adding another panel to array, different make

lamplight

Hi everyone! I haven;t been here in ages as my system has been rjust running along great and no problems..

I have recently found a 110V "apartment" size electric dryer that I had hopes oif running on my solar but I JUST BARELY don't make enough power to run it in full sun. (which she was happy to compromise on in order to finally have a dryer in the house!). since my array is slightly undersized for my battery bank I decvided to just get another panel.

I have the sharp 175W 24V panels (NT-175U1) with these specs:
Voc: 44.4 max short circ voltage
Vmp 35.4 maximum voltage
Isc 5.4 short circuit current
Imp 4.95 maximum current

the panel I want to add is a SUNTECH STP180S 180W 24V SOLAR PANEL:
It's
Voc is 44.8v
Vmp is 36v
Isc is 5.29
Imp is 5.0

I have 6 sharps parelleled at 24v already, and the plan is to add this panel in parallel as well. it's well within the limits of my tristar mppt 60 controller.

I did some research and found that on parallel configs its considered ok to mismatch but i should get as close as possible as the current will be limited to the smaller output panel. I just want to make sure that this is the case and there;s no chance of damaging anything??

I currently have the six parallel panels into a midnight solar 6 breaker junction/combiner box, so the plan is to get a 3 breaker box and 15 amp shutoff/breaker for the panel, and wire that output after the breaker to the output (after breakers) of the MNPV6 combiner box.

All sound ok ?

thank you!!

Matt

Cariboocoot

Re: adding another panel to array, different make

Those Sharp panels are great; I have four of them. Pity they stopped making anything under 200 Watts.

The specs on the Suntech are close enough that they could be added either way without significant power loss.

Here's the issue: will your wiring take another 5 Amps of current?
You've got all six panels in parallel on an MPPT controller? You really should have some in series; up the Voltage, lower the current, reduce the power loss through the wiring. This would mean you'd have to add panels two at a time.

As it is you're pushing up to 30 Amps of current from the array to the charge controller when you only need to be running 15.

You are also under-paneled for 1100 Amp hours of 12 Volt battery, and in actuality your single 60 Amp charge controller is already maxed out at 1050 Watts of array.

In short, you need a system re-design. But that's okay; it's what we're here for.

Hey, at least I gave you the good news first right?

lamplight

Re: adding another panel to array, different make

Hi
thanks for response. I have my panels in parallel due to shading. i had done some testing and ended up with more net power... however at this point you've got me thinking i should probably up to 48v and just get 2 more panels then i wouldn't need a new combiner box, nor need to look at upgraded cabling. Im very close to my battery bank with 10AWG (i think, will have to check) wiring to the batteries, so wiring hasn't been such an issue. i have checked them for temperature gain while pulling in a lot and only slightly get warm.

according to the tristar docs i can go up to 1600 watt array at 24v. I never even approach 60 amps and am sure i won't adding another 5 at 24v.

I definitely need more panels for the battery... maybe i will get two and rewire all to 48v, glad i asked thanks!!

Cariboocoot wrote: »

Those Sharp panels are great; I have four of them. Pity they stopped making anything under 200 Watts.

The specs on the Suntech are close enough that they could be added either way without significant power loss.

Here's the issue: will your wiring take another 5 Amps of current?
You've got all six panels in parallel on an MPPT controller? You really should have some in series; up the Voltage, lower the current, reduce the power loss through the wiring. This would mean you'd have to add panels two at a time.

As it is you're pushing up to 30 Amps of current from the array to the charge controller when you only need to be running 15.

You are also under-paneled for 1100 Amp hours of 12 Volt battery, and in actuality your single 60 Amp charge controller is already maxed out at 1050 Watts of array.

In short, you need a system re-design. But that's okay; it's what we're here for.

Hey, at least I gave you the good news first right?

Cariboocoot

Re: adding another panel to array, different make

lamplight wrote: »

Hi
thanks for response. I have my panels in parallel due to shading. i had done some testing and ended up with more net power... however at this point you've got me thinking i should probably up to 48v and just get 2 more panels then i wouldn't need a new combiner box, nor need to look at upgraded cabling. Im very close to my battery bank with 10AWG (i think, will have to check) wiring to the batteries, so wiring hasn't been such an issue. i have checked them for temperature gain while pulling in a lot and only slightly get warm.

according to the tristar docs i can go up to 1600 watt array at 24v. I never even approach 60 amps and am sure i won't adding another 5 at 24v.

I definitely need more panels for the battery... maybe i will get two and rewire all to 48v, glad i asked thanks!!

Let's just be clear on this: you use a 12 Volt system, right? The specs for charge controllers are on the output side, not the input (except maximum input Voltage). "1600 Watts at 24 Volts" refers to a 24 Volt system, not 24 Volt panels. As in:
24 Volts * 60 Amps = 1440 Watts + whatever Morningstar considers to be acceptable derating = 1600 Watt array.
What you've got is something like this:
1050 Watt array @ 77% typical efficiency = 808 / 12 Volts = 67 Amps peak current potential.
Thus your controller is already at its peak output potential for a 12 Volt system. Adding another panel will actually add nothing to the maximum as the controller cannot pass the extra current.

Right now you have over 6kW hours of potential power stored in batteries that are only getting barely 5% peak charge current without loads. They are already sulphating and going bad. I understand your desire for 12 VDC for running the DC devices, but when you need/want that kind of stored power potential (and you should evaluate whether you really do) it is better to increase the system Voltage.

Look at the power demand of that 110 Volt dryer you want to run. In all likelihood between the heating element and the motor's start-up demands it will instantly shut down your 1500 Watt inverter. If not, then it certainly will be a strain on the batteries & wiring.

Frankly you've got problems at both ends of the system, and in the middle. If I were you I'd seriously consider going up to a 24 Volt system even though it means a major rework involving new inverter and more (different) batteries. If you continue on the way you are going you will be very unhappy with that choice.

BB.

Re: adding another panel to array, different make

By the way, is that a propane fired electric drier or something else? How many kWH per load are you looking at... My natural gas fired drier takes about 250 Watt*Hours per load (similar for the washer).

-Bill

lamplight

Re: adding another panel to array, different make

Oh ok that makes sense...
I just switched the array to 48V and will order TWO of those panels instead of one. and the wiring is already in place.

well theres no way i can reinvest on a new battery config and inverter, it will be cheaper (by FAR!) to add another charge controller. and i do have a spare. my inverter does run the dryer no problem, I'm running it right now: 746 Watts and 57.1 amps output to batts. i think it wants to use about 800-900 watts. the array cant quite keep up and the battery voltage is dropping.. temp is 62 deg F. the inverter has high surge capacity which helps with startup, i bought it for that reason, it can run ANYTHING in the house.

the inverter to battery NEG cable is warm but not hot, the inverter POS cable is not warm.
the controller to battery cables are both room temp.

I wonder if the tristar will run over 60 amps or if limited?

I do have a spare controller, my outback mx60.

so it sounds like 2 new panels is a definite, and a second controller is VERY LIKELY.

for adding the second controller what;'s the recommended config if they are both trying to regulate the charge current? is that a new topic ? LOL

Cariboocoot wrote: »

Let's just be clear on this: you use a 12 Volt system, right? The specs for charge controllers are on the output side, not the input (except maximum input Voltage). "1600 Watts at 24 Volts" refers to a 24 Volt system, not 24 Volt panels. As in:
24 Volts * 60 Amps = 1440 Watts + whatever Morningstar considers to be acceptable derating = 1600 Watt array.
What you've got is something like this:
1050 Watt array @ 77% typical efficiency = 808 / 12 Volts = 67 Amps peak current potential.
Thus your controller is already at its peak output potential for a 12 Volt system. Adding another panel will actually add nothing to the maximum as the controller cannot pass the extra current.

actually I've never seen 60 amps output.. I'm sure it does occasionally peak but whenever I'm testing high loads in summer when its hot, never. in winter i have tons of shade so its rare to get full output plus the tilt isn't optimized.. so there i never see much peaking either. but with the new panels I'm sure i will..

lamplight

Re: adding another panel to array, different make

I did just see it limit at 59.5 amps.. all cable temps and inverter just fine. i have 6 awg cable coming in to batts on a very short run, so its not even slightly warm, room temp. even out of the controller.


ordered two of those 180w panels and a separate Midnight solar combiner box for hooking up to the MX60.

if the panel's series fuse rating is 15amp , i can still use a 15amp fuse/disconnect if i have two in series for a 48V panel, correct?

thanks very much so glad i stopped to checkin i didn't realize i was in such bad shape!!

BB.

Re: adding another panel to array, different make

If you have a MorningStar TS MPPT family charge controller--Also look if it has Remote Battery Voltage Sense Leads... Very nice to connect (if it has them) as it pretty much negates any resistance/voltage drop issues with the Charger to Battery connection.

-Bill

Cariboocoot

Re: adding another panel to array, different make

This is where good wiring becomes vital. Yes the Tristar will limit output to 60 Amps. The MX60 can actually be programmed to 70 Amps, but I wouldn't recommend it. Running the two together is your best bet, as you really want 110 Amps peak potential, which calls for about 1700+ Watts of array.

6 AWG is going to be at its limit at 60 Amps. If you were to measure the Voltage at the controller and then again at the battery while the full current is flowing you are bound to see a difference. By adding the second array & controller you'll take some of that load off and make it easier.

Now here's the thing. You've got three separate but inter-acting circuits to look after.

The first is the array to controller. That will be based on the panel Voltage and current. If configured two in series by three then you have 48 Volts @ 15 Amps to work with, and you'll need a separate fuse on each panel string. This will need to be 7.5 to 10 Amps and capable of handling the Vmp of the strings which will be around 70. If you break this array up so there's only two strings on each charge controller (including the new panels) this is no longer an issue. You'd have 700 Watts on one and 710 on the other. Around 45 Amps output to the batteries per controller. That's about 8% peak charge rate.

The second circuit is from the charge controller(s) to the batteries. If both controllers are programmed with the same Voltage set points they will co-operate fairly well despite being different brands. With the array(s) reconfigured as above and only 45 Amps per controller the 6 AWG connections to the battery will work much better; less Voltage drop. Each controller needs its own fuse/breaker. 50 Amp minimum for the expected current.

The third circuit is from the batteries to the inverter, and is critical when you're trying to draw 746 Watts off 12 Volts (62 Amps). You want to go a bit overboard on wire size here as the draw will drop the apparent Voltage at the inverter. In my opinion this should be at least '0' gauge wire. Again circuit protection is important. Your inverter probably recommends a 200 Amp fuse/breaker.

Another really important thing is making sure the connections are good and tight. Check and retighten them periodically. It's amazing how easily resistance builds up in connections, and 12 Volt systems are very sensitive to wiring faults.

Now all you have to do is watch out for how long that dryer sucks down power. You'll only want to use it when the sun shines. Which brings us to another obvious solution called a "clothesline". They only work when the sun shines too, but they cost a lot less and consume no electricity at all.

ggunn

Re: adding another panel to array, different make

lamplight wrote: »

I did some research and found that on parallel configs its considered ok to mismatch but i should get as close as possible as the current will be limited to the smaller output panel.

That's not correct. Current is limited to that of the lowest current module in a series string. In parallel it's voltage that needs to be matched.

niel

Re: adding another panel to array, different make

matt,
it has been awhile for you. glad to know you are still around though and hope everything else is fine.

i feel under the circumstances, that you can't upgrade the inverter to accommodate a higher battery voltage, that the guys are steering you right with adding the 2nd controller to add more pv power. do watch the power draw with an electric dryer, like i actually need to tell you that.;)

why do you need this on an off grid setup? why not just add more to the gt system?

lamplight

Re: adding another panel to array, different make

Hi Bill


yes they are hooked up. thanks.

BB. wrote: »

If you have a MorningStar TS MPPT family charge controller--Also look if it has Remote Battery Voltage Sense Leads... Very nice to connect (if it has them) as it pretty much negates any resistance/voltage drop issues with the Charger to Battery connection.

-Bill

lamplight

Re: adding another panel to array, different make

tell my wife!! My wifes been very good for years with no dryer but she drops hints here and there and her mother is always giving me the guilt trip.. she is ok just running it only when the sun is out so I'm pretty happy.

Cariboocoot wrote: »

Now all you have to do is watch out for how long that dryer sucks down power. You'll only want to use it when the sun shines. Which brings us to another obvious solution called a "clothesline". They only work when the sun shines too, but they cost a lot less and consume no electricity at all.

lamplight

Re: adding another panel to array, different make

Cariboocoot wrote: »

6 AWG is going to be at its limit at 60 Amps. If you were to measure the Voltage at the controller and then again at the battery while the full current is flowing you are bound to see a difference. By adding the second array & controller you'll take some of that load off and make it easier.

I have done this with no difference but not under a large load. it's only 20' from my MNPV6 fuses/disconnects to the battery. i'll definitely check under load.

Cariboocoot wrote: »

The first is the array to controller. That will be based on the panel Voltage and current. If configured two in series by three then you have 48 Volts @ 15 Amps to work with, and you'll need a separate fuse on each panel string. This will need to be 7.5 to 10 Amps and capable of handling the Vmp of the strings which will be around 70. If you break this array up so there's only two strings on each charge controller (including the new panels) this is no longer an issue.

I'll still have a fuse/shutoff like those designed for MNPV3 and MNPV6 on each string. (10 amps). i rewired the 1050 today so that I have 3 48v strings with a 10amp fuse (the mnpv-10 on each string: http://www.solar-electric.com/mnepv.html). this surely is still a good idea?? I have a spare 15amp one I can use on the string of 180W panels which call for 15A fuse protection.

Cariboocoot wrote: »

You'd have 700 Watts on one and 710 on the other. Around 45 Amps output to the batteries per controller. That's about 8% peak charge rate.

excellent, much better..

Cariboocoot wrote: »

The second circuit is from the charge controller(s) to the batteries. If both controllers are programmed with the same Voltage set points they will co-operate fairly well despite being different brands. With the array(s) reconfigured as above and only 45 Amps per controller the 6 AWG connections to the battery will work much better; less Voltage drop. Each controller needs its own fuse/breaker. 50 Amp minimum for the expected current.

I have one large breaker, will order another I forgot about this part.

Cariboocoot wrote: »

The third circuit is from the batteries to the inverter, and is critical when you're trying to draw 746 Watts off 12 Volts (62 Amps). You want to go a bit overboard on wire size here as the draw will drop the apparent Voltage at the inverter. In my opinion this should be at least '0' gauge wire. Again circuit protection is important. Your inverter probably recommends a 200 Amp fuse/breaker.

I have the appropriate quick blow fuse on there (forget but whatever was recommended in manual). and large cables as far as possible... but the inverter inputs take these little post connectors that only allow connecting a cable about the size of 6AWG, so i had to down convert close to the plugs..used a marine shutoff switch about 6" from input of inverter that is 6AWG, the rest of the cable (about 3') is huge.. maybe 0 AWG. (Im going to take two of the posts to a local place and ask about a thicker cable being attached to it as I'll probably be pulling 800-900 watts or so).

THANKS, have some homework/shopping to do. will report.

lamplight

Re: adding another panel to array, different make

Cariboocoot wrote: »

Those Sharp panels are great; I have four of them. Pity they stopped making anything under 200 Watts.

my last sharp 175w purchased was $576 or so, this new sun tech 180w is like $230!!! both are monocrystaline. (!!!!!)

lamplight

Re: adding another panel to array, different make

niel wrote: »

matt,

why do you need this on an off grid setup? why not just add more to the gt system?

Hi Neil.. nice to hear from you and hope all is well with you too!

I know, but the grid tie system is all legality, permits and professional install fees... not so with the offgrid. plus this is what i started with so it was already in place i just expanded it gradually and it's here so...try to use it, i have AC throughout the house , the washer , lights , home office , web server stuff is just always running off it... not too hard to manage..
we had no power for a few days from that snowstorm last october for the whole city: it was very nice to still have a fridge running , some lights and thew clothes washer .

although i have to say lately the though has crossed my mind to just buy a GT inverter and stick it in the basement
but i have a new battery investment from a couple years ago so that won't be anytime soon. hopefully they are not too damaged from the low charge rate. i have really tried to baby the system as I know the charge rate was low so have tried not to discharge too much.. though i have forgotten about it a few times in winter... OOPS.

lamplight

Re: adding another panel to array, different make

BB. wrote: »

By the way, is that a propane fired electric drier or something else? How many kWH per load are you looking at... My natural gas fired drier takes about 250 Watt*Hours per load (similar for the washer).

-Bill

Hi Bill.

Don't know offhand.. I knew this would not be anything I'd run from my battery bank storage, only in sunlight.. I have a battery meter will post the specs later.. It IS electric.. Something like 900 watts I'm guessing.. Maybe 4 hours to dry. And it's small so only about 3/4 a normal load... BUT it's 120v not 240 and runs fine on the inverter.

Cariboocoot

Re: adding another panel to array, different make

I'd be concerned about how long it runs, even with "getting all the power from the panels". There's only so many hours of daylight available, and if you need half of that to recharge from ... you may run out of sun before the laundry's done!

lamplight

Re: adding another panel to array, different make

Cariboocoot wrote: »

The second circuit is from the charge controller(s) to the batteries. If both controllers are programmed with the same Voltage set points they will co-operate fairly well

Hi

My existing fuse/disconnect here is a heavy duty square d disconnect with a 60amp bussman barrel type fuse. There is a second unused at present slot for another such fuse and inputs. I am going to use this same shutoff with another 60 amp fuse between the 2nd controller and battery bank. This should be completely acceptable and safe right?

Between array and controller:
My current config also has another large circuit breaker between the small mnpv 10 amp fuses between array and charge controller... Is this necessary if I have the appropriate 10 and 15 amp disconnect breakers (mnpv3) between each string and the controller?

Thank you!

Cariboocoot

Re: adding another panel to array, different make

lamplight wrote: »

Hi

My existing fuse/disconnect here is a heavy duty square d disconnect with a 60amp bussman barrel type fuse. There is a second unused at present slot for another such fuse and inputs. I am going to use this same shutoff with another 60 amp fuse between the 2nd controller and battery bank. This should be completely acceptable and safe right?

Yes, it would work. The maximum output of the controllers being 60 Amp and your output potential being 45 I'd pick a 50 Amp but that's me. NEC would want 80 in there I think. They also think controllers should be derated in capacity, which is in my opinion unjustified.

Between array and controller:
My current config also has another large circuit breaker between the small mnpv 10 amp fuses between array and charge controller... Is this necessary if I have the appropriate 10 and 15 amp disconnect breakers (mnpv3) between each string and the controller?

Thank you!

Yes it is.
The individual panel string fuses protect against one string developing a short and being overloaded by the remaining panels. This is a "what if" scenario where a failure causes an additional circuit to develop with the good panels supplying current and a shorted one becoming a "load": the shorted panel can catch fire from being fed 3X (or more) current than its Isc rating.
The circuit protection between the total array and charge controller is to guard against shorts in that circuit, and needs to be able to handle the full output of the array. The individual string fuses will only react based on the amount of current each string produces, which cannot exceed Isc. But with all the panels together the current flowing through the input of the controller could reach full array Isc in the event of a short.

I know the NEC formula applies to this as well, but it's another thing I personally disagree with since the panel output cannot exceed Isc therefore neither can the current even in the event of a short. So if you have three strings with an Isc of 5.4 Amps each that's 16.2 Amps total current possible. NEC regs would have a 30 Amp fuse in there, which could never blow. I would use a 15 Amp which would allow Imp but not Isc. Just one of the things I disagree with them on.

lamplight

Re: adding another panel to array, different make

Cariboocoot wrote: »

The circuit protection between the total array and charge controller is to guard against shorts in that circuit, and needs to be able to handle the full output of the array. The individual string fuses will only react based on the amount of current each string produces, which cannot exceed Isc. But with all the panels together the current flowing through the input of the controller could reach full array Isc in the event of a short.

I know the NEC formula applies to this as well, but it's another thing I personally disagree with since the panel output cannot exceed Isc therefore neither can the current even in the event of a short. So if you have three strings with an Isc of 5.4 Amps each that's 16.2 Amps total current possible. NEC regs would have a 30 Amp fuse in there, which could never blow. I would use a 15 Amp which would allow Imp but not Isc. Just one of the things I disagree with them on.

awesome...i have a spare square D heavy duty shutoff with a 30 amp barrel fuse that i could use, i'll replace with 15A. between the second controller and MNPV3/array.

on the existing I have a 30 amp breaker.. installer sold me that probably knowing about code.

thanks again!

Vic

Re: adding another panel to array, different make

The only additional commen that I'd offer is, that it can be an interesting puzzle to come up setpoints that allow each CC to exit Asorb in a graceful manner. It is not a huge deal much of the time, but at times the first to exit Asorb can leave the remaining CC with insufficient current to maintain Asorb V. The lagging CC can get stuck grinding on the batts, doing some charging, but unable to complete Asorb. This could result in a bit of an overcharge on batts. The OP's bank is, thankfully the very rare single string LARGE 12 V bank. These batts are very tolerant (IMHO).

Am not trying to argue against using 2 CCs -- this seems to be the correct approach. Even with identical CCs, unless they are networked and know how to play together, the exit from even a timed Asorb can be a bit of an issue, at least under some conditions.

End of nit-picking. Vic

Cariboocoot

Re: adding another panel to array, different make

Good point, Vic.

In this instance I'd pick the Morningstar as "primary" charge controller and make sure the settings are such that it would exit Absorb first. The second controller being an MX60 is easily reprogrammed to accommodate the other's needs (set to end by time or Amps).

lamplight

Re: adding another panel to array, different make

Thanks. I have them set to end by amps. Mx60 will need a reprogram for these batteries but that's how I had it set and how the tristar is set. Any Suggestions for settings and how one might differ from the other to ensure one over the other has final control? I knewe I would get to this question myself I'm still too busy getting everything else ready ..

lamplight

Re: adding another panel to array, different make

Never mind I missed it.. So you recommend setting the amp setting to end absorb before the mx60's

Cariboocoot

Re: adding another panel to array, different make

Set up the Morningstar to function as best suits your needs, then adjust the MX60 to work with it.

I would not use Absorb End Amps as that will be wrong when loads are drawing. Absorb Time = Bulk Time usually works best, but I'm not familiar enough with MS equipment to tell you how to set it. But I'm sure someone around here does!

lamplight

Re: adding another panel to array, different make

hi
I'm going to teach the wife not to start a laundry dry load unless it says float so I will still use end amps. I'll report back as I get this setup.. panels delivered tomorrow

lamplight

Re: adding another panel to array, different make

well after 12 hours straight yesterday i have everything installed.. didnt finish till dark. anxious to see how the controllers play together today.

re: 12v battery shutuff/fuse between controllers and batts:

Cariboocoot wrote: »

Yes, it would work. The maximum output of the controllers being 60 Amp and your output potential being 45 I'd pick a 50 Amp but that's me. NEC would want 80 in there I think. They also think controllers should be derated in capacity, which is in my opinion unjustified.

i ordered a 60A fuse as thats what was in there already.. the NEG terminals are all on a bussbar or whatever in this shutoff box (2 controller NEG inputs and output to batt all connected), and I found that the input POS arent connected..this makes sense i guess but hadnt planned on it. i tried jumpering the two but couldn't get cables in the openings, so what i ended up doing was running a second POS output to the battery bank so that each controller has its own POS battery line through its own 60A fuse and shutoff to batts. the single throw lever disconnects both.. question is this: should i run a second NEG to the batteries as well (from the fuse/shutoff)??

re: fuse between mnpv compiners and controllers:

Cariboocoot wrote: »

I know the NEC formula applies to this as well, but it's another thing I personally disagree with since the panel output cannot exceed Isc therefore neither can the current even in the event of a short. So if you have three strings with an Isc of 5.4 Amps each that's 16.2 Amps total current possible. NEC regs would have a 30 Amp fuse in there, which could never blow. I would use a 15 Amp which would allow Imp but not Isc. Just one of the things I disagree with them on.

this makes total sense to me. well i have a 30A barrel fuse installed as that's what i had. your description here makes a lot of sense ill probably get a smaller one at some point..

Cariboo: im refamiliarizing myself with the mx-60: as long as i have end amps set to 00 (what manual says to do to disable this feature) will the absorb last as long as the bulk lasted? its not really clear to me from the manual where and how to set a timed absorb or if even possible on my-60. if so thats what i think i want. i was going to set the tristar to end absorb after an hour and hoped to let the mx-60 take over for the final stage (and then i have no idea what the tristar will do??) . i have no idea how this is going to work with 2 controllers... plan to watch it today..

Cariboocoot

Re: adding another panel to array, different make

lamplight wrote: »

i ordered a 60A fuse as thats what was in there already.. the NEG terminals are all on a bussbar or whatever in this shutoff box (2 controller NEG inputs and output to batt all connected), and I found that the input POS arent connected..this makes sense i guess but hadnt planned on it. i tried jumpering the two but couldn't get cables in the openings, so what i ended up doing was running a second POS output to the battery bank so that each controller has its own POS battery line through its own 60A fuse and shutoff to batts. the single throw lever disconnects both.. question is this: should i run a second NEG to the batteries as well (from the fuse/shutoff)??

Each controller should have its own lines and circuit protection to the battery. The only time you can use one negative common to both controllers is if you can fit wire large enough to handle the combined current of both controllers. Usually you're looking at wire that's too big to fit the terminals then.

Cariboo: im refamiliarizing myself with the mx-60: as long as i have end amps set to 00 (what manual says to do to disable this feature) will the absorb last as long as the bulk lasted? its not really clear to me from the manual where and how to set a timed absorb or if even possible on my-60. if so thats what i think i want. i was going to set the tristar to end absorb after an hour and hoped to let the mx-60 take over for the final stage (and then i have no idea what the tristar will do??) . i have no idea how this is going to work with 2 controllers... plan to watch it today..

Right. With End Amps at zero the Absorb time is controlled by the minimum time set, the length of Bulk, then the maximum time set. So it will run for at least the minimum and up to either the length of Bulk time or the maximum Absorb time depending on which comes first. These settings are under the Advanced menu on the controller.

Try to set the two controllers to function identically, then fine-tune the MX60 to allow the Tristar to work properly. It's easier to adjust the Outback than the Morningstar. They won't work together perfectly, but they will work together.

lamplight

Re: adding another panel to array, different make

ok thanks.. ill run another negative.. i have a cable for it.. I will have to figure out how to manually set the time then on mx60..I don't think I messed wi max time or minimum time..I thought that the mx60 would take over.. oh i know i have the tristar set to do extra absorb time if battery coltage was 12.5... thats probably it.. i will have to experiment read some more... I was finishing up some aluminum bracing for my mount when the sun came out and by the time I checked it the mx60 says absorb and isn't sending any current through..the Tristan is handling it.. I wonder if it would pull current if I turned some loads on and exceeded output of the Tristars array...

after thesis done I plan to do a nice long eq.. I wonder if I'll have to start that on both controllers..

too bad no consistent sun today and I have to leave later this is so fun maybe tomorrow...

I really appreciate all the help, I tell people about this forum all the time when they start asking me about solar. I just hope the batts arent too far gone it was a very large investment.

lamplight

Re: adding another panel to array, different make

Hi

having issues with the two charge controllers... ill start another thread later so that people can find it easier..