I used annual averages from the EIA. This smooths out short term variations (I am looking at a 30-40 year trend). Also be sure whatever price history you're usi

I used annual averages from the EIA. This smooths out short term variations (I am looking at a 30-40 year trend). Also be sure whatever price history you're using is adjusted for inflation. That said, even with short term price fluctuations, the decrease in solar energy costs (100:1) trumps the variation in conventional energy commodities (5:1). The point of the article is the long-term "moore's law" trend and how that will play out over the next 10-20 years.