Need battery disconnect switch advice

Kerry

I'm wanting a switch that cuts off both the positive and negative feeds to my new PV system (see components below). The Blue Sea Systems 6010 m-Series (Mini) Battery Switch Dual Circuit looks like it will work—but I'm concerned about its amp rating for my system.

My thinking is that if I go on vacation I'll be able to trip the (4) 115 amp circuit breakers in the Combiner Box and the (6010 m-Series) battery disconnect switch and I wouldn't have to worry. Yes? No?

Thank you,

Kerry

System components:

(4) 250w PV panels with MC4 male & female connectors on each 3' 12 awg wire. (each panel is rated 30.1v, 8.3 amp).
(4) 6v, 232 amp Deep Cycle batts configured for 12v using 2/0 cables.
(1) Flexmax 80
(1) ProWatt SW 1000 Inverter
(1) Midnite Solar e-panel part MNE125ALT
(1) Midnite Solar-MNPV6 Combiner Box with (4) 15 amp circuit breakers.
(8) Eight 10' long 10 awg wires 4+ & 4-) from array to Combiner Box (connected via MC4 connectors).
SnapNRack fastening system.

Vic

Re: Need battery disconnect switch advice

Hi Kerry,

So, the BSS 6010 will be used to disconnect both the positive AND negative connections between the inverter and the battery?

Normally, simply switching the main DC breaker in only the positive lead to the inverter would suffice ... believe that this is the 125 A breaker on your e-panel.

Believe that there is a typo in the description of the PV Combiner breakers, bet that they are 15 A. Usually, there will be an additional single breaker at the PV input to the FM CC, that would allow the PV input to be disconnected. There is probably a position for this breaker on the e-panel. And, there MUST be circuit protection on the output of the CC, as you probably. For convenience this should really a circuit breaker. These breakers should be sized to protect the cables between the Combiner for the input breaker, and for the CC output breaker, sized to protect that cable, as well. MNEDC breakers should be fine for these ... possibly MNEPV might be fine as well ...

You might well want to leave the system running while you are on vacation, to keep the batteries fully charged.

Why do you want to disconnect both + and -- feeds to your PV system, and guess that this switch disconnects the inverter from the battery ...

Vic

Plowman

Re: Need battery disconnect switch advice

I'm no expert, but seems to me that switch would be fine if you just wanted to switch off loads from the battery bank. I have an older Blue Sea switch between my 2 panels and my charge controller, it's a solid piece of equipment. Why do you want to switch both pos and neg? Maybe just manually disconnect the wires/cables if you'll be gone for a long while?

If you're worried about the battery short-circuiting, I'd suggest a battery fuse/breaker. I'm currently just using a little 40-amp circuit breaker (the kind you get in an auto parts store) installed within a couple inches of my battery bank's positive terminal, but I'll probably end up getting one of Blue Sea's battery terminal fuses.

Depending on how long your vacations are, I'm not sure it's necessary (or a good idea) to shut off the panels. Self-discharge in warm weather, freezing in cold weather due to low SOC, etc.

Kerry

Re: Need battery disconnect switch advice

Hi Vic.

So, the BSS 6010 will be used to disconnect both the positive AND negative connections between the inverter and the battery?

Yes.

Normally, simply switching the main DC breaker in only the positive lead to the inverter would suffice ... believe that this is the 125 A breaker on your e-panel.

I'll know more when it arrives. I don't see any descriptions of the specs of the e-panel's components. I'm thinking I could run the negative from the BSS 6010 disconnect switch to the Main DC Breaker in the c-Panel.

Believe that there is a typo in the description of the PV Combiner breakers, bet that they are 15 A.

My bad. You're correct, they are 15 amp.

You might well want to leave the system running while you are on vacation, to keep the batteries fully charged.

Good point.

Why do you want to disconnect both + and -- feeds to your PV system, and guess that this switch disconnects the inverter from the battery ...

I think it's an engram left over from my submarine days, I seem to recall there were lots of dbl pole-dbl throw switches. I plan on running out and disconnecting the whole shebang so that if lightening strikes it might not damage too much.

Kerry

Kerry

Re: Need battery disconnect switch advice

Hi Plowman,

I'd suggest a battery fuse/breaker.

Good suggestion, thanks. I'm not sure what size fuse I should get. My (4) 6v batts are rated 232 ah each. I have them wired for 12v. I'll be running 2/0 cables from the batts.

Kerry

vtmaps

Re: Need battery disconnect switch advice

Kerry wrote: »

I'm wanting a switch that cuts off both the positive and negative feeds to my new PV system (see components below). The Blue Sea Systems 6010 m-Series (Mini) Battery Switch Dual Circuit looks like it will work—but I'm concerned about its amp rating for my system.

Hi Kerry,

Those Blue Sea switches do NOT meet code for residential systems. Read this recent posting:
http://forum.solar-electric.com/showthread.php?p=189559#post189559

Kerry wrote: »

I think it's an engram left over from my submarine days, I seem to recall there were lots of dbl pole-dbl throw switches.

I know nothing about submarine electrical systems. Are they floating ground? An ungrounded system needs OCP (fuses or breakers) on both pos and neg conductors. One advantage of a grounded system is that you need only protect the pos conductor.

Kerry wrote: »

I plan on running out and disconnecting the whole shebang so that if lightening strikes it might not damage too much.

A disconnect switch will not protect you from lightning. Lightning will jump across the switch. For lightning you need a properly grounded system with some Midnite surge protectors. I seem to recall (from your posting at the Midnite forum) that you are planning to put your combiner in your equipment room. If lightning strikes, you will be letting it into your equipment room. It would be better to put the combiner OUTSIDE your home with a lightning arrester.... divert the lightning to ground OUTSIDE your home.

--vtMaps

Kerry

Re: Need battery disconnect switch advice

Hi --vtMaps,

Good catch about the rotary switch. Thanks also for the suggestions and tips.

Got the panels installed today. They sure look nice.

Kerry