There are non zero probabilities that by 2030 we might have some or all of (i) thin film solar
cells with 40 % efficiency installed for $ 1 /
watt, (ii) «
batteries» with at least five times the capacity of lead acid and one fifth of the weight, (iii) boring old solar thermal plants with no drama plugging away, (iv) there may be some one using solar
cells in space sending power to earth as radio frequency energy.