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

Yes Jim, That's what I was shooting for, because that plays into my particular situation perfectly. I would love to gen charge in the am , followed by solar, but 4 days a week I work, so I usually gen charge in the evening. So, yes, I am concerned with getting as many 'morning boost amps' as possible into the batts.

(I may even start charging early am, when possible. It's just not something I like getting into at 4:30-5am)

jrnymn7 wrote:
Those 100's I'm looking at are rated at 47C (nominal cell temp).

And the blurb says 'point three eight percent', .38%, so wouldn't that be .0038? So, 47 x .0038 = .18 + 21.92 = 22.1v

In your case, 25 x .36 = 9v, not .9

and 25 x .0036 = .09 + 21.9 = 21.99v,

Or is the blurb wrong, and should say 3.8%, not 0.38%?

So, ~ 23.7v at 0C.

Now that I read it with my eyes open, it does say -0.36%/C

Mine gives ratings at STC not "nominal" by which they give themselves lower expectations than STC for output. I always got STC rated Isc from my 12s so that is what I expect.

Whatever controller you get, make sure it has adjustable high set point. IMO ignore temp comp except for long term storage battery Float. While camping you can play with the Vabs if especially hot or cold out.

For nothing but peak numbers, you wont see a huge difference with the panels in parallel. It will net you some in the early morn when the batteries voltage is down, so it may be worth the expense.

I've wanted to try a pair of 12v panels on the Eco-W since they upped the Voc limit. It'll be a while since I just bought the A/C to run off the panels I have now. Should have the system up and running for the weekend.

Yes, I see the solar30 would do well in the summer, but I'm trying to plan for the worse, i.e; darker months.

Those 100's I'm looking at are rated at 47C (nominal cell temp).

And the blurb says 'point three eight percent', .38%, so wouldn't that be .0038? So, 47 x .0038 = .18 + 21.92 = 22.1v

In your case, 25 x .36 = 9v, not .9

and 25 x .0036 = .09 + 21.9 = 21.99v,

Or is the blurb wrong, and should say 3.8%, not 0.38%?

So, ~ 23.7v at 0C.

jrnymn7 wrote:
That's what I thought, BFL, so going with either the 130w or 100w would be well under the controllers limit. And if I was looking to go series, I wouldn't even consider maxing out the Voc on that Eco-W mppt.

At 21.92 Voc, and a .38%/C rise; at 0C, Voc would only be 22v, correct?

My Sharp 130w panel was 21.9Voc and V coefficient of -0.36/C, so dropping 25C would make the Voc go up by 25 x 0.36 = 0.9v to 22.8v

However in the sun, panel temp goes up quite a bit, so I am not sure how the ambient temp matters so much. That's what they say in their blurbs though , to allow for ambient cold.

Eg at 16C ambient my 230w panel (at the back of it) was 44C and Voc was 34 instead of rated 36.8. At 25C panel was 51C and Voc was lower.

The solar blurbs say to expect a 10% loss in output with panel at 50C instead of 25C and that is why I was getting 13.5 amps instead of 15.5 amps more or less with the MPPT which is voltage dependent.

PWM could care less about voltage and you get Isc no matter what. That's why I like the Solar30 and a pair of 12s in the summer instead of a big 24 and MPPT (if the money works out right)

Hi, green,

I figure I need at least 200w for the colder/darker months. And I simply do not have room to store the larger panels. Even those 100's are pushing it. So I figured I'd parallel two of them and use them with an mppt to harvest the most I can out of them. $100 for a real mppt seems reasonable.

In the warmer weather, I may find I only need to use one of the 100w panels to keep the batts up.

I missed the part where jr explains why he wants to parallel them in the first place. If it's to "Max out" the power from the panels, well, once the panels start producing "enough" power you'll get over that "max" idea real quick.

Point these panels at the sun, and you'll harvest a lot more that way than trying to catch every watt that comes out of them. Er, IMO!

That's what I thought, BFL, so going with either the 130w or 100w would be well under the controllers limit. And if I was looking to go series, I wouldn't even consider maxing out the Voc on that Eco-W mppt.

At 21.92 Voc, and a .38%/C rise; at 0C, Voc would only be 22.1v, correct?

jrnymn7 wrote:
Will 0.12 Voc make that much of a difference though?

And if I parallel two 12v panels, does the Voc double?

The usual story with solar controllers is if you go over the Voc limit by even a little tiny bit it will instantly fry it. Can't say if it is really that dicey, but they also warn to allow for higher Voc in the cold so it must be sensitive.

If that second question has not been edited out by the time I post this--:) No it doubles in series. Amps double in parallel.

The Solar30 will do pretty much the same as the Eco-W with a pair of 12s. The Eco-W is really for one big 24v (to 250w)not two 12s in series with that 42-45 limit.