String size question

grunt

I have up loaded a screen shot from the outback screen sizer. I have 22 340 watt 72 cell Canadian solar panels. I plan to use the pre wired Radian system with two flexmax 80s in a batt grid tied system with genset back up . My question is how to I wire the string? I wanted to do two string of 11 but I am under the assumption that they have to be even string to wire properly as the tool show strings of 10. Any help on this would be great!

grunt

https://ironedison.com/images/products/CanadianSolar/Canadian_Solar_CS6U-M-1500V_SPEC_SHEET_Iron_Edison.pdf

Raj174

@grunt
Grid tie inverters can take long series strings and very high voltage PV. The Radian is a grid tied inverter, however, it is battery based and the batteries will be charged with FM80 charged controllers. The maximum panel string is 2 in series. If winters were much warmer then 3 would be possible. So that is 2 panels in series by 5 or 6 in parallel per controller. This may present a problem if charging flooded lead acid batteries because of the higher voltage (64V+) needed for equalization. If using AGM batteries then no problem. 

Photowhit

Schneider and Morningstar make 600 v charge controllers, but with 11 72 cell panels might push the VOC too high in cold climates.

https://www.solar-electric.com/xaxwmp80amp6.html

https://www.solar-electric.com/morningstar-ts-mppt-600v-48-solar-charge-controller.html

grunt

I do plan to use full river AGMs, Is there any thing that prevents me from just running two strings of 11 in parallel with the two flexmax 80's?

Estragon

Yes, string voltage. 150v max to a Flexmax. 11 of those panels in a series string is way too high voltage.

Estragon

I wonder if maybe we're misunderstanding the terms. "Two strings" implies series strings, so voltage adds and you end up with a string with a string voltage ~ 500v +/- temp variance. You would need a 600v controller for that, and even then you'd want to check Voc at record low temp for your location.

Photowhit

Since you have repeated this, the math works out that voltages add but the amperage remains the same when solar panels are in series. If the panels are in parallel, the voltage remains the same and the amperage adds up...

So if you want a 48 volt system(battery bank) you would need 2 panels in series to reach the proper charging voltage for an MPPT type charge controller and you might not be able to run 3 in series due to the VOC being to high in your climate, since the Flexmax is limited to 150 volts, I think it can handle a bit more without production, but please verify that if you want to try strings of 3. I think you can have 12 panels on 1 charge controller and 10 on the other if you want/have 22 panels. 12 panels will be slightly over there suggested 4000 watt max, but there will be very little loss and only in the coldest of days.

For that many strings you will need a combiner box and breakers or fuses on each string. Midnite and Outback make one that will handle 2 arrays with up to 6 strings each.