Polycarbonate or low iron glass for glazing?

[markf57]

I've been looking at the solar roof products and noticed that their panels have twinwall Polycarbonate glazing, but most of the other brands are low iron glass.

I live in Colorado with cold winters and fairly hot summers with plenty of sun. I was wondering which type of glazing is better for my climate?

On a side note, I was wondering what the life expectancy is of new solar thermal panels?

[russ]

Hi Mark - Glass is always the first choice. Anything else is a compromise to save money - no other reason.

Life expectancy? For a first quality panel You should see 15 to 20 years - if well maintained.

Russ

[markf57]

Russ:

Thank you very much for the quick and informative reply. As usual.

We also get hail here, so I'm thinking the Polycarbonate may hold up better. But it's not as efficient as glass from what I read.

[russ]

Hi Mark -

Polycarbonate would have better resistance to breaking - you are quite correct.

Efficiency is a matter of size of the collector or number of collectors. Worst case you add one more collector at a later date.

Russ

[markf57]

Efficiency is a matter of size of the collector or number of collectors. Worst case you add one more collector at a later date.

Russ

That is part of my problem as I don't have a lot of roof space, so I'm leaning on one hand towards a more efficient collector and on the other, a collector that will hold up better to hail.

[Mike90250]

.. a collector that will hold up better to hail.

Mounting angle will have a lot of influence on that too !

But seriously, factory panels have some pretty good hail resistance, up to about golf ball size, and then your roof shingles and car are going to take a beating too.

[russ]

I only find 2 companies using polycarbonate or Lexan on the SRCC list. If breakage was a problem I would expect to find more manufacturers using it.

Two useful links -

1) Solar Ratings & Certification Corporation http://securedb.fsec.ucf.edu/srcc/co...how+Selections

2) Florida Solar Energy Center http://www2.fsec.ucf.edu/en/industry...nual/index.htm

Russ

[LucMan]

The glass is pretty tough, I dropped my 30' Fat max tape measure from about 8 ft above onto on of my flat plate collectors and it suffered no damage. That tape is big and heavy.