Solar Solar system - Hybrid inverter in a shared RCD

[wawyed]

Greetings, I have a solar 5kw system installed with a hybrid inverter (no batteries yet). My electrician decided to add an extension board for the solar installation as my main CU couldn't fit all the required switch due to lack of space.

I have dual rcd consumer unit with no high integrity so both neutral bars are under RCD. I have read that is not recommended to have the inverter on a shared RCD. And I have noticed that when the inverter starts up in the morning + my roomba starts it causes the RCD to trip. Both are on the same RCD.

I would like to have my board replaced with RCBOs since I've read thats the best way these days as you can manage each circut separately. My concern/question is this. My electrician never quoted me on replacing the fuses with RCBOs and I don't know why the put it in a shared RCD if he knew it's not recommended. Am I expected to pay for the RCBOs or should it be part of the initial quote? I'm worried he's goign to want me to pay for it when he should have checked this before hand.

Also is the installation legally complaint if left as it is?

Thank you very much.

 

[SJD]

Reading this, I'm a little confused - you mention first an extra board, then later imply not an extra board? Pictures, we like pictures. Post a photo showing everything installed.

 

[wawyed]

Sorry about that. Here are the pictures. So the small box at the bottom is connected to the main cu at 2-5

 

[SJD]

Nothing is labelled!
Edit: just noticed the chart on the Wylex cover, but too fuzzy to read.

I'd guess the solar is connected to the small Wylex board, which is turn is fed directly from the meter tails?
Or do you mean the small Wylex boad is fed from one of the Hager MCBs via one of the RCDs?

Also the Wylex board has - for some reason - a Hager MCB fitted - when the regs state not to mix brands like that.
It is not as if a Wylex B6 MCB is can't be picked up off the shelf at any electrical supplier.

 

[wawyed]

From what I can understand the Wylex board is fed from one of the Hager MCB in particular the one at the far left 2-5

 

[wawyed]

Nothing is labelled!
Edit: just noticed the chart on the Wylex cover, but too fuzzy to read.

I'd guess the solar is connected to the small Wylex board, which is turn is fed directly from the meter tails?
Or do you mean the small Wylex boad is fed from one of the Hager MCBs via one of the RCDs?

Also the Wylex board has - for some reason - a Hager MCB fitted - when the regs state not to mix brands like that.
It is not as if a Wylex B6 MCB is can't be picked up off the shelf at any electrical supplier.

Hope that makes sense?

 

[kropaske]

There are few problems with your setup. As SJD mention already various brands mcb should not be mixed. No labels on new consumer unit and pv isolators and inverter. Your installer used shared rcd to feed inverter which he should not. Also your rcd is type AC and should be type A or B. Did you get all certification for the job? Did you or electrician request permission from DNO to connect you PV system?

IMHO what he should done is to remove 1x rcd and associated mcb and replace with Rcbo's. This would create additional space and additional consumer unit would not be needed.

As for the tripping you need electrician to run some test to determine weather its down to some appliances or fixed wiring

 

[wawyed]

Techincally the install is not "finished" as there's outstanding issues (the meter on the wyndex is not communicating with the inverter so waiting for replacement) and RCD tripping so I think that's why things are not labeled yet. The electrician has the G99 approved but I haven't recieved yet as per above.

Yes, he has suggested about replacing with RCD with RCBO but he said it would need replacing all of them just not half for some reason.

Am I expected to pay for the RCBO replacement or should this be covered by the initial cost? He mentioned each rcbo is £80!?

 

[SJD]

As kropsake mentions above, there are quite a few issues, and one option would have been to remove one RCD and fit RCBOs for several cricuits, with the remaining circuits on the remaining RCD. Removing the RCD would free up 2 slots.

However, the new Wylex board does include surge protection, which the Hager main board does not. While not mandatory, it would be better if there was surge protection for all the circuits - either in the Hager board or as separate external unit (Hager do such an external surge protection unit, I fitted one a few weeks ago).

I'd guess the original quote didn't cover the cost of any RCBOs, though you might argue you should not now have to pay extra to correct the installation defects.

 

[SJD]

Umm, just seen your last post waywed. Hager RCBOs are available at approx £20 each, possibly with a modest mark-up if your electrician supplies them. Charging £80 per RCBO is a bit outrageous.

 

[wawyed]

What would be the problem with replacing the correct RCD with a type A or B? I'm just trying to understand what's the issue with being shared RCD with other devices? Is that what causes the tripping?

Also is the current installation non compliant (if we ignore the labelling) because of the shared RCD? Could I report him if he decided to leave it as is?

 

[wawyed]

Umm, just seen your last post waywed. Hager RCBOs are available at approx £20 each, possibly with a modest mark-up if your electrician supplies them. Charging £80 per RCBO is a bit outrageous.

That sounds much more reasonable

 

[buzzlightyear]

Techincally the install is not "finished" as there's outstanding issues (the meter on the wyndex is not communicating with the inverter so waiting for replacement) and RCD tripping so I think that's why things are not labeled yet

rip the lot out and put in rcbos the circuits & spd and pv solar on the hager board job done.

 

[davesparks]

I'm just trying to understand what's the issue with being shared RCD with other devices?

The RCD is there to provide additional protection against electric shock. It does this by switching off the power to any circuit downstream of it if it detects an imbalance of current which could be due to a person receiving an electric shock (other faults also cause it to trip). The RCD should trip within 0.3 seconds in order to prevent and electric shock becoming fatal.

Having the solar connected to the downstream side of the RCD means that you have a source of power connected to the downstream side of the RCD.

So if the RCD trips the solar will continue to maintain a live supply to the downstream circuits until the inverter shuts down which can take a few seconds or more.

 

[wawyed]

The RCD is there to provide additional protection against electric shock. It does this by switching off the power to any circuit downstream of it if it detects an imbalance of current which could be due to a person receiving an electric shock (other faults also cause it to trip). The RCD should trip within 0.3 seconds in order to prevent and electric shock becoming fatal.

Having the solar connected to the downstream side of the RCD means that you have a source of power connected to the downstream side of the RCD.

So if the RCD trips the solar will continue to maintain a live supply to the downstream circuits until the inverter shuts down which can take a few seconds or more.

Thank you for the clear explanation. That definetely doesn't sound safe... I'm very surprised the electrician decided to install it in this way initially knowing how unsafe that sounds

 

[davesparks]

Thank you for the clear explanation. That definetely doesn't sound safe... I'm very surprised the electrician decided to install it in this way initially knowing how unsafe that sounds

Unfortunately some electricians seem to struggle with understanding that the solar is a source of power and not just a normal circuit.

 

[wawyed]

Unfortunately some electricians seem to struggle with understanding that the solar is a source of power and not just a normal circuit.

What would be my best source of action? I know I wouldn't like to be told what to do at my job specially from someone without qualifications. But at the same time I want things to be done properly.

 

[wawyed]

Also should be inverter be under RCBO?

EDIT: Looks like my inverter has already protections built in https://www.ginlong.com/uploads/file/Solis_datasheet_S5-EH1P(3-6)K-L_Global_V2,5_2022_12.pdf

 

[paul2020]

The RCD is there to provide additional protection against electric shock. It does this by switching off the power to any circuit downstream of it if it detects an imbalance of current which could be due to a person receiving an electric shock (other faults also cause it to trip). The RCD should trip within 0.3 seconds in order to prevent and electric shock becoming fatal.

Having the solar connected to the downstream side of the RCD means that you have a source of power connected to the downstream side of the RCD.

So if the RCD trips the solar will continue to maintain a live supply to the downstream circuits until the inverter shuts down which can take a few seconds or more.

Can't it be worked around by installing additional RCBO in another direction (from inverter side) ?