Eighty amp Epever MMPT does not produce rated power under perfect conditions.

Rexe

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Apr 8, 2022
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Hi, I am not new to solar power and have been using it hassle free since 2009. I have multiple arrays that have been excellent, and under the right environmental conditions will reach their rated maximum. However, my query is related the latest MMPT controller that I have purchased; an Epever Tracer 8415AN which is rated at 80amp 150v with the ability to be powered by a 50% oversized array.
I have 25 amp wire running from the series panels, (10 amps each group in series) to the bus bar. From the Bus Bar there is a 4m run of wire to the controller, which is 79 amp cable. From the controller there is < 2m of 225 amp cable to the battery bank.

BUT :) if solar array of ten 260 watt x 38 volt panels (5x2 in series then, parallel) is producing >50 amps at 60v and the inverter is using 1.8kw,
Question 1. why does the MMPT solar charge controller not produce its maximum output of 80 amps? It produces about 54 amps after MMPT conversion. Why does the controller not try to keep up with the demand at the 1.8kw inverter?
Question 2. Why if I increase the draw to 3.8kw from the inverter, does the controller then increase output to about 73amps, bearing in mind that the array is producing 100 amps.
Hopefully I have given you sufficient info to answer the questions. Personally I think the controller is faulty, but trying to convince the seller of that is a real challenge.
 

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Bud Martin

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Hi, I am not new to solar power and have been using it hassle free since 2009. I have multiple arrays that have been excellent, and under the right environmental conditions will reach their rated maximum. However, my query is related the latest MMPT controller that I have purchased; an Epever Tracer 8415AN which is rated at 80amp 150v with the ability to be powered by a 50% oversized array.
I have 25 amp wire running from the series panels, (10 amps each group in series) to the bus bar. From the Bus Bar there is a 4m run of wire to the controller, which is 79 amp cable. From the controller there is < 2m of 225 amp cable to the battery bank.

BUT :) if solar array of ten 260 watt x 38 volt panels (5x2 in series then, parallel) is producing >50 amps at 60v and the inverter is using 1.8kw,
Question 1. why does the MMPT solar charge controller not produce its maximum output of 80 amps? It produces about 54 amps after MMPT conversion. Why does the controller not try to keep up with the demand at the 1.8kw inverter?
Question 2. Why if I increase the draw to 3.8kw from the inverter, does the controller then increase output to about 73amps, bearing in mind that the array is producing 100 amps.

Hopefully I have given you sufficient info to answer the questions. Personally I think the controller is faulty, but trying to convince the seller of that is a real challenge.
1) The loads will draw what it needs from the panels via SCC up to the maxinmum the SCC can provide, panels does not push power into the system, loads pull the power from the system.

2) Are you saying that when you increase the load on the inverter output you see the SCC output current goes up to 73A?
As the batteries get to fully charged, it will draw less current from the output of the SCC, and if you the other loads running at the same time, the power will also be drawn by the loads since the loads is basically connected in parallel with the batteries.
I.E, if the battery is full and you only have 1000W loads then only 1000W will be pulled from the system, look at a simple term, your home AC outlet in the US can provide up to 1800W of power, but you only plug in 100W lamp into the socket, the outlet is not got going to push 1800W into your 100W lamp.
 

170watt

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Apr 8, 2022
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From the array specs you can produce 2600 watts at max and ideal conditions. What is your system voltage(battery)? if it is 48volts MPPT at max power could produce 2600/48=54amps at 36 volts it could be 72, if 24 volts max output would be 108 but thats out of range for the charge controller. So the panels will output what they can based on the solar radiation, the state of the battery and the current required to drive the load in combination with the battery. In your first example load of 1800 watts the current needed would at 48volts would 37.5 amps, at 36volts the load would need 50amps and you said that was what is being produced and therefore nothing going in/out of battery. Now with the 3800watt load at 48 volts the current is 79amps that pretty close to what you are saying. At 36 volts the load current would be 105 amps, if that's the situation then perhaps 32amps are coming from the battery and 73 amps from the solar array. Anyway I don't think there is a problem with the controller but rather a result of the solar site response, state of charge on your battery bank etc, which you didn't disclose the system voltage.
 

rmaddy

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There are some issues here. The Epever Tracer 8415AN MPPT SCC has a max PV input voltage of 138V at STC. That is based on the Voc of your panels. You state that your 10 panels are in a 5S2P arrangement. Your panels have a Voc of 38.1V. In 5S that means a total Voc of 190.5V at STC. That's way over what the SCC can handle. I'm very surprised the SCC works at all since that kind of over voltage is really bad.

Perhaps you mean that your panels are in 2S5P. Then the Voc would be 76.2V at STC and that is OK.

I have 25 amp wire running from the series panels, (10 amps each group in series) to the bus bar. From the Bus Bar there is a 4m run of wire to the controller, which is 79 amp cable. From the controller there is < 2m of 225 amp cable to the battery bank.
Why are your panels connected to a bus bar? I've never heard of anyone ever using a bus bar for solar panels. If your panels are setup in 2S5P then you need a combiner box with each string properly fused.

Why 225A wire from the SCC to the battery? The SCC only puts out a max of 80A.

You should also state the actual wire size. It's unusual for someone to list wire sizes based on amperage, at least that I've seen.
 

time2roll

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What is the voltage set point of the controller during the test? What voltage is right on the controller output terminals? What is the battery terminal voltage? Need to measure all with the same meter. I suspect there may not be enough spread in voltage to trigger full output. Possibly repeat the test at a battery at low state of charge and the controller in bulk mode. Some controllers are better than others to hold peak rated amps right to the voltage set point. Does not mean it is necessarily defective.

Also... any chance the controller is derating due to internal heat or something else?
 

timselectric

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Wire capable of carrying 225a, will not fit the terminals of an 80a charge controller.
I'm guessing that this must be a typo.
Or a very robust charge controller.
 

MichaelK

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From what you describe, I'm going to guess that you you have a 24V battery, and your 2600W of panels are wired as 2S5P. That is way your series strings are ~60VDC. You stated you expected to see 100A of current from your array? How did you come up with that number? Looking at the spec sheet of your panels, they can output a MAXIMUM of 8.42A, so 5 strings in parallel would make at most 8.42A X 5 strings = 42.1A. In the real-world, that number is always derated, so if you derate to 85% the real amps is more like 36A.

The 36A at 60V goes into the controller, where it gets transformed down to ~25-26V for bulk charging. So, at best, you are likely to see (36A X 60V)/26Vcharging = 83A. That is at high noon, with perfect panel alignment. So, 73A is pretty good.

BTW, as mentioned above about the bussbar by rmaddy, that is an unusual connection scheme. Is the bussbar you refer to a combiner box, or is it just a simple strip of metal? With 5 parallel strings, for safety, each individual string needs protection from either a fuse or a breaker. A 12-15A fuse/breaker would be appropriate in this application.
 
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