Solar Isolator

Use a fuse block if you meen for use when removing batteries, votronic has one built in to do this.
votronic regulator.png
 
wildebus said:
Bear in mind the amp rating of the switch and if it is sufficient for the current expected from the panels. Wattage quoted is irrelevant as that would be for a 240V system - the same wattage from a solar panel will mean a current around 15 x larger.
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Even then DC switching and AC switching are totally different, there's a good video somewhere on YouTube showing the arcing of the same current with AC and DC.
 
Alshymer said:
Hi
Can someone suggest whether or not I need a solar isolator between my 2x110 watt panels and my Victron MPPT regulator?
Thanks
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A switch isn't strictly necessary, neither is a fuse but a fuse makes a handy switch if you ever find you need to isolate the panels for some reason. Personally I brought my panel cables into the van via the roof gland and then connected the 3 panels in parallel at a 40A double pole switch from Screwfix, less than a fiver and I've used the switch occasionally too.
Panel current is somewhat lower than battery current on an MPPT controller, my controller is 20A, I'd expect somewhere around 15A max current in the panel side so the 40A switch I used is over 250% rated WRT current. It's actually double pole so if required the poles could be paralleled to then carry 80A.
DC switching is indeed different to AC switching due to the fact that when breaking the contact the switch doesn't benefit from the waveform going through zero volts twice every cycle and thus the tendency to arc across the contacts is greater. It's typical to see the 240V AC rating of a switch (or relay contacts) to be similar to the DC rating at around 30VDC or lower, solar panels in parallel are only going to be around the 20V mark. All UK domestic mains switches need to have at least 3mm of gap when they are open, this is large compared to most AC/DC rated switch or relay contacts further assisting with the breaking capacity. A decent domestic mains switch will be fine, just consider the current.
 
You could fit a relay and a 12v auto switch, the ampage of relay will depend on wattage of panels.
 
If you have a Victron Smartsolar MPPT, then it is just as easy to go into the settings and turn the charger off if the reason for the switch is to isolate the panel from the system.
I still rekon it is pretty pointless and I would not recommend using a domestic 240V switch, regardless of what the Part P qualified electrician says :).
If you really want to have a way to isolate, just use a fuse like Trev is suggesting. KISS 💋 ;)
 
Well I must confess, I never knew that switching 10A at 20V was sooooo dangerous and complicated, glad I never went for a 24V system eh, think of the cost of all those special switches.
So just a cautionary word of warning, obviously this arcing phenomenon you get at 20V that's going to burn your van down when you switch off with a domestic 40A isolator rated at 240V AC. Be very careful when you switch off by pulling that fuse, best get some asbestos gloves and a welding mask.
 
merl said:
Well I must confess, I never knew that switching 10A at 20V was sooooo dangerous and complicated, glad I never went for a 24V system eh, think of the cost of all those special switches.
So just a cautionary word of warning, obviously this arcing phenomenon you get at 20V that's going to burn your van down when you switch off with a domestic 40A isolator rated at 240V AC. Be very careful when you switch off by pulling that fuse, best get some asbestos gloves and a welding mask.
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Will work ok but confusing for some if sold on, and dont look right in a 12v system, but to each there own.
 
wildebus said:
I've never fitted one personally. Can't see a reason to TBH.
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I'm considering fitting isolators between the panels and my Victron MPPT controller and also between that and the battery. This is because my Smart Solar 75/15 instructions say to always connect the battery to the controller before the connecting the panel as doing it that way sets the output voltage of the controller. That said, it's just a convenience and you could just physically pull the wiring from the controller terminal block!
 
So, there is no reason to do it or not to do it then from what I read, it is just a bit unconventional it seems, however, I need a junction box right where a switch would be useful, so why NOT a switch on a deep patress, I could get a junction box but a switch may at some point be useful, don't where, don't know when but I know.....

Whale meat again.
 
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