Well, it was certainly an eventful year for the solar power industry. Torrid growth led to serious supply constraints that have only recently eased. Those same growth rates led to some very lofty investor expectations, which have in turn led to some severe disappointments, not to mention capital losses.

I know many solar investors would just as soon wipe their memories of 2008, but I think it's important to take a look back. My intent here is to touch on some key themes and developments, and also to critique my own coverage of the space.

Early warning signs
In January, solar stocks got clocked. Rather than grasp for a causal factor, I interpreted the selloff as a signal of a "speculative component built into these companies' share prices." My colleague Jim Gillies went further, tapping First Solar (NASDAQ:FSLR) as the worst stock for 2008, citing similar valuation concerns. Jim was on the right track, but a 50% decline would actually mark First Solar as one of the best performers in the space!

Also in January, I told Fools to stay away from a recently IPO'd solar integrator with "no discernable competitive moat." That one's now adrift in microcap land. My skepticism at the outset of the year may have won me few fans, but it proved to be the right approach.

The following month, Suntech Power (NYSE:STP) slumped further when it merely maintained production guidance. One could hardly blame them for easing off the accelerator, given the prevailing spot polysilicon prices, but the plunge was another indication of sky-high expectations.

The silicon squeeze drives deals, innovation
In March, I took note of Canadian Solar's adoption of upgraded metallurgical-grade (UMG) silicon. This low-cost alternative to polysilicon fired up a lot of investor imaginations, particularly in the case of Timminco, a Canadian stock that achieved a multi-billion dollar valuation on the back of some pretty far-fetched claims. UMG has also been embraced by Q-Cells and Trina Solar (NYSE:TSL), but it's hard to say whether this lower-quality material will remain relevant as polysilicon prices plunge.

While developments in UMG silicon were notable, thin-film solar technology was clearly the star of 2008. Having witnessed First Solar's high-margin magic, new entrants began piling in by the boatload. General Electric (NYSE:GE) upped its stake in one such startup, while IBM (NYSE:IBM) launched a thin-film venture of its own. Perhaps most dramatic was the rise of Nanosolar, whose semiconductor printing technology attracted hundreds of millions of dollars in venture backing. Disruptive firms like Nanosolar and Konarka are a key reason I've refrained from investing in any of the current crop of public solar companies.

A spring in solar's step
By April, all it took to send a solar stock skyward was an announcement that the firm had secured additional polysilicon supply. Even Trina's agreement with GCL Silicon, a firm with a limited and spotty track record, was treated like a treasure trove. Interestingly, within two weeks of this deal, the silicon capacity outlook had cleared up enough to convince Trina to scrap its move into poly production.

In May, when many solar stocks were soaring, I introduced readers to a few more players for the first time. Whereas my ReneSola (NYSE:SOL) piece was right on target with its focus on potential hurdles, my take on JA Solar (NASDAQ:JASO) was largely uncritical, and I regret that article perhaps most of the five dozen solar pieces I penned this year.

June saw domestic utilities begin to show their appetite for solar even in the absence of a clear regulatory framework. Duke Energy dipped a toe into the market, whereas SoCal Edison went whole hog with a huge solar thermal project.

Shifting summer sentiments
In July, I delivered a pair of scathing solar pieces. By this time, I had become deeply concerned about the cash consumption of certain rapidly growing solar shops, and I pulled no punches here. I got pilloried for these articles, but if I prevented even a handful of Fools from losing (even more) money in the months that followed, it was well worth the angry emails.

The summer months also saw shifts in governmental support for various solar markets. Germany cut its subsidies to a shallower degree than was feared, whereas Spain's new cap led to a dramatic drop in demand for SunPower and others. Meanwhile, Japan increased support for solar, and the U.S. Senate took a shine to the energy source, with a generous eight-year tax credit extension.

Falling flat
After Lehman Brothers did its face plant, the solar picture darkened considerably. Some of the fallout was direct, as was the case with Evergreen Solar's suddenly corporeal phantom shares. More broadly, the full-blown credit implosion led to order delays and outright cancellations. JA Solar idled 40% of its production lines, and Suntech froze its expansion plans.

And that, my Foolish friends, more or less brings us up to date. While I expect at least one or two public solar companies to perish in 2009, the ablest competitors will keep pressing toward grid parity. It's impossible to say what the next 12 months will bring, but I'll be here to give you my take on all the twists and turns.

Suntech Power is a Rule Breakers pick, and Duke Energy is an Income Investor selection. See if you take a shine to any of our Foolish newsletters with a free 30-day trial.

Fool contributor Toby Shute doesn't have a position in any company mentioned. The Motley Fool has a disclosure policy.