Although the recent increase in the adoption of solar PV may come as some surprise to those who aren’t ‘in the loop’ when it comes to advances in renewable energy technology and materials, the solar insiders have been foretelling the coming solar revolution for years. And while we’ve still got a ways to go to see a significant portion of electricity markets dominated by solar, the economics of going solar are already profitable in a lot of places in the world, whether it’s installing a residential solar array or developing a major solar plant, so it’s not a ‘fringe’ or marginal technology by any means.

Solar advocates have been saying for years that it’s only a matter of time before PV becomes a highly cost-effective energy source, and now it turns out that at least one of the ‘Big Energy’ companies has known that as well, but chose to steer clear of investing in it anyways, according to a recent article at Bloomberg.

One of the linchpins of affordable solar has been the cost of crystalline silicon, which is one of the major inputs of solar cell manufacturing, and which was somewhere north of $400 per kilogram in 2008. In order to build a viable product for the end customer, the cost per watt has to be worth the investment, which with high-cost silicon was harder to do. However, a radical drop in the price of silicon began that year, and lasted through 2011, with the price dropping some 94%, and continuing to slowly fall, with a current price of about $15 per kilogram, according to author Eric Roston.

In the article, Peter Eisenberger, a former senior Exxon R&D director and now an environmental science professor, is said to have co-authored an internal report about the cost of solar power back in the mid-80s, after oil prices fell drastically. The conclusion of the now 25-year old report was that the authors foretold that solar would be a worthwhile investment for the company starting sometime around 2012, which happens to be right around the time when solar PV technology did actually start to become truly affordable.

So why did Exxon not pursue solar, knowing it would eventually be a major player in the future of energy?

According to Bloomberg, the answer, at least in part, was the report’s prediction that the future of solar was solar thermal, not PV:

“The report predicted that utilities would embrace solar-thermal power plants, huge mirror arrays that concentrate and store heat. The economics of that technology have turned to be less favorable than those of solar panels installed on homes and businesses—or even, it turns out, in utility-scale facilities.”

Interestingly enough, even in light of advances in solar and a shift in consumer attitudes toward energy, the big oil company still isn’t making major inroads into renewables, other than at a research level, according to the article:

“The oil giant continues to support research into photovoltaics, as well as biofuels and CO2 capture technologies. But as Exxon CEO Rex Tillerson told investors in May, the company isn’t investing in renewable businesses. “We choose not to lose money on purpose,” he said.”