Updated sustainability status of crystalline silicon‐based photovoltaic systems: Life‐cycle energy and environmental impact reduction trends
Vasilis Fthenakis, Enrica Leccisi
Abstract
Abstract This paper provides a comprehensive assessment of the current life‐cycle sustainability status of crystalline‐based photovoltaic (PV) systems. Specifically, single‐crystalline Si (sc‐Si) and multicrystalline Si (mc‐Si) PV systems are analyzed in terms of their environmental and energy performance, providing breakdown contributions and comparisons with estimates published 6 years ago. Results clearly show the significant environmental improvement in the sc‐Si PV system production—mainly at the wafer stage—for which the impacts have been reduced by up to 50% in terms of carbon emissions and 42% in terms of acid gas emissions. The life‐cycle cumulative energy demand is estimated to be approximately 48% lower (for sc‐Si) and 24% lower (for mc‐Si) than previously reported estimates. Energy payback times of currently installed systems range from 1.3 (for c‐Si PV) and 1.5 years (mc‐Si PV) for fixed‐tilt ground‐mounted installations at low irradiation (1000 kWh/m 2 /year), to 0.6 years at high irradiation (2300 kWh/m 2 /year). The resulting energy returns on investment—expressed in terms of primary energy—range from 22 (at low irradiation) to 52 (at high irradiation) for sc‐Si PV systems and from 21 to 47 for mc‐Si PV systems. Furthermore, we examine the effects of cleaner electricity grids and grid efficiency improvements on these environmental and energy indicators.