Re-assessment of net energy production and greenhouse gas emissions avoidance after 40 years of photovoltaics development

Abstract

Since the 1970s, installed solar photovoltaic capacity has grown tremendously to 230 gigawatt worldwide in 2015, with a growth rate between 1975 and 2015 of 45%. This rapid growth has led to concerns regarding the energy consumption and greenhouse gas emissions of photovoltaics production. We present a review of 40 years of photovoltaics development, analysing the development of energy demand and greenhouse gas emissions associated with photovoltaics production. Here we show strong downward trends of environmental impact of photovoltaics production, following the experience curve law. For every doubling of installed photovoltaic capacity, energy use decreases by 13 and 12% and greenhouse gas footprints by 17 and 24%, for poly- and monocrystalline based photovoltaic systems, respectively. As a result, we show a break-even between the cumulative disadvantages and benefits of photovoltaics, for both energy use and greenhouse gas emissions, occurs between 1997 and 2018, depending on photovoltaic performance and model uncertainties.

An Exploration of Divergence in EPBT and EROI for Solar Photovoltaics

“…The two net-energy metrics commonly applied to electricity generation technologies are the energy return on investment (EROI) and energy payback time (EPBT). EROI for electricity generation has been widely studied, especially coal-fired electricity, including carbon capture (Wu et al 2016;White and Kulcinski 2000), wind power (Kubiszewski et al 2010), solar photovoltaics (Bhandari et al 2015;Koppelaar 2016;Louwen et al 2016) and gas-fired generation (Moeller and Murphy 2016). The boundaries and types of analysis vary between studies, but all those just cited adopt the electricity busbar or inverter output as the EROI numerator-electricity distribution and management of the grid system as a whole is typically excluded from the analysis boundary.…”

“…Many of the differences in findings between conventional analyses can be accounted for via meta-analyses that harmonise for key performance parameters (e.g. Bhandari et al 2015;Koppelaar 2016;Louwen et al 2016).…”

“…2) confounds the age-adjustment process for PV EROI and EPBT metaanalyses, unless the primary data sources are traced and adjusted accordingly (Koppelaar 2016). Louwen et al (2016) Of the factors considered in this study, this stands out as potentially contributing to actual rather than apparent divergence in NEA findings, where studies are otherwise equivalent. If the purpose of a study is to consider present or future PV deployment, then the use of earlier data will lead to errors.…”

“…It is also widely adopted in the PV EROI literature. Of the three meta-analyses considered in this study, all apply a 'substitution method' equivalence adjustment to either the investments or output, with primary energy to electricity conversion factors of 0.311 (Louwen et al 2016) and 0.35 (Bhandari et al 2015;Koppelaar 2016). A related study adopts 0.30 .…”

“…Meta-analyses (e.g. Bhandari et al 2015;Koppelaar 2016;Louwen et al 2016) typically adopt a reference inplane insolation of 1700 kWh/m 2 year. However, there is sometimes ambiguity as to whether the insolation refers to in-plane or global horizontal insolation (GHI).…”