[link to www.nbcbayarea.com (secure)]
California moved a step closer Wednesday to requiring solar panels on new homes and low-rise apartment buildings starting in 2020, the first such mandate nationwide and the state's latest step to curb greenhouse gas emissions.

"Adoption of these standards represents a quantum leap in statewide building standards," said Robert Raymer, technical director for the California Building Industry Association. "You can bet every other of the 49 states will be watching closely to see what happens."

-Less then 50%

I'm assuming this will add several thousand to a brand new home. In times people can hardly make ends meet. If it's made so, then we can for sure see all the Liberal states follow. Driving up housing costs. Then just a matter of time before existing housing will be mandated to 'upgrade'.