Update of energy payback time and greenhouse gas emission data for crystalline silicon photovoltaic modules

Abstract

Results of a recent photovoltaic energy life cycle study are presented. The focus lies on the energy payback time (EPBT) and the CO 2 emission rate achievable with state-of-the-art industrial production chains for conventional monocrystalline and multicrystalline silicon modules. The data have been provided by European manufacturers and represent the processes in their European-primarily German-production sites. The analysis covers all steps from metal grade silicon refinement down to assembled modules as shipped to the customer. Balance of system contributions have not been included in the analysis and in the result figures, both for EPBT and CO 2 emissions. The resulting EPBT values for the modules only are 1.09 and 0.93 years for monocrystalline and multicrystalline silicon, respectively, both under southern European conditions. CO 2 emission rates strongly depend on the scenario considered, ranging from 18 g/kWh in southern Europe to 60 g/kWh in northern Germany under worst-case conditions for useful lifetime and degradation.

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

“…24). Comparing this to the values mentioned earlier, that were reported for current PV systems by Wetzel8, we see that the developments in the past decade have been so significant that the GHG footprint of state-of-the-art poly and monocrystalline silicon based PV systems is already 55 to 69% lower, respectively, compared to the averages of roughly the last decade (2004–2014) mentioned at the beginning of this paragraph.…”

“…Still, especially for energy pay-back time (which is calculated from reported system CED according to the procedure described in the Methods section) a clear decrease of environmental footprint over time can be observed. Energy pay-back times drop from around 5 years in 1992 to around just under 1 year for poly-Si and just over 1 year for mono-Si PV systems currently8. Greenhouse gas emissions from photovoltaics, expressed in grams of CO 2 -equivalent per kilowatt-hour (gCO 2 -eq kWh −1 ), show large variations, even for studies analysing PV systems from the same year.…”

“…More recent studies seem to use more congruent methods, resulting in a smaller variation of calculated GHG footprint. The current GHG footprint (harmonized data) is around 20 gCO 2 -eq kWh −1 for poly-Si PV systems, and around 25 gCO 2 -eq kWh −1 for mono-Si PV systems8, down from 143 gCO 2 -eq kWh −1 for poly-Si in 1992 (ref. 19) and 409 gCO 2 -eq kWh −1 for mono-Si in 1986 (ref.…”

“…Over the whole life-cycle of a PV system, it pays back the energy invested and greenhouse gas (GHG) emissions released during its production multiple times6789. As PV systems operate over a period of up to 30 years, there is a significant time-lag between the investments, in terms of cumulative energy demand (CED) and GHG emissions, and the benefits obtained due to delivery of electricity and replacement of high-environmental impact electricity from fossil fuel sources.…”

Off-grid solar photovoltaic systems for rural electrification and emissions mitigation in India

“…Data in this investigation is given in Tables 1-3, which also include assumptions of performance degradation rates and balance of system costs [34,35]. For production of system components in China we assume specific emissions of 1000gCO 2 /kWh and 450gCO 2 /kWh for electricity and thermal energy production respectively [26], and 788gCO 2 /kWh for that of the Indian electricity grid [36].…”