20 years ago, home prices in California were not much different than they are today, when things are still recovering from the collapse of the housing market. You'd have to go back at least 40 years to find home prices that would be attainable for even the lower middle class.
And even then, most of the cheaper homes were condos, not houses, and condos always have associations, and associations always have fees. And Prop 13 or no, property taxes have to be paid. So even if someone bought their home in better days, odds are, if there is any non-insane way to describe them as "poor" now, they no longer have a place to install solar panels.
Either the headline is idiotic bullshit, or California is now giving solar panels to the homeless (who might, in fact, be able to use them to charge their smart phones, this being California, and all).