Comparative life cycle assessment of fixed and single axis tracking systems for photovoltaics

Single axis tracking systems (SATS) are becoming one of the most common types of solar photovoltaic (PV) installations due to improved performance compared to fixed systems. The impact of SATS in terms of various environmental indicators has yet to be fully quantified. The main goal of this study is to understand the environmental differences between fixed and SATS PV systems. For this reason, a comparative LCA between fixed and SATS was performed. A secondary goal is to determine the environmental impact of both systems under different scenarios that includes manufacturing in high and low CO2 intensive electricity grids, installation in different locations and different energy displacement options. The study is attributional and has been calculated with the cut-off modeling of ecoinvent 3.1. Calculations were performed with the software openLCA 1.7.4 with impacts obtained based on ReCiPe, cumulative energy demand and cumulative exergy demand methods. Results show the CO2 mitigation potential, defined as the avoided greenhouse gas emissions of generating electricity with solar PV versus using the electricity grid, of SATS increases between 3.4 t CO2,eq/kW and 14.5 t CO2,eq/kW with respect to fixed systems in the baseline scenarios considered. The extra energy necessary to produce a SATS structure is minimal when compared to the energy intensive panel manufacturing and is quickly recovered after installation due to a dramatic increase in the efficiency of system (8%-25% increase in yield depending on install location). All environmental indicators used (greenhouse gas emissions, cumulative exergy demand, energy payback time, CO2 payback time, CO2 mitigation potential, human toxicity, land use, water depletion and fossil depletion) are superior for SATS compared to traditional fixed systems. The results also show that the energy sources displaced have a larger impact in the CO2 mitigation potential than the irradiation in the place of installation (more than 80 fold variation in the former in contrast to 2-4 fold for the latter). (C) 2019 Elsevier Ltd. All rights reserved.