More expensive houses for now, but maybe cheaper in the long run C alifornia has become the first state to require that new homes be built with solar panels. The rules go into place in 2020 and are part of the state’s ambitious efforts to cut greenhouse gas emissions. But these requirements also make it more expensive to build in a state where housing is already extremely expensive. The new building rules approved by the California Energy Commission apply to all residential buildings up to three stories high (including both single-family buildings and condos). They’ll no doubt help California reach its goal of having at least half of electricity come from renewable energy by 2030. Solar is already responsible for about 16 percent of California electricity. But the new regulations mean that houses will be $8,000 to $12,000 more expensive, according to The New York Times . That’s especially fraught in a state where the median price of a sing...