I'm not aware of any solar tax credit on a CA tax return. The 30% credit that you read about is on the federal return.
They do have some rebate programs and incentives, but I haven't seen any credits that are taken on the tax return itself.
Lisa995 is correct; California discontinued any tax credit some time ago. As she notes, there is still a rebate program for both solar panels and residential energy storage. Note that parts of this program have run out of the initial allocated money and that there are waitlists pending new funds.
Read all about this and apply at https://www.selfgenca.com/