APSystems QS1/YC600 Inverter - Multiple Panels On Each Channel

[kklouzal]

I have a question about the APSystems QS1 and YC600 microinverters.
QS1: https://usa.apsystems.com/wp-conten...th-America-Datasheet_-Rev3.0_2021-02-19-1.pdf
YC600: https://usa.apsystems.com/wp-content/uploads/2018/07/APsystems-Product-Datasheet-YC600-6.29.18.pdf

Both inverters show 'Operation Voltage Range 16V-55V' and 'Maximum Input Voltage 60V'.

My question is, can you attach multiple panels in series up to each channel of the inverter as long as you do not go over the operation and maximum voltage specifications?

Specifically I would like to use 2-3 Renogy RNG-100MB Eclipse panels: https://www.renogy.com/content/RNG-100MB/100MB-Datasheet.pdf
'Optimum Operating Voltage 17.7V' with 'Open Circuit Voltage 21.2V'

Three of these panels in series would make 53.1 optimum voltage and 63.6 open circuit voltage. This way I would have 3 panels attached to each channel of the inverter making 6 panels totaling 600 watts for the YC600 and 12 panels totaling 1200 watts for the QS1.

What are your thoughts?

 

[DThames]

3 in series would exceed the 60v max. Also on a cold day the 21.2v Voc could be higher, making the problem even worse.

 

[kklouzal]

2 in series would be no problem then? I realize these microinverters were intended to be 1 panel per channel but as long as voltages stay within specification then it shouldn't matter from the inverters perspective?

Mind you I am in southern Arizona (hot hot hot), and the panels are mounted at a sub-optimal angle on my roof.

I realize 3 in series and taking into account colder winter conditions pushes slightly over the maximum input voltage (5%-10%) which is why I wrote this question in the first place.
I was curious if the inverter would just clip the excess off or if it would damage the inverter. I also wasn't sure if I should be doing calculations with the Open-Circuit or Optimum voltage rating of the panels.

 

[DThames]

2 in series would be fine. If you feel like risking one of your inverters, you might do some testing. Connect 3 in series. Cover them so they are shaded and can become fairly cool. Then remove the shade and before they can warm up, check the Voc. If it is above 60v, you stand the risk of destroying the inverter if you connect it.

Keep in mind that when the sun comes up, the Voc is going to ramp up and if the inverter starts working right away, the inverter will keep the volts down. But if you have a power blink on a cool day with the sun right overhead, you will be at risk because the inverters will not come back on for 5 minutes and the Voc will be whatever it is for that long.

 

[kklouzal]

I will do some testing to check the Voc under some different extremes. Thank you very much I appreciate the information.

Final question, 'MPPT Voltage Range 22-48V' does this mean the inverter will not produce anything when a channels input voltage is above or below that range?

2 Panels in series would keep within MPPT spec for a significant portion of mid day operation but quickly undervolt in the mornings/evenings.
3 panels in series would come into range early morning and into the late evening but quickly overvolt mid-day.

I have panels mounted on the East, South, and West side of my house to ensure we're producing power for the greatest amount of time each day, not so concerned about getting the maximum wattage out of them. The MPPT spec might throw a wrench into this though..

It is to my understanding that the inverter will produce power between an input voltage range of 16V-55V (possibly all the way up to 60V?) and will just be less efficient outside of the 22V-48V MPPT range?

 

[DThames]

I will do some testing to check the Voc under some different extremes. Thank you very much I appreciate the information.

Final question, 'MPPT Voltage Range 22-48V' does this mean the inverter will not produce anything when a channels input voltage is above or below that range?

2 Panels in series would keep within MPPT spec for a significant portion of mid day operation but quickly undervolt in the mornings/evenings.
3 panels in series would come into range early morning and into the late evening but quickly overvolt mid-day.

I have panels mounted on the East, South, and West side of my house to ensure we're producing power for the greatest amount of time each day, not so concerned about getting the maximum wattage out of them. The MPPT spec might throw a wrench into this though..

It is to my understanding that the inverter will produce power between an input voltage range of 16V-55V (possibly all the way up to 60V?) and will just be less efficient outside of the 22V-48V MPPT range?

I am not sure about that MPPT range but I am guessing you are correct, that is some ideal but not fixed limit. I have panels with 51Voc and they work fine. I am guessing that with only a little load my panels volts are pulled down to the 48v upper MPPT value.

 

[kklouzal]

With the APSystems DS3 being released in a few months hopefully they have a slightly larger operating range across the board.

“The DS3, a completely new architecture”- Interview from Dr LUO, CTO & co-founder of APsystems - APsystems EMEA

APsystems co-founder and CTO, based in Cupertino, Silicon Valley, unveils the technological background of the most powerful microinverter on the market: the NEW dual DS3 (for Dual, Single-phase, 3rd generation) coming approximately September 2021. Dr. Luo, APsystems is planning to launch its 3rd...

emea.apsystems.com

For now I will use few of their current generation inverters (QS1 if 3 panels in series will work, otherwise YC600's) and report back on my findings.