UNI SOLAR

How can you compare Currents in this case when they are hugely different Vmp's?

Andrew

(i recognise that the uni-solar will still not win in the final electrical comparison)

Andrew,
You first ask a question, ( "how can you compare Currents in this case when they are hugely different Vmp's ?" )
then say; you "recognise the uni-solar will still not win in the final electrical comparison"

I believe 4.1 Amps and 14(+) Amps, available from each system is correct :)

The nominated output is only to give a comparison, I'm not saying one system/panel is better than the other, just that the Amps produced and available to charge the battery, is a MAX of 4.1 Amps from system and at least 14 Amps from the other system.

If you are drawing 10 Amps, then you will never have to replace more than 10 Amps when the sun is shining.
However if your drawing the same 10 Amps with a maximum replacement of only 4.1 Amps, you will *never ever* be able to fully recharge the battery.
But you may save some money -> to spend on the extra batteries you will need :)

Maîneÿ . . .

Whilst I will agree that the Sharp panels for the same area put out more power...what also maybe important for the user is a few other small facts that are being over looked ?, the Uni-Solar are lighter, they are flexible , unbreakable , they are" shade tolerant"...I have had an 85w glass panel (Suntech) and on an average day with a bit of cloud around the 64w Uni-Solar(non-flexible) that I now have would put out more power over the full day....cheers

Whilst i don't profess to know much about solar systems, my electrical background gives me an understanding of power theory. To think that some people profess to know solar technology when they cannot understand simple power equations and principles of regulation is beyond me.

Someone shoot me!

Andrew

Bruce,
I was comparing the available *panel output* nothing else, after all the only reason to buy a solar panel is to recharge a storage battery system.
If you can do it with just 4 Amps then the battery system is not getting a lot of use at all, however in a camping situation 14 Amps is a more realistically required panel capacity, it equates to (about) 3 x 80 Watt or 2 x 130 Watt panels.
I'm sure your aware some panels, and not others, will give excelent service on those "a bit of cloud around" days, actually some of the more efficient panels will even increase their output in some overcast conditions.

Andrew,
we are not talking about any "power theory" or even "principles of regulation" here, only the available technical specification numbers that can be read on the manufacturers website.
As I don't want to see you unhappy or your request go unfulfilled
Please consider yourself.... 'shot' :-)

Maîneÿ . . .

The Uni-Solar strips quoted on Mainey's url might only deliver 4.4A, but the loaded output voltage of those strips is 30.8V (48v o/c), so they might not be suitable for 12V applications without a suitable PWM regulator. With a PWM regulator, the regulator output current will theoretically be about twice the panel output current.

Gerry

Hamo's question is: "Has any one had experience with uni solar adhesive modules you stick them on to your roof"
if you google "uni solar adhesive modules" you get this link: unisolar solar adhesive modules

Maîneÿ . . .

whats a Vmp?

Mainey,
I was making technical comment about the panels in first link you provided.

Gerry

The Voltage at Pmax.

Andrew

That 136W (@ Vmp 33V) Uni-Solar panel, when connected to a 12V battery via a MPPT charge controller (as it should be w/- 46.2Voc) will deliver 9.75A (@ 13.6V) to the battery/load, taking into account the modest 2.5% efficiency loss typical of any half-decent MPPT controller...
Into a battery which has been discharged to 11.5V, it will deliver 11.5A

The claim that it outputs a MAX of 4.1 Amps, when taken in the context that the question was asked, is at best deceptive and misleading...........

;-)

Come on fellas, its unfair to have a power theory debate in this post.

Chris,
Who makes these "64 Watt" *stick on* Panels ??

I ask, because the only "64 Watt" panels I'm aware of are rigid framed Unisolar panels, however they do have a PLV 68 flexable panel that I've seen glued to van roof.

Maîneÿ . . .

Mainey,
For my panels my origanl contact was all about 12 volt here in Melbourne. They then put me on to Glen who did the install. Here is a link from their web site for the panels I had installed. http://www.allabout12volt.com.au/indexcat.html
It shows them as 64watt....

Thanks guys and girls for all your answers all helpful,the panel I was looking at was a uni-solar 64 watt,quoted price $760+installing,the output in the shade impressed me,I don't need a lot of amps because I run a gen when needed
hamo

Hamo,

I've had a US 64 watt panel (not the stick on variety, but I assume the technology is the same) for over 5 years. The output in shade or overcast conditions is so minute as to be near enough to useless.

At the money I'd be more inclined to get an 80 or 100 watt folding kit from someone like Mandrake (who advertises on the forum). This allows you to move the panel around to get maximum sun/light. It also allows you to park the van in the shade and stick the panel out in the sun.

Just something to consider.

Regards,

Jim.

No panels work all that well in the shade - don't believe the hype. The laws of physics determine this.
One good thing about the amorphous panels is their better performance when hot (which they will get in the sun). My polycrystalline panels drop about 25% in output current when hot. (don't ask me for figures, but a friend's Uni-Solar amorphous panels dropped much less output in a parallel observation).
Panels fixed flat on the roof will lose a bit of performance, since they're not facing the sun at right angles, but worth it for both mechanical rigidity and more security against theft.
A folding kit lets you follow the sun during the day, but is ripe for theft if you're not around.
The downside of a roof fixture is that you can't park the van in the shade if you want power.
Gerry

Comparing two panels, with known outputs, for example;
# 64 Watt Unisolar panel
# 123 Watt Sharp panel
Both panels have the *exact same* one square metre surface area

Using the manufacturers Amperage numbers, the very *best* performance you can get is 3.9 Amps from 64w Unisolar and 7.3 Amps from 123w Sharp panel.

Worst case scenario the comparison would be;
Sharp, 7.3 Amps, less 40% = 4.4 Amps (would be 5.5 Amps @ only 25% loss)
which is still higher than Unisolar even at their peak performance of just 3.9 Amps, which would possibly also drop to some degree anyway.

If someone bought a solar panel and left it under the bed it would not work at all, if it was left it in a shed it still probably would not work either, however I've seen them work inside a tent :-)

However, if a solar panel is put out in the sun it would give the desired result, so why not put it where it is designed to go, is a bit like having a gererator and expecting it to run with-out adding any fuel, in the case of Solar power the sun is their fuel.

Maîneÿ . . .

There is another solution option and that is to use a semi flexible panel at about 1/2 the cost.

These mould well to the small curve in a cars roof.

In some ways its better , as heat can be taken out of the panel and its actually thinner than Uni-solar.

It is sort of the insert to a normal panel i.e. a sheet of aluminium on which the cells are placed and then covered in clear heavy duty plastic film (about 1mm thick).

I have a 60watt version which I play with , no cross diodes so pretty poor in shade but sizzles when in the sun on a car roof.

E.G.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250562868321&ssPageName=ADME:X:AAQ:US:1123

I think the point that most people are missing with this discussion is that the Uni-Solar panels are a different type of panel to most of the rigid panels on the market. People have eluded to their performance in shady conditions where normal panels stop working if any part of the panel is in any shade as they are an amorphous panel. See this link for descriptions;- http://www.solarquotes.com.au/types-of-solar-panel.html

Forgot to add , that this option wins all of Peter points , except warranty I guess , and shade performance.

It is much smaller in area than Uni-solar think my 60w unit is only around 800m X 600 (don't quote me) , and even then its construction is such that I trimmed the corners with an angle grinder.

Hi Chris

While the mono panels are poorer in shade performance the information given to you by that site is incorrect.

Using the 60watt typical 36 cells panel that I have as an example it delivers about 16w with a sunangle of about 60 degrees.(late afternoon)

If you fully cover one of the 36 cells that output power will drop to 1/4 (4 watts).

If you hold a piece of wood a meter from it and create shade over 2 or 3 cells
its output is more at about 8 watts.
This case the shade which simulates a tree branch etc which still allows some remanent illumination.