Any issues maxing out an Epever Tracer BN?

I’m planning on powering a 40A Tracer BN Series MPPT with a 3P string of 3 450W panels and would appreciate feedback from anyone using Epever BN Series MPPTs if maxing out the charge capacity is something to avoid.

My existing AC-coupled PV array pretty much never exceeds 75% of rated power, so I’m expecting the 3x450W string of panels to only occasionally reach the full 1000W limit of the charger.

Any reason to be concerned or should this be OK?

I found the manual: https://www.epsolarpv.com/upload/file/2103/Tracer-BN-Manual-EN-V2.0.pdf

Which states that the maximum panel rating feeding the 4215BN should be no more than 1560W when charging a 24V battery.

So I believe the 1350W array I’m planning to use should be OK, but just want to know from any users/owners/experts out there if Epever’s specifications for the BN MPPTs should be taken with a grain of salt and there are reasons to plan for rated power below these specifications.

you can over-watt a controller, but not over volt. I have a 6415an and the book says you can have 50% more wattage than rated. But, if you exceed the max voltage AND max wattage, you can damage the controller. As long as you respect these two conditions, you should be fine.

jnrhome said:

you can over-watt a controller, but not over volt. I have a 6415an and the book says you can have 50% more wattage than rated. But, if you exceed the max voltage AND max wattage, you can damage the controller. As long as you respect these two conditions, you should be fine.

Click to expand...

Yeah, I understand the importance of the voltage limit (Voc adjusted for coldest possible temps).

Epever specifies a 150% max PV array wattage, and I’m not sure what’s behind that. Obviously, the controller has to be able to push voltage well past panel Vmp to drive down current once the battery is full (ideally all the way to Voc to reduce current and power to 0W), so I’m not sure what drives the ‘max PV array’ spec but I suspect it may have something to do with maximum hours of continuous operation at peak current rating (my peak output levels typically last ~2hours bracketing midday and if I went to 150%, that peak may increase to 3 hours).

The BN Series also specifies a maximum of 50% overpanelling, so that seems to be a common design specification for Epever.

What size array do you have connected to your 6415AN and if powerful enough to max it out, what is the longest time it’s run at a full 60A continuous?

I have 2-350w panels in series, 2-190w panels in series and 4-445w panels in 2 series sets. Total wattage is 2,860, just below the 3,000w max at 48v. I still have a pair of 190w panels that i havent added yet. I also have a 50a circuit breaker on the array just before the 60a fuse in the controller. I am hitting 52 amps on occasion with this setup and the breaker holds (so far). The last two panels would put me at 3,240w which would theoretically generate more than 60a, so would top out at 60a. I haven't pushed it that far yet because I need to get the controller dialed in to the new battery first. I've been struggling with that stage so am glad that I'm just under max. That keeps that potential problem out of my equation.

Cool. Are you putting panels of the same wattage in 2-series strings or mixing panel types within a 2S string?

If you’ve got 2 190W panels in a series string in parallel with 2 450W panels on a series string, you’ll get far less output than you would putting a 450W panel in series with a 190W panel and putting multiple strings like that in parallel. You want the Vmp of each of your series strings to be as close as possible before putting them in parallel.

Aside from the input end and overpanelling, I’m interested in what charge settings you are using and the struggles you are having - is it a LiFePO4 battery?

mixing wattages in parallel. The Vmp delta of the various wattage panels are less than 4 volts so really not making any significant impact on total wattage delivered. I'm still exceeding rated output. I have detailed my ongoing configuration trials and tribulations in the "Epever 6415AN doesn't respect my settings" thread.

jnrhome said:

mixing wattages in parallel. The Vmp delta of the various wattage panels are less than 4 volts so really not making any significant impact on total wattage delivered. I'm still exceeding rated output. I have detailed my ongoing configuration trials and tribulations in the "Epever 6415AN doesn't respect my settings" thread.

Click to expand...

OK, yeah, if string Vmp is close, it’s better to keep similar panels on series strings (so currents match).

With the new panels added you’ll be at 3240W but at what string voltage?

When you state ‘the 60A fuse in the controller’ you mean a fuse you added or a fuse integrated by Epever?

I’m confused why a 60A Charge Controller would have a 60A fuse (no headroom)?

fafrd said:

The BN Series also specifies a maximum of 50% overpanelling, so that seems to be a common design specification for Epever.

Click to expand...

I am running 400W(2x200W in series ) at 45V through a Morningstar 15A MPPT controller. That is 100% over paneled. Their documentation says the controller will protect itself and limit output current to 15A no matter how many Watts are input at under 60V. I know do give up Amps when I hit the 15A limit.

In contrast, this 150% limit in Epever seems like some king of design deficiency.

48 nominal, 88Vmp, runs between 60-80v normally
integrated fuse in the controller
dunno exactly. It's been my experience that the rated amperage has the same fuse, no headroom
I think the 150% cap is a circuit protection. If you run above the rated wattage, but under the max wattage AND you run at the max voltage, you can damage the controller. I think it's best to stay under at least one of these for safety's sake. I run under the max voltage so can comfortably go over rated watts.

gelmjw said:

I am running 400W(2x200W in series ) at 45V through a Morningstar 15A MPPT controller. That is 100% over paneled. Their documentation says the controller will protect itself and limit output current to 15A no matter how many Watts are input at under 60V. I know do give up Amps when I hit the 15A limit.

In contrast, this 150% limit in Epever seems like some king of design deficiency.

Click to expand...

My 4kW array maxes out at 3kW of Microinverter capacity and I’ll usually just touch upon that limit in the middle of a bright, clear, high-production day.

So I’ve been assuming 75% of panel rating is a realistic maximum to plan for if ifon’t want to waste power by saturating the SCC.

75% of panel rating would mean I’d want 0.75kW of SCC capacity for 1kW of panel rating or alternatively, if I want a peak of 1kW of SCC output, I’d need to overpanel with 1.33kW of solar (33% overpanelling).

A few members here told me 75% of rating seems low, so I’ve dug more deeply.

First, the actual max I’ve seen out of my 4.02kW array is 3.36kW, not 3.0kW, so that is 83.6%, not 75%.

Second, my Microinverters have a conversion efficiency of 95.5%, so 3.36kW out means 3.53kW in, or 87.5% of rating.

And finally, these panels are now 5 years old, and guaranteed to have <= 3% degradation on their first year of service and <= 1% degradation per year of service after that.

So if I assume my original 4.02kW array rating has degraded by 7%, that translates to an adjusted rating of 3.7386kW and my peak output represents 94.4% of that adjusted rating.

So I’m not as hungry-ho about overpanelling my SCC as I once was.

The minimum overpanelling I want to plan for is 1/94.4% = 6% and if I think I can afford to spill the first few years of peak production, the maximum overpanelling I’d be comfortable with is 1/87.5% = 14%.

I’ve not yet had any clear explanation from a vendor what the paneling limit in their specifications actually translates to. As long as they can drive the voltage all the way to Voc, they should be able to choke off any size PV array.

They are certainly concerned about their customers not ‘wasting energy’ or ‘wasting money’ so it may be nothing more than that.

Or it could be that there is a minimum granularity on voltage control that gets too abrupt when array input power gets too large.

Or it could be that these cheapo controllers cannot run for a full 8-10 hours at their maximum current rating so they use limitations on array size to assure they will only be at peak output levels for a shorter portion of the day...

In any case, I appreciate the datapoint, though so I am less interested in overpanelling than I was when I started the thread..,

jnrhome said:

48 nominal, 88Vmp, runs between 60-80v normally
integrated fuse in the controller
dunno exactly. It's been my experience that the rated amperage has the same fuse, no headroom
I think the 150% cap is a circuit protection. If you run above the rated wattage, but under the max wattage AND you run at the max voltage, you can damage the controller. I think it's best to stay under at least one of these for safety's sake. I run under the max voltage so can comfortably go over rated watts.

Click to expand...

If that’s a 60A fuse on the input, I get it. These controllers all have a minimum Vmp which is > Vbattery.

For Epever, Vmp_min is Vbattery + 2V, so if you are charging a 16S LuFePO4 with discharged voltage of >= 52.8V (3.3V/cell), your array voltage will never be below 54.8V.

At a minimum voltage of 54.8V, the 3000W maximum power of your 60A MPPT is 54.7A, 9% below the 60A fuse.

It’s a little unclear to me what Epever (and others) mean by ‘Vbattery’ - if it is the actual voltage being read off of the battery at any point in time, it’s clear.

If that case, if you allow your battery to discharge all the way to 40V (2.5V/cell), Vmp_min = 42V and 3000W translates to 71A. You’d need maximum radiance at the same moment battery is at 0% SOC for that to happen and between the speed with which a depleted battery increases voltage once high-current charging starts, voltage drop across the cables and IR of the battery, and ~10%+ headroom on any fuse, it’s unlikely that even that extreme corner-case could cause your 60A fuse to blow.

But if you want to be extra-safe, you should limit your battery discharge voltage to no lower than 48V ( 3.0V / cell).

Well, yes, panels run at normal operating conditions(NOC) which are less that STC.
I figure with that and with no tilt, we are fortunate to get 50% of STC Wattage as input. However, there could be that unique moment we are above 10000ft(cool temps) at the equator on Jun or Dec 21stat solar Noon(direct sunlight) and we might get the STC Watts. In that case, I am safe and within specs.

Overpanelling for me is due to my piecemeal acquisition of solar stuff. Now I am trying to use what I have.

gelmjw said:

Well, yes, panels run at normal operating conditions(NOC) which are less that STC.
I figure with that and with no tilt, we are fortunate to get 50% of STC Wattage as input. However, there could be that unique moment we are above 10000ft(cool temps) at the equator on Jun or Dec 21stat solar Noon(direct sunlight) and we might get the STC Watts. In that case, I am safe and within specs.

Overpanelling for me is due to my piecemeal acquisition of solar stuff. Now I am trying to use what I have.

Click to expand...

Totally understand. The cost of ‘overpanelling’ is absolutely linked to what you can realistically expect to get out of your specific panels in your specific location day in and day out...

When I planned my A/C coupled array, the Microinverters were rated for 250W max and I originally planned to use 250W panels. As I learned more about overpanelling and realistic output levels, when I got a great deal on 335W panels, I jumped on it (34% overpanelling).

I’m glad I did because between the higher 300W peak (not continuous) rating of the Microinverters, the 4.5% conversion loss, and the annual panel rating degradation, 5 years in I am getting pretty much a full 33% more power than if I had not overpanelled.

So many lessons to learn in this field ,