Mass production of both along with greater effieciencies in manufacturing and installation. There are huge factories that churn out solar panels, and the instal

Mass production of both along with greater effieciencies in manufacturing and installation. There are huge factories that churn out solar panels, and the installation systems have become simpler and faster. On the domestic side it can now take just a couple of hours to fit the panels once the brackets are in place, it used to take a day or more. Basically both technologies have been matruring for a number of years, getting cheaper and better at the same time, so the cost per kwh drops. On the wind side of things, the turbines have also got larger, which increases output significantly (power is proportional to the square of blade length, roughly). We also seem to have hit a price point where there is ample capital to invest in projects of all scales. Add in the flexibility of gas to deal with varying demand and the you have a better market to invest.