When will be the time for switch-over
The rise of Big Solar: Growing pains | The Economist
"Solar energy is popular because it is clean and abundant. The problem is that it remains expensive. According to recent calculations by the International Energy Agency, power from photovoltaic systems (solar cells) costs $200-600 a megawatt-hour, depending on the efficiency of the installation and the discount rate applied to future output. That compares with $50-70 per MWh for onshore wind power in America, by the IEA’s reckoning, and even lower prices for power from fossil fuels, unless taxes on greenhouse-gas emissions are included. The costs of solar are dropping; in some sunny places it may, in a few years, be possible to get solar electricity as cheaply from a set of panels as from the grid, and later on for solar to compete with conventional ways of putting electricity into the grid. But for the moment there would be no significant market for solar cells were it not for government subsidies."