50a breaker tripping

[Greenmachine 1973]

Hello,
First time posting. I followed your plan for a 24v 4000 watt system. I am using the 40a mppt charge controller. Everything has been running great. I recently purchased 10 265watt panels off Ebay to upgrade my system array. I started by hooking up 6 of the solar panels 3 in series and then tying in the 2 strings in parallel for a total of 1590 watts. The problem I am having is the controller is now tripping the 50a breaker to the battery. Any insight into what can be causing this would be helpful.

Thanks,
Greenmachine

 

[Craig]

Im thinking t does not like the extra power your panels are putting out you are getting about 60 Amps worth.

I t should be ok but with those Epevers I would be leary

 

[jasonhc73]

Ok,

Step 1.

Picture of the label on the back of the panel.

And go:

 

[Greenmachine 1973]

 

[Craig]

whats max input voltage of epever?

 

[Greenmachine 1973]

I reduced the array to 4 panels and seems to be holding fine. My guess is the epever tracer 40a controller can't handle 1590 watts

 

[Greenmachine 1973]

whats max input voltage of epever?

150v 40a

 

[jasonhc73]

You can probably still do 6 panels, just keep it at 2S. It sounds like you were actually overvolting, not over amping.

2S
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 8.20
Current at Pmax (A) 7.5
529.95 watts max at STC

With 2 strings:
2S2P
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 16.40
Current at Pmax (A) 15.0
1059.9 watts max at STC

With 3 strings:
2S3P
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 24.6
Current at Pmax (A) 21.5
1519.19 watts max at STC

Bear in mind that as the temperature goes down the Voltage of the PV panels can go much higher than the sticker shown. The sticker is only for STC - 25°C 1.5ATM 1000 w/m²

 

[Greenmachine 1973]

You can probably still do 6 panels, just keep it at 2S. It sounds like you were actually overvolting, not over amping.

2S
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 8.20
Current at Pmax (A) 7.5
529.95 watts max at STC

With 2 strings:
2S2P
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 16.40
Current at Pmax (A) 15.0
1059.9 watts max at STC

With 3 strings:
2S3P
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 24.6
Current at Pmax (A) 21.5
1519.19 watts max at STC

Bear in mind that as the temperature goes down the Voltage of the PV panels can go much higher than the sticker shown. The sticker is only for STC - 25°C 1.5ATM 1000 w/m²

Over voltage at 132 watts on a 150v 40a charge controller? I get what you're saying and I will give it a shot and see if that helps. I will need to buy more connections for 3 strings.

 

[jasonhc73]

You don't need anything more complicated than a branch connector or a combiner box.

 

[erik.calco]

50a x 24V = 1200 watts.

 

[Greenmachine 1973]

You can probably still do 6 panels, just keep it at 2S. It sounds like you were actually overvolting, not over amping.

2S
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 8.20
Current at Pmax (A) 7.5
529.95 watts max at STC

With 2 strings:
2S2P
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 16.40
Current at Pmax (A) 15.0
1059.9 watts max at STC

With 3 strings:
2S3P
Open-Cirgcuit Voltage (VOC) 88.4
Voltage at Pmax 70.66
Short-Circuit current (VMP) 24.6
Current at Pmax (A) 21.5
1519.19 watts max at STC

Bear in mind that as the temperature goes down the Voltage of the PV panels can go much higher than the sticker shown. The sticker is only for STC - 25°C 1.5ATM 1000 w/m²

I tried 3 two panel strings this morning. After a couple hours and the sun was higher the breaker tripped again. I may need to clarify that the 50a breaker is between the battery and charge controller. Here are a couple photos. This was the current volts and amps a few seconds before it tripped.

 

[Craig]

Probably a bad breaker. Those are known to not meet spec. If you have a clamp meter you could test current flow.

 

[Greenmachine 1973]

Probably a bad breaker. Those are known to not meet spec. If you have a clamp meter you could test current flow.

Is it a good idea to bypass it until I get a new one?

 

[erik.calco]

50A seems pretty low to me. Mine is 150A and that is less than the 170A I wanted. But, obviously, there are many reasons why yours could need to be lower than mine, number one being cable size and length.

Is there any heat in the wires, connections or your batteries right before your breaker trips? The primary purpose of the breaker is to protect the wires. What kind of batteries do you have? What is their charging limit? What gauge and length of wires do you have? If you are considering replacing the breaker, not a bad idea to recalculate specs and look for low lying fruit to upgrade, such as possibly heavier gauge wires if that's all you need for a higher amp breaker.

Also, very worthwhile to invest in a quality breaker.

 

[Greenmachine 1973]

50A seems pretty low to me. Mine is 150A and that is less than the 170A I wanted. But, obviously, there are many reasons why yours could need to be lower than mine, number one being cable size and length.

Is there any heat in the wires, connections or your batteries right before your breaker trips? The primary purpose of the breaker is to protect the wires. What kind of batteries do you have? What is their charging limit? What gauge and length of wires do you have? If you are considering replacing the breaker, not a bad idea to recalculate specs and look for low lying fruit to upgrade, such as possibly heavier gauge wires if that's all you need for a higher amp breaker.

Also, very worthwhile to invest in a quality breaker.

My battery is a 24v forklift battery. After the breaker tripped I felt the wires with my hands and they did not feel hot. I believe the wires going from the controller to the battery is 4 gauge, the one specifically from the controller to the breaker may have come with an old inverter. I was thinking it was a bad breaker from the beginning, due to the fact that it tripped between 35 and 40 amps.

Everything I have researched about forklift batteries when charging is that they need more than 50a dc to charge it fully. My inverter charges at 90a dc. Maybe this is a factor and the breaker is to small like you said.

 

[jasonhc73]

Is it a good idea to bypass it until I get a new one?

Just make sure there are no brakes in the wire to short out against anything.

Your panels are only making 24 amps at most, so it would seem that the breaker is faulting.

But if there really is a short circuit, it might really be working properly.

Move the breaker to the + wire on the panel side. See what happens.

 

[tictag]

Just want to clarify something here ... you have an Epever MPPT SCC rated for 150V | 50A (Max PV Voltage | Max Charging Current) and by the look of it from your image, you have model Tracer4215BN.

If correct, this product has a Maximum PV Voltage of 138V (at 25℃) with a Maximum PV Power limit of 1,040W into a 24V(nominal) battery system according to your product's datasheet.



So some considerations:

• Your SCC is not capable of supporting your new array (max: 1,040W at 24V(nominal))
• Your SCC can support 3 x 265W panels = 795W, or if you wanted to push the boundaries, 4 x 265V panels = 1,060W (note: this exceeds your SCC specs and would likely void any warranty).
• With a Voc = 44.20V you can connect up to three panels in series before you breach the 138V Maximum PV Voltage, but, as your current SCC only supports 3 x 265W panels anyway, you will be restricted to connecting them all in parallel (or 2S2P if you choose to push the boundaries).
• In order to make use of your new 2,650W array you're going to need to upgrade your SCC. I might recommend the Victron 250|100, which supports up to 2,900W into a 24V(nominal) battery system and up to 250V array Voc, meaning you can connect your full array up as 5S2P, which would produce 176.7V and 15A at Pmax = 2,650W*
• Pushing 2,650W into a 24V(nominal) battery system will produce around 110A (ignoring losses) - your battery-side system will need to spec'd for this e.g. breakers, cable size, battery maximum charge current etc.

Please stop trying to make your new array 'fit' your existing system components ... it won't.


*note: if there is any chance of partial shading across your series strings, consider lowering the series-connected count.