jr, for maximum value start with a cheap PWM controller and nominal 12V (~18V) panels. Make them somehow portable, even if only to lean against your RV. Run these for a year and then figure out what the ideal system would be, and spend your big money and drill holes for that.
I wish I'd done this, I'd be $1500 richer right now. My Kyocera 315 panels and my FlexMax 80 are nothing but museum pieces, while my Renogy portables and cheap PWM actually get the job done. If I buy enough Renogy panels to bump the voltage, maybe I can get some use out of the Flexmax. But until then I've basically pineconed myself.
--"Cost per amp" of panel at 12v PWM. Now SUBTRACT the cost savings of PWM vs MPPT.
--"Amps per square foot" of panel at 12v PWM. These are "actual amps" vs "potential amp gains" of MPPT, subject to heat loss, light clouds, etc etc etc.
Dont spend $500 additional on an MPPT (it really IS MPPT) controller than cannot possibly harvest an extra $500 worth of power over its service life.
I'm happy I started with a 100w portable setup. People say there are too many compromises with portables. So yes, they require handling, and maybe a locking cable depending on where you are. But on the plus side, you can often park in the shade while putting the panel in the sun, harvest a lot of watts, with minimal installation hassles, and cheaply. All of those good features are compromised on roof mount panels. :) :) :)
Someone who travels around a lot should have roof panels, no doubt. But the typical person who camps someplace for a week or so, with two batteries, LED lights, and commonsense use of energy, can get a lot or maybe all of his needs from 100 to 200 watts on the ground.
Now I'm going to add roof panels as the next step. But since I like shade, I expect to have to supplement with the portables when we camp in the summer.
Don Pianotuna once reported that in leafy shade, his Unisolar panels generate 41% of normal. For those on sale now, 41% equals 56 watts for 3348 sq. inches, or 0.017w/sq in. Based on anecdotes I've seen here about crystalline panels in leafy shade, and doing the same math, I'm guessing those generate ~0.01w/sq in.
This is purely a wild guess. Hopefully I'll have some hard data at some point. So very very roughly, the Unisolar might be somewhere around twice as productive in shade per square inch or cm.
Using their $200 250w/24v crystalline panel for comparison, the Unisolar only produces 40% of the watts of the crystalline per square inch or centimeter. We know the Unisolar outperforms in cloudy or shady conditions. But to what extent per square inch? I'd love to see data on that.
Begs the question: Is the reason for the switch:
A) to disconnect the house in order to not run down the batteries, or
B) to disconnect the batteries for safety or some other reason, while connected to shore power.
For me, the benefit comes from A. I haven't run into B yet.
Thanks, it's good to see the different rationales for each way. The way I'm leaning is to put it on the battery side. That way if I plug into shore power I'm sure to get a battery charge. And if nothing works in the house, I'll realize the switch is OFF. OTOH if I connect it to the house side instead, I could plug into shore power but forget to turn the battery switch. My house circuits would work but my batts would not charge.
So, the downside of putting it on the battery side is that I could not completely isolate the batteries. I'd have to switch off the converter to accomplish that. I'm trying to think of what happens to make that become an issue.
I'm trying to make it idiot-resistant. :)
But I have to imagine which consequences of idiocy would be more likely, and which ones worse.
Simple question; hard to pin down in search mode.
For a standalone deck mount converter, would you wire the + output to the battery side of the battery cutoff switch, or to the load/house side? Those are the only two choices! :)
Here's an offer I got accepted last night on ebay. $65 asking price, $58.00 best offer, accepted, for this Morningstar 25A SunSaver Duo PWM controller with remote temp capability. Needs an optional temp wire to do that.
Says it is for 2 battery banks, but it will work normally with just 1. I confirmed that with MS.
Free shipping to USA. I think it's a very good deal.
Solar Blvd: MS Sunsaver Duo on ebay
Renogy has a better price on Amazon than on Ebay. They do offer a poly panel, too.
I just looked, and that is not the case now. Ebay is about $20 cheaper for their 100w panel.
Don, you've been a big fan of poly over mono too, I see in the archives. What have you read or seen?
mdelleman, if you buy that panel, please post what offer price you were able to get accepted. That panel is in my short list for buying, mostly because of the 21" width, which helps me a lot.
Jim, I'm wondering if your mono-poly results simply reflect one bad mono panel?
When I search here, the only Ecoworthy results I get are for their controllers. Does anyone have any experience with their 12v panels?I have never read a problem with any panels ever having issues.
Go by the specs and they should be fine.
Yeah, when I think about it, no one here ever talks about panel brands except to just say this is the one I have or the one I'm looking at. Not like the debates and problems with controllers, inverters, converters and such.
When we bought our mid-90s MH about 8 years ago, we found that dealers had much, much better prices than private owners. We took our time, searched all over the country, and ended up doing business with a dealer in OR. So far, so good ...
I notice that too.
We looked at one and thought it was a great floor plan. However then I read up on it at the Yahoo View/Navion discussion group, and a lot of people complained about the air mattress used in the folding bed. It would lose a lot of air during the course of a night. So I recall, anyway. If you don't get any owners to show up here, take a look at the Yahoo group.