Is there a requirement to ground the solar panels?

*NOTE: The information below is directed towards installers. Only trained electricians are allowed to install Ferroamp’s products.  

Answer:

There is currently no general requirement to ground the solar panels. However, it is possible and sometimes required to ground the solar panels if the manufacturer of the panels demands it.

To clarify the concepts around grounding, the following excerpt from the Swedish Electrical Safety Authority's website applies:

Class I - Electrical equipment of class I means that protection against electric shock is not based solely on basic insulation but that an additional safety measure has been taken by connecting exposed conductive parts to ground.

Class II - Electrical equipment of class II means that protection against electric shock is based solely on basic insulation and an additional safety measure, such as double insulation or reinforced insulation.

Some terms and expressions to keep in mind are:

• Functional earth (FE): Grounding to increase/ensure functionality.
• Protective earth (PE): Should be a green-yellow conductor. Commonly referred to as Protective earth (PE) in English.
• Stray currents: Unwanted currents that occur between different potentials where the return current does not follow the metallic conductors intended for the return circuit. For example, between two grounding points or a water pipe and a grounding rod.
• PUS - Potential Equalization Strip: Often means potential equalization, which is a collective term for equipotential bonding and functional bonding. A building can have several strips for potential equalization, known as PUS strips. In each building, there should be only one main grounding rod, and it should be clearly marked.

Various types of grounding

As described above, there are different ways to ground. These are described with several symbols as seen below.

Something important to consider is that not all ground is equal. Ground can have different protection classes. Protective earth (PE) and Functional earth serve different purposes. Functional earth can be fed from protective earth, but protective earth should not be fed from functional earth.

What does this mean for the Ferroamp system?

All Ferroamp products should always be grounded with PE conductors. The EnergyHub gets its protective earth from the power grid, while the DC grid including SSOs and batteries gets its protective earth from the EnergyHub in turn.

So, regarding whether to ground the solar panels, here are some different options:

Your own local grounding point

A separate grounding point can be established using an iron rod or by burying a metal plate in the ground. The grounding point in the ground is then connected to the functional earth for the solar panels.

Connect the functional grounding point to the earth terminal where the other PE is connected

The functional earth is connected to the same earth terminal where all other grounds (both protective earth and functional earth) are connected.

Connect the functional earth to a separate earth terminal (separate from protective earth)

The functional earth is connected to a separate earth terminal, but the earth terminal itself is part of the same earth terminal. This is a compromise between options 1 and 2 above.

Which option is best depends on local conditions. It's important to note that if you want to ground your solar panels functionally, the cable should not be yellow-green to clearly indicate that this is not a protective earth. It can then be connected to the SSO's outer earth terminal as long as the SSO itself is grounded with the rest of the DC grid.

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