What applies to the PV surge protection?

What applies to the PV surge protection? 4

Since October 2016, the PV surge protection has been mandatory. The transition period lasted until 14 December 2018 and has now expired. But what does the new surge protection standard DIN VDE 0100-443 actually specify?

Rules for surge protection

The overvoltage protection standard DIN VDE 0100-443 states that overvoltage protection of the photovoltaic system is mandatory should it affect the following:

  • Human life
  • Public facilities
  • Gatherings of people
  • Commercial and industrial facilities
  • Residential and office buildings of individuals, should equipment belonging to overvoltage category I or II be connected there.

This means that PV surge protection for the PV system has been mandatory since December 2018. Almost all buildings connected to the electricity grid are affected by these regulations. Just as old buildings are forced to be retrofitted, you must ensure your PV surge protection. This regulation also comes into force as soon as you make structural changes or extensions to an existing installation. The reason for this is the increased safety for you as the user of the power connection. Both you and the electrician are therefore responsible for ensuring adequate PV surge protection.

What does this mean for photovoltaic surge protection?

The new overvoltage protection obligation also includes the PV overvoltage protection. Therefore, as the operator of a PV system, you are also obliged to comply with the standards. Important: The PV surge protection applies both to existing installations and to additional extensions of solar modules.

Why is photovoltaic surge protection important?

The aim of a PV overvoltage protection is to protect the solar system from overvoltage. For you, this arrangement means that your investment is protected. However, PV surge protection is not about the interception rods that are intended for external lightning protection. Rather, it is about the active components that protect both your PV system and all electrical appliances in the house. After all, lightning does not have to strike directly to trigger very high voltage spikes. The PV surge protection protects against this excessive voltage. Because both electrical devices and the inverter all react very sensitively to such spikes.

Surge protection outside and inside the building

To ensure that the photovoltaic system is protected against overvoltage, protective devices must be used in all cables within the building. Special focus is placed on the solar cables of the PV modules as well as the regular connection to the power grid. Due to the increasing number of storms, this precautionary measure provides you with the necessary safety.

While interception rods at the ridge and down conductors at building corners provide external lightning protection, you also need internal lightning protection. This lightning protection equipotential bonding is a mains connection (alternating current, AC) that is already present. This means that you have two variants available for the PV surge protection that serve as arresters. These are always located on both sides of the inverter - i.e. on the AC and the direct current (DC) side.

How to protect your building from lightning surges

You can keep all DC lines separated with a module field. In doing so, you maintain the separation distance to all components for external lightning protection. However, the calculated protective distance against lightning flashover is difficult to implement structurally. In this case, the module array for surge protection of the PV system is comparatively small.

Alternatively, you can integrate the module array for external lightning protection. This means you can completely neglect the separation distance of the module array. For this to work, connect the mounting system to the arrester wires at all crossing points and corners. If lightning strikes, the direct lightning potential is present on all cables and modules. The disadvantage of this approach is that it involves a higher risk of damage, including fire.

If you choose the second approach for your PV surge protection, it is important to avoid damage to the building's electrical system and the inverter. For this purpose, an arrester is required at the building entrance of your DC line. You need an additional arrester on the AC side of your inverter. This variant is most frequently implemented for PV surge protection due to the unlimited roof occupancy.

Important: Your building does not have external lightning protection according to VDE 0185-305-3? In this case, a type II arrester is recommended for PV surge protection. Such an arrester should be located on both the AC and DC sides. If no such type 2 surge arrester has been installed at the mains connection so far, you must retrofit it.

Lightning protection: Which surge protection do I need?

The PV surge protection always concerns the technical devices that help you to protect your devices from overvoltage. This makes PV surge protection an important part of lightning protection. Basically, as with other protection against overvoltage, a distinction is made between the interior and the exterior of PV surge protection.

  • External lightning protection concerns all the measures you take to protect your building. The aim is to prevent lightning from striking or rolling over. Classically, you use earthing cables and lightning conductors for this purpose. These are called type 1 surge protection devices.
  • Internal protection against overvoltage concerns type 2 of protective devices. This includes, for example, surge arresters, which are usually found in the floor distributors. Such arresters limit the remaining overvoltage to less than 600 to 2,000 volts should a lightning strike occur.
  • Special devices such as sockets with protection against overvoltage or overvoltage plugs are also part of the internal protection measures. These are classified as type 3 and protect particularly sensitive equipment. The voltage is reduced to around 230 volts.

For small offices or residential buildings, you also need a PV surge protection. This is always necessary if you operate equipment that falls under category I or II. Laptops, PCs, telephones, printers or washing machines, for example, belong to this category.

A lightning conductor on a normal residential building, on the other hand, is not obligatory. You only have to install one if the building is particularly vulnerable. This would be the case if it is an exposed building or one that could suffer significant damage from a lightning strike.

 

About the author

TRITEC has specialised in the generation of solar power through photovoltaics for over 34 years. We are active worldwide in both photovoltaic wholesale and large-scale plant construction. In addition to our proven PV mounting system, we also offer our own intelligent system solutions for the planning, design and performance control of photovoltaic systems, as well as branded products from leading photovoltaic manufacturers.