More Solar for "Us"

[MrWizard]

Ok, I went off.the deep end?
Bought 3 used 37watt uni-solar panels and a blue sky 2000e controller for the hefty price of $400,
They were being listed as 75w panels, they are not

The tested open circuit voltage was 21+, short circuit amps 2.9
I tested each panel multiple times tilted into the sun and laying flat on the ground , got the same readings each way, that was the deciding factor, they appear to put out full power while laying flat, I will try to mount them tomorrow before it gets hot, right now 104°F
I will use the existing wiring until I buy & install the new wire

[KendallP]

I THINK what Sal is trying to say is that since these Uni-solars mount directly to the roof, there is no surface area between the panel and the rooftop, i.e. half the surface area to conduct heat away from the panel.

Did I get that right Sal?

This is, of course what many have already mentioned. Sal just gave us the scientific explanation of why we have concerns about not having any airspace between the panels and the rooftop.

[Salvo]

No, I didn't misunderstand you. I suggest you get a grip on thermodynamics before providing misinformation.

1. The panels do not RADIATE heat. Heat transfer is through CONDUCTION.

2. Glass is a pretty good thermal conductor. It's 100 times better conductor than air. It's conductivity is similar to thermal grease.

3. Since all the heat needs to be conducted to air, air is the weakest link in the equation. The surface area of the panel that makes contact to air is the dominate factor in keeping the panel cool.

Sal

pianotuna wrote:

You misunderstood I believe. The glass heats in traditional panels and it is a pretty good insulator, so the panel remains hot longer. Part of that is because it is heavier to start with, i.e. more massive.

The Unisolar panels will cool down faster, and radiate better.

Salvo wrote:
I hope they're not teaching that at our schools now.

The mass of the glass has little effect on heat dissipation. The prominent factor in heat dissipation is surface area. These panels have half the surface area. It's a no-brainer.

Sal

pianotuna wrote:
Heat dissipation is superior in non glass panels, as they have less mass.

[pianotuna]

Hi Salvo,

You misunderstood I believe. The glass heats in traditional panels and it is a pretty good insulator, so the panel remains hot longer. Part of that is because it is heavier to start with, i.e. more massive.

The Unisolar panels will cool down faster, and radiate better.

Salvo wrote:
I hope they're not teaching that at our schools now.

The mass of the glass has little effect on heat dissipation. The prominent factor in heat dissipation is surface area. These panels have half the surface area. It's a no-brainer.

Sal

pianotuna wrote:
Heat dissipation is superior in non glass panels, as they have less mass.

[MrWizard]

the five panels I added are unisolar thin film,noglass but mounted in a frame

physically the 60w panel is approx 3/4 the size of a kyocera 135w panel , its more surface area per watt not less (less watts per sq ft of panel), they are very good at heat dissipation

I would not walk on the adhesive then film panels , your shoes or xxxxx stuck in them will scratch and damage the panels
IMO the pix of the guy standing on them is an adv gimmick

if you slipped and fell on the panel, you would not break it like a glass coverred panel, and IF YOU WANTED , you could spread a blanket and sit or sun bathe on them without harming them, and the thin film panels are very llite weight, but when you sell or trade the vehicle the adhesive panels stay with the rv, IMO not removable,

if you are setting up a large array and want the.most.wattage from the area covered get conventional framed panels

IMO if you want the most amphrs produced per day, from A GIVEN AMOUNT of wattage, then get thin film panels, they produce more amps at lower angles of sun and from a broader spectrum of light

[KendallP]

HobbyTalk wrote:
Their ad sounds a bit "snake oil" to me. They claim their 68W panel will recharge 2 6 volt batteries in 7 to 10 hours. How is a 68W panel going to recharge a 220Ah battery pack in 10 hours? That's not even enough to recharge a single 100Ah 12v battery that has been discharged to 50%.

They leave out enough details to cover themselves. For example, they don't say "recharge," they say, "charge." And they don't specify which panel. They could be talking about their 18' long, 144W unit. And of course they fail to mention any details about how far the batteries are drawn down.

However, your point is still well taken. It's pretty misleading. But I think that's the retailer. I wouldn't blame Uni-solar for that.

I almost bought one of the longer units for a killer price! But alas... it was just too long for my rooftop. Wattage per surface area is definitely not their strong suit.

[pnichols]

You guys are a tough sell for anything new in the solar world - since so many of you have years and years of experience with the older technology stuff. I don't have any experience at all ... nevertheless without having to buy to get educated down through the years ... I'm not happy at all regarding the older solid panel solar technologies with respect to A) base conversion efficiency, B) shade and angle tolerance, C) broadness of light spectrum sensitivity, and D) ease of mounting ... for best gas mileage, no holes through the roof, and for walking around them when up on the roof.

I'm not going to argue point-for-point for new versus old. What might be beneficial is an open mind to reading and studying more about this particular high-warranty flexible rooftop solar panel. For starters, one might want to begin by reading a little more here:

http://www.flexenergydelsol.com/advantages/

http://www.flexenergydelsol.com/wp-content/themes/energy_del_sol/pdfs/uni-solar-flat-roof-data.pdf

http://www.flexenergydelsol.com/wp-content/themes/energy_del_sol/pdfs/uni-solar-side-by-side-compari...

[Salvo]

I hope they're not teaching that at our schools now.

The mass of the glass has little effect on heat dissipation. The prominent factor in heat dissipation is surface area. These panels have half the surface area. It's a no-brainer.

Sal

pianotuna wrote:
Heat dissipation is superior in non glass panels, as they have less mass.

[pianotuna]

Hi,

The panel in the link is a Uni-Solar. It is true it requires more room but it does have a 20 year warranty on output. There is also no glass to break. Heat dissipation is superior in non glass panels, as they have less mass.

vcallaway wrote:
I'm not a fan of thin film panels. They require more surface area to generate the same amount of power. They also degrade faster than standard panels. Probably not an issue for an RV though.

I also agree about air flow. Thin film panels are subject to the same heat issues as any other. The air gap does make a difference.

[HobbyTalk]

Their ad sounds a bit "snake oil" to me. They claim their 68W panel will recharge 2 6 volt batteries in 7 to 10 hours. How is a 68W panel going to recharge a 220Ah battery pack in 10 hours? That's not even enough to recharge a single 100Ah 12v battery that has been discharged to 50%.

[vcallaway]

I'm not a fan of thin film panels. They require more surface area to generate the same amount of power. They also degrade faster than standard panels. Probably not an issue for an RV though.

I also agree about air flow. Thin film panels are subject to the same heat issues as any other. The air gap does make a difference.

[HobbyTalk]

I have yet have anyone answer what happens when/if you have to replace the roof material? I wonder how good the heat dissipation is since there is no air circulation under the panels?

[pnichols]

FWIW, if I was to install solar on the roof of my motorhome it would be these panels using adhesive, instead of screwed-down or adhesively mounted solid panels:

http://www.flexenergydelsol.com/

[MrWizard]

i wish it was 73%, its more like 48%

I added (2) more uni-solar panels 60w @, my total is 321w

they would do better with tilt mounts, but I moved to much and too many panels to be tilting, still not to bad, I'm anxious to see what the summer time output will be

[bigfootford]

MrWizard wrote:
Tuesday Dec 7th, 14 days from winter.Solstice

707.7 Whrs
51.37 Amphrs
10.46 peak amps
146.20 peak watts

Now this isn't too bad at all eh?

You have 4 panels <>22watts total 90
3 panels at37 watt total 111
combined 201

Peak watts measured 146

That is really good for the sun angle, almost Solstice, and your panels laying flat...
You should be quite happy. <>73%.

Congrats...such a bargain you found.

Jim

[MrWizard]

Tuesday Dec 7th, 14 days from winter.Solstice

707.7 Whrs
51.37 Amphrs
10.46 peak amps
146.20 peak watts