Switch between solar panels and controller?

[Gareth E]

I have 375w of panels going to a 30a Tracer. Every few months the fuse I installed between the controller and batteries fails. It's a bit strange really, the fuse doesn't blow, if I take it out of its holder and re insert it will usually last a few days before going again. Seems to wear out somehow.

 

I'm aware that the controller should be connected to the batteries first rather than the panels. There's no on-off switch on the controller so it's either wait until dark or the faff of covering the panels. I'll admit that sometimes I just insert a new fuse and to hell with it. I've got away with this so far but I'd rather do things properly.

 

Could anyone recommend a suitable switch that I could install between the panels and the controller so I can switch them off before changing the fuse? Would I install this in the positive or negative wire?

 

Cheers. 

 

 

[Jen-in-Wellies]

Have you tested the fuse with a multimeter after you have taken it out? Multimeter set to resistance, or continuity test. If the fuse isn't actually blown it says the fault is elsewhere. Most likely a loose, or corroded joint betwixt batteries and solar controller. Especially likely if reinserting the old fuse temporarily "fixes" the problem.

 

Jen

[Robbo]

20 minutes ago, Gareth E said:

Could anyone recommend a suitable switch that I could install between the panels and the controller so I can switch them off before changing the fuse? Would I install this in the positive or negative wire?

 

Have a gander at...

 

https://www.electricalguys.co.uk/salzer-dc-isolator-for-solar-installs-h226-81400-710n1.html

Edited July 18, 2018 by Robbo

[larryjc]

I did this when I fitted my tracer - all I use is a standard battery isolations switch - fitted in the plus line - like this one:

https://www.amazon.co.uk/Techniks-BS01HD-Battery-Isolator-Switch/dp/B009CRM34I/ref=sr_1_1?s=automotive&ie=UTF8&qid=1531917286&sr=1-1&keywords=battery+isolation+switch

[Horace42]

1 hour ago, Gareth E said:

I have 375w of panels going to a 30a Tracer. Every few months the fuse I installed between the controller and batteries fails. It's a bit strange really, the fuse doesn't blow, if I take it out of its holder and re insert it will usually last a few days before going again. Seems to wear out somehow.

 

I'm aware that the controller should be connected to the batteries first rather than the panels. There's no on-off switch on the controller so it's either wait until dark or the faff of covering the panels. I'll admit that sometimes I just insert a new fuse and to hell with it. I've got away with this so far but I'd rather do things properly.

 

Could anyone recommend a suitable switch that I could install between the panels and the controller so I can switch them off before changing the fuse? Would I install this in the positive or negative wire?

 

Cheers. 

 

 

If the panels work after replacing the suspected 'dud' fuse, then it suggests the fuse is OK. Like Jen #2 says it sounds more like bad terminals or connectors caused by joints that could be loose or corroded.

If it is, putting in a bigger fuse won't help much.

[Gareth E]

Thanks for the replies just to expand a little: When I take a fuse out that's stopped working there's noticeable wear on the blades of the fuse, a very slight groove where it's clamped in the holder. I don't see it being a connection problem elsewhere otherwise putting a new fuse in wouldn't solve it. I think it's likely that replacing the fuse holder would solve the problem, I'll probably do this sometime, but it's still handy to have a way of isolating the panels from the controller.  

[Tony Brooks]

As you talk about "blade" one can assume this is a standard automotive fuse and they are not best suited to being installed d close to batteries on many boats (too damp etc.). Be ware it can be very easy to get a blade down the side of one of the female receptacles and thus get intermittent contact. Look very closely at where and how the fuse is going into the holder.

[PeterF]

On mine I have the bolt in midi fuses for a positive contact.

 

Midi fuse holder,  Midi fuse

5 hours ago, larryjc said:

I did this when I fitted my tracer - all I use is a standard battery isolations switch - fitted in the plus line - like this one:

https://www.amazon.co.uk/Techniks-BS01HD-Battery-Isolator-Switch/dp/B009CRM34I/ref=sr_1_1?s=automotive&ie=UTF8&qid=1531917286&sr=1-1&keywords=battery+isolation+switch

Most battery isolation switches are rated for max 48V, which many solar installations with panels in series exceed, the Salzer is rated to a much higher voltage.

[larryjc]

1 hour ago, PeterF said:

On mine I have the bolt in midi fuses for a positive contact.

 

Midi fuse holder,  Midi fuse

Most battery isolation switches are rated for max 48V, which many solar installations with panels in series exceed, the Salzer is rated to a much higher voltage.

Yes but mine are in parallel as I don't want shadows on one stopping both working so the voltage is only about 36.

[PeterF]

Fair enough, I just thought I would put a warning in for the less technically savvy. Mine are in series, quoted as 23.9V open circuit x 2 = 47.8V, I originally bought a battery isolation switch but on second thoughts as I was so close to the rated 48V I decided to change to a higher voltage rated switch.

[dunfixing]

Most controllers require the panels to be connected first, this is so the controller can assess the battery voltage before it starts to charge. I fitted a battery isolation switch between controller and battery,

I had the same fault as you, it was caused by a loose connection on the controller,

give the wires a tug, 

[rusty69]

3 minutes ago, dunfixing said:

Most controllers require the panels to be connected first, this is so the controller can assess the battery voltage before it starts to charge. I fitted a battery isolation switch between controller and battery,

I had the same fault as you, it was caused by a loose connection on the controller,

give the wires a tug, 

Eh? How can they do that if the battery isn't connected. 

[Robbo]

5 minutes ago, dunfixing said:

Most controllers require the panels to be connected first, this is so the controller can assess the battery voltage before it starts to charge. I fitted a battery isolation switch between controller and battery,

I had the same fault as you, it was caused by a loose connection on the controller,

give the wires a tug, 

I think you mean requires the batteries to be connected first.

[Scholar Gypsy]

This is what I installed in my setup, after discussion with Bimble. One  breaker between panels and controller, one between controller and batteries. A pompous notice (written by me) on the wall telling people in what order to turn them on and off.

 

A bit overkill, but I wanted my system to be such that I can easily remove one or both of the panels. The MC4 connectors do say "not to be disconnected under load".

 

 

[Chewbacka]

Having checked the short circuit current from a second hand panel by pushing meter probes into the connector I fully understand why they tell you not to disconnect under load.  

[dunfixing]

On 19/07/2018 at 13:48, Robbo said:

I think you mean requires the batteries to be connected first.

No. my Mppt controller instructions clearly state,  connect panels first then the batteries.

my controller automatically adjusts to 12volts or 24volts to match the batteries,

if you reverse the startup process it would most likely result in an over voltage, over current overload.

[Robbo]

1 minute ago, dunfixing said:

No. my Mppt controller instructions clearly state,  connect panels first then the batteries.

Mine clearly states the opposite.

[rusty69]

2 minutes ago, dunfixing said:

No. my Mppt controller instructions clearly state,  connect panels first then the batteries.

my controller automatically adjusts to 12volts or 24volts to match the batteries,

if you reverse the startup process it would most likely result in an over voltage, over current overload.

What controller have you got? 

1 minute ago, Robbo said:

Mine clearly states the opposite.

Both of mine do too. Goes to show, read the instructions and don't assume. 

[Sea Dog]

11 minutes ago, dunfixing said:

No. my Mppt controller instructions clearly state,  connect panels first then the batteries.

my controller automatically adjusts to 12volts or 24volts to match the batteries,

if you reverse the startup process it would most likely result in an over voltage, over current overload.

As I understand it, this is normally the reason to connect to the batteries first as they then provide the reference voltage for the auto set up. Maybe some are different. 

[dunfixing]

On 19/07/2018 at 13:46, rusty69 said:

Eh? How can they do that if the battery isn't connected. 

Mppt controllers work by assessing the batteries then switch the panel input on. You could connect batteries first, but you would only be safe doing this in the dark.

350watt of solar panels could have as much as 200volts output off load, the sudden voltage spike could damage the controller beyond repair, a switch can and often does create quite a large spark across its contacts when opened or closed, not unlike a small lightning strike, harmless for the operator, but not what it is connected to, best not to try your luck.

[dunfixing]

On 18/07/2018 at 12:19, Gareth E said:

I have 375w of panels going to a 30a Tracer. Every few months the fuse I installed between the controller and batteries fails. It's a bit strange really, the fuse doesn't blow, if I take it out of its holder and re insert it will usually last a few days before going again. Seems to wear out somehow.

 

I'm aware that the controller should be connected to the batteries first rather than the panels. There's no on-off switch on the controller so it's either wait until dark or the faff of covering the panels. I'll admit that sometimes I just insert a new fuse and to hell with it. I've got away with this so far but I'd rather do things properly.

 

Could anyone recommend a suitable switch that I could install between the panels and the controller so I can switch them off before changing the fuse? Would I install this in the positive or negative wire?

 

Cheers. 

 

 

I have a tracer controller and had a connection problem, if you don’t undo the securing screws far enough the wire won’t get clamped in place, the wire might look ok, but give them a tug. one of mine came out same symptoms as yours.

[reg]

23 minutes ago, dunfixing said:

No. my Mppt controller instructions clearly state,  connect panels first then the batteries.

my controller automatically adjusts to 12volts or 24volts to match the batteries,

if you reverse the startup process it would most likely result in an over voltage, over current overload.

Never heard of that and is counter to everything I have heard, which controller is it as it makes no sense to me. How can it adjust to 12v or 24v if batteries are not connected? 

[rusty69]

9 minutes ago, dunfixing said:

I have a tracer controller and had a connection problem, if you don’t undo the securing screws far enough the wire won’t get clamped in place, the wire might look ok, but give them a tug. one of mine came out same symptoms as yours.

Just read my tracer mppt instructions. It says battery  first, nothing about connecting in the dark. 

 

What model tracer do you have? 

Edited July 20, 2018 by rusty69
Made a mistake

[reg]

Now that you have said you have a tracer controller, is this the one you have been referring to because the tracer clearly says. 

Battery First

Load Second

Panels Last. 

Have you misread the instructions? 

 

Was typing same time as Rusty69. I think you may of been lucky if you have been doing it the wrong way around. 

 

I would suggest you edit your original post so that future readers will not be misled and use bad practice. 

Edited July 20, 2018 by reg

[Richard10002]

Tracer BN Manual

 

http://www.epsolarpv.com/en/uploads/news/201710/1508813495487522.pdf

 

I have a breaker between panels and controller so I can disconnect the panels.

 

The Tracer manual suggests that it is protected against over voltage and current from the panels and batteries, so it shouldn't really matter what you do in terms of damaging the controller.