The following link will take you to the California Department of Housing and Community Development, CA Accessory Dwelling Unit Handbook. The Handbook provides excellent information on Accessory Dwelling Units (ADUs) and Junior ADUs (JADUs), including recent statutory requirements for the permitting of ADUs/JADUs.
The Solano County ADU Handout describes rules and regulations that the County has adopted relating to ADUs and JADUs.
The recently adopted Ordinance 2020-1817 amended Chapter 28 Zoning Regulations regarding Dwellings, including Accessory Dwellings and Junior Accessory Dwellings.
Additional resources regarding Accessory Dwelling Units (ADUs):