The size of your PV system will depend on a number of factors including your energy usage, roof configuration, and goals. For example, some customers seek to maximize their return on investment by sizing their system to reduce their usage just enough to avoid paying for electricity at extremely expensive high-tier rates. Other customers opt to eliminate their carbon footprint by sizing their system to offset 100% of their usage.
The purpose of net metering is to install a system to meet the on-site electricity use. All net metered customers are required to interconnect with PG&E’s grid and PG&E does not generally allow customers to interconnect systems that exceed 110% of on-site electric demand.