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Old 09-16-20, 04:50 AM   #3
Hong Kong
Join Date: May 2010
Location: Hong Kong
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Originally Posted by SDMCF View Post
I have 90 tubes and they perform very well on cold days but do not perform at all well on overcast days. The most productive time of year for me is February/March when the temperature can be -30C but the air is clear and the snow on the ground reflects extra light onto the tubes.

My system uses antifreeze and I have no experience of drainback systems but I will comment anyway. The water flowing through the manifold is effectively just flowing through a pipe (22mm copper on my manifolds). So long as that pipe is angled so the water will drain back under gravity I don't see a problem.
Thank you so much for your feedback, SDMCF.

I know about the manifolds being vertical. The issue is if they have a kink in the middle, and leave water standing there. Of it there is any other lock in the system. I could use a compressor to force all air out, but then it gets a bit too complicated ... I also want to recycle the air, so oxygen isn't added to the system (components will start to corrode faster).

About your tubes in overcast weather: THAT is EXACTLY what the main purpose of my system is. I am building a solar panel system which will be optimized for low and diffuse light, even during cold weather. I am combining several known and (so far) unknown principles, to make this possible. There will not be any more energy coming out than what is in the light. But the point is to get something, rather than nothing - when it is needed the most.
Space heating/cooling and water heating by solar, Annual Geo Solar, drainwater heat recovery, Solar PV (to grid), rainwater recovery and more ...
Installing all this in a house from 1980, Copenhagen, Denmark. Living in Hong Kong. Main goal: Developing "Diffuse Light Concentration" technology for solar thermal.
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