Here in California there is a law called Net Metering that requires the power utility to buy electrical power from a residential system at commercial rates - BUT only up to the dollar value of the power consumed by the residence.

While this is a fairly good deal for high electrical power users who can bankroll a big solar array to generate during the day to pay off heavy usage at night, it does not really provide much incentive to the average citizen.

A simple change in this law to require power utilities to buy ALL the generated power and pay the citizen for ALL the power in excess of their usage would have two huge incentives:

1) investment in a solar array would become a profit source for the citizen

2) to maximize profit, citizens would be motivated to be more efficient

These motivations would stimulate substantial investment in residential solar systems with a net power generated during peak usage times during daylight would still be a good deal for the power utilities instead of adding more capacity in centralized power stations - nuclear, coal, etc.