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We have (12) 370W, 34V, 10.87A solar panels / 250 MPPT charge controller - currently in 2 parallel series of 6 panels. We have been running into a "Fault" on our panels when the winter weather gets below 10 degrees and it is super clear sunny day - when the sun hits the panels, it will "Fault"
Is this because the voltage will jump over what the system can handle because of the cold weather?
Has anyone experienced this before? Any solutions? Should it be rewired to 4 series of 3?
Thank you!
do you no full spec for your panels i.e. voc - isc vmp and imp ?
from your small spec
am I right in saying CS3L-370 panels
Voc 40.8v --- Isc 11.54 A ---- vmp 34.1V ---- imp10.86 A
currently in 2 parallel series of 6 panels. do you mean 6 panel in series x 2 strings so 12 panels in total ? if so
| PV max. voltage @ min. temperature | 274.8 V |
@pc15 Yeah, the cooler the panels are, the higher the panels voltage. At -10c your panels Voc is likely to be 10% higher than the spec sheet stc figures (stc = 25c).
It would be a good idea to rewire your array as 4 series x 3 parallel before the smoke comes out of your mppt.
Please use the Victron mppt calculator. to ensure the mppt never sees over 250v, and the array Isc is below the Isc mppt's rating.
| PV input voltage | |
| PV max. voltage @ min. temperature | 274.8 V |
| PV min. voltage @ max. temperature | 164.1 V |
your 6 panel in series x 2 parallel so 12 panels in total = PV
-----------------------------------------------------------------------------------------------------------
| PV input voltage | |
| PV max. voltage @ min. temperature | 183.2 V |
| PV min. voltage @ max. temperature | 108.3 V |
your 4 panels in series x 3 parallel 12 panels in total = PV
this is because the voltage coefficient for solar panels is always negative.
Take a look at the solar panel data sheet.
That means the voltage rise on lower temperature... always.
I always calculate Uvoc + 5% for lower temperature.
