Watts247 8 in/ 2 out Combiner Box: Internal Component Temps Seem Dayum Hot !!

[MrM1]

OK so I just this weekend installed a Watts247 8 in / 2 out combiner
Specs
- 15 amp fuse on each of the 8 input string
- 63 amp quad breaker on each of the 2 output groups

Doing Some Temp Testing of this box now that it is installed

Here is how the panels are connected

The panels connected are in 8 strings of 3 panels each string and go out to 2 midnite solar Classic 150s.
- String voltage is less than 90v dc
- Amps per sting is 8 amps or less
- Tested the output amps going out of each of the 63 amp quad breakers and the amps are 28-30 amps each quad breaker
- Max watts out on either of the 63 amp breakers is 2300 watts at 79 to 84 volts DC
- I have #8 THHN connected to the 63 amp breakers in the combiner going to the 2 Midnite solar classics

So nothing is over loaded according to spec

BUT ...

The temps seem off the chart to me

The breakers at the wire connection screws are 123°F to 150°F.

But at the circuit board above the fuse holders where the 8 red lights are, (at both screws that have the red wire connected to them). Both screw terminals are 202°F on the stand off that is attached to the circuit board and the top of the combiner on the outside is over 150°F just above the circuit boards



The circuit board itself is also over 150°F.

I have the plastic inside cover off the combiner and the door is open. The location of the combiner is in an attic space. The temp of other metal boxes right next to the Watts 247 8in/2out combiner are 98°F. Also, Solar wire to THHN terminal block connections in that metal box (this goes out to the Combiner) are also at 98°F . So it is not because of attic temps are wire size issues



The temps in the combiner are getting above operation temp for a typical circuit breaker and if this temp transfers to the breaker during the day it would trip the breaker.

So why are the temps so high in the box? Especially at the circuit board? Thoughts? Is this too hot?

Here is the completed install. But I am running the combiner with the door open because of these temps.

 

[MrM1]

Here are my readings into the classics at array max power right now

Classic 1



Classic 2


So definitely not over the listed spec of the Watts247 combiner

@timselectric what am I missing?

202°F in the combiner at the circuit board seems awful hot

 

[timselectric]

202°F in the combiner at the circuit board seems awful hot

That's absurdly hot.
What are the circuit boards purpose? (Diodes? )
That seems to be the heat source. The wires are probably carrying the heat to everything else.
Are the fuse holders also hot?

 

[MrM1]

Yes diodes.

Fuse holders are about 120F

Hotest spot is where that single red wire screws to the board. 202F+ the screw

There's some kind of black 1x1 black box on the back of the circuit bored too but it's glued down so I cannot see what it is

 

[timselectric]

If it were mine. I would remove the blocking diodes. They're not needed. A few of us have done testing on them.

 

[JRH]

Yes diodes.

Fuse holders are about 120F

Hotest spot is where that single red wire screws to the board. 202F+ the screw

There's some kind of black 1x1 black box on the back of the circuit bored too but it's glued down so I cannot see what it is

View attachment 154526

View attachment 154528

I have pretty much exactly what you have with a watts 24/ 7 combiner… about the same power load , the same voltage… similar ga wire …etc….. I am assuming these temps are when the system is loaded up and working…
my system is off due to lightning tonite .
I will turn it back on in the morn and check it when it’s running…
I did check it when first hooking it up about 3 months ago , and saw nothing over about ambient temp 70 F ( it’s outside) under the panels on a flat trailer in the pasture.

if I do have this issue I want to know it…it will be about 75 tommorow and I will check it at about noon and see what it reads temp wise With about 2000 watts of solar coming in…and about 2000 going out to the RV.
Will let you know what I see…

J.

 

[Quattrohead]

There's some kind of black 1x1 black box on the back of the circuit bored too but it's glued down so I cannot see what it is

Bridge rectifier.

 

[timselectric]

I'd get rid of that too.

 

[MrM1]

Bridge rectifier.

why would that be in there? Seems like that might be the source of the heat just based on location

So @timselectric you're saying pull the entire circuit board and bypass it?

my only concern is the diodes. I have 18 285w panels in 3s x 6 strings and then 6 335w panels in 3s x 2.
- I tested with and without the 2 335 3s strings.
- Same heat with or without them

But Don't I need the diodes for the watt and voltage difference of the mix-n-match panels ? some say it matters, so say it dont

 

[timselectric]

So @timselectric you're saying pull the entire circuit board and bypass it?

Yes

But Don't I need the diodes for the watt and voltage difference of the mix-n-match panels ? some say it matters, so say it dont

The diodes don't help. You will get the same output, with or without them. But you will lose the heating and extra resistance, without them.

 

[JRH]

Yes

The diodes don't help. You will get the same output, with or without them. But you will lose the heating and extra resistance, without them.

I have the same thing… why would they be in there… what purpose do they serve… hell , I didn’t even know I had them… shucks I felt good all day , now I’m nervous…?‍?

 

[MrM1]

now I’m nervous…?‍?

Me too

 

[MrM1]

I've got an email into Watts. Mine is new. This should be a warranty issue. but what good is a replacement if it's designed the same and it's a design flaw

But I also have two of these combiners out at my off grid Farm and they have been tripping output Breakers the past 6 weeks. Now I'm thinking the out put Breakers are tripping because the whole system is overheating.

 

[MrM1]

Yes

The diodes don't help. You will get the same output, with or without them. But you will lose the heating and extra resistance, without them.

But I'm wondering if I pull out the circuit boards , would I still leave the surge protection devices? I'm not sure how those would wire in. I guess we just have to study it and figure it out

 

[JRH]

Me too

I have a feeling you have somthin going on with that combiner , but I may be wrong…I have no idea… I just know I have the same thing… I will reserve judgment till in the morning…
as they say , it’s always somthin … everyday it somthing…… and then one day you die… and ya don’t have to worry anymore.

 

[JRH]

I've got an email into Watts. Mine is new. This should be a warranty issue. but what good is a replacement if it's designed the same and it's a design flaw

But I also have two of these combiners out at my off grid Farm and they have been tripping output Breakers the past 6 weeks. Now I'm thinking the out put Breakers are tripping because the whole system is overheating.

Just a thought….. are you aware that some units ( mine) were shipped with the main output line marked backwards under the out put terminals… IE , the pos is the neg and the neg is the pos… I discovered this before turnin* it on by checking with a multimeter and it kept showing reverse polarity of my wire…
I called Ian at 24/7 and asked him what’s the deal.. he said they had stamped it backwards in manufacturing and he was including a written notice with each unit.( which I never saw) so I wired it pos to to neg and neg to pos and it read correctly on the meter and has worked great ever since…
I don’t know enough about electrical theory stuff to know if this could cause excessive heat or trip breakers. I do know mine is wired backwards from the stamped in the plastic polarity indicators we normally rely on and it works great… see pic and look at main wire outputs to the SCC red to neg and black to pos .. they are backwards..im just doing what I was told by the guy who sold it to me…and it works…

 

[Hedges]

200F at the screw - check that it is tight.

Check tightness of all terminals of fuse holders & breakers to wires.
I think I see some ferrules. Especially where stranded wire is held in a screw terminal, wiggle wire in a motion that rotates it back and forth in the terminal while tightening. That helps strands to settle.

Fuses do generate heat, as do thermal breakers. Higher amperage ones would be lower resistance. Magnetic-hydraulic breakers do not have designed-in resistance. But 8A per fuse and 30A for 63A breaker means a fraction of the heat generation and temperature rise (goes as square of current).

Must be poor connections.

 

[MrM1]

Just a thought….. are you aware that some units ( mine) were shipped with the main output line marked backwards under the out put terminals… IE , the pos is the neg and the neg is the pos… I discovered this before turnin* it on by checking with a multimeter and it kept showing reverse polarity of my wire…
I called Ian at 24/7 and asked him what’s the deal.. he said they had stamped it backwards in manufacturing and he was including a written notice with each unit.( which I never saw) so I wired it pos to to neg and neg to pos and it read correctly on the meter and has worked great ever since…
I don’t know enough about electrical theory stuff to know if this could cause excessive heat or trip breakers. I do know mine is wired backwards from the stamped in the plastic polarity indicators we normally rely on and it works great… see pic and look at main wire outputs to the SCC red to neg and black to pos .. they are backwards..im just doing what I was told by the guy who sold it to me…and it works…

I saw that on the breakers but thought it had to do with them being paralleled.

That said, if backwards would that have caused an error in my charge controller?

Oh and while the breakers are that way on mine, the stickers on the case are correct

 

[MrM1]

200F at the screw - check that it is tight.

Check tightness of all terminals of fuse holders & breakers to wires.
I think I see some ferrules. Especially where stranded wire is held in a screw terminal, wiggle wire in a motion that rotates it back and forth in the terminal while tightening. That helps strands to settle.

Fuses do generate heat, as do thermal breakers. Higher amperage ones would be lower resistance. Magnetic-hydraulic breakers do not have designed-in resistance. But 8A per fuse and 30A for 63A breaker means a fraction of the heat generation and temperature rise (goes as square of current).

Must be poor connections.

If it's a poor connection I can't find it, everything is tight. No wire is loose.

But I'll check again. It would be on the "factory" side because I can disconnect (pull the fuse) of any combo of my strings and still have an issue.

 

[JRH]

I saw that on the breakers but thought it had to do with them being paralleled.

That said, if backwards would that have caused an error in my charge controller?

Oh and while the breakers are that way on mine, the stickers on the case are correct

I don’t know… the whole thing was weird to me… im just telling you what I found… had I hooked it up the normal way I may could have hurt somthing… not sure.. I have read it is not good to reverse the panels polarity or whatever…. not sure why … you would think the factory would at least check the stuff before they permanently stamp the plastic polarity markers backwards… im just throwing that out as a possibility… I dunno…