Combiner box on pole or in house?

Started by pablo, June 18, 2016, 08:52:27 PM

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Vic

Hi pablo,

YES!  You have the nature of that top busbar correct.

We do not know the  nature of your inverter,  and any electrical boxes that you are using that are from the original system.   So you may only need to use the MNPV6 as the breaker box for the FM CC.

MidNite does make some boxes for dealing with the cables and breakers for inverters,  plus CC  DC breakers,  etc ...  plus some breakers for AC in and out cables.   These start as the MiniDC,  and go up to a series of e-Panels,  if you really need a way to deal with additional breakers and cables.   Will add some Links later.

It is possible that your now-absent electrician was thinking that you were going to add quite a lot of additional PVs,  later,  and that is why you have the 1/0 cable from the PV field,  as well as the MNPV6 Combiner.   This combiner should do fine,  for now as a breaker box.

Later,    Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

Vic

pablo,

You may have seen the MidNite Mini DC boxes,   but here is a Link:
http://www.solar-electric.com/installation-parts-and-equipment/midnite/elenanddcdi/midcdipoce.html

The MidNite e-Panels are usually made for a specific inverter,  if you need a new way to manage all of the breakers and cables these can centralize all of this at a fairly low price,  if you have nothing that is doing this job at this point:
http://www.solar-electric.com/installation-parts-and-equipment/midnite/misoe.html

FWIW,    Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

pablo

Attached is my design for my small off-grid 12 Volt system for my yurt (cross posted)  Hopefully self-explanatory.  Page 1 of the design is my proposed system, components are already purchased and installed, but just need to be wired together.   My existing 12 Volt system includes the batteries on page 1 and everything on page 2 (did not include existing solar panels which are hard-wired to my batteries w/o charge controller). 

Questions: 

1.  I'm using my combiner box as a DC disconnect box.  Does the PV minus bar also serve as a battery minus bar?  If not, where does the negative feed from the charge controller go to?  I'm trying to get away from connecting everything directly to batteries!

2.  Do I integrate my inverter with the disconnect box or just leave it as-is, directly wired to the battery?   Same question for my Genny charger.

3.  I have a lot of connections direct to my battery.  Is that proper?  Seems like a lot of connection stacked on top of each other makes for bad connections.

4.  Do I need a fuse between the inverter and the AC panel?

I wish I would have bought a proper DC box as everybody has mentioned, but these are the components I have and am stuck with because I am out of money.   :P

thank you!
Off grid 12 volts, 2 Trojan L16RE batts, Samlex 2K inverter, Xantrex 40 Amp charger, Outback Flexmax 60 Amp MPPT charge controller, 2 Solar World 285 W panels, Honda 1000 Watt genny.

pablo

page 2 of my diagram
Off grid 12 volts, 2 Trojan L16RE batts, Samlex 2K inverter, Xantrex 40 Amp charger, Outback Flexmax 60 Amp MPPT charge controller, 2 Solar World 285 W panels, Honda 1000 Watt genny.

Vic

Quote from: pablo on July 08, 2016, 11:45:47 AM
Attached is my design for my small off-grid 12 Volt system for my yurt (cross posted)  Hopefully self-explanatory.  Page 1 of the design is my proposed system, components are already purchased and installed, but just need to be wired together.   My existing 12 Volt system includes the batteries on page 1 and everything on page 2 (did not include existing solar panels which are hard-wired to my batteries w/o charge controller). 

Questions: 

1.  I'm using my combiner box as a DC disconnect box.  Does the PV minus bar also serve as a battery minus bar?  If not, where does the negative feed from the charge controller go to?  I'm trying to get away from connecting everything directly to batteries!

2.  Do I integrate my inverter with the disconnect box or just leave it as-is, directly wired to the battery?   Same question for my Genny charger.

3.  I have a lot of connections direct to my battery.  Is that proper?  Seems like a lot of connection stacked on top of each other makes for bad connections.

4.  Do I need a fuse between the inverter and the AC panel?

I wish I would have bought a proper DC box as everybody has mentioned, but these are the components I have and am stuck with because I am out of money.   :P
thank you!

Hi pablo,

You can certainly use the Negative Busbar in the MNPV6 as the Negative for the PVs.

A breaker between the Inverter and the battery is very convenient,  but not necessary,  as you are using the Class T Fuse.  Those fuses are expensive,  so,  later you may wish to go with a MN MiniDC,  or e-panel.

If you wish to use the PV6 as a place for the inverter breaker,  the largest breaker that is DIN rail,  is the double-wide 100 A  (MNPV100, IIRC).

It is better to have a proper box for the Inverter breaker,  and all of the other connections to/from the battery there.   Some say that a direct connection to the battery from the CC's output breaker is better than connecting the CC + battery connection to the inverter breaker's input from the battery positive (but,  I do not do it that way).

Yes,  your TC40 needs a DC breaker.

You are correct about all of the connections going directly to the battery.  It can be messy,  less safe (generally),  and can result in connections that are a bit sketchy.

More later,  off to a remote site.

FWIW,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

pablo

Well, everything is up and running.  I only almost-electrocuted myself once but did not blow up any of my equipment or start any fires.  I had left the 110 circuit live in order to provide good lighting in my electrical closet while working on my DC circuits.  At some point I moved from DC work to AC work w/o turning off the 110!  I actually had a screw driver inside the AC panel connecting ground wires etc when I realized what I was doing.  Lucky.  Lesson learned... just turn everything off...

The only significant error I made was sizing my PV breaker too small.  Amperage increased with my parallel wiring and I think my supplier had assumed I was going to wire in serial (which I now am... :)

"Some say that a direct connection to the battery from the CC's output breaker is better than connecting the CC + battery connection to the inverter breaker's input from the battery positive (but,  I do not do it that way)."

Vic, could you explain this to me again?  I don't quite follow.  I am using the former method.  Can you connect the CC+ to the inverter's circuit breaker? Directly? or via a splice or something?   It sure would be nice to reduce the number of direct connections to the battery.  I wonder if I could do this when it is time to tie my battery charger into the system?

Also, my inverter cables are 4/0.  Are there actually CBs that can manage a 4/0 cable?


Thank you!
Off grid 12 volts, 2 Trojan L16RE batts, Samlex 2K inverter, Xantrex 40 Amp charger, Outback Flexmax 60 Amp MPPT charge controller, 2 Solar World 285 W panels, Honda 1000 Watt genny.

Vic

Hi pablo,

Great that everything is up and running,  congratulations!   And  congratulations on NOT electrocuting yourself,  as well.

Regarding the connection from the CC's output breaker to battery,  it can take place at the battery,  or at the battery side of the Main DC breaker that powers the inverter's positive DC input.   The battery side of the inverter breaker is usually where I place this connection.

Forget just what inverter you are using (cannot see the Signature while Posting).  There are large frame DC breakers that are common in our battery-based systems.   Normally,  we would use a 125,  175,  or 250 Amp breaker,  depending on the Surge capability of the inverter,  and the size of the cable.  4/0 cable often has lugs with a clearance hole for a 3/8" bolt,  and these large breakers use 1/4" studs for the 125A,  and 3/8" studs for the 175 and 250 A.   Here are some large breakers,   the first three in this link are probably what you are looking for:
http://www.solar-electric.com/catalogsearch/result/?q=Panel+Mount+DC+Circuit+Breaker%2C

Have mentioned the MN Mini DC box,  and the MN e-Panels,  previously.   These usually include the Inverter breaker,  in a size that you specify when ordering.  Know that cash is tight,  but  you may wind up getting one or the other of these boxes later.   These large frame DC breakers should really be mounted in a fairly large metal enclosure,  and adapting some inexpensive box will take some time ...

OK see that you have a 12 V 2K Samlex inverter.   More later,   Have Fun with the new system.
Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

pablo

Awesome.  Thanks for the link.  I'll put those CBs on my wish list and start saving. 

Generated 1.3 KW today!
Off grid 12 volts, 2 Trojan L16RE batts, Samlex 2K inverter, Xantrex 40 Amp charger, Outback Flexmax 60 Amp MPPT charge controller, 2 Solar World 285 W panels, Honda 1000 Watt genny.