Disconnecting Batteries with Solar?

[theczar]

So I am new to solar. I noticed corrosion on one of my battery cables and want to remove and Clean it. I do not think I have an on/off switch on the solar charge controller. Is it OK to remove the Battery cable with Sun out and the charge controller on? If not, how should this be done? Thanks!

[red31]

Hi PT, just asking Twriter a simple question if he and that forum recommend fusing both + and - as bussman does! His link was less than useful for me.

[pianotuna]

red31,

If the negative is the ground then fuse on the positive side.

[red31]

TechWriter wrote:


You'll get better advice on MidNite Solar Forum.

Do the forum posters recommend a fuse on both the + and - ?

[pianotuna]

Fine with me if you put in needless and useless fuses.

There are no RV systems that use inverters that I am aware of, but it would be possible to design one. If you did--then fuses would be needed. But anyone who is working at that level would know fuses are required.

[TechWriter]

pianotuna wrote:

A quote from the Bussman Solar Article "For arrays with only one or two sub-arrays and sub-array cables adequately sized, fusing may only be required if local installation regulations or codes require them."

TechWriter wrote:

And right after that quote is this:

"However Cooper Bussman recommends fuse link protection in all PV systems as unpredicted fault currents may occur in the event of inverter failure."

pianotuna wrote:
Which refers to grid tied inverters. I don't know any RV'er who uses them.

You can't have it both ways. Either you use what the Bussman recommends or don't bring it up in the first place.

OP, one of this thread's posters actually recommended using just plain wire as a fuse in a previous solar fusing thread.

You'll get better advice on MidNite Solar Forum.

[pianotuna]

Which refers to grid tied inverters. I don't know any RV'er who uses them.

TechWriter wrote:

pianotuna wrote:

A quote from the Bussman Solar Article "For arrays with only one or two sub-arrays and sub-array cables adequately sized, fusing may only be required if local installation regulations or codes require them."

And right after that quote is this:

"However Cooper Bussman recommends fuse link protection in all PV systems as unpredicted fault currents may occur in the event of inverter failure."

[Boon_Docker]

westend wrote:

Traveler7 wrote:

2oldman wrote:
There's no compelling safety reason for fusing solar. It's not like they are batteries capable of runaway amperage starting fires.

Well, A lightning strike on the panel might give you a compelling reason...

For sure.

I like that inline manual breaker that Denver Transplant linked to. Here: Inline breaker I used a Bussman manual breaker and they are twice that price. It sure is handy to have a switch on that circuit, though.

That breaker also makes a great disconnect between panels and controller.

[red31]

and this

'Cooper Bussmann recommends using fuse links in positive and
negative cables, each with adequate voltage'


2 strings and they would recommend 6 fuses.
2 for each sub-array and 2 for total array.

[TechWriter]

pianotuna wrote:

A quote from the Bussman Solar Article "For arrays with only one or two sub-arrays and sub-array cables adequately sized, fusing may only be required if local installation regulations or codes require them."

And right after that quote is this:

"However Cooper Bussman recommends fuse link protection in all PV systems as unpredicted fault currents may occur in the event of inverter failure."

[Traveler7]

westend wrote:

Traveler7 wrote:

2oldman wrote:
There's no compelling safety reason for fusing solar. It's not like they are batteries capable of runaway amperage starting fires.

Well, A lightning strike on the panel might give you a compelling reason...

For sure.

I like that inline manual breaker that Denver Transplant linked to. Here: Inline breaker I used a Bussman manual breaker and they are twice that price. It sure is handy to have a switch on that circuit, though.

I have a 20 amp inline breaker just like that on the positive cable. Also using a 60 amp version on my Wagan Elite 1000 Watt pure sine inverter.

[camperguy99]

I think it depends on what MPPT CC you have. Mine states that you should disconnect the panels from the CC but no damage will occur if you don't disconnect. I've done both many times without damage. Don't especially recommend my unit, but it is a CNBOU MUSE 40 amp, 150 volt unit. Seems to work well with my 720 watts of series/parallel panels. I often see the full 40 amps charge current going into 3 series pairs of GC2 batteries. Sorry for the off topic ramble.

[pianotuna]

Hi,

You need to be able to disconnect the panels first, so the wire may not be a good plan.

The breaker between the controller and the battery bank should be extremely close to the battery bank end of the wire.

Spridle wrote:
for my small (3)100 watts solar panels i used this for disconnects breakers and fuses:

http://www.midnitesolar.com/productPhoto.php?product_ID=79&productCatName=BOX%20ENCLOSURES&productCat_ID=10&sortOrder=1&act=p

I used one 20 amp breaker to disconnect the solar panels to the charge controller and one 30 amp breaker to disconnect the charge controller feeding the battery's. use bushings in the holes of the box. I tied the breaker handles together with a piece of tie wire so they both disconnect at the same time.

http://www.midnitesolar.com/productPhoto.php?product_ID=184&productCatName=Breakers&productCat_ID=16&sortOrder=6&act=p

[Spridle]

for my small (3)100 watts solar panels i used this for disconnects breakers and fuses:

http://www.midnitesolar.com/productPhoto.php?product_ID=79&productCatName=BOX%20ENCLOSURES&productCat_ID=10&sortOrder=1&act=p

I used one 20 amp breaker to disconnect the solar panels to the charge controller and one 30 amp breaker to disconnect the charge controller feeding the battery's. use bushings in the holes of the box. I tied the breaker handles together with a piece of tie wire so they both disconnect at the same time.

http://www.midnitesolar.com/productPhoto.php?product_ID=184&productCatName=Breakers&productCat_ID=16&sortOrder=6&act=p

[pianotuna]

Hi BFL13,

Thanks for finding that.

A quote from the article "For arrays with only one or two sub-arrays and sub-array cables adequately sized, fusing may only be required if local installation regulations or codes require them."

BFL13 wrote:
This explains all about the real requirements for solar array fusing. Scroll down to string and array protection.

http://www1.cooperbussmann.com/pdf/1b416a65-f5ac-4730-ab77-9e2faa147945.pdf