Running 24v and 12v Solar in parallel???

I'll be traveling past Markham twice, this Friday, and am considering picking up a pair of those 24v panels, on the way back.

I originally went with 12v panels, planning on a portable pwm set-up, but changed my mind, given the circumstances in which I boondock ~ 6 months a year... it's one thing to overnight at a walmart or casino, come weekends, but another to "hide" in say downtown Toronto, 4 nights a week, where there's a city wide ban on overnight parking in any plaza; including walmarts. :(

But I'm continually adding to my nightly "hiding" places... many of which are all about hiding in plain sight. :) Being stealth-like in a not-so-rv-friendly society has its challenges. In fact, I recently discovered I may have a (so-called) family member taking it upon themself to get me kicked out of parking spots that I had property-manager-level permission to park in. Nice, eh?

Anyhoo, I have just enough room for 4 panels, flat... so working out a tilt/twirl system for at least two of them is a little more challenging than it was when going with only 2 panels... but, then again, may not be needed if going from 280w to 780w, anyway. (maybe a tilt only set-up???)

Either way, as you point out, the 30a tracer would not handle the amps, on its own, so its either a bigger mppt, or a parallel system. All I need for a paralleled set-up is the 24v panels and some more cabling.

westend wrote:
For the OP's situation, it may be more economically efficient to sell the 12 V system and add a third 24V module.

Or series the 12vs and parallel to the two 24s.

Everything I've read about controllers seems to state not to mix panels with different electrical characteristics as the controller will oscillate between them trying to pick the MPP. That is for panels connected in parallel.
For a series connection, the advice may be moot as the controller sees only one voltage and current.

For the OP's situation, it may be more economically efficient to sell the 12 V system and add a third 24V module. That removes a bit of complexity. If jrnyman is using some modules as portable (trying to beat the shade), then the addition of modules makes a lot of sense.

jrnymn7 wrote:
Wouldn't the different voltage ratings have an adverse effect, in that case?

No, I don't think so. Voltages can be different in series configuration. I think of it as a series of water pumps, where each pump adds to the pressure of the water given to it.

It would be easy to verify that if you have those panels handy.

2oldman,

Wouldn't the different voltage ratings have an adverse effect, in that case?

I don't know if you've even considered it, but I'll toss this out:

I would consider running all the panels in series to one controller. Why do I think this would work? All of those panels Isc is close.. about 8 amps. Since the current is the same everywhere in series circuit, then I would have to conclude that a series setup, given these particular panels, would work.

Of course you'd need a much better controller.

Even for real time comparison purposes? IOW, would 'comparison test' results be skewed? Would I need to split the bank to get proper data?

(I know for basic charging, things would work well, but for comparing? sorry, I should have premised that)

Did it last year with my 230w and 130w with Eco-W and Solar30, both set to 14.8 worked great.

Two controllers will not be any trouble at all.

This would be the equipment used:

two 250w/24 poly panels

mppt

two 140w/12v poly panels

solar30 pwm