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For 3x400 W Sunpower Maxeon (400 W, Voc 75.6, Isc 6.58) solar panels in series, is MPPT 250/60 a good choice? I have three 48V Pylontech 5000 batteries.
The MPPT excel calculator says it is ok, but I am not sure if I have everything right and if I have entered all the data correctly in the excel.
At minus 19 degrees, the spreadsheet says that the MPPT 250 is no good. Should I expect such a cold panel temperature?
@Global Nomad The maths in the calculator is correct, 248v @-15c for a string of 3 panels.
If your array is subject to temperatures of -15c, your array Voc will approach 250v.
How cold will it get?? Use record low temp data.
Thank you for the answer!
In the excel you can set the temperature of the panel, but it will probably be warmer than the air temperature. The question would be, how cold would the air have to be to get the panel temperature to -19 degrees Celsius in sunny conditions? -25C? -30C?
Use the lowest recorded temperature for the area you live in from weather reports. They don't get colder than that and it is a safe assumption.
Make sure you have entered the temperature coefficient figures correctly for the panel data.
Check basic expected irradiance figures as well.
It will be installed on a motorhome and is planned to be used on several continents in varying climates.
What continents and regions? Anything above 250V would be a no-go for this setup. And If you plan on going wintercamping in Canadaor anything like Norway/Finland or Sweden -15 would be surpassed..
Considering you are using them on a motorhome (with probably less than 30years of expected use) why would you use such an expensive panel? Various other 400WP panels with similar sizes, a small bit wider... If that isn't the issue I'd go with those.
@PatrickNL@Global Nomad Some pretty good points there.
I would not expect panels to be colder than actual air temp.
A couple of things to add though.
The Vmp of the panels is high enough so that a 3 parallel array can charge 16 series LiFeP04 batteries (not LA though), even at panel temps of 75c. (Vmp of 58v) Voc of a 3 parallel array is OK for a 150v mppt..
The Isc of a 3 parallel array is 20.3a (@ 75c), might need series fuses or diodes. 20a is well within the rating or a single 6mm run of PV cable. 20a is well under the 30a limit for MC4 connectors.
Plenty of options...
