Enrichment means increasing the ratio of the U-235 isotope (which is the fissile fuel for the reactor) to the non-fissile U-238 which is not fissile. Uranium as mined is only about 0.7% U-235. This is not enough to sustain a nuclear chain reaction so it is enriched to 3~5% for used in most power reactors. This is why 99.3% of all the refined uranium is of no use for power generation in typical reactors (it is called depleted uranium). This is also why people who talk about "peak uranium" should be careful to specify U-235, there is plenty of U-238.

Thorium does not need to be "enriched". A thorium reactor first converts Th-232 to U-233 which is fissile. All of the Th-232 can potentially be converted to U-233.

U-233 is probably not a significant proliferation risk, as produced it is inevitably contaminated with U-232 which produces hard gamma radiation from its decay products(pdf). This makes it very hard to handle and very easy to detect, not great attributes for building a bomb.

A more credible proliferation risk (IMHO) is that once you've perfected breeding U-233 from Th-232, you might well have gained all the expertize you need to breed Pu-239 from U-238.

Thank the Japanese & Europeans for lead-free solder. CA had nothing to do with it.

The original point you made is basically FUD. It's little different from the "OMG peak Uranium!" FUD that started the topic. Billions of dollars have been spent by pretty conservative bankers on building utility scale solar plants, based in part on reliability assumptions of the panels (because its fundamental to the rate of return they will earn on their investment). A lot of science and engineering was done to convince them it was a sound investment. So if you think they've all made a huge mistake then please tell us how.

The reliability tests that are used to certify panels today are the result of 30 years of study and testing of panels in the field. They are the best ways we know to test reliability to ensure the rated lifetime. Its fine to be skeptical, but go study the science and at least be an informed skeptic. One good place to start would be this History of Accelerated and Qualification Testing of Terrestrial Photovoltaic Modules: A Literature Review(pdf).

The fact that I have personally seen old panels still working is not an anecdote. Especially as it's used to illustrate the point that there is existence proof that at least some panels can last that long. The facility I visited is called PVUSA in Davis CA, it was built in 1986. Its well worth a tour to see how solar technology has evolved over the last 25 odd years often in response to the reliability issues discovered there.

We respect to recycling, First Solar offers a recycling program today. This is mainly to address the issues of the Cadmium in the panels escaping into the environment if the panels were dumped. However it is very reasonable to assume that the precious metals in a solar panels can be recovered using methods that exist today to recycle old electronics. The materials used are very similar (glass, Silicon, Aluminum, Copper, Silver, numerous organic resins & some polymers). Whether it will be economic or not remains to be seen.

Solar is very happy to be in deserts and on dry arid land that is of little alternative use. Solar farms are also relatively less harmful to the immediate environment - you will see a lot more wildlife in and around a solar farm than you see inside the typical coal fired power plant. Nobody thinks we would use lead batteries for grid scale energy storage. More realistic low tech solutions are hydro - pump water up a mountain, thermal - store hot water or molten salt in underground caverns or compressed air in caverns. A high tech solution would be flow batteries which are cool but still small scale and early stage.

Today's panel are certified for a life of 20 years, they will very likely last longer. I have seen panels that were manufactured in the early 80's still generating power after 25 years. Quality panels made today are quite a bit better than those early efforts, due to the last 30 years of putting panels outside and testing them. We may not get 50 years like a coal plant, but you won't have spent a bundle on maintenance over their life either. Then after everything is done you can recycle them.

Yes, why isn't anyone talking about the horror of peak silicon! The vast bulk of material in a solar panel by weight is silicon in the form of solar cells and glass. It's the second most abundant element in the Earth's crust so we will run out of it just before we run out of oxygen. There are other rarer elements in solar panels such as silver for example, but only very small amounts are used and people are working hard to find cheap (i.e. common & abundant) replacements.