Grounding, earthing and lightning protection for solar panels

[Dylboy]

100%, earthing, bonding and lighting protection are all separate.

There needs to be a clear definition and purpose to either, earth, bond or lightning protect panels and from there we can figure out what needs to be done and tests to be done.



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[Isetech]

I was called out ot a site a couple years ago, no power in the house.

Popped the Db off put the tester on the mains, 230 VAC, no problem, put the leads on the top of the ELU, 230 VAC, no problem.

Pressed the test button on the ELU nothing, put the leads on the bottom of the ELU, nothing. Popped the ELU out and noticed it was super light. It was empty> I noticed a small hole in the front, picked up the DB cover and noticed a hole in the same place.

I took it back to the workshop and cut it in half, that was something I have ever seen once in 40 years of working as an electrician. I can only assume that it was hit by lightning which melted all the metal components in the unit, there is no other explanation. the thing that I dont understand why all the other equipment didn't melt. I have seen some strange thing and witnessed the result of a dead short that tripped a 1500 amp breaker and another incident 2500 amp breaker. Fortunately the second one, the panel was closed so I didnt get burnt, but took the wind out my sail. For those who have experienced the big bangs , will know what I talk about when I say the sound of the bang is so different. More like the sound of a car bomb, you sort of feel the after affect before you hear that noise it makes. Fortunately I was sitting in a position that the glass and debris didnt hit me, I just got the pressure of the explosion (thanks to Mcbrides efforts, which got him a top position in the police ) I can say the same for the 2 women who's bodies were part of the debris from through the door and everyone else who was sitting in the front part of the building.

I wish I had kept it like all the old electrical equipment I use to collect. Got a bee under the bonnet and dumped everything.

[Gene]

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?

[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.

[StepupEnergy]

Grounding and earthig of PV systems

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.

[Shadyshaun]

I am yet to see an earth mat installed for a solar installation. That is why specialized tasks should be carried out by people who are specialists in that field, not by a bunch of clowns who think randomly knocking in a bunch of earth spikes around a property is going to cut it.

The earthing on for instance a tower with an earth mat in the ground will take the ionization that forms in the air down to earth using the earth mat to dissipate the voltage
At the point in time the potential difference in the earth will lift closest to the earth mat and become less further away - Animals legs are 1,5m apart and therefore the potential difference can increase between the legs briefly and sufficiently to electrocute them - The increase in potential difference is dependent on the proximity on the lightening
Is the reason you should shuffle if walking outside in a thunderstorm and the reason why the 2 guys carrying an extension ladder of 5m in a thunderstorm took a big hit - It was not a direct strike but just that they were in close enough proximity of where the lightening happened to hit the ground and the distance between them joined with an aluminum ladder increased potential difference across them .

The potential difference of the ground depending on the size of the strike can be in a conical effect over a distance of 2KM - the attached oic gives an idea

[ATTACH=CONFIG]8692[/ATTACH]

[Gene]

It makes sense Shadyshaun but what if the authorities requires an earth spike?
So bonding the solar panels to your DB earth,- in an event of thunder would fry the earth wires?

[Shadyshaun]

The site assessment and design will determine the specifics. Electricians are not design engineers, nor are they lightning specialists and therefore should not be offering solutions, which do not fall within their scope of expertise. It would appear (reading comments on social media) that many electricians feel that one size fits all and every application is exactly the same, you will even be rewarded with certification once you have completed a certain number of installations.

If the design criteria specifies an earth spike, it should be installed.

Would an earth wire fry, it would depend on the intensity of the strike. Without testing the resistance of the earth wire, you would never know the impact of the strike. It may appear to be ok, however in some cases the wire could reach such extreme temperatures that it would render the wire pretty useless.

If you have been in the electrical industry for a while, you would have noticed wires which are no longer "shiny bright copper" , they are not as flexible and turn a blue/black colour, they should be replaced.

It makes sense Shadyshaun but what if the authorities requires an earth spike?
So bonding the solar panels to your DB earth,- in an event of thunder would fry the earth wires?

[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.

[GCE]

T
If you have been in the electrical industry for a while, you would have noticed wires which are no longer "shiny bright copper" , they are not as flexible and turn a blue/black colour, they should be replaced.

Where the wires are Blue/Black in color it would mean that excessive current has been drawn through the copper and you would need to see why before just replacing.

It is one of the reasons that running an earth wire all the way down to a Borehole pump is no longer needed as the earth to the pump ended up being the best earth around and taking excess current down to the "earth Rod hanging in water 100m down" - You would always find a borehole earth wire went blue/black in color

[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.

[Shadyshaun]

Generally, we would scan the electrical installation with a thermal camera, use a clamp meter to measure the current, check the overload protection rating, review the data and create a report with recommendations.

There are many factors to be taken into consideration, loose connection, bad contacts in the switch gear, unbalanced loads just to mention a few. We have also found that in some case it is just due to the high demand over a long period of time.

Where the wires are Blue/Black in color it would mean that excessive current has been drawn through the copper and you would need to see why before just replacing.

[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.