This is an added comment to see if the blog can be edited after posting.
Additional post (1/11/12): Now it's winter and we're working on a new collector. The 40 gal. external tank type works very well, but there is some loss in the pipes leading to and from the collector. Therefore, it works best with long use loads, e.g. showers, baths, dishwasher, clothes washer.
The new type is just a collector. The hot water is circulated into the existing house storage tank. The highest temperature reached so far is 151F. in the storage tank. A thermal mixing valve prevents scalding and makes the hot water go further. We can run 3 loads of laundry, a dishwasher full, and take showers and still have 130F. storage tank water when we're done.
