I'm considering building a solar kiln of some sort for my personal use. My biggest issue is that there is no grid power where this kiln will be situated. I've looked at a lot of the various adaptations of the Viginia Tech solution and that's still an idea that I'm willing to persue. My biggest issue with that style of kiln is the lack of insulation on the sloped, translucent panel. Any heat that is scavenged by the system is quickly lost though that panel once the sun goes down. The rest of the kiln can be very well insulated but for obvious reasons, that sloped front panel can't be.
I've toyed with another idea that would basically consist of a fully insulated and sealed shipping container. The heat source would be provided by an external vacuum tube array that would circulate heated water or glycol through radiators inside the container. I would need enough solar generated electicity to run the recirc pump as well as the fans on the radiators. I just think that if I can get the heat into the box, I should be able to do a better job of keeping it there if it's completely insulated. Also, if I add a small wood fired heater in the circulation loop, I can probably keep heat in it over night too. Although, I'm not sure how I would provide for the electrical needs at night.
I have a system here that looks like the picture below. It's a series of vacuum tubes that is meannt for hot water heaating. Since it's been taking up space in my shop for about 5 years, it might be time to find a use for it. The heat the it produces is incredible but the math will tell me wheither it's the right way to do it or not. From what I've seen, it looks like solar tubes will produce about 5kWHr/m^2 per day. I should be able to easly come up with an R20 wall usinig spray foam insulation. I guess I need to go blow the dust off a few text books and see if I can figure out which method wil retain the most heat in a 24 hour cycle.
Does anyone else have any experience using a closed, insulated kiln and heating it from an external source?