Re: Art, where's the buzz on nanotech saving America today?

Straydog wrote:

<snip>

You guys are not reading the newspapers. I don't have it handy, but there were about two WSJ articles where out in california quite a few new homes have solar panels built in (they get a tax break, I think) as a supplement
in case they have brownouts or rolling blackouts and everyone is happy with the direction this is going in. Its got a long way to go but the technology is already here and been here for 1-2 decades.


I know what you're referring to as, if I remember correctly, it has the backing of the governor. What I meant was about how systems are designed and what the present technology is like.

PV modules can convert only a small fraction of the available insolation into electricity. One of the main limitations is the semiconductor materials that are used. Until something more efficient becomes available, there's little that can be done about it.


Everyone knows this. The point is that solar power is now, in low unit quantities, a $7 per watt source of renewable energy.

Compared with about $1/W for a liquid-fuelled IC engine generator.

Last night I
looked up the electric generation capacity in the USA and made a very very very rough calculation that if the DoD budget were diverted to solar power generation, we could be totally off non-renewable, non-radioactive, no waste products energy sources in about 100 years. That is all with
_existing_ technology, the _existing_ conversion efficiency, and no unknowns o
r breakthroughs needed. If we had started some 30 years ago, we would be
about 1/3 the way and research of all kinds might have improved cost/unit
figures and maybe even lifetime and efficiency.

Back then, PV and WTGs weren't economically competitive with conventional energy sources, plus many people had a "What, me worry?" attitude, along with lots of NIMBY.


PV module capacities are, at the most, on the order of a few hundred peak watts. That means that if one were to use them to, say, power a house, they would need a large area of land to properly site and space them.


I made rough calculations and found that about 1/2 of the area that is needed is already on 1-story house roofs.

But, as I mentioned earlier, they won't be as effective as those modules that have variable tilt angles and, possibly, trackers. This assumes that the modules are located in flat open areas. Locating them in surroundings where there are reflective surfaces or, for that matter, anything which shades them changes their performance.

The rest could be obtained by
using a "fence" behind the house. I thought about this for our retirement house but at my age would not recoup the investment before I died. It would take commitment at an early age.

Building

them into houses restricts their usefulness as their orientations would be fixed. In order to better utilize the available insolation over the year, the elevation angle should change to follow the angle of the sun with respect to the horizon. In some cases, modules can be set up to follow the sun during the day using solar trackers, but that can make the installation more expensive.


My brother got into the panels about 10+ years ago. Gets about 1/3 of all of his electricity needs. And, he used only a fraction of his house roof.

There are several ways one can accomplish this. One is to reduce overall load demand at a given time, which, depending on what essential appliances one has (such as a fridge or stove), might not be that easy. Another is to shift the use of such appliances or, for that matter, peak load demand to a more convenient time of day. That's something I plan on investigating.


A lot of systems are over-sized, so that means that a lot of the power they produce could be wasted after meeting the required load demand.


Or fed back into the grid and make money for the owner.

Subject to applicable regulations. There are people, however, who attach their PV systems to the grid without permission. Doing that is very foolish as their connections are often of poor quality and would never pass inspection even if they were legitimate.


Some of it

can be stored, but that's limited by battery size as well as the charging current. (Avoiding gassing is important, particularly if one uses, say, lead-acid batteries.) Unless one has either an auxiliary load, which operates if the power is available, or it can be put into a utility grid (obtaining permission to do that can prove to be a regulatory headache),


At least in some areas the laws are already on the books to just read the meter even if it runs backwards and pay the owner.

I know of someone who set up his house to run on PV and sell the excess back into the grid. Getting permission, not just from civil authorities but his neighbours as well, took him several years.


whatever's left is often dissipated.


Better put on the thinking cap and do something with it. At least I would.

Optimizing the surplus or deficit is critical. That was one of the things I investigated for my thesis and which I'm working on right now.



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