Price per watt of solar PV is on an exponentially improving trend line, since the late 1970s. http://cleantechnica.com/2013/05/24/solar-powers-massive-price-dr

Price per watt of solar PV is on an exponentially improving trend line, since the late 1970s. http://cleantechnica.com/2013/05/24/solar-powers-massive-price-drop-graph/ http://cleantechnica.com/2013/05/24/solar-powers-massive-pri... Natural gas is, well, much less predictable. But hasn't gone below its 1990s price. http://www.tradingeconomics.com/commodity/natural-gas http://www.tradingeconomics.com/commodity/natural-gas