Originally Posted by noelex 77
... The other option to consider is multiple smaller controllers. This provides some redundancy that is valuable since MPPT controllers are not very reliable. However, this will need some rewiring, which can sometimes be very involved. If you do decide to install multiple controllers the Victron models are hard to beat if you want relatively small units.
I'm with Noelex on this. We just upgraded our array from 8x120W (36-cell so 12v nominal, wired in 4 parallel strings of 24v) panels
running through a single
Blue Sky SB50, to 3x400W (72-cell, so 24v nominal) panels each feeding its own MPPT. The SB50 (from 2001!) is handling one of the panels, while the other 2 are going through their own SRNE ML2430 MPPTs, since that's what the dealer in Davao (Philippines) had available ($140 each, including remote
This setup is sub-optimal in a few ways. The ML2430s require a special cable or Bluetooth adapter to program them, & none of the MPPTs are talking to each other, so to get net current produced by the whole array, I have to do some mental arithmetic. But it's cheap
, simple, & it performs well while giving me a bit of redundancy (the SB50 can almost handle 2 panels).
If you're trying to control 60A, you've got multiple panels. Running them in parallel means that if one gets even a little shaded, it won't be able to reach the MPPV of the other strings, so it will simply drop out of production. But if each series string of panels is feeding its own MPPT, then such a drop in voltage can still contribute meaningful current to your batteries
. And multiple small MPPTs is often cheaper than a single large one (certainly was in my case).
I started a thread about finding the "best" MPPT a while ago. It seemed that Victron had the most integrated approach, but you needed to buy multiple units & get them all talking Bluetooth together. While RF signaling minimizes wires, my (very limited) experience with bluetooth is that it's not reliable enough for prime-time yet.
But whatever you get, if you're charging
(FLA, sealed, Gel, or AGM) then you REALLY need to get an MPPT that measures current into the batteries
(usually via your amp-hour shunt). I'm appalled at how many charging
systems don't have this ability, as it's critical to knowing the state of charge of the batteries, & when to switch down to Float. Many just use timing algorithms, which are hopeless on a cloudy day. Even worse, if you leave the dock
with fully charged batteries (or you've been motoring all night) then time-based algorithms will try to over-charge your batteries for 2 hours! I killed a $3,000 bank of Sonnenscheim Gels in about an hour by accidentally over-charging them. Get a solution that knows the state of charge of the batteries by measuring the current into them.