MPPT parameter double check please

[flpilgrim]

Good morning.

We will be installing part of our system in a couple weeks over thanksgiving. I bought a Schneider system and a pallet of panels from Signature on Saturday hours before their free shipping deal went out so I realize that some if this is going to seem a little backwards, but life isn't linear, so I'm ok with a few backhanded comments if necessary.

I bought more panels than necessary because we're going to add on to our system next year at tax refund season and the price was right.

We're getting a Schneider 100/600 MPPT charge controller. If I am understanding the piles of information I've read/listened through this past weekend, I can run up to about 8500 watts/550 volts on this one controller to charge a 16kw battery bank. My panels will have a low temp voc of 43 volts at 400 watts so I can run 10 panels serial connected to produce 4000 watts at 430 volts (at max low temp. the rated voc is 36.8). The charge controller has inputs for two strings.

My question is:

Can I run two of those 10 panel strings and wire each string directly to the controller or do I need to put them in parallel before I get to the controller for 8000 watts at 430 volts? Is this a question for schneider? I'm roof mounted and don't have to worry about long wire runs.

Thanks!

 

[pvgirl]

Can I run two of those 10 panel strings and wire each string directly to the controller or do I need to put them in parallel before I get to the controller for 8000 watts at 430 volts? Is this a question for schneider? I'm roof mounted and don't have to worry about long wire runs.

Thanks!

Either is acceptable, all the 2 string inputs on the MPPT do is connect them in parallel, for convince. The choice comes down to what is easiest for your install.

 

[sunshine_eggo]

My panels will have a low temp voc of 43 volts at 400 watts

What is "low temp voc"? Did you calculate the Voc of the panels based on the panel Voc temp coefficient and your record low temperature? If so, awesome.

100A MPPT is only going to output ~5600W at peak battery voltage.

As long as you stay under the Voc and PV input current limits, over-paneling is fine.

430Voc vs. 600Voc is a large safety margin if 43Voc is the STC Voc.

 

[flpilgrim]

What is "low temp voc"? Did you calculate the Voc of the panels based on the panel Voc temp coefficient and your record low temperature? If so, awesome.

100A MPPT is only going to output ~5600W at peak battery voltage.

As long as you stay under the Voc and PV input current limits, over-paneling is fine.

430Voc vs. 600Voc is a large safety margin if 43Voc is the STC Voc.

correct. labeled voc is 36.8, 43 is voc at our max low temp, although i doubt we'll ever get close to that at my latitude and roof pitch. schneider has some pretty robust electronics so i'm not too worried, just wanted to make sure im thinking straight, thanks.

 

[flpilgrim]

Either is acceptable, all the 2 string inputs on the MPPT do is connect them in parallel, for convince. The choice comes down to what is easiest for your install.

thanks, i assume you meant convenience. id much rather use their connection architecture if possible

 

[sunshine_eggo]

correct. labeled voc is 36.8, 43 is voc at our max low temp, although i doubt we'll ever get close to that at my latitude and roof pitch. schneider has some pretty robust electronics so i'm not too worried, just wanted to make sure im thinking straight, thanks.

This isn't a thing. 600V is a NEVER EXCEED under any circumstances. Fortunately, you've already factored in cold temps, so you could put up to 13 panels in series.

 

[AHTrimble]

Sounds like you have put it some serious thought to this, well done.
Have you considered a combiner box with SPD?
Could protect and control each string with its own breakers and have SPD as well.
Just a thought.

 

[740GLE]

What is "low temp voc"? Did you calculate the Voc of the panels based on the panel Voc temp coefficient and your record low temperature? If so, awesome.

100A MPPT is only going to output ~5600W at peak battery voltage.

As long as you stay under the Voc and PV input current limits, over-paneling is fine.

430Voc vs. 600Voc is a large safety margin if 43Voc is the STC Voc.

I’m sure he’s factoring some over paneling for those less than ideal days.

Although I didn’t hear him mention the short circuit current limit of the Schneider unit.

 

[Hedges]

SPD is only good for microsecond or millisecond surge. Like coupling from a nearby lightning strike. Or switching surges on AC grid side. Won't help with PV over-voltage which would just burn it up.