A climate rationale for research and development on photovoltaics manufacture

Abstract

Photovoltaic (PV) power generation is critical to many climate policy goals, as PV electricity results in little or no greenhouse gas (GHG) emissions during use, utilities and governments view PV installations as a way to accelerate progress towards emissions reduction targets. However, typical analyses of the GHG implications of the PV lifecycle ignore inter-temporal effects, in which the initial GHGs emitted in PV manufacturing phase must be offset by avoided fossil-fuel combustion emissions during use. Thus, the overall climate benefits of PV are a function of both GHG efficiency of PV manufacture, and electricity generation efficiency of deployed modules during use. Improvements to PV manufacture result in immediate climate benefits, in contrast with improvements in module efficiency which may offset greater GHG emissions, albeit over decades of useful life. This study presents a novel framework using the cumulative radiative forcing(CRF) metric to demonstrate the significant climate benefit of improving PV manufacturing processes predominantly located in GHG-intensive geographies and determines the equivalent increase in module efficiency that provide the same climate benefit. The findings show low-carbon PV manufacturing increases the life-cycle climate benefit by 20% and is equivalent to increasing the module efficiency from a baseline value of 17% to 21.7% and 16% to 18.7% for mono-Si and multi-Si modules, respectively. With commercial module efficiency having increased annually by only 0.25% over the last 12 years, the implication is that improving PV manufacturing may be more effective than module efficiency improvements for increasing the climate benefit of terawatt scale PV installations.

Identification of higher order silanes during monosilane pyrolysis using gas chromatography-mass spectrometry

“…This process, normally carried out in a Siemens reactor, constitutes an expensive and energy demanding step in the production of polysilicon. A recent study [3] indicates that reducing the energy consumption for solar grade silicon production by 15-17 kWh/kg-Si gives -in a CO 2 emission perspective -the same result as a 1% increase in the baseline efficiency for mono-and multicrystalline Si PV modules. Developing procedures to produce solar cells at lower energy consumption is therefore essential for reducing their energy payback time [3].…”

“…A recent study [3] indicates that reducing the energy consumption for solar grade silicon production by 15-17 kWh/kg-Si gives -in a CO 2 emission perspective -the same result as a 1% increase in the baseline efficiency for mono-and multicrystalline Si PV modules. Developing procedures to produce solar cells at lower energy consumption is therefore essential for reducing their energy payback time [3]. One way of reducing the overall energy consumption during solar cell production is by replacing the Siemens process (pyrolysis of trichlorosilane) by pyrolysis of gaseous monosilane [3].…”

“…Developing procedures to produce solar cells at lower energy consumption is therefore essential for reducing their energy payback time [3]. One way of reducing the overall energy consumption during solar cell production is by replacing the Siemens process (pyrolysis of trichlorosilane) by pyrolysis of gaseous monosilane [3].…”

“…Despite their proven capability of producing polysilicon with significantly lower energy demand than the Siemens reactor [3,6,7], these monosilane based reactor technologies encounter limitations related to dust formation during the monosilane pyrolysis process [6][7][8]. Dust (fines) is formed when reactant gas molecules decompose homogeneously (in the gas phase), rather than heterogeneously (on a surface) [9,10].…”

Optimal operation modes of photovoltaic-battery energy storage system based power plants considering typical scenarios

“…Among the different renewable energy sources, photovoltaic (PV) has received much attention and the capacity of deployment is envisaged to quickly increase in the future [1]. It is well-known for the stochastic nature of the PV power generation [2][3][4][5].…”