perspex sheets

[twinscythe12332]

Hi All,

Does anyone have a contact that I can get clear UV resistant Plexiglass sheets from? I've taken on the task of building my own solar panel, and I need about 1500mmx700mm sheets for relatively cheap. I'm in the durban area, so if I can go to the place it will make things easier. Thanks ^^

[IanF]

Perspex and cheap don't go together.
Anyway phone Maizey, then look for other sign supply shops like Falcon.

[AndyD]

Durban plastics. Toughened glass would be better but I'm not sure about the price. Perspex will go from transparent to opaque over time and might have a notable effect on efficiency.

[twinscythe12332]

I was also thinking of toughened glass... Plexi glass doesn't have too many issues, other than it's massive price. I will look into toughened glass as well.

[adrianh]

Plexiglass is certainly not the right material for the application. You are far better off using toughened glass.

[AndyD]

I don't think any of the options will be cheap. I think toughened glass is a fair few humdred Rands per square meter and you need to be accurate because it can't be cut once it's toughened. Maybe look at laminated glass like in windscreens, certainly weatherproof and shouldn't deteriorate to any noticable degree. If you can find it in flat pieces it might be cheaper because of the larger volumes of sales.

[dfsa]

You need to look at efficiency options. low-iron glass or plexiglass. what you would need from the suppliers is the following.

It should be clear in their spec.

1) What heat gain do the product have.
2) What is the light transmitting from the product and transmitting loss over time while exposed to UV.


low-iron glass would be my option, but you need to compare pricing.

You don't want to loose efficiency and you would need to put them into an aluminum frame for added strength

[daveob]

Previous research that I did on solar panels indicated that plexiglass discoloured over time when exposed to UV.

The best and cheapest option always was glass.

If worried about hail or other damage, consider the laminated glass - i think PG call it "intruder proof", but there are other generic types of the same thing.

Recently had a bedroom window replace with this stuff. Was about 1,3 x 1,3m and cost about R800

You might just find it cheaper to buy the pre-made panels from a supplier / importer.

[Justloadit]

What do you mean by solar panel?
Heating water, generating electricity?
This will influence the decision you make.

[twinscythe12332]

I've bought a bunch of solar cells off bidorbuy, so generating electricity. Durban seems to receive hail decades apart... so I'm not too worried about hail. I just need something to protect it from the elements and the odd cat/monkey who might decide to walk on it .
I will be taking a look at the local PG glass and glasfit in my area to see who is the cheaper option.
My current objective is to build a 144W, 18V, 6.6A solar panel for less than 2.3K (ie, I'm looking to make a solar panel that costs less than buying one off a solar specialist site).
I have most of the stuff except a frame to house everything and the glass to cover it. my original reason for plexiglass was its strength, but I doubt I'm going to need this thing to be that intense.
It's also a nice project... I like to keep busy, and I especially like it when there is some additional reward (in this case, renewable energy).

[AndyD]

PV panels become noticably innefficient as the temperature rises so this might also be a consideration in your choice of materials for the frame and cover. As a rule of thumb you could lose 0.5% of the output for every degree Celsius over 25C. Figures may vary for better or worse depending exactly what type of cells you're using also terms and conditions apply.

Good luck with you project, keep us informed of your ups and downs.

[Justloadit]

Just remember that the PV cells require quite a bit of UV to make them work, that is why there is still energy from the cells when it is overcast. The light refraction due to the air between the glass and the cells will also play a part in the efficiency, so any glass which has lead in it, and majority do, it is what makes them translucent, will have a serious effect on the cell efficiencies.

As a matter of interest - how much did each cell cost you?

Solar panels are really dropping in price, so shop around and you may be surprised at the cost. There are figures around R11 per watt being bandied around, and there are suppliers who wish to clear their stocks out to replace with cheaper more efficient panels.

To get the kind of voltage you want, you are going to have to put cells in parallel, which will require diodes to ensure they are independent on each other, the volt drop across a diode plays a part in the losses as well. A silicon diode with 0.7V drop across it at 7 amps will create a loss of 4.9Watts, on 140watts that is just over 3.5%, with all the other lossy items you are going to use to make your panel, it may be that the effort will not really pay off.

[twinscythe12332]

paid 27 rand per cell, I'll need to put them in series otherwise the voltage will never reach the 18V mark... will keep you all up to date on how it turns out =)