Ganging Panels of Different Wattage in Series?

[Thomas Matica]

I have 2 sets of HF panels and will soon have 2 DM 145 watt panels. I plan to get an MPPT controller. I don't know what the DM wiring is like, but the HF cable is pretty thin; 20 awg. It doesn't seem feasible to hook all of the above panels in series if the HF wiring is not adequate to carry the current.

If I use the HF wire, am I limited to running 2 parallel loops to the controller; one with the 2 HFs and one with the two DMs? In general, is it possible to series wire panels of different wattage's. The HF and DM panels combine to 380 watts, 48 volts if in series for a nominal 8 amps or less. I do understand that the heavier the wire the less the voltage drop will be.

Obviously I am not a solar wiring expert.

Comments please.

[Dale Marshall]

Thats not a problem, I do the same thing with my 2 set of HF panels with 4 125 ' I wired for 24 volt and no problem, As long as your withing 1- 2 volts of each other its all good. I had chance to look at some the DM panels a last weekend, The voltages are pretty well in sync with the HF panels.

Just make sure you Tie your DM panels together then you HF panels together Separately, Then you can tie them togther for 24 coming in. You will be fine.  Tie your panels together is Series...2 X 145 and  2 X 15 On the HF each set. Then take the combined 2 and wire them in parallel this bring up the amps not the voltage.

[Thomas Matica]

Thanks, Dale. I'll run the HFs in series and the DMs in series at 24 volts for each set. Then tie them in parallel into the controller at 24 volts.

But, as an aside, when does one step up to the higher voltages? is it not worth it for the low wattage systems?