Energy learning curves of PV systems

Abstract

The energy demand of photovoltaic (PV) systems is an important part of energy sustainability of PV systems. PV systems are considered sustainable energy systems when the produced energy is higher than the energy needed for the PV system on a life‐cycle basis. This paper employs financial learning curve concepts to determine the energy demand of major PV module technologies and systems. General PV module and PV system energy learning curves are calculated by weighting energy demand of different PV systems according to their share in PV market. Additionally, the contribution of module efficiency for reducing specific energy demand is considered. We find an energy learning rate of 17% for PV modules and 14% for PV systems on the basis of a market weighted mix of technologies and volumes. Energy payback time (EPBT) and energy return on energy investment (EROI) in 2010 and for the year 2020 are calculated via the energy learning rate and indicates a further significant progress in energetic productivity of PV systems. To the knowledge of the authors this publication shows for the first time that the energy consumption in PV manufacturing follows the log‐linear learning curve law similar to the evolution of production cost. This allows calculating EPBT or EROI for future prognoses. Furthermore, it shows significant evidence of how sustainable PV systems are and justifies their growing share in the energy market. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 914–923, 2016