Grounding, earthing and lightning protection for solar panels

[Isetech]

When we do install an earth spike we generally connect it to the AC control board next tot the inverter with a 16 mm wire connected to the earth bar. I dont know of any electricians who have ever done a proper earth spike test or even own a tester capable of testing earth spikes

This is something we will be looking into in the new year.

Sorry - am trying to find if there is an earth spike for the solar panels - does that earth spike need to be connected to the supply earth spike at that incomng supply?

[StepupEnergy]

The first question, what is the purpose of the earth wire connected to the rails system? Lightning protection or to create a path to ground in case of leakage current.

How do you determine if the installation requires lighting protection or just a leakage fault path?

Then we should be asking, do we need to bond each panel in a daisy chain fashion.

Do grounding lugs/plates mounted between the rail and the panel (stainless steel plate with points) create a suitable low resistance path?

The earth spike, it seems to be another topic where people seem to feel that adding an earth spike is the right thing to do, but is it?

Grounding and earthing are two different concepts but interrelated.
Bonding is to ensure that all the metal items are at the same potential to protect persons and animals.
Earthing plates, which have small spikes on both sides, are a good idea between the panels and rails to avoid corrosion high resistance.
The rails are bonded to the DC surge protection using 6mm yellow/green wire and then on to the DB earth bar.
The inverter and battery casings are also bonded individually to the DB earth bar topreserve the integrity in the event of one item being removed.

Adding to the importance of the panel earthing is that panels can be damaged and leak to the frame. Some inverters can detect this and cause an alarm.

The NRS standard only allows one earth, namely the TN-S earthing system of the Supply authority.
Additional earth spikes are not permitted due to the potential difference of a nearby strike. This creates a current flow through the bonding causing possible damage.
GCE covers this well in another reply.

[Shadyshaun]

The panels we use, are class II rated so they should not be leaking power to the frame. The solar cabling is also double insulated, so unless someone is going out of their way to damage the equipment, you shouldn't experience leakage problems.

Adding to the importance of the panel earthing is that panels can be damaged and leak to the frame. Some inverters can detect this and cause an alarm.

[GCE]

The panels we use, are class II rated so they should not be leaking power to the frame. The solar cabling is also double insulated, so unless someone is going out of their way to damage the equipment, you shouldn't experience leakage problems.

SANS 10142-1 requires that the frames shall be bonded to earth - The reason for bonding is in case of a fault like somebody intentionally/unintentionally damaging the equipment


Extract from SANS 10142-1
6.12.3.3 Metallic frames and metallic enclosures of electrical equipment shall
be made electrically continuous.

6.13.2.4 Roofs, gutters, down pipes and waste pipes
If a building is connected to an electricity supply, the roof(s), gutter(s), down
pipe(s) and waste pipe(s) shall be bonded and earthed and the resistance of
the earth continuity path shall not exceed 0,2 Ω, unless
a) the supply voltage does not exceed 50 V,
b) the supply uses an underground service connection,
c) the roof is made of, or covered with, non-conductive material,
d) the gutter(s), down pipe(s) and waste pipe(s) are of non-conductive
material, or
e) the gutter(s) and down pipe(s) are attached to a metal roof that is covered
with non-conductive material.

[Shadyshaun]

You seem to be a smart person with a fair amount of insight into he SANs regulations, do you know why this section of the code was created many many years ago? I doubt it has anything to do with class II double insulated solar panels.

The next question I would ask, if the frame poses a risk, why dont the panels have a simple certified method for bonding, supplied or attached to the panel, similar to the MC4 connector?

Just imagine if light fittings where supplied with a hole and a symbol, do you think electricians would bother connecting an earth wire. The only reason some electricians consider connecting the cover of certain lights to earth, is because there a spade connector provided.

6.13.2.4 Roofs, gutters, down pipes and waste pipes
If a building is connected to an electricity supply, the roof(s), gutter(s), down
pipe(s) and waste pipe(s) shall be bonded and earthed and the resistance of
the earth continuity path shall not exceed 0,2 Ω, unless
a) the supply voltage does not exceed 50 V,
b) the supply uses an underground service connection,
c) the roof is made of, or covered with, non-conductive material,
d) the gutter(s), down pipe(s) and waste pipe(s) are of non-conductive
material, or
e) the gutter(s) and down pipe(s) are attached to a metal roof that is covered
with non-conductive material.

[GCE]

You seem to be a smart person with a fair amount of insight into he SANs regulations, do you know why this section of the code was created many many years ago? I doubt it has anything to do with class II double insulated solar panels.

The next question I would ask, if the frame poses a risk, why dont the panels have a simple certified method for bonding, supplied or attached to the panel, similar to the MC4 connector?

Just imagine if light fittings where supplied with a hole and a symbol, do you think electricians would bother connecting an earth wire. The only reason some electricians consider connecting the cover of certain lights to earth, is because there a spade connector provided.

Bonding of external parts has also been part of the code and PV panels have also been around for years and if you want to have more relevant codes specific to PV panels then 7.12.7.6 refers you to that particular clause ( extract pasted below )

Clause 6.12.3.1 e - clearly states earthing terminal of all permanently connected electrical equipment - The PV panels have a earth point referred to as grounding point - check your panel spec and warranty document - The manufacturers of structures have provided simplified bonding arrangements for a reason

Clause 5.1 clearly states that you need to comply with manufacturers requirements .

Clause 7.15.2 of SANS 10142-1 also requires bonding of wireways etc in DC systems and under 7.12 you are referred to 7.15

Then if you are still trying to convince yourself that SANS 10142-1 is not relevant to PV panels then clause 7.12.7.1 from SANS 10142-1 refers you to SANS 60364-7-712 which has numerous references to earth including the earthing of structures and uses the word " Shall" - extract pasted below


SANS 10142-1
7.12.7.6 If applicable, all exposed conductive parts may require earthing as
prescribed in 6.12.3.

5 Fundamental requirements
5.1 General
All commodities in an electrical installation shall be installed in accordance
with the requirements in this part of SANS 10142 and with the manufacturer's
instructions, where applicable.
NOTE 1 This clause contains the general safety principles applicable to electrical
installations.
NOTE 2 The manufacturer's instructions may contain more stringent requirements.

Extract from SANS 60364-7-712
712.542.103 Bonding of PV metal structures
Where such bonding is necessary (e.g. to facilitate the correct operation of the array
insulation resistance detection referred to in 712.531.3.101.1), the metallic structures
supporting the PV modules (including metallic cable trays) shall be bonded.
Such bonding may be necessary, for example, where a transformerless PCE induces an
electrostatic charge.
The bonding conductor shall be connected to any suitable PE terminal.
Where these metal structures are of aluminium, appropriate connection devices shall be used.
The bonding conductors (insulated or bare) shall have a minimum cross section of 4 mm2
copper or equivalent.
PV array bonding conductors shall be run as close to the positive and negative PV array and
or sub-array conductors as possible to reduce induced voltages due to lightning. See also
712.521.103.

[Derlyn]

The panels we use, are class II rated so they should not be leaking power to the frame. The solar cabling is also double insulated, so unless someone is going out of their way to damage the equipment, you shouldn't experience leakage problems.

Bonding and earthing the panel frames is not only in case of any leakage, but extremely important on houses with overhead supplies, irrespective of whether the panels are class II rated or not. If the overhead wire breaks and touches the panel frame, you will want that supply to disconnect immediately otherwise the frames are "live". This can only be achieved by earthing the frames. This is the same reason that metal roofs, gutters and down pipes must be earthed.

[Shadyshaun]

This is why it is so important to visit the site.

Bonding and earthing the panel frames is not only in case of any leakage, but extremely important on houses with overhead supplies, irrespective of whether the panels are class II rated or not. If the overhead wire breaks and touches the panel frame, you will want that supply to disconnect immediately otherwise the frames are "live". This can only be achieved by earthing the frames. This is the same reason that metal roofs, gutters and down pipes must be earthed.

[StepupEnergy]

Grounding and earthing are two different concepts but interrelated.
Bonding is to ensure that all the metal items are at the same potential to protect persons and animals.
Earthing plates, which have small spikes on both sides, are a good idea between the panels and rails to avoid corrosion high resistance.
The rails are bonded to the DC surge protection using 6mm yellow/green wire and then on to the DB earth bar.
The inverter and battery casings are also bonded individually to the DB earth bar topreserve the integrity in the event of one item being removed.

Adding to the importance of the panel earthing is that panels can be damaged and leak to the frame. Some inverters can detect this and cause an alarm.

The NRS standard only allows one earth, namely the TN-S earthing system of the Supply authority.
Additional earth spikes are not permitted due to the potential difference of a nearby strike. This creates a current flow through the bonding causing possible damage.
GCE covers this well in another reply.