Solar Installation Safety Precautions for a Photovoltaic System (Lightning and Short Circuit Faults)  

What is lightning arrester? What is its functionating and what materials are used?

A lightning arrester is a device used on electric power transmission and telecommunication systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester has a high-voltage terminal and a ground terminal. A lighting arrester uses grounding to bleed off the energy of a lightning strike to the energized circuits. These can be made of various materials, such as bronze, copper or zinc-plated steel, preferred to be made of copper or copper-plated steel rods, driven several feet into permanently moist ground. This may be tin-plated copper tape or bronze tape, as fat as you can manage.

Fig. 1 Lightening arrester with PV Panels

Aluminum could be used but is discouraged because of the difficulty in ensuring good connections at the joints. Copper and aluminum are two of the most common materials used. The tensile strength of copper is roughly 40% higher than that of aluminum also has a lower thermal expansion coefficient than its aluminum counterpart. Copper has a significantly lower electrical volume resistivity: 0.017241 (Ω x mm2)/m for copper, compared to 0.0282 (Ω x mm2)/m for aluminum. In fact, for the same current-carrying capability, an aluminum conductor needs a 56% larger cross-sectional area than copper.25.

What is an Earthing Rod? What is its functionating and what materials are used?

Earth rods and their fittings are used to provide the interface to ground in all soil conditions to achieve satisfactory earthing systems in overhead and underground electricity distribution and transmission networks – providing high fault current capacity on low, medium and high voltage substations, towers and power distribution applications.

Fig. 2 Earthing of Inverter

Depending on the corrosive condition and electrical conductivity of the ground condition the earth rod can be specified to achieve safe, reliable, and long-term earthing protection.

Earth Rod Types

• Stainless Steel Earth Rods
• Galvanized Steel Earth Rods
• Copper bond Threaded Earth Rods
• Solid Copper Earth Rods

solid copper is recommended for high fault current installations whereas copper bonded rods are usually installed for smaller sections. Copper bonded steel core earth rods are the most specified due to electrical and mechanical strength, resistance to corrosion as comparatively lower cost compared to solid copper or stainless-steel types – the lowest cost galvanized rods for usually installed non-critical, short-term, or temporary earthing requirements.