PV Modules: Evolution and Frontiers

In the 70 years since Bell Labs unveiled the solar cell, Solar Photovoltaics (PV) have been continuously developed to increase efficiencies and drive down cost. The commoditisation of solar has enabled the technology to take over as the fastest deploying and one of the cheapest forms of renewable energy available [1] [2].

Within the past two years, the industry has pivoted away from the established PERC modules and made significant investments to expand new TOPcon manufacturing lines. This was driven by increasingly larger research costs in pushing PERC modules above their current efficiency. Advancements in manufacturing processes reduced TOPcon manufacturing costs such that they are now in line with PERC, but offer higher efficiencies, a reduction in Light Induced Degradation (LID), more efficient operation at higher temperatures and better low light performance [3].

While TOPcon takes over as the dominant technology, the industry continues to research what the next step could be for modules. Evolutionary changes such as back contact are on the horizon, while revolutionary technologies such as tandem cell are a few years away from commercial manufacturing level. Although module technology is a significant driver of progress in the sector, business intelligence and AI can also be applied throughout the Solar PV value chain to bring value to all stakeholders.

An example of an evolutionary step, back contact simply means moving the busbars which carry the current generated by the solar cells from the front of the module to the rear. This exposes a larger area of the module to direct sunlight and increases the power output of a panel. Although most modules installed today are bifacial, the increased coverage of cells on the rear side has little impact on the output of the module due to the relatively low levels of irradiance.

Tandem cells layer multiple photovoltaic materials together which have different bandgaps, thus capturing a wider spectrum of light [4]. This can lead to significantly higher modules efficiencies, at the cost of more complex manufacturing. Materials such as perovskite can be deployed in tandem cells alongside silicon or other substrates to capture wider bandgaps of energy. Implementation of perovskites can also reduce costs and defect rates alongside the efficiency gains [5].

Business Intelligence and AI can be introduced by manufacturers, installers and asset owners to greatly improve the performance of Solar PV installations. Image recognition models implemented during factory flash/IR testing enable manufacturers to identify defects in components and modules prior to shipping and introduce quality checks throughout the manufacturing process. With one PV module leaving the production line every 18 seconds, automation of quality checks is key to ensure high quality products can be delivered at volume.

Drone technology has become a widely accessible technology that can bring significant value during the development, construction and operation phases of projects. During development, drone surveys provide significant value by accurately mapping constraints across a site and giving insight to the topography makeup of the land. This enables designers to mitigate constraint and interferences early during a project’s development. Once a project is being constructed, regular drone surveys give another dimension of quality control to asset owners. Regularly carrying out surveys means a track record of all construction activities such as piling, trenching and foundations can be geo-located and compared to construction issue drawings. Conflicts between contractors over the positioning of trenches are easily resolved when the drawings can be overlayed with what was constructed. Operational drone surveys focus on catching issues such as hot spots on modules which can cause under-performance. [6]

Thousands of data points are captured by SCADA equipment on each PV plant and can be levered by asset owners to schedule highly effective predictive maintenance, cleanings and repairs. As digital twins become industry standard, these predictive models will continue to improve, and lessons learned from development, construction and operation can be more easily incorporated into future projects.

Bibliography

[1] Essay “Solar Power is going to be Huge”, The Economist [Online]. Available: https://www.economist.com/interactive/essay/2024/06/20/solar-power-is-going-to-be-huge

[2] “Sunny Uplands”, The Economist [Online]. Available:  https://www.economist.com/news/2012/11/21/sunny-uplands

[3] “TOPCon vs PERC”, PV Magazine [Online]. Available:  https://www.pv-magazine.com/2022/01/20/topcon-vs-perc/

[4] “The Solar Spark – Tandem Solar Cells”, The University of Edimburgh [Online]. Available:  http://www.solarspark.chem.ed.ac.uk/science/solar-technology/tandem-solar-cells

[5] “Perovskite Solar Cells”, U.S. Department of Energy [Online]. Available: https://www.energy.gov/eere/solar/perovskite-solar-cells

[6] “Inspections”, Above [Online]. Available:  https://www.abovesurveying.com/solutions/inspections/