Although the installation of PV systems, especially rooftop PV systems have been increasing in demand and volume of installation, very few contractors are concerned about the lightning protection system that should form part of the PV rooftop installation. The new SANS10142-3 standard being developed; is aimed at providing some guidance with regards to the installation standard for embedded generation. Due to the possible surges that could be experienced during lightning conditions, it is imperative for contractors to familiarise themselves with the various standards relating to earthing, surge and lightning protection mechanisms.
- Four options for LPS exist:
- Photovoltaic plants on buildings without lightning protection
- Plants on buildings in the protected zone of existing lightning protection
- Photovoltaic plants with additional lightning protection measures
- Connection of photovoltaic generators to dedicated lightning protection measures
SANS62305 Part 1,2 & 3 is fairly specific with regards to the various steps needed to be taken in order to ensure a safe installation. During the next couple of months we will be exploring the standards and consider various aspects with regards to protecting a rooftop PV installation that would include the cable design, earth resistivity testing, earth spike placement, etc. In the absence of an established local standard, we will be taking a look at what other standards specify and what could be deemed ‘good practice’ as far as protection mechanisms on a rooftop PV system is concerned.
- It is the installer’s responsibility to see that all regulations and guidelines regarding lightning protection are followed for solar PV systems (DIN V VDE V 0185 ; Guideline VdS:2010 : 2002-07 (01)
- Potential equalisation for all metal parts of a plant that could be touched is compulsory according to DIN VDE 0100, part 712.
- According to VdS2010 a lightning protection concept of the protection category three has to be provided for photovoltaic plants above 10kW
- the existing lightning protection of a building can be affected or disabled by a photovoltaic plant
- The potential equalisation in the whole generator according to VDE 0100 is necessary
- General hint:Some insurance companies demand that wires generally have to run on the outside of a building from the roof to the connection to the power grid. In this case not only the PE but also the DC wires have to be on the outside.
- Additionally a safety distance between the photovoltaic plant and all parts of the lightning protection system has to be kept. The calculation of the distance is made according to DIN V VDE V 0185-2. In practice a distance of app. 0.5m has proven of value.