type of infrastructure which is typically installed in remote or exposed geographical locations.

Lightning impact and potential damage

In a single lightning strike, as much as 200kA[2] can be discharged in a cloud-to-ground strike, and so it is easy to imagine how destructive lightning can be. It has the potential to cause loss or disruption of services, irreparable damage to buildings, equipment, and plants, economic or monetary loss to infrastructure, and even injury or loss of life to people or livestock.

In terms of lightning-related damage, there are two main sources to consider;

• A direct lightning strike, either to a structure or a line/service entering a structure. These types of strikes are less common; however, they deliver large amounts of current, causing structural damage, fire, explosion, sparking, failure of internal electrical systems, and injury to persons due to touch and step voltages.
• An indirect lightning strike near a structure or a line/service entering a structure. These are far more common, where a lightning discharge to the ground several kilometers away may induce significant energy into nearby metallic services to cause loss of electrical and electronic systems as well as dangerous sparking at the termination point of these services.

Taking solar farms as an example, statistical data for Germany[3] suggests that 31.2% of damages to photovoltaic systems are due to lightning, with typical damages including defects of the electronic parts of the solar array, damage to inverter electronic and communication components, and cable insulation damage. These damages can potentially cause significant disruption to the operation of the plant as well.

Quantifying lightning risk

The risk of loss for a UK renewable energy generation installation can be calculated using the guidance and principles of the British Standard (BS EN) 62305². Using the methodology within the standard, the risks of loss of human life, loss of service to the public, and loss of economic value can be determined. Where risks exceed tolerable levels, the components and lightning protection level (LPL) of a lightning protection system can be specified and designed.

Mitigating lightning risk

A lightning protection system can be broken down into two elements;

• A structural lightning protection system whose function is to intercept a lightning strike (air termination component), safely conduct the lightning current to the earthing system (down conductor component), and disperse the lightning current to ground (earthing system component).
• Electrical system protection, as the name suggests, protects sensitive electrical and electronic systems against resistive, magnetic, or electric field-coupled lightning current surges. This may take the form of equipotential bonding, segregation and the implementation of surge protection devices.

Using a solar farm as an example, a typical lightning protection system may comprise of free-standing lightning masts or air termination rods fixed to the module racks themselves and supplemented by a buried earthing system (of copper conductors), achieving a resistance of less than 10Ω. Electrical system protection measures are also typically required with surge protection devices fitted on AC, DC and data systems installed within the solar farm.

How PSC can help

PSC utilizes its extensive industry experience to support our clients in accurately assessing the lightning hazard posed to their installations. We develop bespoke lightning protection system designs, utilizing world-leading CDEGS SESShield 3D modeling software (as shown in the figure below) that adheres to industry standards.

If you have a new renewable generation development and the risk of lightning is to be considered, please contact our specialist team to learn more about how we can support you.

• [email protected]
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References

[1] Digest of UK Energy Statistics (DUKES): annual data, 31 October 2023, National Statistics

[2] BS EN62305, Protection Against Lightning, 2011 / 2012, British Standards

[3] Impacts of Lightning-Induced Overvoltage on a Hybrid Solar PV–Battery Energy Storage System, 2021, Nor Izzati Ahmad et al