Breaker on my Combiner box keeps tripping all of a sudden.

[Josh M.]

Solar has been working normally for nearly a year now and all of a sudden yesterday the breaker in my combiner box has started tripping. Nothing has changed (at least that's obvious). Wire connections are all good. No frayed wires. No (obvious) damage to panels. I reset the breaker after it trips and it will stay on for a while and then trip again.

Any ideas as to why this might be happening all of a sudden?

 

[FilterGuy]

Solar has been working normally for nearly a year now and all of a sudden yesterday the breaker in my combiner box has started tripping. Nothing has changed (at least that's obvious). Wire connections are all good. No frayed wires. No (obvious) damage to panels. I reset the breaker after it trips and it will stay on for a while and then trip again.

Any ideas as to why this might be happening all of a sudden?

Is this a string breaker or an output breaker. If it is a string breaker, it means there is a short someplace on that string.

COuld you provide a diagram of the panel layout and breaker box.

 

[Josh M.]

Is this a string breaker or an output breaker. If it is a string breaker, it means there is a short someplace on that string.

COuld you provide a diagram of the panel layout and breaker box.

It's a 4-string combiner box.

 

[FilterGuy]

Is it the blue breaker that is popping?

What kind of panels are you using? What is the Isc?

How many panels on each string?

What charge controller is it hooked to?

 

[Josh M.]

Is it the blue breaker that is popping?

What kind of panels are you using? What is the Isc?

How many panels on each string?

What charge controller is it hooked to?

yes, the blue breaker.

Eco-Worthy 12v 100w panels configured 2S4P. (Set up for 24v system)
panel specs...


2 panels per string

Charge Controller is also Eco-Worthy 60a PWM

Running 4ea. 105Ahr lead acid batteries also config 2S4P.

 

[wiseacre]

Pull the breaker and check for a burn mark on the back.
I had the same problem with an Eco Worthy combiner box
Visually it all looked OK, connections seemed tight but on removal I found a burn mark on the back.
I must have been a bit careless, the negative out wasn't seated properly causing excess heat and over time (about a year) it started to fail

 

[Josh M.]

Pull the breaker and check for a burn mark on the back.
I had the same problem with an Eco Worthy combiner box
Visually it all looked OK, connections seemed tight but on removal I found a burn mark on the back.
I must have been a bit careless, the negative out wasn't seated properly causing excess heat and over time (about a year) it started to fail

Will definitely check that. Thanks!

 

[FilterGuy]

The Blue breaker is a 63A breaker. The most a 2s4p array of 100A breakers would create is 30A (Probably less)

Either there is something wrong with/around the breaker or there is reverse current coming from the controller. Assuming the string fuses are not blowing, it seems highly unlikely there is a reverse current from the controller.... So I would assume it is something with the breaker.

The Suggestion from @Josh M. of checking the connections is a good one. If you see a burn mark anywhere on the breaker, replace it. The breaker is a 250V 63A 2-pole DC breaker. There are a *lot* of breakers that meet this spec. Try and find one with a known brand name.

 

[Josh M.]

The Blue breaker is a 63A breaker. The most a 2s4p array of 100A breakers would create is 30A (Probably less)

Either there is something wrong with/around the breaker or there is reverse current coming from the controller. Assuming the string fuses are not blowing, it seems highly unlikely there is a reverse current from the controller.... So I would assume it is something with the breaker.

The Suggestion from @Josh M. of checking the connections is a good one. If you see a burn mark anywhere on the breaker, replace it. The breaker is a 250V 63A 2-pole DC breaker. There are a *lot* of breakers that meet this spec. Try and find one with a known brand name.

I really appreciate the help!

I'm not super knowledgeable when it comes to electrical and solar. I'm still learning so this may sound like a very dumb question, but should I disconnect the charge controller from the combiner box before I remove the breaker?

 

[FilterGuy]

I really appreciate the help!

I'm not super knowledgeable when it comes to electrical and solar. I'm still learning so this may sound like a very dumb question, but should I disconnect the charge controller from the combiner box before I remove the breaker?

Yes. You should also disconnect the MC4s between the panels before you do anything.

 

[Josh M.]

Yes. You should also disconnect the MC4s between the panels before you do anything.

Got it. Thanks again!

 

[wiseacre]

Instead of disconnecting the MC4s you can open up the fuse holders

Not to contradict someone with vastly more knowledge than I - but if you're unsure of what you're doing I'd disconnect the SCC to be safe
I don't believe you need to disconnect the SCC once the fuses are out
At least I didn't, - no power coming in from the panels means no power going out of the box to the SCC

 

[FilterGuy]

Instead of disconnecting the MC4s you can open up the fuse holders

Not to contradict someone with vastly more knowledge than I - but if you're unsure of what you're doing I'd disconnect the SCC to be safe
I don't believe you need to disconnect the SCC once the fuses are out
At least I didn't, - no power coming in from the panels means no power going out of the box to the SCC

Yes, opening the fuse is a good idea, but it still leaves the full potential of the array going into the box. By disconnecting the MC4s, there is no power going into the box from the PV.

Yes, there is *probably* no power back-feeding through the PWM.... but 'probably' is not good enough for me. Particularly since one possibility is that a back-feed current is one (remote) possibility for the breaker to be popping.

Someone could probably do the work by just opening the fuses and as long as they are carefull, everything would be fine. In fact, I would be tempted to do just that. After all, it sounds like it is a 24v system so how bad could it be? However, I try to fight those temptations. It is best to just not take a chance. Most of the time you will get away with it...... but eventually things will go south and suddenly it is not worth it anymore.

 

[Josh M.]

I do know enough in regard to connecting and disconnecting the equipment. I disconnected the SCC as well as the panel array from the combiner. Unfortunately, I was not able to figure out how to remove the breaker from the combiner. I could not find any screws that hold it in. Only the screws/clamps that secure the wires into the breaker. Which of course makes me feel like a total idiot. I have worked a good number of construction jobs in my life and can hold my own for the most part, but when it comes to electrical (and plumbing), I just can't seem to get a handle on it. Is the breaker supposed to just pop out or something? It kind of felt like it but I didn't want to break anything, as I gave it a pretty hard pull and it still didn't come loose.

As an update though, the breaker has not tripped again since I disconnected and reconnected the SCC and panels. I plan on continually checking it throughout the day though, just in case.

 

[Zwy]

Isn't that breaker DIN rail mounted? If so, you need to move the release.

 

[FilterGuy]

I was not able to figure out how to remove the breaker from the combiner. I could not find any screws that hold it in. Only the screws/clamps that secure the wires into the breaker.

It is a DIN rail Mount.

 

[Josh M.]

Ah! Ok, thanks again, guys!! Will check it this afternoon.

 

[Dr._Prof_ECECS]

I experienced this for the last two days and will share my thoughts based on my vast experience (my screen name says it all). I have a simple 2S2P panel config, (24V, 3KVA Eco-Worthy AIO inverter; Week ago, I went from a single series-two-12V batteries to Two such in parallel -- two 12v in parallel; two such in series for a 24V system; I have not added a balancer yet; my combiner looks exactly the same in the figure above but not from EW) that too, used panels bought as by one get free So, I have OC voltage of 80, maximum of SC current of 16A. I live in Tucson, AZ, hot (105 Max and dry) and my box is facing SE (I never thought about this; either I could have put it in another direction or taken it to inside the house). I am an ancient person too and hate to go out in the day time.
1. I suspected dirt, heat and used a portable blower to blow away whatever that I can do.
2. I kept the box open and put a temporary wood canopy to prevent the sun rays. It has been working well for the last 3 hours. Need to keep an eye on possible rain.
3. I suppose one can work in the late evening when the sun is completely gone and not worry about disconnecting MC4 and so. PITA for my age.
4. I also have to try the suggestions given here. Perhaps if I buy the replacement 63A CB first, it will tell me how it went in.

 

[Dr._Prof_ECECS]

The Blue breaker is a 63A breaker. The most a 2s4p array of 100A breakers would create is 30A (Probably less)

Either there is something wrong with/around the breaker or there is reverse current coming from the controller. Assuming the string fuses are not blowing, it seems highly unlikely there is a reverse current from the controller.... So I would assume it is something with the breaker.

The Suggestion from @Josh M. of checking the connections is a good one. If you see a burn mark anywhere on the breaker, replace it. The breaker is a 250V 63A 2-pole DC breaker. There are a *lot* of breakers that meet this spec. Try and find one with a known brand name.

I experienced this for the last two days and will share my thoughts based on my vast research experience (my screen name says it all). I have a simple 2S2P panel config, (24V, 3KVA Eco-Worthy AIO inverter; Week ago, I went from a single series-two-12V batteries to Two such in parallel -- two 12v in parallel; two such in series for a 24V system; I have not added a balancer yet; my combiner looks exactly the same in the figure above but not from EW) that too, used panels bought as by one get free So, I have OC voltage of 60V, maximum of SC current of 16A. I live in Tucson, AZ, hot (105 Max and dry) and my box is facing SE (I never thought about this; either I could have put it in another direction or taken it to inside the house or put it under the ground mounted solar panels). I am an ancient person too and hate to go out in the day time.
1. I suspected dirt, heat and used a portable blower to blow away whatever that I can do.
2. I kept the box open and put a temporary wood canopy to prevent the sun rays. It has been working well for the last 24 hours. Need to keep an eye on possible rain.
3. I suppose one can work in the late evening when the sun is completely gone and not worry about disconnecting MC4 and so. PITA for my age.
4. I also have to try the suggestions given here. Perhaps if I buy the replacement 63A CB first, it will tell me how it went in.

Since you are a solar consultant, let me ask another question. I am thinking of going for a small micro-inverter based power generation but I want it to be off-grid. I was thinking perhaps I could make the MI output synchronize to the output of a UPS AC output since all it needs is a reference AC signal. Why I want to do that? Tucson power has what is known as Peak demand power charge from 3 to 7 PM summer. Like $10 per KWH (ouch). I thought I will use a local power like this to power a room or two window AC and not use the main power during that time. Thanks.