I've seen a DIYer on Youthube that installed copper pipes to his heat exchanger
with large PVC pipes over them as insulation. He vacuumed the air out of the PVC
and got a real low rate of loss..
If you vacuumed a flat panel you would need to have support inside, to prevent collapse.
That support would have to be something with low heat transfer..
And, nature abhors a vacuum.. You would have to worry about leaking panels..
Rubbery paint on the outside of all seams might help..?.
Wow, the stock market crash has slowed my web speed way down!!
