Duel Solar Charge Controllers

[Maine Sail]

Originally Posted by sailsunfurled

On two of those installation pictures - they need to have a fuse/breaker between the output of the charge controller and the bus bar leading to the battery(s). All the battery bus bar current is exposed to the charge controller in the event of problems.

The fuses would go as close to the battery as possible, preferably within a few inches... Often the controllers are a few feet away which could mean six + wire run feet that could short out, chafe etc. between the battery and controller. We are not protecting the wire from the controllers but rather from the battery bank..

[Maine Sail]

Originally Posted by a64pilot

When you connect the multiple controllers to one bus, isn't that essentially the same as multiple panels in parallel connected to one controller?


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With PWM, yes.
With a PWM controller in bulk the input and output voltage are the same because it is essentially a direct connection between PV and battery..

With MPPT no.
The MPPT controller isolates the PV from the battery and the PV side can be at say 24V and the battery side at 12.6V this allows the MPPT controller to convert excess voltage into a boost in current output.

One panel per controller allows each controller to track the maximum power point (voltage) of the panel it is connected to and deliver the maximum harvest in amperage to the battery from that panel...

[sailsunfurled]

Originally Posted by Maine Sail

The fuses would go as close to the battery as possible, preferably within a few inches... Often the controllers are a few feet away which could mean six + wire run feet that could short out, chafe etc. between the battery and controller. We are not protecting the wire from the controllers but rather from the battery bank..

Correct, but in two those pictures, the charge controller output that goes to the bus bar is not fused. If there is a short to ground inside the charge controller, the full current of the bus bar will back-feed into that short inside the charge controller through the smaller wire. As pictured, the fuse needs to be sized for the current capabilities of the charge controller and the output wire size feeding fed into the bus bar from the charge controller output.

So, in those 2 pictures, the wire is not protected from the bus bar to the charge controller. The only fuse is the feed to battery from the bus bar. and if that fuse is sized for the larger battery wire then you may have a problem.

[zboss]

We put circuit breakers on both the pos AND neg near the battery and fuse all of the pos circuits before and after the controllers.

People think we are crazy for fusing of negs and pos but the neg will often be the one that trips first, leaving the pos untouched. Of course you need to make sure that pos has no other place to go.

[a64pilot]

Originally Posted by zboss

We put circuit breakers on both the pos AND neg near the battery and fuse all of the pos circuits before and after the controllers.

People think we are crazy for fusing of negs and pos but the neg will often be the one that trips first, leaving the pos untouched. Of course you need to make sure that pos has no other place to go.

Unless I'm wrong, and I often am, the flow of current is actually from the neg to the positive, not pos to neg like we seem to think, I believe the Brits with their positive ground cars of times past, actually had it right.


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[a64pilot]

Maine sail, thanks I understand now,


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[Beausoleil]

Originally Posted by a64pilot

Unless I'm wrong, and I often am, the flow of current is actually from the neg to the positive, not pos to neg like we seem to think, I believe the Brits with their positive ground cars of times past, actually had it right.


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It's long been known in the telecom world that positive ground systems have less electrolysis corrosion than negative, hence the -48V power systems in that industry.

I read somewhere long ago that it was the introduction of solid-state electronics that drove the automotive industry to negative ground systems, since PNP transistors were more expensive and handled less current than NPN transistors. I'd Google it, but I'll leave that to someone else to prove me wrong...

Oh - and this has been bugging me: it's "dual", as in two, not "duel", which still involves two, but usually leaves only one ;-)

[zboss]

I challenge you to a dual duel!

[Wotname]

Originally Posted by a64pilot

Unless I'm wrong, and I often am, the flow of current is actually from the neg to the positive, not pos to neg like we seem to think, I believe the Brits with their positive ground cars of times past, actually had it right.


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Thread drift alert

It depends!

Really depends on one's concept of current flow. The usual thought is that electrons move along the conductor and with that model, then the flow is indeed from -ve pole to +ve pole. The thought being that there is an excess of electrons sitting at the -ve pole wanting to get to the shortage of electrons found at the +ve pole and when the poles are joined by a conductor, the little bugga's tear off down the wire!

However equally valid is the concept of missing electrons in the outer orbit of the atoms of the conductor thus being a "hole" in the outer orbit and leaving the atom with a net positive charge. These "holes" thus flow from the +ve pole towards the -ve pole.

What is sure though is that a "free" electron doesn't move straight along the
wire, rather one of them moves from the outer orbit of the atom nearest the +ve pole, and a nearby electron jumps into the vacant spot of the first atom and then the next atom along gives up one of it's electron to that new vacant spot and so on. The electrons are just shuffling along the conductor and it can take some time before any particular electron finally travels the full length of the conductor.

OK, back to regular programming

[Nicholson58]

Originally Posted by RHoodJr

Sorry if this question has been over discussed before, but I wasn't able to find any in my search.

I am planning on installing two 140 w solar panels and using a Genasun GV-10 controller for each panel. Should I wire each controller directly to house bus or battery? Individually with it's own wire or combine each through a junction then use one feed to the house bus? I have seen some conflicting information about controllers fighting one another and burning themselves out.

Distance from controllers to battery bus will be 6 feet and using 6 gauge wire.

"The more I read, the more I realize how many soles are smarter then I am."

Thanks for the help.

We are about to make our solar system hot. 3 panels 220 watts each; 54 VOC. These are in parallel to the Morning Star MPPT charge controller. The output, both + & - are switched using a manual rotary switch to bank A or B. Sense wires to the controller are also switched. Outputs are direct to the battery banks with a 2-pole circuit breaker as an isolator. 2-pole breakers on each panel also can isolate the panels.

[socaldmax]

Originally Posted by Nicholson58

We are about to make our solar system hot. 3 panels 220 watts each; 54 VOC. These are in parallel to the Morning Star MPPT charge controller. The output, both + & - are switched using a manual rotary switch to bank A or B. Sense wires to the controller are also switched. Outputs are direct to the battery banks with a 2-pole circuit breaker as an isolator. 2-pole breakers on each panel also can isolate the panels.

You lost me here. First you say that outputs are switched to bank A or B. I'm assuming that is battery banks A and B.

Then you say that outputs are direct to the battery banks, but then go on to say through a 2 pole circuit breaker.

Can you clarify? Is the output of your solar controller connected to an A/B switch, a manual rotary switch (the A/B switch?) or directly to the battery banks?

The reason I'm asking is that many (all of the ones I've seen, 5 different brands) solar controllers specifically warn against removing battery power to the unit with power coming in from the solar panels. Perhaps they were being overly cautious, but it was a fairly serious warning in the owner's manual. Installing a switch in the output of the controller could allow one to remove power when it's not supposed to be removed.

[zboss]

Originally Posted by Nicholson58

We are about to make our solar system hot. 3 panels 220 watts each; 54 VOC. These are in parallel to the Morning Star MPPT charge controller. The output, both + & - are switched using a manual rotary switch to bank A or B. Sense wires to the controller are also switched. Outputs are direct to the battery banks with a 2-pole circuit breaker as an isolator. 2-pole breakers on each panel also can isolate the panels.

Not sure about yours but our genasuns have warnings about cutting off the batteries when the panels are generating power.

Why not just use an Echocharger between the banks?

[Nicholson58]

Originally Posted by socaldmax

You lost me here. First you say that outputs are switched to bank A or B. I'm assuming that is battery banks A and B.

Then you say that outputs are direct to the battery banks, but then go on to say through a 2 pole circuit breaker.

Can you clarify? Is the output of your solar controller connected to an A/B switch, a manual rotary switch (the A/B switch?) or directly to the battery banks?

The reason I'm asking is that many (all of the ones I've seen, 5 different brands) solar controllers specifically warn against removing battery power to the unit with power coming in from the solar panels. Perhaps they were being overly cautious, but it was a fairly serious warning in the owner's manual. Installing a switch in the output of the controller could allow one to remove power when it's not supposed to be removed.

Sorry, the Black Arts are hard to follow.

3 X 22 watt panels 54 VOC. Each panel has a 10 amp 2-pole CB as the first hardware in line. This provides both protection and an easy way to disconnect a panel entirely from the system. All panels have internal diodes built in to protect from partial shading of part of a panel.

Next is a combiner junction. (Big terminal block) Here, the + & - from the 3 CB's are combined in parallel from 3 X #8 to one # 4 for each leg.

The 2 #4 legs from the junction blocks are landed on the array + & - terminals of the Morningstarr 45 MPPT.

The boat battery banks are 2X 360 AH 24 VDC.

Output from the MPPT + & - goes to a 40 amp 2-pole CB. This is as on the panels, both protection & isolation.

Output from the 40 amp CB goes to the rotary switch with 8 X side by side circuits. I don't need so many circuits but will operate several in parallel to decrease losses at the switch. The switch was on hand and so, saves me $$$.

The switch now has two output + & - circuits. One set per battery bank.

The MPPT has a sense connection, 2 terminals. There is a DPDT rocker switch to select which battery is 'sensed'. 2-amp quick blow glass Buss fuses are used here per Morningstar instructions.

There is also a battery temperature sensor from the battery box to the MPPT.

I contacted Morningstar regarding the set-up. They were perfectly OK with it. They noted that since the MPPT is powered from the battery and my switch is break before make, the MPPT will reset any time the battery is switched. I think this is what I want to happen anyway.

I wrestled with adding fuses instead of CBs but the recommended wiring also called for isolation switches. CBs cost less (AMAZON) and take less space. Also, the high amp side fuses & blocks were looking expensive.

I hope this helps. Lots of different was to skin this cat. A lot depends on the hardware you have. If you are wired safely & correctly, the only thing you can really get wrong is sizing wires too small.

[socaldmax]

Originally Posted by Nicholson58

Sorry, the Black Arts are hard to follow.

3 X 22 watt panels 54 VOC. Each panel has a 10 amp 2-pole CB as the first hardware in line. This provides both protection and an easy way to disconnect a panel entirely from the system. All panels have internal diodes built in to protect from partial shading of part of a panel.

Next is a combiner junction. (Big terminal block) Here, the + & - from the 3 CB's are combined in parallel from 3 X #8 to one # 4 for each leg.

The 2 #4 legs from the junction blocks are landed on the array + & - terminals of the Morningstarr 45 MPPT.

The boat battery banks are 2X 360 AH 24 VDC.

Output from the MPPT + & - goes to a 40 amp 2-pole CB. This is as on the panels, both protection & isolation.

Output from the 40 amp CB goes to the rotary switch with 8 X side by side circuits. I don't need so many circuits but will operate several in parallel to decrease losses at the switch. The switch was on hand and so, saves me $$$.

The switch now has two output + & - circuits. One set per battery bank.

The MPPT has a sense connection, 2 terminals. There is a DPDT rocker switch to select which battery is 'sensed'. 2-amp quick blow glass Buss fuses are used here per Morningstar instructions.

There is also a battery temperature sensor from the battery box to the MPPT.

I contacted Morningstar regarding the set-up. They were perfectly OK with it. They noted that since the MPPT is powered from the battery and my switch is break before make, the MPPT will reset any time the battery is switched. I think this is what I want to happen anyway.

I wrestled with adding fuses instead of CBs but the recommended wiring also called for isolation switches. CBs cost less (AMAZON) and take less space. Also, the high amp side fuses & blocks were looking expensive.

I hope this helps. Lots of different was to skin this cat. A lot depends on the hardware you have. If you are wired safely & correctly, the only thing you can really get wrong is sizing wires too small.

Or sizing CBs too small.

Thanks for clarifying your previous post.

[ghostlymoron]

Originally Posted by zboss

Yes, they work as advertized.

The only thing I would do different (and may still do) is add a voltmeter,, ampmeter, totalizer meter with a shunt so I can keep track of overall production better.

What purpose would the additional instrumentation do apart from satisfy your curiosity? It wouldn't increase your charge. As we say round here "you don't fatten a pig by weighing it".