(solar) too good to be true

Topic: (solar) too good to be true (Read 1701 times) previous topic - next topic

(solar) too good to be true

April 11, 2014, 01:53:41 am

This bears further investigation...

We are down for the night in a well lit Walmart parking lot, first time out with my new solar panels. I realize Uni Solar said these panels produce electricity at low sun angles...but well after sunset?

The charge controller says it is sending 4+ Amps into the batteries. I guess at Walmart's expense.

And the charge controller appears to be telling the truth during the day.

Re: (solar) too good to be true

Reply #1 – April 11, 2014, 10:08:24 am

I suppose it's possible, my chrge controller often shows an amp or more going in whilst under the adco cover on an overcast day.

Re: (solar) too good to be true

Reply #2 – April 11, 2014, 11:27:38 am

If you park close to their parking lot large output lights you may find they give you a few amps too.
JohnH

Re: (solar) too good to be true

Reply #3 – April 11, 2014, 11:39:33 am

Just to be nosey, are these the flexable surface mounted panels?? pc

Re: (solar) too good to be true

Reply #4 – April 11, 2014, 11:42:52 am

Yes. A pair of Uni-Solar 136Watt panels. In a couple of weeks I'll have two 90Watt Global Solar flexible panels added.

I like to keep a clean roofline.

Re: (solar) too good to be true

Reply #5 – April 11, 2014, 02:41:08 pm

That is awesome Tom! I've tested our Uni-Solar panels in severe shading, fading sunlight, twilight, and they have always had open circuit voltage that was surprisingly close max. I didn't have any loads on them though, so it's nice to see that they function even under the conditions you describe...

if the Global Solar panels are even close to the Uni-Solar, it's going to make going off the grid much quieter for us

when my install is all said and done, we will have 476 watts of UniSolar panels and 360 watts of the Global Solar.
Don & Tys

Re: (solar) too good to be true

Reply #6 – April 11, 2014, 07:20:31 pm

Don,
Did you do anything different with your peel & stick panels to get them glued down?? pc

Re: (solar) too good to be true

Reply #7 – April 11, 2014, 09:10:56 pm

PC,
I haven't installed them yet, but the plan is to wash the roof, and then buff with a fine silicon free compound, wipe the roof with acetone before installing the panels and finally roll them out with a vinyl flooring roller. I may install a piece of aluminum trim on the leading edge screwed to the frame member or perhaps lap them with some eternabond tape.

Many projects in the works right now. Current plan: First is the hose and shore power reels along with relocating the noisy Progressive Industries EMS to the utility compartment if I can shoehorn it in

(Glendinning Hosemaster Model-M Model M - Glendinning Products, LLC., Shore Power Reel (Glendinning CRR-50 CRR-50 - Glendinning Products, LLC.). Next is the fridge install (Vitrifrigo DP2600iAC AC/DC 8.1 cu ft Marine Refrigerator Vitrifrigo DP2600iAC refrigerator ? 8.1 cu ft AC / DC powered for marine and RV), inverter with the optional ARC50 remote and battery monitor (Magnum MSH-3012M Magnum Energy MSH3012M hybrid inverter and charger for marine, RV, and solar), the solar panels and the Midnight Solar Classic Charge controller and associated cabling, and some other stuff that escapes me now. I have all the parts for the projects listed above except the solar controller and cables.

Don

Quote from: pocketchange – April 11, 2014, 07:20:31 pm

Don,
Did you do anything different with your peel & stick panels to get them glued down?? pc

Re: (solar) too good to be true

Reply #8 – April 11, 2014, 09:33:46 pm

Don,

Are you going to be using Bill's shop with the new pit for all those projects??

Larry

Re: (solar) too good to be true

Reply #9 – April 11, 2014, 10:59:00 pm

Luckily non of those jobs need to get under coach for!!
I have ordered the pit from Amazon but it has not arrived yet!!
Johnh

Re: (solar) too good to be true

Reply #10 – April 11, 2014, 11:42:10 pm

John is right... None those projects would really benefit from a pit, But it sure would be handy for chasing down air leaks, flaky solenoid valves, and a hundred other maintenance items!

Don

Quote from: ohsonew – April 11, 2014, 09:33:46 pm

Don,

Are you going to be using Bill's shop with the new pit for all those projects??

Larry

Re: (solar) too good to be true

Reply #11 – April 12, 2014, 08:16:11 am

Quote from: ohsonew – April 11, 2014, 09:33:46 pm

Don,

Are you going to be using Bill's shop with the new pit for all those projects??

Larry

Bill's shop does not have pit. (John H was a "N SHOW")

Re: (solar) too good to be true

Reply #12 – April 12, 2014, 09:10:05 am

Quote from: Tom Lang – April 11, 2014, 01:53:41 am

This bears further investigation...

We are down for the night in a well lit Walmart parking lot, first time out with my new solar panels. I realize Uni Solar said these panels produce electricity at low sun angles...but well after sunset?

The charge controller says it is sending 4+ Amps into the batteries. I guess at Walmart's expense.

And the charge controller appears to be telling the truth during the day.

I think what you are experiencing is normal. The solar panels on my house start to produce power before sunrise on a clear day and do not shut off until after sunset. Just a few watts, but it's something. If it's cloudy it takes longer before start up. You are not stealing anything from Walmart, the lamp consumes the same amount of power regardless of whether you are parked underneath.

Re: (solar) too good to be true

Reply #13 – April 12, 2014, 09:40:24 am

Photons are photons. They don't know any different.

It's not the same as drafting on a bicycle in the Pelaton in the Tour de France.

Or the way birds draft by flying in formation (which, by the way, is a lot more complicated than it looks).

Why Birds Fly in a V Formation | Science/AAAS | News

best, paul

Re: (solar) too good to be true

Reply #14 – April 12, 2014, 09:40:55 am

Something else about solar, there is a phenomenon called solar boost that can occur with a light overcast. The panel gets strong diffused light from several directions, then if the sun shines through a break in the clouds, the output is more than the sun alone. Total output on a day like that is less than on a clear day, so clear days are best. Humidity in the air can reduce output, and cool days are better than warm days.

Re: (solar) too good to be true

Reply #15 – April 12, 2014, 10:09:43 am

"cool days are better than warm days"

You got that right. We're hopeful that today in El Centro, CA it will get to only 90 F

And we're promised a high of only 80F next week. Whooohoo!

best, paul

Re: (solar) too good to be true

Reply #16 – April 12, 2014, 04:53:23 pm

Just went to Amazon to check on getting the Uni-Solar 136Watt panels and there is a note there that these have been discontinued by the manufacturer. Interesting, no replacement or alternative mentioned.

Re: (solar) too good to be true

Reply #17 – April 12, 2014, 07:25:41 pm

Quote from: arwilson – April 12, 2014, 04:53:23 pm

Just went to Amazon to check on getting the Uni-Solar 136Watt panels and there is a note there that these have been discontinued by the manufacturer. Interesting, no replacement or alternative mentioned.

The manufacturer, Uni-Solar is out of business, but their panels are still readily available. I found mine on EBay, 136 Watts x 2 for $326. I also have a pair of Global Solar panels, also flexible, 90 Watts x 2 for $350. These are physically smaller and better fit in the roof space now available.

Re: (solar) too good to be true

Reply #18 – April 12, 2014, 09:26:01 pm

Which is good for us, because when the company was still in business, these panels were selling for a whole lot more. List price for the 136 watt version was supposed to be over $600 apiece! Downside is warranty support, as in nada. The UniSolars were advertised as being able to be walked upon. The Global Solars... not so much. Different construction. Not as flexible and probably not as durable. But the size is right for the aft section of our coach's roof. I think it would be okay to walk on if covered by a rubber mat and maybe a thin piece of plywood over that. Where they are going on our coach is to the street side of the ladder so walking on them won't be routinely needed. I plan to tread lightly even on the UniSolars and mostly won't have to.
Don

Quote from: Tom Lang – April 12, 2014, 07:25:41 pm

The manufacturer, Uni-Solar is out of business, but their panels are still readily available. I found mine on EBay, 136 Watts x 2 for $326. I also have a pair of Global Solar panels, also flexible, 90 Watts x 2 for $350. These are physically smaller and better fit in the roof space now available.

Re: (solar) too good to be true

Reply #19 – April 13, 2014, 06:17:40 pm

What are the VOC (volts open circuit) and MPPV (maximum power point voltage) of Unisolar panels and Global panels. If they are not almost the same, the higher voltage ones will overpower the lower voltage ones and you will not get the rated output from all the panels.

I am quite interested in how well stick on panels stay attached over the years and how well they perform at higher temperatures.

My panels are not horizontal and are mounted with an air gap for cooling.

Re: (solar) too good to be true

Reply #20 – April 13, 2014, 07:39:05 pm

Wyatt,
I am interested to hear what your thoughts are about these panels. After a bit more research, it appears I either need to lose or add a 68 W panel to make my system work. I have the panels already and I can always find a use for any that don't get used on my 40' Conex box.

The STC (Standard Test Conditions) VOC (Voltage Open Circuit) and Vmp (Voltage at Pmax) of the panels;
UniSolar 136 Watt
VOC =46.2 V, Vmp =33.0 V
UniSolar 68 Watt
VOC 23.1 V, Vmp = 16.5
Global Solar
VOC 22.0 V, Vmp = 16.5
Don

Quote from: P. Wyatt Sabourin – April 13, 2014, 06:17:40 pm

What are the VOC (volts open circuit) and MPPV (maximum power point voltage) of Unisolar panels and Global panels. If they are not almost the same, the higher voltage ones will overpower the lower voltage ones and you will not get the rated output from all the panels.

I am quite interested in how well stick on panels stay attached over the years and how well they perform at higher temperatures.

My panels are not horizontal and are mounted with an air gap for cooling.

Re: (solar) too good to be true

Reply #21 – April 13, 2014, 08:22:21 pm

Treat the 4 panels as two, 46 volt panels in parallel give 46 volts, 23 volt[or close to it] panels in series give 46 volts. Wire as such, and then parallel the two. You will probably need a mppt controller to handle the 46 volt input.

Re: (solar) too good to be true

Reply #22 – April 13, 2014, 09:04:27 pm

I currently have two UniSolar 136W panels in series and have two Global Solpr 90W panels soon to be added in series. My total open circuit voltage will be under the mppt controller's 150v max.

If I were to add more panels, I would parallel one or both identical pairs.

Re: (solar) too good to be true

Reply #23 – April 13, 2014, 10:32:41 pm

Quote from: P. Wyatt Sabourin – April 13, 2014, 06:17:40 pm

What are the VOC (volts open circuit) and MPPV (maximum power point voltage) of Unisolar panels and Global panels. If they are not almost the same, the higher voltage ones will overpower the lower voltage ones and you will not get the rated output from all the panels.

When the panels are wired in series it's not so important to "match" the panels. One of the major reasons I chose the Midnight Solar "Classic" which can handle up to 150vdc and convert that down to 12vdc for the battery bank.

Quote

I am quite interested in how well stick on panels stay attached over the years and how well they perform at higher temperatures.

There was a web page about installation of these "self-stick" Unisolar panels that mentioned a metal carrier but this was for a building installation. How they work on a fiberglass-roof RV should be very interesting. I have two of the smaller (70-watt) Unisolar panels that I originally planned to install on the curved sides of the roof of our U225 but I now think I'll stick them down for a walkway on the roof top. We also have two "standard" 240-watt 24vdc panels but might add a third (or another Unisolar).

Quote

My panels are not horizontal and are mounted with an air gap for cooling.

I plan to mount my rigid panels with an air gap. It would be very interesting if someone could "shoot" their Unisolar panels with a Harbor Freight laser temperature gun when they're in the hot sun and post the temps.

I am still waffling about whether I'll make the panels so they tilt. As I get older I get far less excited about going up onto the roof. Actually, going up isn't so bad; it's the coming down fast and hard that makes me think twice about it.

Craig

Re: (solar) too good to be true

Reply #24 – April 13, 2014, 10:45:22 pm

Craig,

I installed two of the long self stick panels last year. Have not used them yet as coach is still in storage but they were very easy to install. Will post results when I use coach.

Keith

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