check me over before I pull the trigger - SUN HE-SUN-420 & Midnight Solar Clasic 200

[Racing4funn]

I want to run four of these panels. a pair in series and the other pair in series and parallel the pairs.

thus sending a max of 170 volts at 13 amps to the clasic 200.

this is for an off grid Ham Radio room. Am I over looking anything that might cause problems?


Panel info:

Peak Power (+/
–
5%)
P
max
430 W
Cell Efficiency
η
20.5 %
Panel Efficiency
η
20.1 %
Rated Voltage
V
mpp
72.9 V
Rated Current
I
mpp
5.97 A
Open-Circuit Voltage
V
oc
85.6 V
Short-Circuit Current
I
sc
6.43 A
Maximum System Voltage
UL
600 V
Temperature Coefficients
Power (P) – 0.38%/K
Voltage (V
oc
) – 235.5 mV/K
Current (I
sc
) 3.5 mA/K
NOCT
45° C +/– 2° C
Series Fuse Rating
20 A
Grounding
Positive grounding not required

[solar_newbie]

I guess I do not know how to dodge bullets ... Let me run before you pull trigger

[inetdog]

The one thing that comes immediately to mind is that you have not taken into account the increase in Voc caused by lowering the temperature.
The temperature coefficient of voltage, ~200ma/K degree - 200ma/C degree seems a bit small for a silicon cell.
More typical values are around .4% per degree, which in the case of a 90V panel would be .36V/C.
But even with the .235ma/C figure a drop in temperature in the winter to -20C would raise the Voc by about 10 volts.
That would put the string voltage (Voc) above the operating threshold of the Classic 200.
The HyperVoc feature of the Classic would prevent any damage to the CC all the way up to about 248V with a 48V battery. So you do not have to worry about damage, but the CC may not start up as early as you would like on a cold winter morning.

Other than that, my quick glance (as I ducked for cover) did not find any other problems.

[Racing4funn]

The panel has a Open-Circuit Voltage of 85.6V

How does that work? Dosent that mean that around 85 volts the panel shorts or caps? meaning that the panel never produces over 85 volts? So if two panels were parralel then cap voltage would be 170 volts?

If it is truly an issue then I can get the clasic 250

[inetdog]

The panel has a Open-Circuit Voltage of 85.6V

How does that work? Dosent that mean that around 85 volts the panel shorts or caps? meaning that the panel never produces over 85 volts? So if two panels were parralel then cap voltage would be 170 volts?

If it is truly an issue then I can get the clasic 250

The open circuit voltage is the limit produced by the way the cells convert light to electrical energy. Sitting with outputs open will not, in general, harm a cell or a panel. The insulation can take much higher voltages than that.

And yes, the open circuit voltage of two panels would then be 170V, and adding 10V per panel for low temp would only take you to 190V, which should be fine for the Classic 200. The 250 will have a lower maximum output current, so sticking with the 200 is probably a better idea. Unless you get reallllllly cold winter temps.
I think that I rounded 85.6 up to 90 in the process of my calculations.