Electric cars hooked to renewable sources of energy like roofsolar are a major component of the kind of carbon-free infrastructure required to keep temperatures below the critical ceiling as defined by the International Panel on Climate Change. The good news is that the market for electric cars has been booming. Sales in 2014 in the world’s 10 biggest markets increased by 72% over 2013. One major reason is the steady decline in the cost of batteries, EV’s main component. According to a study published in Nature Climate Change, the cost of battery packs used by market-leading battery electric vehicles manufacturers stands at US$300 per kWh. That’s the tipping point that the International Energy Agency estimated would enable electric vehicles to achieve cost parity with internal combustion engine. Its 2013 analysis had concluded, however, that this would not happen before 2020. Fortunately, it seems the industry is in a hurry after all.