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Themoog

Solar panels tripping rcd

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Themoog

Hi there. A few months ago I had the cu replaced in the garage as the old one was well past it. Since the replacement one of the RCDs in the cu has been tripping on a regular basis.

I have narrowed it down to the solar panel system. The odd thing is that it only trips in damp or rainy weather and normally between 9- 10:30am- this may coincide with cooker/kettle/toaster being used also though. I did contact the system manufacturers and explained the problem. They said that it should run through a min 100mA rcd and that is why it is tripping. It runs through a 30ma rcd at present. 

Where should I go from here? Is there a way to check for earth leakage from the panels? My research tells me to have a separate rcbo (?) for the solar system- is that correct?

I have noticed that the inverter clicks and the other day I was watching the rcd after resetting it and when it clicked the rcd tripped immediately.

Could someone please explain.. 

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Sharpend

Yes your solar should be on its own rcd/rcbo. 

This click is the inverter switching on? You probably have a bad joint somewhere and damp is getting in? 

I’ll tag @binky as he knows his solar stuff 

Edited by Sharpend

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Murdoch

I would be checking the earth leakage across the entire installation - and yes most electricians have the equipment to do this.

 

Regarding your new CU ............. the installer should know that solar shouldn't be on an RCD shared with other circuits in your house.................... did they give you a certificate?

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Themoog

Yes i have a certificate for the installation. From what i can gather this is a common mistake by some electricians- not wrong but not correct either if you see what i mean. I have contacted him and he is going to stop by and take a look.

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Murdoch
1 hour ago, Themoog said:

Yes i have a certificate for the installation. From what i can gather this is a common mistake by some electricians- not wrong but not correct either if you see what i mean. I have contacted him and he is going to stop by and take a look.

 

I would disagree with that. Having solar on a "shared" RCD means its almost impossible to meet the disconnection times ...............

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binky
3 hours ago, Murdoch said:

 

 

Regarding your new CU ............. the installer should know that solar shouldn't be on an RCD shared with other circuits in your house.................... did they give you a certificate?

Actually, not many electricans are aware of this, apart from not meeting the disconnection times (although inverters do have  a mains fail function that should meet reasonable times of around 0.4s ) the main issue is the relay in the inverter upsetting RCDs, especially when shared. My preferred option is always to keep thesolar separate to everything else. His means a high integrity board should be fitted, or a Mini CU solely for the solar system, which also means if RCD protection is required a 100mA or 300mA RCD can be fitted - 300mA works best.

 

The clicking you can here is the AC mains relay, it tends to' 'chatter'  afew times morning an evenings, the inverters have some meaty capacitors for smoothing the AC output, so a combination of chattering and throwing some biggish voltages down the earth upsets the RCD almost every time. 

 

NB if anyone is dealing with an inverter as part of doing other works, be careful of the earth from the inverter, it can give quite a tingle until the capacitors have fully discharged - think electric fence! :swear:

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Themoog

i know about capacitors- i got a shock off my hot tub pump when i replaced the capacitor.. 

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Murdoch

^^ Another classic failure by the regs makers to clearly state what is acceptable and what isn't. 

 

Its the Solar installers who seem to do this the most IMHO - and often with a 3rd party MCB !

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binky

The NICEIC used to state we could connect solar into a socket ctt such as the upstairs ring main - that didn't last long. Being a new industry the regulatory bodies have been playing 'catch-up', and missed a few points. The inverter manufacturers also have their own ideas, but it does concern me that some regard upto 300mA as acceptable earth leakage - you wouldn't accept that from any other home appliance! 

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