It is a bit disappointing to me that there is not more work going on to come up with new designs for solar water heating systems -- particularly on the part of larger businesses. The current commercial systems have hardly changed from the 80's, and the prices for solar water heating systems appear to be on the rise if anything.
There are a few individuals and start-ups working on better collector/system designs that use new materials or simplified designs to make more cost effective systems -- here are the ones I know of:
Modified Trickle Down Collector (MTD) this collector by John Canivan and Richard Heiliger is a new version of the Thomason trickle down collector. Full details from Richard ....
Davis Group's SunCache Solar Water Heating System.
This solar water heating system was developed by the Davis group, and is now being commercialized by www.harpiris.com.
The $1000 Solar Water Heating System.
This is a system I have been working on (and use for our hot water). It combines a simple and low cost collector design with a simple and low cost combined storage tank and heat exchanger.
The Solar Pond Solar Water Heating System -- This is a system that Nick Pine and I have been working on. It holds promise for a very simple, but cold weather capable solar water heating system.
Gary September 25, 2008