Quick wiring question panels to controller

dlone

I have 2 strings about 30 amps each,and my controller is an 80 amp. My question is can I wire both pos and both neg to 1 breaker?

mike95490

Re: Quick wiring question panels to controller

dlone wrote: »

I have 2 strings about 30 amps each,and my controller is an 80 amp. My question is can I wire both pos and both neg to 1 breaker?

Best stop now, before you blow yourself up, and consult wit someone. AFIK, you should not wire + & - to same breaker

dlone

Re: Quick wiring question panels to controller

I called and talked to a reppiable solar store and asked what I would need and they told me I would need a 250 amp breaker box,1 80 amp breaker. I thought I would have needed 2, but?

dlone

Re: Quick wiring question panels to controller

mike90045 wrote: »

Best stop now, before you blow yourself up, and consult wit someone. AFIK, you should not wire + & - to same breaker

I know pos go to the breaker and neg to bus bar or shunt. Can both pos be on the same breaker? I would have thought they would of suggested 2 breakers?

niel

Re: Quick wiring question panels to controller

the negative end is not wired to the cb, only the pos. to put both to the cb will cause a short circuit and is what mike was inferring to in his comment. the cb will only be put in series with the pos lead. the store probably figured you would combine the 2 strings together at the 80a cb input. you can do this for 2 strings, but for 3 or more it would necessitate individual breakers for each string. if you feel better about having a cb on each string then you may do so with 2 40a cbs.
does this help you?

dlone

Re: Quick wiring question panels to controller

niel wrote: »

the negative end is not wired to the cb, only the pos. to put both to the cb will cause a short circuit and is what mike was inferring to in his comment. the cb will only be put in series with the pos lead. the store probably figured you would combine the 2 strings together at the 80a cb input. you can do this for 2 strings, but for 3 or more it would necessitate individual breakers for each string. if you feel better about having a cb on each string then you may do so with 2 40a cbs.
does this help you?

Thanks, thats what I wanted to know. It was a quick question, didnt specify that I know that breakers are it interupt current on the pos side. Thanks though.

BB.

Re: Quick wiring question panels to controller

Slow down and describe what you are trying to achieve first...

If you have one or two parallel strings of solar panels, you generally do not need a breaker/fuse anywhere on the PV Array input.

If you have three or more parallel PV Arrays, then you should use use a combiner box with a fuse/breaker on each PV strings (to limit short circuit current if a panel or panel wiring shorts out). These fuses are typically in the 10-15 amp range (actual rating depending on series fuse rating/Isc of the solar panels).

Next from the charge controller to the battery bank (charge controller output), yes, you would need a circuit breaker that is rated 1.25 times the expected maximum current from the charge controller (i.e., 60 am charge controller with large PV array = 60a*1.25=75amps minimum--80 amp breaker/fuse/rated wiring minimum).

Each positive wire that "leaves the battery bank" should have a fuse/breaker sized for the wire (one to inverter, another to a backup AC charger, others to DC loads, etc.).

The "-" lead from the battery bank is then run through a "shunt resistor" (for battery monitor/current meter) then to Earth Ground/Negative Ground bus. The shunt measures all current flow through the battery bank and, by safety convention, there is never any fuse / breaker in the negative lead of a negative grounded power system. All fuses/breakers are always in the +/positive leads.

Now, for the confusing details :roll:...

First, Outback appears to rate their circuit breakers differently... Their 80 amp circuit breaker is for use with their 80 amp charge controllers. Normally we would do the 80a*1.25=100amp rated breaker.

Second, NEC "requires" a ground fault detection circuit for solar arrays.

I am high dubious of this setup--but they make a setup to do this... Basically, there is a ground wire from the array "-" connection through a 1 amp Circuit Breaker to the system earth/safety ground rod. A second 80 amp (or whatever size is require) breaker is ganged with the 1 amp breaker... If there is a solar array to ground sort, it "pops" the 1 amp breaker which trips the 80 amp breaker handle--turning off the PV array.

If you choose to use a Ground Fault setup for your Off-Grid system, there are prewired panels setup to hand this part. Also, for some controllers (like the Xantrex/Schneider XW MPPT controller) have the Ground Fault circuit built in (you need to read the manuals for any controller you install--there can be real issues if you don't follow the instructions for specific models).

And regarding "positive breaker/fuses in wiring" are only for negative grounded systems. There are a few positive grounded systems (telecommunications and others) that would then have the breaker in the negative leads.

-Bill

dlone

Re: Quick wiring question panels to controller

BB. wrote: »

Slow down and describe what you are trying to achieve first...

If you have one or two parallel strings of solar panels, you generally do not need a breaker/fuse anywhere on the PV Array input.

If you have three or more parallel PV Arrays, then you should use use a combiner box with a fuse/breaker on each PV strings (to limit short circuit current if a panel or panel wiring shorts out). These fuses are typically in the 10-15 amp range (actual rating depending on series fuse rating/Isc of the solar panels).

Next from the charge controller to the battery bank (charge controller output), yes, you would need a circuit breaker that is rated 1.25 times the expected maximum current from the charge controller (i.e., 60 am charge controller with large PV array = 60a*1.25=75amps minimum--80 amp breaker/fuse/rated wiring minimum).

Each positive wire that "leaves the battery bank" should have a fuse/breaker sized for the wire (one to inverter, another to a backup AC charger, others to DC loads, etc.).

The "-" lead from the battery bank is then run through a "shunt resistor" (for battery monitor/current meter) then to Earth Ground/Negative Ground bus. The shunt measures all current flow through the battery bank and, by safety convention, there is never any fuse / breaker in the negative lead of a negative grounded power system. All fuses/breakers are always in the +/positive leads.

Now, for the confusing details :roll:...

First, Outback appears to rate their circuit breakers differently... Their 80 amp circuit breaker is for use with their 80 amp charge controllers. Normally we would do the 80a*1.25=100amp rated breaker.

Second, NEC "requires" a ground fault detection circuit for solar arrays.

I am high dubious of this setup--but they make a setup to do this... Basically, there is a ground wire from the array "-" connection through a 1 amp Circuit Breaker to the system earth/safety ground rod. A second 80 amp (or whatever size is require) breaker is ganged with the 1 amp breaker... If there is a solar array to ground sort, it "pops" the 1 amp breaker which trips the 80 amp breaker handle--turning off the PV array.

If you choose to use a Ground Fault setup for your Off-Grid system, there are prewired panels setup to hand this part. Also, for some controllers (like the Xantrex/Schneider XW MPPT controller) have the Ground Fault circuit built in (you need to read the manuals for any controller you install--there can be real issues if you don't follow the instructions for specific models).

And regarding "positive breaker/fuses in wiring" are only for negative grounded systems. There are a few positive grounded systems (telecommunications and others) that would then have the breaker in the negative leads.

-Bill

So your saying it needs to be in the negative wire?

BB.

Re: Quick wiring question panels to controller

So your saying it needs to be in the negative wire?

I am not sure what "it" means.

For a positive ground system, all fuses/switches/circuit breakers should only be in the positive lead from the battery bank.

For fuses and breakers, they should be "close" to the battery bank (source of the high current).

The DC Shun Resistor (for battery monitors and battery current meters)... the negative leads of the battery bank (all battery leads if 2 or more parallel strings) should go to a common connection at one end of the shunt, then to the "common ground" where all negative system connections are made... This allows the current shunt to measure all current through the battery bank (generally what people want to do).

The battery shunt is placed near the ground connection so that all wires are near zero volts (like the voltage sense leads) and will not need a fuses to prevent shorts.

Here is a simple drawing of a battery bank and shunt... All wires leaving the + side of the battery wiring should have fuses/breakers/switches.

At the "-" of the battery bank (to the "Left" of the shunt) is where all negative/return leads from DC appliances should connect. Also, that is generally the point where RV chassis ground and/or a safety earth/ground rod is also tied in.

-Bill