Environmental and Economic Impacts of Early Residential Photovoltaic Retirement in California

Photovoltaic modules have an expected lifetime of 25–30 years, yet premature replacements due to weather damage or declining efficiency can shorten their operational period. This study evaluates whether residential solar systems replaced early in California generated sufficient electricity to offset their economic cost and the carbon and energy expended in their manufacturing. Information on photovoltaic system design, including tilt, azimuth, module model, and specifications, was gathered for residential modules installed between 2003 and 2019 from the 2019 California Net Energy Metering database. Module specifications sheets were used to estimate the cumulative electricity generated over the system's lifetime using the System Advisor Model. The life cycle carbon footprint, cumulative energy demand of installed photovoltaic systems, and historical and future electricity grid mixes of California and photovoltaic manufacturing countries were used to calculate the photovoltaic carbon, energy, and economic payback times. The average carbon payback time was 2.1 years, and the energy payback time was 1.7 years. The payback times decrease over time due to improvements in module efficiency. However, as California's electricity grid continues to get greener and include more renewables, energy and carbon payback times will increase. Little research exists on the economic motivations driving early (before 25–30 years) photovoltaic replacement. Most assume consumers wait until their investment is recouped through electricity savings. Our economic analysis shows that the value from electricity production was more than the cost of the system before replacement for only 1 of the 61 systems, and the average cost payback was 58 % of the system cost. These findings highlight the need for further research into photovoltaic replacement and policies to optimize the sustainability and economic viability of photovoltaic systems.