Freddy wrote:I sum it up this way: Solar power.... make hot air, OK idea. Make domestic hot water, pretty good idea. Make electricity, dumb idea.
If I was going to try to heat with solar I would go with evacuated tube collectors like they use for DHW. The vacume tubes allow them to produce 180* hot water even on a -20* day. Radiant floor heating works with 120* water as opposed to 180* for baseboard hot water. Put a 1500 gallon water tank down cellar and heat it to 180 degrees during the day. That's 12,000 lbs of water. It would give off 12,000 x 60 = 720,000 BTU when cooling from 180 to 120. That is equivelent to 5 gallons of oil which is enough to heat my house on an average winter day. A 20 tube collector is supposed to provide 40,000 BTU per day, so I would need 720/40=18 collectors to heat the water at $1000 per collector. By the time everything was installed I would be looking at around $30,000.
I would still need to keep my current heating system in place to cover cloudy days or extreamly cold weather. It would still cost something to run the circulator pumps. Assuming it saved 600 gallons of oil a year it would pay for itself in about 30 years if oil prices stay the same. Of course in the real world oil prices are going to go up, as will other energy costs, so the payback time will be less. But even with rising energy costs I don't see that system paying for itself in what's left of my life time.
For someone younger with a long future of rising energy costs to look forward to it would be worth considering, especially as the costs for building a system decline. Up till now the tubes have been pricey but that is changing. Might be worth it to go with a smaller system that could cover all heating till it got down to 30* and then just suplimented my coal heat below that temp. That would allow me to fully utilize my investment over a larger portion of the year.
I know there is no love lost between us folks that are just trying to get by and the save the world greentards, but there is nothing wrong with saving resources if it saves you money too. I drive a Prius, not because it's going to save the world, but because 50 mpg saves me money. It also does ok hauling coal