Hi, I am designing my solar array and seeing what the options are for the MPPT trackers. This is for 3 rows of 12 panels (datasheet below) one of the solutions is to put them in groups of 4 in series and then 6 in parallel: MPPT Calculator (the other controller taking 2 strings). This could save me on cables since I could pair 2 parallel via a y connector (3 pairs vs 6 pairs). However, the MC4 connectors are rated at 30A, if I check the datasheet Isc is 14.65, thus that gets me barely below the 30A total. However, since these are the 455Wp bifacial panels, one table lower we get an Isc of 15.73A (and this might go up if conditions are even better) which would be slightly over 30A.
The question: is the 30A limit for the Isc or the Imp? With the Imp I should be below the max.
Datasheet:
ps: I optimize for december, I don’t mind the overpanneling.
I would recommend you some other type of connection like e.g. Wago 221-613. These are rated for 41A. Or screw terminals for hat rail. You have to mount this into some warterproof box, but you have definetly the better contact.
I have a 2s 4p installation with 460Wp modules, at peak I see up to almost 50A. I use screw terminals.
Yes, there are MPPT chargers with screw terminals. There you can connect easily 16mm², so you can take thicker cables anyway than going with MC4 that is limited to 6mm².
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
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FWIW, the MPPT RS 450/100 and 450/200 only come in MC4 bulkhead versions now. We remove them, install cable glands, and wire directly to the studs inside the controllers. We never order the smaller MPPTs with MC4s; just the Tr versions. Anytime you can eliminate mating connectors you also eliminate a potential failure point.
Interesting to read that a screw terminal is considered less of a failure point than the connector.
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
7
We have far more issues with mating MC4 connections than a properly installed and torqued screw terminal. Customers like to buy whatever MC4 connectors they find cheapest on Amazon and wonder why they have mating issues.
ah yes… I bought a few pre-mades as well myself, the connectors were not even tightened correctly (they basically fell off by themselves). Have my own tools for making the cables ever since.
there is MC4, invented and sold by swiss company Stäubli
As it was / is to expensive for the chinese panel manufacturers to buy these “official” plugs - they “invented” new plugs, called them NC4, JC4,… - all MC-4 Compatible
I only have Micro-Inverters, low voltage
I crimped some of these plugs myself for extensions
I wouldn´t have a good feeling knowing there are these kind of plugs on my roof, handling many hundred volts in a high current range
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
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