Finished my solar-heated winter watering system the other day and was so excited to see if it worked! I set it outside just before a couple of 30* nights.
Not too bad looking for being made out of scraps, eh?
To test it, I put two identical buckets outside at the same time. Each had two gallons of water and both started at 63*. One was tucked inside the solar heater, the other set outside exposed.
By mid-morning the temp outside had reached 41* and was rainy when I checked on them. The one inside the solar heater was at 55*. Ok, but the other was surely at 41, right? Nope… at 52*, a mere 3* difference.
But water’s a great heat sink, so… maybe I just needed to give the buckets more time to differentiate? Or maybe it was too overcast to really heat up the solar water.
The next morning was clear and 45* after a night in the 30s. The exposed bucket was at 44*, and the solar bucket? … a disappointing 49*. 5* difference? That’s it? And the same the next time I checked as well. A puny 5* sure ain’t gonna keep the water from freezing when the daytime high is 20*!
Well, crap. They can’t all work out, I guess.
I still think the idea of a solar water heater is solid in theory though, and worth seeing if I can rework it. Some ideas:
- replacing the wood panel in the front with glass (somehow), to remove the shadow on the bucket. No idea how I’d do this and keep it structurally sound. Maybe I can just cut a window in the wood panel instead of remove it completely?
- Maybe there needs to be something inside that can suck up more heat and release it slowly at night to help out the water – like a thick sheet of metal painted black. Or something.
- Maybe I need to think more along the lines of a solar cooker instead of the dehydrator that was my inspiration (in a dehydrator the food ought not be exposed to sunlight). I notice that in solar cookers, there are huge slanted reflective panels to direct the sunlight directly at the target. Like the one below, retailing for a cool $99 from amazon.com.
Failures just teach us more, right? (Actually I’m not all that disappointed – I’m kind of excited to fool around with it more and see if I can make it better.)
Any more ideas? Leave me a comment, lemme know!