The rules take effect in 2020 for all new home construction and major renovations. Though it will increase the upfront cost of a new home (a little), overall it will decrease total monthly costs for the homeowner. Current estimates are a $40 monthly increase in mortgage payments in exchange for an $80 monthly savings on utility bills.
Mandatory solar is part of the California Energy Commission’s (CEC) Title 24 rules, along with more stringent energy efficiency standards. The efficiency and the solar together are intended to reduce the home’s electricity use to zero kWh annually!
These new rules do not address the existing housing stock. Because existing homes are generally not as efficient as new construction, the economic payback for solar can be much higher for existing homes. Those who currently own their own home can capture the full 30% solar tax credit if they go solar in 2018 or 2019. And even if they finance their system purchase, their loan payments will generally be less than their utility savings.