we have two 150/60 MPPTs side by side both connected to the same size array of panels 3S4P total Voc is 99V one is cool to touch the other is extremely hot but still working have checked all connections and are tight
asked
Very hot MPPT
Even though you said that you checked your terminals and that they are tight, I submit that it could still be I ^ 2 * R losses at the terminals.
(The Accepted Answer - that MPPT's run hot - can't be correct, because you, yourself, said that one of your MPPT's runs cool.)
Victron calls for hard to find "Unicorn" Wire to the terminals of the MPPT, a high count, very fine multi-stranded wire. As you probably know, the finer stranded wire can make better surface area contact with the terminals in the MPPT.
Unable to find Unicorn wire, I have been using more conventional thicker strand multi-stranded wire.
Even though I only see a max of 900 W Solar and a max of 30 A to the batteries (24 V), I have had heat problems in the past.
I have found that after a week of operation (heat cycles) that I was able to tighten my "tight" terminals more, which reduced the heat. So you might recheck your terminals (all four) for tightness.
In my case, I was able to buy some Unicorn wire recently and I plan to rewire, using it from MPPT connections spliced it in to my existing solar cables.
I still don't rule out that the installation has some serious mistake. We need more information that he did not provide, namely the PV power each MPPT is converting. For me, oversize PV is the likely issue, simultaenous with setup mis-conception. But as of now is just a guess.
What are you trying to achieve? Please break the array in 2x 3S2P and connect each half to each MPPT.
Then, if they are smart version, you can put them to work effectively in parallel. But even if they are not smart, you should not share the input. Only the output.
I believe that you may have misunderstood the OP description of their arrays. They stated that their two arrays are equal in a (their individual) 3s4p arrangement, "we have two 150/60 MPPTs side by side both connected to the same size array of panels 3S4P total Voc is 99V".
I suspect that there may be a cooling issue and possibly the one that is running hot is not getting enough air flow through the heatsink.
I have almost similar setup with one lot of solar on the front, the other on the back of a houseboat. In the morning I get full output from the front, 50/50 at midday & full from the rear in the afternoon. I'm guessing if one is providing the bulk of the current it would be running warmer?
Mine aren't Victron but are 150v/60A & the 60A limit is 'shared' by both.
Shade from top deck is 'solved'!
Assuming you are not connecting both MPPT's input to the same pannels, please describe better your setup:
- Power of each pannel
- Configuration of each individeual array of each individual MPPT
- Voltage and battery features both MPPTs are charging
- Any other "particularities" you did, for example if you grounded anything...and how...
They generally do just run very hot, It bothers me but both of mine get up to 50C
