Are all solar photovoltaic (PV) cells created equal? No, but the differences in quality and energy output are rooted in more than their respective manufacturers and designs. Local climate also plays a pivotal role in how they perform in any given residential, commercial or utility-scale deployment.
How climate accounts for differences in solar cell output
The variance of solar cell performance from one locale intuitively makes sense because of differing levels of sunshine. In the U.S., many of the states with the most installed solar capacity are located in the Sun Belt, the region running across the entire southern edge of the lower 48, from California to North Carolina.
State laws and incentives account for some of the regional disparities, but higher numbers of sunnier days in the South are inevitably influential, too. A solar PV cell in Florida - the Sunshine State - is naturally going to have more opportunities to capture energy from the sun than one in South Dakota.
Researchers at MIT sought to quantify the exact difference by testing both traditional silicon and thin-film cadmium telluride panels in two meteorologically disparate locations: Singapore and Perrysburg, Ohio. The observed variance between the two sites was up to 5 percent and was most pronounced with the cadmium telluride cells. The Singapore installation, with its hotter, more humid climate, demonstrated the highest energy output.
The study implies that similar differences would be observable with metal-halide perovskites as well as gallium arsenide, each of which also has a high electronic band gap like cadmium telluride. What do the results mean for residential solar customers, though?
Predicting solar PV cell performance: An inexact science
Coverage of the MIT study has focused on how climate made a bigger difference than expected. A related point is the inexactness of predictions about solar PV cell yield, which struggle in particular with tropical climates.
Many cells are lab-tested or field-tested in the relatively temperate climes of the U.S., Europe, China and Japan. As a result, they typically have no benchmarks for how they will stand up to the real-world conditions in places like Singapore. Performance can be heavily affected by meteorological extremes in temperature, wind and irradiation.
Current yield prediction software often struggles to produce accurate forecasts for specific solar PV cells, due to their baselines in unrealistic laboratory results. Cutting-edge models do a bit better by incorporating data on transient effects such as wind, as well as on nearby thermal gradients. Their mean square root errors can be as low as only 2.5 percent.
Better understanding of climate-related fluctuations can support superior decision-making about what types of solar PV cells to use in specific locations. For example, a deployment situated in a hot climate might benefit from cells incorporating perovskites and other materials capable of capitalizing on the unique advantages of the local environment, if such technologies are cost-effective and superior in performance to silicon.
Looking ahead at possibilities in solar PV cell materials
While the MIT study highlighted the potential of cadmium telluride and similar materials, it is worth noting that crystalline silicon panels still dominate the market, especially in utility-scale solar. The Annual Electric Generator Report from the U.S. Energy Information Administration found that they held 70 percent of the market in 2016, compared to 28 percent for thin-film alternatives.
In the latter category, cadmium telluride accounted for virtually all installed thin-film capacity in the U.S. However, its growth has lagged silicon in recent years due to advances in silicon manufacturing that have helped reduce costs and accelerate deployments across all categories. Thin-films have niche use cases – i.e., in hot environments, or for applications requiring minimal cell weight – but silicon retains numerous advantages in cost and abundance.
As an established and experienced solar manufacturer, Trina Solar can help you select the right infrastructure for your deployment. Learn more by visiting our Products and Solutions page today.