Price check on Isle windows

[speedfunk]

I found some double pane sliding glass door 6' x 6'8 which I think would work really good on my solar collectors for my earthberm allowing easy access to put in compost. The would be angled toward the sun and sit in pairs to catch east and west sun.

I know prices vary across the country  but he wants 150 per piece and said he would take 125 for 6 , I forgot I need 9 so maybe I can get him to 100 dollars.  Does this seem fair?  I have to drive 50 mins each way to go pick them up and they might weight so possibly two trips.  Unless i get a friend with bigger trailer to help.

I originally just wanted to use sheet class of single pane nature which has a solar gain rate of 90% compared to 80%.  So I think I am comparing this to single pane glass of the same size.  However double glass retains the heat 2 times as long which will give my mass (dirt or maybe water to slow heat so earth can absorb).  So There are some benefits to double pane.  In the winter I think I will have insulated covers that might double as reflectors when open increase total amount of solar gain. 
/
Opinions on both the cost and the compromise/benefits of double vs single VERY welcome!

[Redoverfarm]

If you get them don't haul them lying flat.  I am not that versed on Rvalue but alot of these double pane have UV inhibitors which when used for composting might not be your best bet.  .   They are insulated but they could have the adverse effect other than what you want in the winter months.  I have some friends that have used them for hot beds in the spring for plants and seem to work fairly good.

[speedfunk]

Redover,

Yeah I made sure there was no LOW E film or anything on them.  If they have anything like that I wont get them.  THis is the main system for collecting solar gain so it needs to be clear glass for sure..thanks