Installing solar panels

[Thys LOW Elektries]

Then we need to discuss the earthing and bonding on the rails and where the earth wire from the panels should be connected. Should a dedicated spike be installed or do we just connect the earth wire directly to an earth bar shared by all the other earthing and bonding. (No this has nothing to do with relays and earth/neutral bonding, we will go into that as we learn and understand why one or the other is safer)

What size earth wire should be installed from the panels down to the earth bar or spike.

Do you need to bond the panels together and what size wire should you use to bond the rails or panels if required.

You maybe asking why I am wasting my time with threads like this, because I believe the only way to improve this industry that is falling through its own butt crack and winning the race to the bottom is by educating people.

Hopefully my small contribution will add a little value to the industry and hopefully make them want to improve their workmanship.

You might say that there are training courses, we all know how many employees send their staff for training. Those same employees lacking the training required are the same people being dropped off on site. Thanks goodness electricity is not dangerous.

Having a separate earth and earth spike is always a good idea, especially with hybrid or island systems. I'm not sure about the regs part on this though. The supply earth can get lost due to theft or maintenance and your installation will float since it have no earth
Installers tend to rely on the supply side for safety and forget the supply can be disconnected and then you have safety

[Isetech]

These panels become an interesting topic because of the voltage (50-1500 VDC) and their exposure to the elements.

We need to ask what are the risks and what steps should be taken to reduce the impact.

What is the risk of contact between the cell voltage and the frame?

What if the frame or rails take a direct hit?

Should we link the frame and rail earthing and bonding to mains?

Should we earth the negative and connect it to earth or use a surge arrestor instead?

[Thys LOW Elektries]

Surge arrestor and fuses, if installed correctly plus correct type, can handle high voltages at high speed. Whereas a breaker must get warm before it trips, with lightning and a big short the breaker can melt or explode instead of tripping.
Also if you get to that fault level a breaker will give you little protection and you might lose sensitive equipment, fridges and freezers, a bad thing to happen.
We recently installed a solar system on the roof of a barn, closest point to Eskom supply, lightning hit the house about 300m from our installation. The house had big damage, the solar system only blew a fuse on ac side. If we didn't earthed everything and put an earth around the building, in the ground, things might have ended differently for us.
Having two seperate earths are a good thing, I have seen installations where the installers had put a fuse between the pv eart and the ac earth, maybe an overkill, but I can understand why

[Isetech]

The solar panels create an ungrounded DC supply between the DC combiner box or directly to the MPPT of the inverter.

What does this mean? That at no point is the neutral (negative - ) of the DC supply connected to ground (earth) between the panel and the combiner box.

Why would you want to install and earth wire with the DC wires?

Then you ask yourself, do you connect the negative at any point or do you install DC surge protection instead?

Then what would be the purpose of an earth wire connected to the frame of the panel?

Why would you connect an earth wire between the panels and the grid supply, as part of a lightning protection?

What would be the purpose of installing earth wires for and ungrounded DC system?

Why would you bond all the panels and rails together and run an earth wire from the roof to an earth spike and makes sure the resistance is less than 10 ohms, when you could just connect it directly to the main grid earth terminal.

[Derlyn]

The question to ask is what the earth is for. With dstv dishes, the earthing has nothing to do with lightning but everything to do with discharging any static build up. Lets face it, a 2,5mm wire means nothing if the dish is struck by lightning.

Now I ain't a solar boffin and I'm just asking a question. Is the bonding and earthing of the solar panels not maybe to discharge any static builup on the frames ?

[GCE]

Earthing on PV systems is used for Ground fault detection , can come into play to help prevent PID which is speeded up with leakage between panels and the frames .

Some Inverters have internal check mechanism's between earth and the DC cables which is why you need to run the earth with the string wiring

Have pasted an extract that was publisjhed in SANS 10142-1-2 before being withdrawn , but gives you an idea on the thought process when the regs where being looked at

5.4.3 Bonding
5.4.3.1 All the exposed conductive parts of the PV system (i.e., panel frames, cable trays, and
inverter chassis etc) shall be bonded together with a minim cross-section of 6 mm2 copper cable or
other materials with an equivalent current-carrying capacity.
5.4.3.2 The module mounting rail manufacturers earthing method (earthing plates) is acceptable
where PV modules are bonded together, this shall be tested by measuring in accordance with
SANS 10142-1.
5.4.3.3 All bonding connections shall be bonded back to the protective earth at the consumer earth
terminal including the local earth electrode where installed.
5.4.3.4 Both the AC and DC earth electrodes where installed shall be bonded together via the
electrical continuity conductor (ECC) with a minimum cross-section of 6 mm2 copper cable or other
materials with an equivalent current-carrying capacity.
NOTE 1 A structure with an external lightning protection system (LPS), where the LPS is bonded to the PV
system, a minimum cross section should be 16 mm2 copper or other materials with an equivalent current-carrying
capacity.
NOTE 2 There is a risk that embedded generators can generate capacitive coupling, harmonics and unsafe
working conditions, which could impact the performance of a solar PV system. In the event where this
phenomenon is experienced, the design and quality of equipment should be carefully considered, please see
7.12.5.1.2 of SANS 10142-1:2021 for possible mitigation options.
5.4.3.5 Bonding continuity to be tested in accordance with the requirements of SANS 10142-1.

[Isetech]

Do I understand this correctly?

If the new regs were approved and not withdrawn, you would have to run a 6 mm wire with your positive and negative wire from the panel. However because the regs were with drawn it doesnt apply?

This must start getting rather interesting if we start looking at panels mounted on a tin roof with an over head line.

[Isetech]

https://esv.vic.gov.au/wp-content/uploads/2021/03/ESV_LEIGuideEarthingPVSystems_Mar2021.pdf

[GCE]

Do I understand this correctly?

If the new regs were approved and not withdrawn, you would have to run a 6 mm wire with your positive and negative wire from the panel. However because the regs were with drawn it doesnt apply?

This must start getting rather interesting if we start looking at panels mounted on a tin roof with an over head line.

It is all covered under SANS 10142-1 - just need to look up the parts vs it being under a particular heading
Also under manufacturers specification

Tin roof with overhead supply always has to be earthed ( 6.13.2.4 ) - Everybody forgets and then runs a supply to the steel carport and does not earth the carport - Same with panels

You have aluminum frames that depending on the panel , humidity and temperature can have stray currents from the panel which is where the PID comes into play.
There have been studies done on the effect of a ground fault without have a good grounding point causing irreparable damage to panels due to PID
Some inverters at night create a slight reverse feed to the panels to repair the effect of the electrons all flowing in one direction during the day
Some panels and inverters require that the neg leg is earthed

From SANS 10142-1


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.



7.15 D.C. installations
7.15.2 Earthing
Earthing and bonding of power supply circuits for d.c. installations shall
comply with the following requirements:
a) the "O V" (earth) polarity of each d.c. power system of a telecommunication
system shall be bonded with a solid connection to an earthing terminal at
the point of supply of the d.c. power plant, which shall be the main earthing
terminal;
b) if an earth electrode is required, it shall comply with the requirements of
SANS 1063, be installed in accordance with SANS 10199 and be bonded
to the main earthing terminal of the electrical installation;
c) the main earthing terminal shall be bonded to the consumer's earth
terminal (see also 6.11);
d) the common bonding network shall be bonded to the main earthing
terminal at least at one point;
e) all accessible conductive parts of the installation (rectifier cabinets,
equipment racks and cabinets, enclosures, grids, wire-ways, etc.) shall be
bonded to the common bonding network; and
f) the d.c. return path in its entire length shall be capable of carrying
overcurrents in the case of a fault between a live power conductor of the
secondary supply and the common bonding network;
NOTE 1 Earthing of telecommunication installations is multifunctional and used for
the following purposes:
a) electrical protection;
b) protection against lightning and surges;
c) to provide a reference plane for signalling; and
d) to comply with EMC requirements.
NOTE 2 The earthing practices in telecommunication d.c. power systems deviate
significantly from the earthing standards given in this part of SANS 10142. Main
points of deviation are
a) the multiple earthing or bonding connections to current-carrying conductors at
points beyond the point of control, and
b) the current that flows in the protective earth bonding conductors, and in all
metallic parts bonded to the system. Correct sizing of power conductors
generally minimizes this.

[Isetech]

What do we take from this thread.

Solar PV systems are ungrounded DC systems which connect to a DC combiner box, using fuses for overload protection, a switch disconnector to safety isolate the panels from the inverter and surge protection devices to create a low resistant path to ground.

Now you take an earth wire and link all the rails and panels together, run an earth wire next to the ungrounded DC wires (maybe 4/6 or 10 mm solar wires) and connect it to an earth terminal, which you link to the mains earth and hit an earth spike into the ground and join all the earth wires together.

[Isetech]

Once we take care of the lightning protection, then we have to consider leakage currents between the cells and the metal components of the panels.

Do we turn the system in to a grounded DC system and bond the negative wire to earth?

I get the feeling that people are just installing earth wires because someone mentioned it might be a good idea to have lightning protection, so long as you install an earth wire ( the bigger the better) from and earth point on the roof and knock a spike in the ground, your system is legit and ready for the COC.

Do you know of any panel companies which suggest you ground the panels?

[GCE]

Do you know of any panel companies which suggest you ground the panels?

All of them - That is why the rail and clamping system is designed to accommodate a stainless steel earthing clip that fits between the clamp and panel

[Isetech]

I dont mean grounding as in installing and earth wire, I mean grounding as in connecting the negative to the earth, like we do with the neutral earth bond.

All of them - That is why the rail and clamping system is designed to accommodate a stainless steel earthing clip that fits between the clamp and panel
[ATTACH=CONFIG]8685[/ATTACH]
[ATTACH=CONFIG]8686[/ATTACH]

[Isetech]

Not the smartest thing connecting stainless Steel and aluminum.

All of them - That is why the rail and clamping system is designed to accommodate a stainless steel earthing clip that fits between the clamp and panel
[ATTACH=CONFIG]8685[/ATTACH]
[ATTACH=CONFIG]8686[/ATTACH]

[Isetech]

Something I was taught a long time ago, always look at the manufacturers installation requirements.

Lets say we are going to install Canadian panels, you would need to read the installation installation instructions, something us tradesmen are not very good at (should I say some of us)

https://www.canadiansolar.com/wp-content/uploads/2020/08/Installation_Manual_of_Standard_Solar_Modules_en.pdf