Alternative to Conext MPPT 80-600V Charger for (2) Distinct PV Arrays?

[Hedges]

Sounds like a perfect fit of SCC and panels. Maybe a bit over-paneled, which is good. 4800W (STC) of panels, ~3600W into battery.

-10 degrees C.
So long as that is correct for your balmy New York location.

The coldest temperatures ever recorded in New York State

The coldest temperature ever recorded in New York State was in Old Forge.

cnycentral.com

If your two strings have different orientation, that should flatten production during the day. It could reduce total Wh/day, though, especially in winter. Depends on tilt and orientation.

With significantly different orientation, might support a 3rd string (or you could do that with additional SCC, some redundancy.) Expansion thoughts for the future.

 

[Old_Skewler]

Sounds like a perfect fit of SCC and panels. Maybe a bit over-paneled, which is good. 4800W (STC) of panels, ~3600W into battery.

Yes, thanks to another members recommendation for 108 cell panels, which happened to fit better in my roof area. So far I am good with the selection and they way things are moving forward.

-10 degrees C.
So long as that is correct for your balmy New York location.

Okay, you caught that aggressive temperature assumption
Reality is, it is a seasonal cabin and in the winter we need to rely on generator for battery recharge. It has worked well and reliably.

Expansion thoughts for the future.

Right now I just want to figure out these last minute questions so that I can finally order equipment and have this basic setup installed... expansion fever will remain a distant dream for now...

 

[Hedges]

Okay, you caught that aggressive temperature assumption
Reality is, it is a seasonal cabin and in the winter we need to rely on generator for battery recharge. It has worked well and reliably.

The issue is, if sun shines on those panels when really cold, Voc goes higher than SCC can withstand and smokes it.

Then have to consider the question of whether that design of SCC passes full PV voltage through to BMS, smokes it, and over-charges battery to the point of causing a fire.

If temperature can be colder, then one fewer panel is series should be used.
That would be 5s2p. Consider 5s3p or 4s3p (when 3 parallel strings are used, should have fuse per string.)

 

[Old_Skewler]

The issue is, if sun shines on those panels when really cold, Voc goes higher than SCC can withstand and smokes it.

Very true but I've updated the Victron calculator with panel temperature coeff and readjusted the temperature to -25C and the setup still runs under 250V.

It is a risk I am taking.

 

[Hedges]

250V is 13% above nominal Voc, so makes sense the math says its OK.

 

[sunshine_eggo]

Either PV hubris, or someone has some meaty clackers...

 

[Hedges]

At -25 degrees C, my 24s AP120 would be exactly 600V, max allowed for Sunny Boy ?

(But I'm in San Jose, not Frozen New York. I know if I make a portable rig it'll need more margin for Tahoe.)