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

Yeah, all you little straps, quit tryin to be big straps when you don't understand it all !

Heres a hint, 12v panels are for RVs and boats. 24v panels are made for houses,.....take it !

My 12v 300w system w/ a $8 controller works great. If I ever need another panel or 2, I would maybe series them up and go MPPT, but it sure isn't on my wish list.
BTW, I have a brand new 20 amp MPPT still in the box, not to speak of several PWMs, so if you think MPPT is so great, send me a $50 bill, and its yours. But tell ya right now, I only paid 12 bucks for it :)

Listen, when it comes to MPPT vs PWM, Mono vs poly vs amorphous, 12v vs 24v, etc etc etc. Don't get hung up on one thing because for every advantage, there is a disadvantage to deal with.

BLF brings up the heat issue with MPPT. As Paul Harvey use to say, this is the rest of the story.

PWM cost you watts early on in the charging process. The rated watts of a 12v panel is at a higher voltage than your battery will be early on, so you will get the watts available at that voltage, not the rated voltage. MPPT doesn't waste the power early on.

jrnymn7 wrote:
o.k. so it's a voltage issue, got it.

I did notice the similarity in the two controllers while browsing around. In fact, it crossed my mind there could be some re-branding going on? I will look closer at the various controllers and try to weed out the posers. In fact, this is why I am so curious about those buck gizmos... having switched from a converter to two psu's, I'm pretty much game to try anything!

As usual, thanks for your help.

Morninstar Inc. has a variety of controllers and a very good documentation library. Good products and good reference.

jrnymn7 wrote:
The specs for that P30L only say 'float voltage 13.8v (adjustable)'? No info on max voltage. Too low a voltage will cause wasted current not getting to the batts when they're at a higher soc.

I will have to check mine to be sure the range but I do know it goes from 13.2 to 15 I think. I kind of remember it ranging from 12.? to 15.2 but that could be one of the other settings.

o.k. so it's a voltage issue, got it.

I did notice the similarity in the two controllers while browsing around. In fact, it crossed my mind there could be some re-branding going on? I will look closer at the various controllers and try to weed out the posers. In fact, this is why I am so curious about those buck gizmos... having switched from a converter to two psu's, I'm pretty much game to try anything!

As usual, thanks for your help.

jrnymn7 wrote:
"If you start with a 12v panel and PWM, you can add more 12v panels and then choose to stay 12v in parallel with PWM or put them in series as 24 or more and go MPPT."

That's actually how I was considering it. With 12v you can always series/parallel up, but you can't go down from 24v.

But what's the deal with pwm and mppt then? There are 12v kits with mppt. Is pwm sufficient when dealing with lower amps?

You mean is it sufficient with lower voltage--yes. With higher voltage the PWMs don't have a high enough intake voltage limit on their bucks so you must go MPPT. The PWMs are buck but only from 12v panel voltage levels. The MPPTs can buck a 24v panel to 12v

You get about the same amps and daily AH haul with 230w and MPPT as you would with two 115s and PWM. In hot sun on the panel you can get more amps from the PWM than from the MPPT while in cold temps you can get more amps with the MPPT. The differences are trivial for camping purposes where your solar is always a rough and ready amount each day anyway due to changing cloud cover.

Beware of eBay $15 "MPPT" controllers. they will not run a 24v panel They are fake MPPT and are really PWM. cheapest real MPPT seems to be Eco W and other brands priced at about $100 and on up. I don't know if any of the usual suspect 12v kits have a fake MPPT controller. Most seem to have a normal sort of PWM controller.

Study the kit and look up the controller it has to read its manual and discover what it really is. Some are quite good, like that windynation one that is like the Solar30.

"If you start with a 12v panel and PWM, you can add more 12v panels and then choose to stay 12v in parallel with PWM or put them in series as 24 or more and go MPPT."

That's actually how I was considering it. With 12v you can always series/parallel up, but you can't go down from 24v.

But what's the deal with pwm and mppt then? There are 12v kits with mppt. Is pwm sufficient when dealing with lower amps?

Before looking for deals, usually you try to figure out how much solar you need. :)

BTW, there is a lot about RV solar to learn, so you can read forever or get an initial "learner set" and then go from there over the years.

If you start with a big panel and MPPT you cannot add a little more solar later but only a lot more with another big panel. 24s and 12s don't mix.

If you start with a 12v panel and PWM, you can add more 12v panels and then choose to stay 12v in parallel with PWM or put them in series as 24 or more and go MPPT.

Bosch 245w 24v mono, each has it's own Eco-w controller, there is also a 230w Schott poly 24v that's good for up to 16a with a Eco-w. We prefer to not have to run the generator. ;)

JIM :

34 amps!!!??? What kind of panels are those?