Solar PV DC Isolation Switches

[Skyliner33]

Just wondering how many people have a solar power isolation switch fitted to their system?
Something like this:

Kraus & Naimer DC Isolation Switches

Cost effective switches with a simple easy to install design.

www.windandsun.co.uk

Also was your system self fit or not?

Trying to decide whether to fit on or not?

 

[Rioja John]

I used one of these Jon in my solar set up.

John.

https://www.amazon.co.uk/QWORK-Circuit-Breaker-Inverter-Protection/dp/B08JLGVJHX/ref=sr_1_4?crid=31BZJ70YKVA6F&dib=eyJ2IjoiMSJ9.V6iU59iAhvIKTrqAngonWLWIHX3PjBt4Xhpz1Utz52xCGnHHjr2JU5l5jIUH6AFvT9lM2ptR64ySK4tmBeUiQ7XT6n7_AD1bXrtuWIgZacIhhooMlUEbM3pzSV7qp2yOskJ8y39Wj0YtVrqwEQveIsoeVz9D2RPFsoE4AKJHPGj_oJmwbnyRSswBAR9k62fTK8hnWnYnTsHqoxT6iZpLrixB2pYAln31fGj1vhWl6Wk.pLmRA-ckjWap3GICKgkwh0-4lZQWDSN1ud32W3bb0R0&dib_tag=se&keywords=20+amp+12+volt+isolation+fuse&qid=1711268417&sprefix=20+amp+12+volt+isolation+fuse%2Caps%2C1374&sr=8-4

 

[EAN]

@Rioja John Voltage rating is quite low, depending upon your solar panel.

 

[ginkster]

I will be fitting one when I do my panel. Just waiting for the weather to improve. I’ve gone for this (63A) from Amazon:



Fitted into this from Screwfix:


Whatever you go for needs to be double pole (2P) to isolate both pos and neg simultaneously.

 

[Rioja John]

@Rioja John Voltage rating is quite low, depending upon your solar panel.

Thanks @EAN Yes you are right I posted the above as I couldnt remember what I fitted, I will check it out this morning but I think I fitted a 40 amp isolator on my 200 watt solar system.

John.

 

[EAN]

Thanks @EAN Yes you are right I posted the above as I couldnt remember what I fitted, I will check it out this morning but I think I fitted a 40 amp isolator on my 200 watt solar system.

John.

Remember to check the voltage rating as well as the current rating, to ensure both are compatible with your setup.

 

[Dellmassive]

Just wondering how many people have a solar power isolation switch fitted to their system?
Something like this:

Kraus & Naimer DC Isolation Switches

Cost effective switches with a simple easy to install design.

www.windandsun.co.uk

Also was your system self fit or not?

Trying to decide whether to fit on or not?

I have that switch on the domestic PV system.

It's massive and not best suited to van stuff.

If you want a switch, get a smaller one, or a dedicated DC breaker.

As above make sure it's DC rated and have suitable voltage and current handling. Ie above 50v DC and 20A.

 

[Dellmassive]

I've seen these mini isolator switches used aswell, for panel mount.

they are a nice touch. . . they fit in a 20mm hole.

https://amzn.to/4acRDJy

 

[Salty Spuds]

I don’t have an isolator on my panels, just a fuse. It’s adding complication & failure points imho. You have to find somewhere to mount it, it can be inadvertently turned on/off, it’s adding joints in the cable which will squander your precious solar yield. KISS.
Just my 2 penneth fwiw.

 

[Dellmassive]

I don’t have an isolator on my panels, just a fuse. It’s adding complication & failure points imho. You have to find somewhere to mount it, it can be inadvertently turned on/off, it’s adding joints in the cable which will squander your precious solar yield. KISS.
Just my 2 penneth fwiw.

agreed and very true.

( in fact a fuse insnt even necessary for small camper PV as they don't generate enough current to burn out a 4mm PV cable, or even blow a 1000v/30A PV fuse)
- https://amzn.to/4a3OWcV

as you say each connection reduces overall power to the mppt.





++++++++++++++++++

but there are two situations i can think of where a DC PV isolator may be required.

1- to disable PV in winter time when you have a lithium battery with no Low Temp protection.

2- to disable PV input to combi dc-dc+MPPT chargers ( like the renogy DCC50s ) to get full power from the engine bay and not split 50/50.



.....

 

[Salty Spuds]

agreed and very true.

( in fact a fuse insnt even necessary for small camper PV as they don't generate enough current to burn out a 4mm PV cable, or even blow a 1000v/30A PV fuse)
- https://amzn.to/4a3OWcV

as you say each connection reduces overall power to the mppt.


View attachment 234237


++++++++++++++++++

but there are two situations i can think of where a DC PV isolator may be required.

1- to disable PV in winter time when you have a lithium battery with no Low Temp protection.

2- to disable PV input to combi dc-dc+MPPT chargers ( like the renogy DCC50s ) to get full power from the engine bay and not split 50/50.



.....

Fair point, but in those 2 scenarios, you’re adding an isolator to overcome flaws further down the line. Scenario 1 could certainly be eliminated by speccing a decent battery. I’m not sure about scenario 2 as I’m not familiar with the kit, but it sounds like a fudge.

 

[Dellmassive]

Yep, again agreed.

Some people cheap out, and get the basic options that miss out on features,

The PV isolator is a cheap way to get around these missing features.

I don't do this myself, I chose a lifepo4 with low temp protection, and run a separate MPPT alongside my dc-dc charger.

 

[Salty Spuds]

Yep, again agreed.

Some people cheap out, and get the basic options that miss out on features,

The PV isolator is a cheap way to get around these missing features.

I don't do this myself, I chose a lifepo4 with low temp protection, and run a separate MPPT alongside my dc-dc charger.

Yup, same here

 

[Skyliner33]

Thanks for all the input.

 

[TallPaul_S]

If you have a master battery isolator switch right next to the LB and fuse you'd want a PV isolator too, right? As there's big warnings about not connecting the panels to the MPPT controller without first connecting it to the battery. And if you use the main isolator switch, the PV would still be connected without its own switch.

 

[Stay Frosty]

My solar tails come through into the wardrobe where I've got a single pvc surface box with a domestic white moulded 30A double pole switch, think cooker switch here without a neon indicator and that's what I've got.
Turning off the solar means the Renogy DCC50S sends up to 50A to the leisure battery from the alternator via the starter battery and turning the solar back on calms things down by reducing the alternator input to 25A out of the DCC50S plus whatever the solar is actually producing as I drive around.
With two 175 watt Renogy flexy panels on the pop top the most output I normally see is sub 300 watt, maybe 260 odd watts and just sub 20A at 13.4V via the leisure battery shunt display.