Besides the difficulty of convincing the people’s representatives to pass such
a law, the first technical problem faced would be the intermittent nature of the solar
radiation, available only during the day and strongly reduced in overcast skies. Energy
storage would solve this problem but no cheap storage method appears on the horizon.
Nevertheless, well-developed electric grids may accept large amounts of PV electricity
by turning off some conventional power plants when PV plants are delivering power.
Adequate grid management would allow up to 20 to 30% of the electric production to
be intermittent [4].