Breaker for main board

[familywats]

Hi all
A very stupid question that for some reason I cannot work out.
3.6kw inverter connecting through breaker to main board. What size trip or does it need to be a rcd breaker and how does it wire into main board. Bring tails from supply in to trip and wire in inverter and connect to distribution! A diagram would help me get my head around this
Thanks

 

[Hedges]

Link to inverter spec sheet?

I'll assume that is a 3.6kW 240V grid-tie PV inverter.

3600W / 240V = 15A
15A x 1.25 = 20A minimum breaker.

In the US there is something called "120% rule", we are allowed to have multiple sources feeding a breaker panel totaling 120% of its rating.
For instance, 100A breaker panel (busbar) x 120% = 120A of supply breakers allowed.
100A main breaker at one end of panel + 20A backfed PV breaker at other end of panel = 120A, which complies.

"RCD" implies you are elsewhere in the world, commonly used for grid connection to house. I think you're OK with PV backfeeding downstream of that.

(In the US we have "GFCI" for individual outlets. We do not use "RCD" for whole house due to a different grid connection and grounding scheme.)

Oh, always connect ground wire (does such thing exist where you are??) from house wiring to inverter chassis. And connect ground wire from inverter chassis to PV panel frames. Even if manual says not to ground PV; they are referring to PV+ and PV- which are to be isolated. The metal frame of all PV panels must be electrically connected to inverter chassis, otherwise the frames can shock you (default situation for many brands.)

 

[familywats]

Thanks…..in the UK

 

[SeaGal]

As @Hedges said... 20A MCB is correct for a 3.6kW inverter in the UK.

Make sure you have at least 2.5mm2 T&E connection, preferably 4mm2, between the inverter and the CU.

With all due respect, based on your questions, do you have the necessary experience for this? There are a number of technical regulations and processes that need to be adhered to, and qualifications are required for some electrical work - I think I summarised them in this posting...

Octopus Energy will no longer require MCS certification in the UK

https://gtec.co.uk/clause-5-8-octopus-opens-up-the-solar-pv-market-with-a-paragraph/ I'm not sure how exactly the UK's permitting and approval process works but this sounds like a major win for DIY.

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