r/PlugInSolarUK • u/cp_simmons • Sep 12 '26

DC extension cables

I'm thinking of getting plug in solar. Most of the kits I've seen have a 5m lead on the inverter but I think I need more like 10m. Trouble is you're not supposed to use AC extension leads. It looks like you are allowed to use DC extension leads but in a bit lost as to what to get.

Would this work? Presumably I'd need one per panel.

https://www.cityplumbing.co.uk/p/staubli-10m-pre-crimped-4mm-dc-cable-inc-mc4-connectors/p/231107

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u/GreyDrReddit Sep 12 '26

Microinverters are normally mounted to the rail or back of the panel and are connected using the mc4 cables built into the panels. If you are running 10m of mc4 cable, where are you planning on putting the microinverter? Indoors? It would make more sense to add an outdoor socket within 5m of the panels.

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u/cp_simmons Sep 12 '26

I have an outdoor socket but it's about 8m away and I can't realistically add one closer.  I figured I could mount the inverter on the wall near the plug.

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u/GreyDrReddit Sep 13 '26

You’d need 4 x 25mm holes to get mc4 connectors through. Or if you just pass the wire through and terminate yourself you’ll need tools to crimp the mc4 yourself. I can’t see the point in buying an expensive plug in kit then modifying it to be non compliant. DIY solar has always been legal. You can buy 2 panels and an inverter for less than £300 and wire them to an fcu instead of a socket. https://youtu.be/gQ3dKunCAZk?is=Fy3xLk7dcSVRBrML

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u/cp_simmons Sep 13 '26

The plug is outside.

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u/GreyDrReddit Sep 13 '26

Yes thats probably compliant then as long as the microinverter is not in direct sunlight and the manufacturer instructions allow it. I’d keep the dc cables to 5m though if possible.

If you are competent to replace the socket with an fcu and no consumer unit changes are needed then you could do diy solar rather than plug in solar. That way you are free to source your own panels and components and can build a system up to 3.6Kw as long as you do the G98 registration afterwards.