Hi all, I want to drill a hole in my home wall to feed solar panel cable from my battery inside to panels outside but the cable heads / connections are way to big for that; does anyone know if I take apart the connectors if they’re hard to get back together or if there’s alternative cables that will work (anyway the standard ones are forever out of stock so any alternative would be great)?
Many thanks
Just…NO. Terrible idea. This is a fire hazard waiting to happen. Not to mention possible mold growth from water ingress problems along with other things like pest infestation. You’ll need a minimum a waterproof junction box on both sides and the proper tools to drill through the wall material from the outside the inside along with a way to properly seal it all off. You can’t just punch a hole through the wall and stick a conduit pipe or the wires through it and call it a day.
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Thanks but i should have elaborated; it’s just to charge a stand alone battery (AC200Max) not connected to the house power. The battery would be sat under my computer powering for the sunny seasons, not all year; the plan was to leave the cable connectors (official Bluetti one) in a waterproof box attached to the the wall outside during wet season (and tidy up the panels).
For the ‘hole’ through the wall - it would ofc be sealed up, same way the internet and other cables have been installed here by professionals (its old stone house so drilling is only way, or via the plastic/metal window frames).
Sorry for the newby Qs, in that case it still needs a Junction box if not being used by the house power (or its a case of any splice in the cable needs to go to Junction box regardless)? If we can drill a hole large enough to get the connectors through, then surely no need for Junction right?
After a bit more research the cable itself (mp4 type apparently?) seems to be very simple just one core so seems reassembly is easy to reassemble. I was expecting a multi layer interior or something… so that’s something anyway. Thanks again
Solar MC4 cable connectors are single time crimped. You can thread suitable cable through the hole and then crimp on connectors if you have access to the right tools or an electrician friend. Do not try and solder them!
Watch very carefully where you get cables from, most of the cheaper solar cables sold on well known online stores are not genuine MC4 connectors, often use CCA not copper wire, are insulated to 36v standard only and are very badly crimped so can start fires. If you cut the end off the Bluetti cable and then stuck it through and fitted a new MC4 that ought to work.
You should be using double insulated copper cable from a reputable source. If you do that, use real MC4 plugs and have the correct crimping tools you’ll be fine although you might need a few tries to get the hang of it (it’s not that different to crimping battery terminals).
The other popular alternative is to use so called “super flat” cables through a window opening. These are insulated wide thin copper strips with MC4 each end that are thin enough you can stick them through a typical window and then shut the window fine on it.
Bluetti AFAIK don’t themselves sell flat cables but a certain rival beginning with E does sell good quality ones, and they work fine with Bluetti kit as the MC4 connectors are a standard.
In terms of going through the wall then you need it properly sealed so a junction box is one option but there are others. Silicon sealant and prayer I wouldn’t recommend however. I took my office ones through the window with flat cables as it’s easier, especially as I have 0.5m thick stone walls 8)
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Also it would be worth putting an MC4 fuse in line from the solar panel as an extra precaution.
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There is an easier way to get cables into a house and being under an eave, less likely to have water ingress. 
Use split conduit on the cable, that way no plugs need cutting, up the wall into a IP rated junction box for MC4 connections, up and over the wall through the eave and into the room through the ceiling. Fix the cable with saddle brackets to suit.
The junction box can be where you are able to reach it, or high enough to need a ladder to stop little fingers playing with it…
In the junction box, you can cut the plugs off and join with a terminal strip, which enables sealed conduit use.
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thanks all for the help and great info-suggestions, think I’ll go with those flat cables they are def easier and give us the chance to change things up in future, thanks @EtchedPixels !
The Bluetti has internal protection and the cable should be sufficient to carry the full theoretical current of the panel anyway. In that situation much guidance says that a fuse should not be fitted as it’s actually increasing not decreasing risk.