epever mppt cc max current bypass

[fabieville]

The Epever Tracer series MPPT comes with various max current handling. I have one that is rated for 40A. Is it possible to increase the max 40A rating without damaging the controller by implementing additional cooling?




What i would want to know is how does the controller know that it has reach the 40A max? Is it that the controller monitors the temperature so once the heatsink or mosfets reach a certain temperature then the current limiting capability kicks in so therefore the temperature/current does not pass that level so therefore if you have additional cooling on it to keep the mosfets/heatsink cool at all times you can trick the controller to produce more current output than the rated 40amp?




Or is it that the current limiting features kicks in base upon some I.C or circuit/sensor to know when you reach 40A max so in essence there is no way to bypass that feature?




Reason for my question is due to the fact that my epever tracer is rated at 12/24v 40A 1040Watt. I have (4) 320watt panels which total is 1280watt so that surpass the max wattage by 240watt and i would like to be able to can draw close to the 1280watt which would be that i would be pulling more than max 40amp from the controller so I would like to hear your comments on this regard.

[bob-n]

Cooling is good for lifetime, but won't increase current level. It's internally limited.

They allow paralleling multiple boxes for higher power. That may be your best solution.

[Mike90250]

It senses amps internally, and it's a hard limit, set by the transistor choice. A thermal sensor also limits power to safe thermal levels too, so when the controller gets hot, current might limit below 40A, to protect itself.
When I get a cloud lens event, my 60A controller might get up to 65A before it limits back to 60A, in only a couple seconds.

[fabieville]

if i connect (3) of the 24v 320watt panels in parallel to charge my 24v battery bank will the charge controller operate in mppt mode seeing that the input voltage is not 1.5 times or 2 times my battery voltage?

The input voltage will be close to my battery voltage. I will have about 33-35volts coming in while my battery is going to be around 25 or 26V.

So with this in mind will i be able to can pull close to my 960watt total in optimum conditions?

[Mike90250]

MPPT controllers generally require 1.3x charging voltage, for the MPPT conversion to work, otherwise, they fall back to PWM mode. So your panels in parallel will pretty much insure the MPPT will be nearly useless.

But your will LOOSE power in that condition, your 320W panel at 34V is 9.4 amps, pull that down to battery voltage of 27V while charging, and you have made a 254W panel out of your 320w. Best to run your system 2S2P to get the best out of your gear. The output will limit to 40A, but running all in parallel will limit you to 37.6A under the very best conditions, where MPPT will consistently give you 40A for much longer time periods.

[fabieville]

Vmp rating is 33.3v. I am wondering if running all 3 in series with my input voltage reaching 100volts or maybe as high as 105v would surpassing the 100volt limit by just a few voltages cause the controller to be damage? if i surpass the 100volt limit by just a few volts and keep the controller as cool as possible with additonal fan cooling would it be damage with the increase voltage over the 100volt by just a few?

[bcroe]

The Vmp is only 80% of the maximum (open circuit) voltage, 3 in series will put you
far above the 100V limit. That voltage is not so much the heating of the unit, but
rather the breakdown voltage of the transistors which cooling will not help. Better
stay away from that limit, for open circuit and coldest temps. Bruce Roe

[Mike90250]

3 in series WILL fry the controller in seconds.

2series, and then parallel with the other 2 series, is the best way to use your 4 panels. this gives the controller 66V @ 18 A to work with, and will bees your best operating point.

[fabieville]

Suppose I use (2) 24v 320 watt in series along with (2) 24v 200 watt in series then parallel the 2 set of strings giving me a total of 1040watt which is the max wattage rating of the controller, would I be able to can pull the max 40amp in mppt mode giving the fact that the 320watt vmp is slightly just a few volts different from the 200 watt vmp?

[Mike90250]

The voltage will be pulled down to the lowest voltage series panels.
Somehow, I thought you had 4 panels all the same. Sorry. To mix panels ,
Series need to be the same amps - limited by the lowest amp panel.
Parallel needs to be same volts - limited to the lowest voltage panel.

Post the Vmp and Voc of each style of panel you will be using, if you want help making a 2S2P array

[fabieville]

I have 4.same panels. I also have 2 200 watt from. Previous installation.

[littleharbor]

A bit late to the discussion but thought I'd add this chart from EP showing the max overpaneling limits.

EP max panel power chart.jpg

[Mike90250]

I just replaced the bypass diodes on a friends PV panel Jbox, because he hooked the panel up backwards to a battery. Mistakes can happen.