Hi Guys, I would like to get some info before makings some decisions and also ensure system is complaint to avoid insurance issues later on.

1. When was it a legal requirements when installing solar that you have DC Breakers installed between incoming pv and the inverter, so that you can isolate the PV Strings when needed? Currently there are only fuses, and essentially you cannot isolate the pv strings during the day safely. Installer wants to charge for doing this, stating that it's a new regulation?

2. Regarding the solar panels earthing, Should each panel be connected together from a single source down to the earth spikes or is it allowed to connect the earth wire to the first panel, and then jump between them, daisy chaining. Basically what I am trying to understand if there is a break between 2 panels for the earth then the earthing will not work how it should. Any break between any panels should not break earthing as a whole - Just want the legal requirement here to ensure its compliant and no issues when insurance time comes....

Thanks

On 1, it is a requirement to have a PV disconnector that can isolate the panels from the inverter UNDER LOAD in case of an emergency. So most installers add a DC circuit breaker or isolator before the fuses. But there is a little difference; if you have multiple strings, you must have fuses, as current from one string can feed another under a fault. If you have one string (a single series arrangement of panels), then a DC circuit breaker with the correct rating is sufficient, and fusing is not required, as the circuit breaker can act as the overcurrent device and the isolator.

I don't know if you have a clear instruction on the DB box stating to isolate the AC and battery breaker first before opening the fuses (that is enough in my opinion, as that is basically no load). If an installer/insurer would consider that ok, but SANS does say isolation under load, unfortunately.

On 2, A single earth cable, connected from one panel to the next and then from the last panel to the earth spike, is sufficient. An earth cable of at least 6mm2 is required. They must all be earthed together. The rails must also be earthed. Pulling multiple earth cables from each panel to the earth spike is very unnecessary in my opinion. The panel spike and the house earth must be bonded together also, a minimum earth cable for this must be 10mm2 if I am not mistaken.

This is how I understood the SANS 10142. @TaliaB He is an installer, and he can give better answers than I.

Edited November 17, 2025Nov 17 by Denns

2 hours ago, Morelz said:

When was it a legal requirements when installing solar that you have DC Breakers installed between incoming pv and the inverter, so that you can isolate the PV Strings when needed? Currently there are only fuses, and essentially you cannot isolate the pv strings during the day safely. Installer wants to charge for doing this, stating that it's a new regulation

It is not a new regulation from Sans10142-1

“As prescribed by SANS 10142-1, each energy source shall have its own, appropriately rated, isolation device. The disconnecting device may be a circuit-breaker … or a switch-disconnector.”

2 hours ago, Morelz said:

Regarding the solar panels earthing, Should each panel be connected together from a single source down to the earth spikes or is it allowed to connect the earth wire to the first panel, and then jump between them, daisy chaining. Basically what I am trying to understand if there is a break between 2 panels for the earth then the earthing will not work how it should. Any break between any panels should not break earthing as a whole - Just want the legal requirement here to ensure its compliant and no issues when insurance time comes....

SANS does NOT require individual earth wires back to one point. It allows daisy chaining, BUT:

All metallic parts must maintain electrical continuity (< 0.2 Ω)

A single break must not isolate any section from earth continuity testing is required.

"7.12.7.6 – PV parts require earthing “as prescribed in 6.12.3.”

What this means for PV arrays:

PV panel frames, rails, mounting structures, and metal junction boxes must be bonded together and earthed.

"6.13 – Bonding conductors

Minimum size 2.5 mm² copper if mechanically protected

Minimum 4 mm² copper if not protected

Must be arranged to avoid accidental disconnection"

"8.6.2 – Continuity of bonding

Test voltage 4–24 V

Minimum 0.2 A test current

Resistance must be ≤ 0.2 Ω

This test MUST be performed on:

All PV frames

Rails

Array bonding conductor

Inverter chassis

DC combiner box metallic parts (if applicable)"

Edited November 17, 2025Nov 17 by TaliaB

2 minutes ago, TaliaB said:

It is not a new regulation from Sans10142-1

“As prescribed by SANS 10142-1, each energy source shall have its own, appropriately rated, isolation device. The disconnecting device may be a circuit-breaker … or a switch-disconnector.”

Does it state under load? I think I recall that the isolation device must be capable of doing it under load which a fuse holder cant do unless it is a DC-21B/A type. Him killing the battery breaker and AC breaker to isolate would not be sufficient I assume?

And I am curious about fuses. Are fuses necessary for single PV strings? Can the breaker work as the protective and isolative device alone?

1 minute ago, Denns said:

And I am curious about fuses. Are fuses necessary for single PV strings? Can the breaker work as the protective and isolative device alone?

The fuse requirement comes from overcurrent protection, not isolation. A single string cannot feed fault current into itself, so no overcurrent device is needed.

Multiple strings in parallel(2+) fuses OR string-level OCPD is mandatory, even if an isolator is installed. If one string faults (shorts), the other strings can back-feed into it. Fuses protect the wiring and solar modules from this reverse current.

2 minutes ago, TaliaB said:

The fuse requirement comes from overcurrent protection, not isolation. A single string cannot feed fault current into itself, so no overcurrent device is needed.

Multiple strings in parallel(2+) fuses OR string-level OCPD is mandatory, even if an isolator is installed. If one string faults (shorts), the other strings can back-feed into it. Fuses protect the wiring and solar modules from this reverse current.

Thanks, I asked as I don't have fuses on my inverter array. It's just a single string, but I have a 16A DC breaker 500VDC that I use for isolation and in the event of a short inside the inverter, it will trip as the SC rating of my panels is a little over 18A.

Edit: I didn't see it necessary to have a DC circuit breaker to isolate AND have fuses for protection if the circuit breaker can do both.

Edited November 17, 2025Nov 17 by Denns

This is the isolation device i use on each series string no fuses. This dc isolator is rated for 1000v dc @ 30A

41 minutes ago, Denns said:

Edit: I didn't see it necessary to have a DC circuit breaker to isolate AND have fuses for protection if the circuit breaker can do both.

You need to put fuses on each solar panel in parallel connections, especially when connecting three or more panels in parallel. A fuse on each panel's positive line isolates a faulty panel, preventing current from other panels from flowing back into it, which could cause a fire. The fuse should be rated to match or be slightly higher than the individual panel's specified maximum fuse rating, which can be found on the panel's label.

Below panel fuse and wiring diagram when individual panel fuses are required.

Edited November 17, 2025Nov 17 by TaliaB

The above drawing i posted is not very clear below link to the website for those who would be interested.

https://explorist.life/how-to-fuse-a-solar-panel-array-and-why-you-may-not-need-to/

39 minutes ago, TaliaB said:

This is the isolation device i use on each series string no fuses. This dc isolator is rated for 1000v dc @ 30A

You need to put fuses on each solar panel in parallel connections, especially when connecting three or more panels in parallel. A fuse on each panel's positive line isolates a faulty panel, preventing current from other panels from flowing back into it, which could cause a fire. The fuse should be rated to match or be slightly higher than the individual panel's specified maximum fuse rating, which can be found on the panel's label.

Below panel fuse and wiring diagram when individual panel fuses are required.

Thanks a lot for the information. I am a bit surprised that they say no overcurrent devices are necessary for single strings. A fault in the inverter, in my opinion, will just keep getting supplied until it burns out the components that are inside, even though the cable and the panels will be fine. Thanks again, TaliaB!

Edited November 17, 2025Nov 17 by Denns

As @TaliaB mentioned, he uses an 'isolator", a circuit breaker will create an arc when opened/closed under load, so have to us a Nork breaker or an actual isolator

33 minutes ago, Tariq said:

As @TaliaB mentioned, he uses an 'isolator", a circuit breaker will create an arc when opened/closed under load, so have to us a Nork breaker or an actual isolator

True, but most installations use a DC circuit breaker as an isolator before the fuse. If it is rated for the current and voltage, they are designed to handle the arc. They are designed to open under load and at the voltage rating they have (500, 600VDC, etc). What you can't do is open a fuse holder under load, as they are mostly DC20 B-rated.

9 hours ago, Tariq said:

As @TaliaB mentioned, he uses an 'isolator", a circuit breaker will create an arc when opened/closed under load, so have to us a Nork breaker or an actual isolator

A circuit breaker is meant for opening/closing under load. An isolator should just isolate during no load. I cannot agree on the arc statement as a circuit breaker has a snap action and isolators normally not.

I am not implying one should not use an isolator but the way of operating is to use it under no load.

Edited November 18, 2025Nov 18 by Scorp007

3 hours ago, Scorp007 said:

I am not implying one should not use an isolator but the way of operating is to use it under no load.

There is 2 types dc isolators the ones you must only switch at no load, then there is the one in my picture that is a DC load break isolator that can be open at full load 1000v 32A .

4 hours ago, Scorp007 said:

A circuit breaker is meant for opening/closing under load. An isolator should just isolate during no load. I cannot agree on the arc statement as a circuit breaker has a snap action and isolators normally not.

I am not implying one should not use an isolator but the way of operating is to use it under no load.

It’s all to do with ratings. As mentioned, isolators with a DC21A/B rating are designed to open under load. DC22A/B can do inductive loads and all other types.

You also get fuse holders that can be pulled under load. FSDs are their acronyms or Fuse Disconnect Switch.

3 minutes ago, TaliaB said:

There is 2 types dc isolators the ones you must only switch at no load, then there is the one in my picture that is a DC load break isolator that can be open at full load 1000v 32A .

Thanks for clarifying and the basic description. The rotary type is great but not the frame size that would normally be used in a PV combiner box as per residential installations where one needs the isolation function.

8 hours ago, Scorp007 said:

Thanks for clarifying and the basic description. The rotary type is great but not the frame size that would normally be used in a PV combiner box as per residential installations where one needs the isolation function.

They exist. I was looking at this one the other day. Fits in a typical combiner box. Very good specs also. Note the DC21B Rating.

https://www.zjbenyswitch.com/DC-Isolator-Switch/Dc-Isolator-1200V-32A-OPEN-TYPE-BYT%202A-32-IECAS-2018.html

Easypower solar sells them for 210 rand.

Edited November 19, 2025Nov 19 by Denns

2 hours ago, Denns said:

They exist. I was looking at this one the other day. Fits in a typical combiner box. Very good specs also. Note the DC21B Rating.

https://www.zjbenyswitch.com/DC-Isolator-Switch/Dc-Isolator-1200V-32A-OPEN-TYPE-BYT%202A-32-IECAS-2018.html

Easypower solar sells them for 210 rand.

Thanks this is a good find. Cannot belief the price is so low. 😀

10 hours ago, Scorp007 said:

The rotary type is great but not the frame size that would normally be used in a PV combiner box as per residential installations where one needs the isolation function.

This is the way I use the isolator in some installations, all disconnect devices installed at the bottom of inverter for quick isolation of all connected sources handy in case of emergency.

1 hour ago, TaliaB said:

This is the way I use the isolator in some installations, all disconnect devices installed at the bottom of inverter for quick isolation of all connected sources handy in case of emergency.

Thanks for the detail tip. We have to learn from our installers as far as equipment goes. You guys are on top of all the newer products. Keep it up informing us.

5 hours ago, TaliaB said:

This is the way I use the isolator in some installations, all disconnect devices installed at the bottom of inverter for quick isolation of all connected sources handy in case of emergency.

Very good. My disconnects are all over the place. I know where they are, but in an emergency, or when an electrician wants the PV system out of the way, your solution means less guesswork and scratching of heads.

On 2025/11/17 at 8:12 PM, TaliaB said:

It is not a new regulation from Sans10142-1

“As prescribed by SANS 10142-1, each energy source shall have its own, appropriately rated, isolation device. The disconnecting device may be a circuit-breaker … or a switch-disconnector.”

SANS does NOT require individual earth wires back to one point. It allows daisy chaining, BUT:

All metallic parts must maintain electrical continuity (< 0.2 Ω)

A single break must not isolate any section from earth continuity testing is required.

"7.12.7.6 – PV parts require earthing “as prescribed in 6.12.3.”

What this means for PV arrays:

PV panel frames, rails, mounting structures, and metal junction boxes must be bonded together and earthed.

"6.13 – Bonding conductors

Minimum size 2.5 mm² copper if mechanically protected

Minimum 4 mm² copper if not protected

Must be arranged to avoid accidental disconnection"

"8.6.2 – Continuity of bonding

Test voltage 4–24 V

Minimum 0.2 A test current

Resistance must be ≤ 0.2 Ω

This test MUST be performed on:

All PV frames

Rails

Array bonding conductor

Inverter chassis

DC combiner box metallic parts (if applicable)"

The current fuses which are used with SPD's clearly state they should not be opened under load. Would this then be legally/compliant installed using just 2 fuses and spd's and no DC isolator? Fuses used are Suntree SRD-30 DC1100V . 10x38 (PV is 1 string of 6 panels of 545W)

1 hour ago, Morelz said:

The current fuses which are used with SPD's clearly state they should not be opened under load. Would this then be legally/compliant installed using just 2 fuses and spd's and no DC isolator? Fuses used are Suntree SRD-30 DC1100V . 10x38 (PV is 1 string of 6 panels of 545W)

My 2c is that without the isolating device it is not compliant as the fuse carries the warning of not to be operated under load. A switch disconnector should be safe to operate if needs be under load.

@TaliaB to confirm the answer.

2 hours ago, Morelz said:

The current fuses which are used with SPD's clearly state they should not be opened under load. Would this then be legally/compliant installed using just 2 fuses and spd's and no DC isolator? Fuses used are Suntree SRD-30 DC1100V . 10x38 (PV is 1 string of 6 panels of 545W)

Not compliant. You need a disconnector that works under load as @Scorp007 says even though if you kill the AC load and battery you are technically no-load and can pull the fuse holder with no issues.

Edited November 24, 2025Nov 24 by Denns

22 minutes ago, Denns said:

Not compliant. You need a disconnector that works under load as @Scorp007 says even though if you kill the AC load and battery you are technically no-load and can pull the fuse holder with no issues.

The thing is with AC loads disconnect the PV is still charging the battery. The PV is disconnected before the battery. Battery is last.

1 minute ago, Scorp007 said:

The thing is with AC loads disconnect the PV is still charging the battery. The PV is disconnected before the battery. Battery is last.

Does the inverter care in which order the battery and PV are disconnected? Especially if the AC loads are off? What are the implications of doing it wrong? If I kill the battery then there is no charging and hence no load being supplied by the panels. I can safely pull the fuse holder.

Edited November 24, 2025Nov 24 by Denns