The submitter used the word "poorest", which seems chosen rather... poorly. The SFGate article uses the somewhat less extreme term "low income", but toward the end it is also more specific about the criteria: "To qualify, applicants must live in a neighborhood designated as disadvantaged by the state. They must own their homes and make no more than 80 percent of their community’s median household income." The provider, GRID Alternatives, promises "to make renewable energy technology and job training accessible to underserved communities", which seems more in line with what is actually going on.
So, one view of this is that this is a program to direct cap-and-trade money (generally collected to be used specifically for environmentally beneficial projects) into areas of the state that wouldn't get it otherwise. It uses donated equipment and labor as well as the C&T funding, so it's not at all tax funded. Besides helping recipients in the targeted areas get cheaper power, it is possibly reducing overall electricity demand in a green way (though this is debatable, given the limits of solar power as a baseload source).