another mixed panels question

[cardamon]

Northern arizona wind and sun had a nice price on some modules so I just picked up a kyocera kd 135 and will add it to my 2 older kc 120's.  the 120's have a mpv of 16.9 and the 135's are 17.7.  For now they will all be paralleled to my 12v batts as I cant afford an mppt controller at the moment, but I will get one soon since 370 watts of solar is getting into the realm of the gains being worth it.  Am I correct that short of getting a mppt for each matched set which would not be worth the cost, the best way would be to track all three together in series and the loss from the different mpp's would be minimal?  What exactly will happen in this case when three current limited sources with different currents are connected in series?  I would say that when the load resistance decreases further form the point where max current is drawn from the smallest source, the voltage will start to drop to keep ohms law satisfied.  Or put simply, the higher current devices will not be able to contribute anything beyond the max current of the smallest device?  Do I have that right?

[Flux]

In a series circuit the current is dictated by the panel with lowest current.  You probably have the short circuit figures and can compare them. From the watts and volts yo give they are reasonably similar. It looks as your older panels will reach the knee of the curve before the new one but they are close.

It looks as though you will get a bit more than 3 of the 120s in series. It certainly will be near enough and the loss will most likely be less than the loss from another mppt converter if you tried to deal with the 135 on its own ( when you consider the extra converter cost then it is obvious that 3 in series on the one converter is the way to go).

Flux

[cardamon]

Thanks Flux, Ill look forward to my one mppt controller then which should give me some nice gains (I have cold winters).  Until then I have enough 6 awg to do a few parallel runs to keep the voltage drop to 5%, which would likely be lost without mppt anyway...