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I don't think I've ever seen a more undeserved insightful mod. That was non-specific heckling without a point.

Here are some points for you: the amount of innovation in green energy is tremendous these days. Take your pick, some of these are from this very site:

24/7 baseload electricity from the sun for utilities, great for sunny climates, cost-competitive with coal
Steady large-scale wind power from stacked kites
Cutting consumption and greenhouse gasses with microgrids
As seen on this very site, cost-effective solar thermal energy used to drive a stirling engine
Highly cost-effective thin-film solar electricity
Solar thermal panels for directly heating water
For efficiency, passive solar design for buildings
Inserting vertical wind turbines into electric towers for using existing structure
Tidal energy, pros and cons; Denmark certainly believes in the pros

That's just off the top of my head. Renewable energy is a matter of studying your surroundings and finding what is appropriate. Each locale is different, and of course, all of us can benefit from more efficient design than what we used on this past century while presuming that fossil fuel energy is cheap and disposable. All we need to do is stop being sloppy and wasteful. ...Or you can just be pointlessly negative on the internet. :)

With all that said, I recall seeing that the best rate of return (much higher than stocks, etc.) can be had by investing in a solar water system for your hot water needs. Even in Canada, it is possible to get more than 50% of your hot water needs via solar, and I am sure that most readers here are in places with better numbers than that. These folks claim a return rate of around 15% - and again this is "tax free".

I looked into PV panels for the roof of my home, which is not large, and does not use electric heat. $80k to provide for my electricity requirements. I was hoping it would be 1/5 that, as loan repayments would be reasonable if I had a zero electric bill in summer and a small bill in winter. Unless the quote I had gotten was way off, it doesn't seem feasible in the short-term.

The flip-side to that, is that I live in a 30 year old home. From what I understand, new construction can be had that will greatly reduce heating and cooling costs while increasing the price of the home by small (around 10%) amount, via passive solar heating and natural cooling.

Does anyone realize there is a really big one of these powering a community in Arizona? http://www.azsolarcenter.com/technology/electric.h tml

Indeed, I took the cell numbers as functionally equivalent to module efficiency (ie mirrors can be 98+% efficient). But reading the literature, It's clear that cheap is the goal (cheap focusing elements). In fact, the production price for multijunction concentrators being discussed is 12-50 cents/Wp. WOW! $0.12/Wp for 30 years is $0.0015/kWh! (of course this doesn't include BOS, but even with, its amazing)
Commercial Efficiencies:
Entech - 30% net concentrator efficiency, 33% cells (2001)
Sharp - 28% net concentrator efficiency (FYI-uses non imaging optics)
Sharp - 17.4% MODULE efficiency (not cell)
Sunpower - 16.5% MODULE efficiency (21.5% cells)

Now take into consideration that the spectrapower cells Entech is using are now up to 37.3% (2004) efficiency, which will increase module efficiency to 33.5% from their 2001 announcement (which is in line with a claims of the VC I spoke with).

So at 30% efficiency (using published value) we need to increase our land base values by 33%. So All US ENERGY Needs from 13,491 Mi^2 or 5% of TEXAS (including shading at an average of 1800 kwh/m^2/year).

Thanks for calling that one, I'll update my database of facts. I haven't been reading the solar journals very closely over the last 4-5 years as the company I am working for is developing storage technologies, so I put most my time that technology and market trends therein (which we will get to).

Indeed, I took the cell numbers as functionally equivalent to module efficiency (ie mirrors can be 98+% efficient). But reading the literature, It's clear that cheap is the goal (cheap focusing elements). In fact, the production price for multijunction concentrators being discussed is 12-50 cents/Wp. WOW! $0.12/Wp for 30 years is $0.0015/kWh! (of course this doesn't include BOS, but even with, its amazing)
Commercial Efficiencies:
Entech - 30% net concentrator efficiency, 33% cells (2001)
Sharp - 28% net concentrator efficiency (FYI-uses non imaging optics)
Sharp - 17.4% MODULE efficiency (not cell)
Sunpower - 16.5% MODULE efficiency (21.5% cells)

Now take into consideration that the spectrapower cells Entech is using are now up to 37.3% (2004) efficiency, which will increase module efficiency to 33.5% from their 2001 announcement (which is in line with a claims of the VC I spoke with).

So at 30% efficiency (using published value) we need to increase our land base values by 33%. So All US ENERGY Needs from 13,491 Mi^2 or 5% of TEXAS (including shading at an average of 1800 kwh/m^2/year).

Thanks for calling that one, I'll update my database of facts. I haven't been reading the solar journals very closely over the last 4-5 years as the company I am working for is developing storage technologies, so I put most my time that technology and market trends therein (which we will get to).