Sustainability at the Terawatt Scale

Energy transition to carbon-free electricity will require a massive scale-up of photovoltaic (PV) manufacturing and deployment worldwide. Producing and deploying PV requires large up-front investments in materials, energy, funds, and other resources, and we must identify the most sustainable options very quickly. Sustainability can be challenging to quantify, especially for renewable energy systems.

We developed a mass and energy balance model for PV manufacturing, deployment, and end-of-life management, called PViCE, to quantitatively compare options for TW scale deployment. We used the deployment forecast from the recent Solar Futures study as a demonstration case which predicts using about 1TW of PV by 2035. PViCE includes an updated material and performance baseline for silicon PV technology. The model can also be used for thin-film technologies with user-supplied data.

Here, we investigate the material and energy impacts of technology changes and end-of-life disposition options to find a path yielding the highest capacity for electricity production with the lowest embedded energy. We find that high-efficiency modules with long service lifetimes (>30 years) are the most optimal PV for decarbonization. Circularity practices like re-manufacturing, repair, and recycling can help offset material and energy requirements, but they do not make up for short module lifetimes (< 20 years) or poor performance.