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tough as old boots! - they're made to withstand hailstones of over an inch in diameter - they're borosilicate glass (think "Pyrex") 8)
When they are vulnerable is on installation - like many vacuum tubes, there's a little "tit" where they seal the vacuum in (in this case, right at the "bottom" of the tubes), look at it wrong, they go pop! Once they're installed, the weak spot is well protected inside a neoprene cover - the "walls" are really tough! 8)
To give you an idea of how far they take design - there are small reflectors that sit between the tubes to help get every scrap of sun into the tubes - but they are only around half the length of the tubes, if they were longer, they would stop the throughflow of air between the panels, and could cause "lift" problems! 8)

Fair enough, thanks mate!

Nev

When I was doing chemistry we had a guy drop a pyrex beaker and it didn't shatter, it just bounced. So the fellow who dropped it yelled, hey look everyone, its one of those new shatter proof beakers................and dropped it again!

Nev

I was just looking at these yesterday having camped last weekend at Eweleaze Farm (I blogged the weekend here) and used their solar showers and was thinking more in terms of it being a great project for my kids rather than having a hot shower in my garden (somehow the apeal of showering in my council estate garden isn't quite the same as a Dorset hillside) and came accross this project - thought you guys might like it!!

http://www.thesietch.org/projects/solar ... /index.htm

List,

B&Q sell black plastic waste pipe 32mm and 40mm for a couple of quid a length.

I have it on good authority that this stuff makes an excellent DIY solar collector. Just put it in a wooden box and cover with a sheet of perspex. The big bore is ideal for thermosyphoning, and 20 tubes is almost half a tank of hot water (50 litres) before you start.

Alternatively get a load of plastic pop bottles and cut the bases off. Thread each bottle onto a 2m length of 22mm copper or plastic pipe - preferably painted black. 12 bottles will do for a 2m length of pipe.

The bottles act as a mini-green house. The water will reach about 70 C on a good sunny day.

These simple low cost schemes will capture 200W per square metre on a good sunny day.


Ken Boak

School of Suburban Sustainability, Redhill, Surrey.