GH roofing advice needed

Hi. Finally I am building my "almost" dream greenhouse. It will be a 11x12 lean-to on the south wall of a large block shop (Protection from nasty north winds). The GH will have a 2' base wall made of block (brick layers in the family). They will be topped with 54" tall single-pane, aluminum windows. A door will be placed on the east side, also protecting it from windy days.

All windows are operable -- I think, actually haven't tried them all, still have to clean years of dust and mud-dauber nest off. Wanting to put a ventilator across the full length of the roof as discussed in another thread -- "Best greenhouse ever" (think that is the subject title).

Wanting to put black 55 gal drums filled with water along the north wall -- seems I should need 11 -- Wow, that will take up one whole section of my greenhouse wall. Also wanting to collect rainwater from shop behind greenhouse to water plants .

The floor will be patio pavers (18") which I have plenty of from prior dreams that never formulated.

Playing with the idea of using some insulated curtains I recently took down in the house. Thinking I can attach them to a pipe that will be attached at top of windows, then close curtains when the sun goes down to keep warmth in the GH.

Now, my question, any ideas for the perfect roof? Am looking at polycarbonate -- $$$$$ Pricey! (with shipping). It needs to withstand hail and wind. Snow is not a real problem around here. Have any of you used this and found a good cheap source to buy it.

Thanks for any input and suggestions.

North of you in Amarillo,just finished my greenhouse,also a lean to ,I went with the polycarb panels here as well when I lived in Wichita Ks,there I used those from lowes,but here I ordered from a company called Ecologic Technologies,PO,Box1038 Pasadena MD,21123-1038,Tel410-431-7106,web site www.ecologictechnologiesinc.com,expensive but good stuff.

Tropicman, very nice looking greenhouse.

Thank you

Thanks for the advice Tropicman. Yes, your greenhouse does look good. I think I'm jealous. Hoping mine is will quickly get out of the planning stages.