benjamin said:builtitsolar is the place to go. lots of examples and a fair commentary of what looks like it will work and what won't.
Be sure you think the whole system through so it makes sense as a system. There are way too many professionally installed systems with new quality components out there that don't work well because the system isn't designed well, even if all of the components and installation are top notch. Consider what you're trying to accomplish, simple unglazed panels might be best for keeping the chill and dampness out of a workshop, but if you're using lots of 160 water all summer then commercial panels with selective surface copper absorbers would make a lot of sense.
Also don't expect a hot water system to provide heat, using the winter sun to heat water to DHW temperature and then using that to heat air at 70 is a serious bottleneck. Maybe there's a controller out there that will provide space heat in the morning and afternoon, and then restrict the flow (and allow the temp to rise) during the midday to produce DHW?
Wallyworld said:I made a 10 by 16 copper aluminum collector following what Gary did on www.builditsolar.com. Wasn't hard to do, took some time and so far its done what I wanted it to do and thats keep my shop from freezing. I'm using it on a radiant floor, 22 yds of concrete, 1100 feet of 1/2 pex buried in the crete. Lowest temp I've seen yet is 44 and this has been a rough winter for sunshine here in Maine, lots of snow, average temps. I have a stove for when I'm out there for any length of time but I've found when temps is around 50 I can do some work pretty comfortably for a hour or 2. Its obvious I need more collector to really do the job but I thinks its worked pretty well considering. I have $2500 or so in the whole setup including the pex in the floor. Lots of labor but I'm not a slave to heating my shop, and based on my experience with solar DHW in my house maintenance should be minimal. One thing I thought once february hit I'd see high temps in my floor but it takes some energy to get 22 yds of 44 degree concrete up. My Delta T across the collector is usually 5 or 6 degrees.
Wallyworld said:I made a 10 by 16 copper aluminum collector following what Gary did on www.builditsolar.com. Wasn't hard to do, took some time and so far its done what I wanted it to do and thats keep my shop from freezing. I'm using it on a radiant floor, 22 yds of concrete, 1100 feet of 1/2 pex buried in the crete. Lowest temp I've seen yet is 44 and this has been a rough winter for sunshine here in Maine, lots of snow, average temps. I have a stove for when I'm out there for any length of time but I've found when temps is around 50 I can do some work pretty comfortably for a hour or 2. Its obvious I need more collector to really do the job but I thinks its worked pretty well considering. I have $2500 or so in the whole setup including the pex in the floor. Lots of labor but I'm not a slave to heating my shop, and based on my experience with solar DHW in my house maintenance should be minimal. One thing I thought once february hit I'd see high temps in my floor but it takes some energy to get 22 yds of 44 degree concrete up. My Delta T across the collector is usually 5 or 6 degrees.
benjamin said:Dang! I'm jealous. That's a lot better performance than I'd expect, you must have a pretty tight shop there. I don't know what kind of underslab insulation you have, but regardless, the subsoil has cooled off over the course of the winter, which is holding down the temp. Even if the solar barely keeps the temp above freezing, the heat sure helps keep things dry. I've been planning to do something similar eventually, about 12'x28' vertical unglazed steel and poly collector, ie black painted rib formed steel siding with 3/4 poly run in the ribs, extremely low efficiency, but high btu/$. I don't mind working in freezing temps at all, especially if there's sun coming in the sliding glass door, I'd be happy to keep my tools dry.
Gary, another excellent writeup and excellent system. IMHO the best system out there for retrofit to conventional construction, bar none. Your discussion of optimizing for heat vs hot water said what I was trying to say a lot better.
If I ever get it done I'll send you some alternative ideas for solar heat/storage for unconventional construction, as if there aren't enough of those already!
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