Jump to content

Recommended Posts

What is the SANS specification and best practice on earthing a solar system?

Below is how my system is earth. Is this sufficient?

Solar Panels
All my panel frames (2 x 6) are linked on one 10mm2 cable to a 4ft earth spike far away from my inverter


Batteries
My batteries are earth with a 10mm2 cable on my Eskom earth. Should this be on a earth spike as well?

Inverter
My Eskom power goes through a circuit breaker into my inverter. There is no RCD on my inverter grid supply as I don't have any Non-essential loads (Is this a requirement). I have a RCD on the output of my inverter before my Main DB. 

My Eskom earth, Inverter output earth and inverter casing are all earthed on my Eskom supply.

Thank you 

Link to comment
Share on other sites

2 hours ago, ErickvWyngaard said:

Batteries
My batteries are earth with a 10mm2 cable on my Eskom earth. Should this be on a earth spike as well?

I do not see a need for a battery to be specially earthed, other than earthing it as normal white appliances are earthed, ie if a metal box is used it needs to be earthed. The battery feed itself is highly isolated and even in the inverter itself it is galvanically isolated from the high voltage dc bus and the ac feed. 

The pv, yes, is altogether a different story, although the pv feeds themselves should never be earth, only the frames. The frames open up a large attack surface for surges and lightning. For this reason a private earth with spike is important, your 10mm size is overrated but of coarse ok. 

Edited by BritishRacingGreen
Link to comment
Share on other sites

12 minutes ago, BritishRacingGreen said:

I do not see a need for a battery to be specially earthed, other than earthing it as normal white appliances are earthed, ie if a metal box is used it needs to be earthed. The battery feed itself is highly isolated and even in the inverter itself it is galvanically isolated from the high voltage dc bus and the ac feed. 

The pv, yes, is altogether a different story, although the pv feeds themselves should never be earth, only the frames. The frames open up a large attack surface for surges and lightning. For this reason a private earth with spike is important, your 10mm size is overrated but of coarse ok. 

In addition to this, your inverter should be fitted with a neatral to earth bonding arrangement. This allows the ac load output neatral to have a gaurenteed hard earthed neatral when the grid supply goes off. This is important and you must insist that the installer and/or COC certifier test the downstream earth leakage detection, using plug tester, when there is no grid. Today inverters has this bonding built in, but there are some inverters that requires an external bonding relay. 

This is important to gaurentee safe ELD operation in islanding mode, meaning when there is no escom grid. 

Edited by BritishRacingGreen
Link to comment
Share on other sites

14 minutes ago, BritishRacingGreen said:

In addition to this, your inverter should be fitted with a neatral to earth bonding arrangement. This allows the ac load output neatral to have a gaurenteed hard earthed neatral when the grid supply goes off. This is important and you must insist that the installer and/or COC certifier test the downstream earth leakage detection, using plug tester, when there is no grid. Today inverters has this bonding built in, but there are some inverters that requires an external bonding relay. 

This is important to gaurentee safe ELD operation in islanding mode, meaning when there is no escom grid. 

EDiT: many people have asked why automatic earth bonding is required when the grid feed neatral is already bonded. 

The answer is not hard to find. A typical reason for grid loss could be an upstream trip in your db box. Now typically such breakers are double cut and there your inverter grid neatral is now left floating. As a result it renders an otherwise usefull ELD null and void, and no protection to humans and faulty appliances are offered during loadshedding. 

Edited by BritishRacingGreen
Link to comment
Share on other sites

Thanks for the feedback. I have a Sunsynk inverter and have a neutral Earth bond. I don't have a RCD on the grid input of the inverter, so my neutral earth bond is permanent. If I install earth leakage protection I will have to use the Islanding signal function to  make my bond. I don't see the reason for an RCD because it will only feed my inverter an not any plugs. 

Does the specification say that you need a RCD?

Link to comment
Share on other sites

7 hours ago, ErickvWyngaard said:

Thanks for the feedback. I have a Sunsynk inverter and have a neutral Earth bond. I don't have a RCD on the grid input of the inverter, so my neutral earth bond is permanent. If I install earth leakage protection I will have to use the Islanding signal function to  make my bond. I don't see the reason for an RCD because it will only feed my inverter an not any plugs. 

Does the specification say that you need a RCD?

The  earth bonding i am reffering to is applicable to your essential load in the case of sunsynk. The ELD i am reffering to is therefore  in the essential load output, in order to protect the plugs on that circuit. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...