Thermo-economic principles to assess the global economic sustainability of solar photovoltaics

Thermodynamic limits are intrinsically insurmountable, whereas economic limits may be disregarded without infringing any physical laws, provided societies accept the resulting economic consequences. This study is rooted in the existence of a limited sustainable range of long-run energy-expenditures to Gross-Domestic-Product ratios. Instances exceeding affordability thresholds signal heightened risk of economic downturn. Within this framework, we investigate whether photovoltaics can expand without pushing economies beyond the Bashmakov-Newbery range of energy-expenditures, identified as globally sustainable. Using gross-domestic-product, primary energy, and energy intensity data, we analytically derive an affordability corridor of (94 ± 20)$/BOE for primary energy and (38 ± 8)$/GJ for electricity. A new conception of global-economic-sustainability becomes essential, as energy conversion systems operating above the affordability threshold would undermine prosperity. As no thermodynamic imperative enforces declining energy prices limits, we formulate a normalized thermo-economic efficiency index that links thermodynamic and economic principles within an original simulation framework, enabling assessment of whether photovoltaics complies with the global economic sustainability constraints. Incorporating capital, technological and maintenance costs, the model sets the global-economic-sustainability benchmarks for photovoltaics, across residential, solar-community, and utility-scale sectors, including storage and booster-reflector setups. Results indicate that, to produce electricity within the global economic sustainability requirements, utility-scale photovoltaics can follow a pure unsubsidized pathway even quite ahead of their lifetime horizon. When storage is included, costs approach their critical threshold, unless favorable long-term projections are assumed. Booster-reflectors can aid solar projects to reach global economic sustainability. By contrast, residential sector faces critical scenarios, even over the entire lifetime horizon, being dominated by significant soft-costs.