Plug in solar

QrizB

I wasn't sure if there was variation in the connections from solar panels to go to the rest of the plug in solar kit?

These days most solar panels and almost all inverters use MC4 connectors. The more important thing to check is the voltage and current from the panel is within the working range of the inverter.

We had some discussion of this on this thread in April:

https://forums.moneysavingexpert.com/discussion/comment/81974727#Comment_81974727

Qyburn

https://forums.moneysavingexpert.com/discussion/comment/82042412#Comment_82042412

I guess for greater piece of mind, the best bet is to install a type B RCD either in the Consumer Unit, or directly on the mains output from the inverter.

I don't think that would necessarily be a complete solution, while the upstream RCD is in place. Accepting that there's no evidence that your kit has any such fault, and that this is the absolute worst case. The absolute worst case is DC leakage insufficient to trip a Type B or any other RCD. This will desensitise the upstream RCD (referred to as "blinding") so that it won't trip at the correct threshold.

Incidentally I don't think I've seen a full description of the "bidirectional" issues. For RCDs the concern is electronics being damaged if the circuit remains energised on what would normally be the load side, and the solution is an additional contact. But there's something about MCBs as well. But I don't think Ive seen anything suggesting either would be damaged just by the fact of current flowing the "wrong" way.

I suppose it's worth mentioning that RCDs have been around for decades, as has solar PV. Yet these requirements (bidirectional and two pole) have only been made in the last couple of years. I can't lay my hands on a photo of the RCBO that was originally installed for our solar in 2024, but it definitely wasn't two pole.

QrizB

This was published last week, without much ado (I turned it up when searching for something else):

https://www.gov.uk/government/publications/plug-in-solar-electrical-safety-study

It might help allay some of the concerns in this thread?

lohr500

https://forums.moneysavingexpert.com/discussion/comment/82038728#Comment_82038728

@QrizB Same document was buried in the link that @TroubledTarts posted a few days back, but thanks for posting it separately.

Also buried in the link was this :

https://assets.publishing.service.gov.uk/media/6a31167d15f2a70fac7e6026/plug-in-solar-interim-product-specification.pdf

Regarding the discussion about the risk of DC on older RCD's ,in the above document there is the following paragraph:

5.7 Influence of residual current devices (RCDs) Plug‑in solar shall comply with the requirements relating to DC residual current components in accordance with BS EN 62109‑1, Clause 7.3.8. The device shall be designed such that it does not adversely affect the operation of upstream residual current devices.

There doesn't appear to be any differentiation between Type A, AC and B RCD's in this or subsequent paragraphs as far as I can see. But then again it's not an easy read!!!

martyp

https://forums.moneysavingexpert.com/discussion/comment/82042499#Comment_82042499

Much appreciated, thanks. Definitely want to be sure I'm considering everything before going ahead.

tfhnota

Still loads of older houses with simple fuse-boxes out there, assume they won't burn out due to current running the wrong way.

Current reg's have just changed so that the total possible amps of the house (ie everything turned on) has to be matched to the main fuse so not sure if you can fit a new RCD without at the same time upgrading the consumer unit to match the new reg's?

Qyburn

https://forums.moneysavingexpert.com/discussion/comment/82039092#Comment_82039092

Quoting to save retyping ..

lohr500

https://forums.moneysavingexpert.com/discussion/comment/82043043#Comment_82043043

Thanks , So many posts now in this thread I missed your reply on the 18th!!!

Qyburn

https://forums.moneysavingexpert.com/discussion/comment/82043001#Comment_82043001

Unless there was a major change in Amendment 4, which I've not seen mentioned, it won't be with everything switched on. Standardised diversity factors will apply to calculate maximum load, for example a cooker is (or was) assessed as 10A plus 30% of the remainder.

tfhnota

last efixx youtube video but only viewed in passing