Updated: Feb 18, 2021
International safety standards require that all solar installations be earthed. If mounted on metal racks, it is a standard requirement to also have the racks earthed. However, since solar panels are double isolated, they need not always be earthed except under special circumstances.
The Physics of Grounding And/Or Earthing
To earth an electrical system is to connect its non-current-carrying components or the body or enclosure of the system to the earth. The earthing component is connected between the equipment body or enclosure and the earth pit which is placed under the earth surface. The goal is to discharge the electrical charge directly to the earth.
Note: 'Earthing' may be used interchangeably with 'grounding' but technically, they do not necessarily mean the same thing. To earth means to connect the non-current carrying components while to ground means to connect the current carrying components to the ground. Solar panel systems are mostly earthed.
Your Panels May Need to Be Earthed if:
They are in the immediate vicinity of a lightning conductor system.
A transformerless inverter is being used. As implied in the name, transformerless inverters do not have inbuilt transformers. The function of the transformer in the inverter, which is to step up the voltage generated through the solar panels or batteries, is replaced with computerized multi-step processes and other electronic components. They are thus less complex in their designs and thus more prone to surges and shocks.
Read all about transformerless inverters here.
If earthing is required for a PV system, the following components will be needed:
An Earth Cable. Most earthing cables are made of copper strips instead of a single bare copper rod. This conductor is used to connect all the metallic parts of the PV system. It is required that the earth wire in the cross-sectional area must be less than the solid wire used in the electrical wiring system.
Earthing Joint. The earthing joint includes the conductors that fixes the earthing conducted to the earth. The lead of the ground must be low size, straight, & should include a minimum amount of joints.
Earth Plate. This is the part that is hidden underground. It is linked to the earthing joint. It can be a pipe, plate or metallic rod, or plate, which has extremely low resistance for carrying the fault current to the ground safely. It can be made of copper or iron rod and must be placed in wet earth. In the case where the moisture is of low content, then some water is to be poured into the earth plate. It is to be placed in the vertical position and the area around it covered with salt and charcoal lime.
Earthing may be done in these three ways:
Plate Earthing System
A plate that made up of copper or GI (galvanized iron) are placed vertically in the ground pit less than 3m from the earth.
Pipe Earthing System
A galvanized steel based pipe is placed vertically in a wet pit. This is the most common type of earthing system. The pipe size mainly depends on the soil type and magnitude of current. Usually, for the ordinary soil, the pipe dimension should be 1.5 inches in diameter and 9feets in length. For rocky or dry soil, the pipe diameter should be greater than the ordinary soil pipe. The soil moisture will decide the pipe’s length to be placed in the earth.
Rod Earthing System
This type of earthing system is similar to pipe earthing system. A copper rod with galvanized steel pipe is placed upright in the ground physically or using a hammer.
Earthing is a way of transmitting any instant electricity discharge directly to the ground through low resistance wires or electrical cables. This instant electricity discharge is mostly in the form of lightning. The goal is to protect the appliances for voltage surges, but much more, the users from electrocution.
Our engineers at SolarKobo will help you decide if your system needs to be earthed.