1 oopsie...linky on da blinky.

2 You're oppressing me with your patriarchal ideas that all links have to go somewhere. Why? Maybe a link can be enjoyed all on its own without some sort of testosterone-driven notion that it has to "go" to another website. I'm trying to help my readers evolve to the point that they enjoy the more static, woman-friendly static links that will encourage them to look inward for answers. Either that, or I blew it again . . .

3 And look! It took me only nine minutes to oppress you with my testosterone-driven demand for functional links! That must mean I'm stalking you as well. I don't see a real breakthrough for solar power until the present worth of unsubsidized solar power installations exceeds that of other energy sources. As it is right now, even many subsidy programs make it barely a breakeven proposition over the expected twenty year lifespan of the equipment. For this to happen, the cost per watt has to come down substantially.

4 I think David's point about safe, cheap storage was pretty important. I assume that in your neck of the woods, as in mine, solar is pretty universal for the heating of swimming pools--not that such a fringe use will lead solar to the tipping point, but it does help, no?

5 Well, no it doesn't help. You are talking apples, oranges and kumquats. The solar pool heaters don't use silicon in their manufacture--not the purified grade, anyway, that goes into photovoltaic(PV) panels and silicon chips. Solar thermal panels are essentially pipes in a box, sometimes with a glass(yes, silica, but not the kind we are talking about) front panel. And in the short-term, PV panel costs(and silicon chips)will rise as they both compete for the same scarce supply of purified silicon. The new plants will help--maybe--assuming they do their homework to increase process efficiency(or increase plant throughput) to offset the higher costs associated with the newer costruction. The balance of sytem(BOS) costs exceed the cost of the panels now, and probably will for the foreseeable future. These costs include the power inverters, power conditioners, storage batteries, wiring, disconnects, panel protection diodes, panel supports, etc. Unit cost O&M on some of the more delicate components can exceed the cost of utility-purchased power by itself. Without the subsidies, PV wouldn't have a prayer. No breakthroughs---yet. Your best bet to use solar power economically is still passive solar. And will be for quite some time.

6 So, on a cold day I should just go read in my car, where the sun makes it nice and toasty?

7 Precisely! Maybe with cashmerer gloves, hats, and socks for your size 5s... Right now all these active solar projects just make people feel good at great expense to society---taxpayers. The money would be better put to use on projects that don't cost 2-5 times more than the conventional alternative. Or on projects to actually save people money, like insulation, upgrading ineffeicient space conditioning equipment, etc. As a nation, we have to take advantage of the geothermal resources sitting free beneath our feet. And get known, available equipment like gas and electric heat pumps to a broader audience. Don't forget utility-scale power generation, either.

8 Darrell..what do you mean by "Don't forget utility-scale power generation?" Also, consider that the power electronics surrounding solar is also subject to scale economies, and these may be helped by the increasing role played by electricity for automotive applications.

9 We haven't begun to take advantage of the potential for large-scale(100-600MW) solar thermal plants in areas of the country where it makes sense, like the Southwest. Economic incentives here make a lot more sense than for individual residential systems. The exceptions are cheap and quick solutions that should be part of all new construction like supplemental water/pool heating, and readily-available and well-understood little tricks like Trombe walls. Sure, I'm all for cheaper and more reliable power inverters and conditioners, and storage batteries. Hybrids will help here, but I don't know how much. I can't wait for automotive fuel cells! Or better/cheaper DC motors, for that matter and DC appliances of all sorts to avoid the necessity of power inverters.

10 Solar thermal...I believe this refers to using mirrors to concentrate solar energy on a boiler of some kind, and then generate the electricity with a heat engine in the normal way? (I think I've heard this referred to the "tower of power" concept) For large-scale use, this may have some significant advantages over solar cells...for one thing, there would be at least some inherent storage capacity, maybe several hours' worth if something like molten salt is used in the cycle. I wonder how the mirrors all get cleaned, though..robots? Or a new career opportunity, "solar mirror cleaner"....

11 Solar thermal is reserved for any use where you are just interested in the heat, like those solar water heaters. For utility applications, you can have mirrored parabolic troughs with a pipe running above, or the central power tower you described, with mirrors concentrating the solar energy on the tower. Yes, they do clean them and some have built-in systems to assist. And, no. They don't do it at night. They move the mirrrors... There is another solar thermal strategy by the way, OTEC--ocean thermal energy conversion relying on the differences in water temp at the surface and deep below. Wind energy is technically solar thermal, also. I know LMA is a stickler for completeness and I don't want to face her wrath!