Eco-Worthy 12v solar panels, Now drifting to... mono vs poly

RE; Series vs. Parallel,

Until now, I have only considered going parallel. So would there be any advantage, in my situation, by going in series?

So, two 100w panels thru a 20a pwm...

I'm thinking less current (say 5a in series vs. 10a in parallel) running thru the wiring from panels to controller, and therefore less voltage drop... so perhaps, overall, a little bit better? But at such low currents, either way, is there really any significant advantage? I'm thinking, no.

And I would think 50' of 10ga cable would easily handle 10 amps.

Moreover, going series would limit my choices of pwm, seeing as I would need one that can handle the higher Voc. So, again, no advantage.

Just like comparing the mppt with the pwm. On Salvo's chart, yes there was a gain of about 11% overall, but 11% of only about 6 a/h average. So with two 100w panels, perhaps a gain of about 13 Ah's over ten hours. And on a shorter (winter's) day, perhaps only 5Ah's over 5 hours.

On a small solar set-up, it all seems rather irrelevant.

PWM for 12v solar panels in parallel, up to 360W, MPPT when you need to buck voltage from 24v panels or greater, down to 12V, or you exceed about 25 amps of input on a 30 amp charge controller that is PWM 12v.

Figure out what it takes to fill your needs and how many options there are in filling them. Out of those options figure out which holds the best advantage for your situation and budget. Should you need the slight advantage of a MPPT controller or the features it has, comparing it to a PWM controller is senseless.

jrnymn7 wrote:
I worked out the average Ah's from Salvo's chart. The mppt put out an extra 6.5 Ah's in 10 hours. That's an extra 1.5% on my 430Ah bank. That makes for a staggering difference between doing a 70-84% with the pwm, and a 70-85.5% with the mppt!

Surely those extra 6.5 Ah's /day are well worth the extra hundreds of dollars for an mppt! That's gonna save me a whopping 5 minutes of generator run time AND about $0.05 in gas! :(

Yes but that only works with 12v panels. With 24v panels you have no option except to go MPPT. Nobody sells a controller that bucks 24 to 12 that is not MPPT. You can even go 48v. Apparently those inverters that go with 48v also have MPPT in them, so MPPT is not just for the solar controller.

You do have an option to say go two 12s and PWM or one 24 and MPPT. Then you juggle roof real estate, cost of panels, cost of controllers, thinner wire on the panel to controller run (same wire on the controller to battery run though because that run is 12v), ease of man-handling panels as portables, etc.

BFL,

That's why I was asking... I think maybe it's the way to go. I'm pretty sure one of you posted the link just recently.

This might be the one?

http://www.ebay.ca/itm/20A-MPPT-Solar-Panel-Battery-Regulator-Charge-Controller-12V-24V-Auto-Switch-KJ-/171112316078?pt=LH_DefaultDomain_0&hash=item27d716bcae

I worked out the average Ah's from Salvo's chart. The mppt put out an extra 6.5 Ah's in 10 hours. That's an extra 1.5% on my 430Ah bank. That makes for a staggering difference between doing a 70-84% with the pwm, and a 70-85.5% with the mppt!

Surely those extra 6.5 Ah's /day are well worth the extra hundreds of dollars for an mppt! That's gonna save me a whopping 5 minutes of generator run time AND about $0.05 in gas! :(

jrnymn7 wrote:
So, back to topic at hand:

BFL what is the RJspecial? Do you have the link? I think I saw it linked somewhere?

Thanks.

Last year a forum member, RJfishing, posted that he had bought an MPPT controller on eBay for about $15. Before checking that out more, I got one too. Only after that did we do some research and learned about the "fake MPPT" phenomenon.

So I call those "RJ Specials" in his honour. Actually it worked great as a regular 20a PWM controller so the money was well spent. :)

The RJ special is a PWM controller falsely labeled as a MPPT controller trying to take advantage of the ignorant. Very tempting after seeing all of the high dollar units that are real MPPT controllers. As far as I know the Eco-W is still the least expensive functioning MPPT controller out there.

So, back to topic at hand:

BFL what is the RJspecial? Do you have the link? I think I saw it linked somewhere?

Thanks.

Yeah, it appears I'm on a roll!

... and boatandrv's specs say the 75 pulls 10 amps, not 12.

I did notice the label says 13.8 Vabs, not 13.6.

Gonna charge with it, pre-mod, this evening or tomorrow.

And yet another spec sheet:

https://s3.amazonaws.com/ecodirect_docs/POWERMAX/PM3_Series.pdf

According to this one, you need a 20a circuit to handle 1300 watts?