Five years of tests show PV systems perform better than expected

Researchers from Tennet, University of Twente, The Netherlands, conducted a five-year financial, technical, and environmental assessment of building-integrated photovoltaic (BIPV) farade and found that the systems performed better than expected.

The research team analyzed the performance of south-, east-, and west-facing vertical PV for the period 2018-2023. These performance values were then compared to traditional “optimally oriented” rooftop PV systems.

All PV systems were modeled using the Sandia PV Array Performance Model (SAPM) and meteorological data from the city of De Bilt in the central Netherlands. Silevo Triex-U300 Black 300w panels were used for all enclosures. Dutch day-ahead electricity spot market prices were used to calculate the different matrices studied.

In particular, the academics analyzed the economic, environmental and technical value realized by the systems. The first metric measures the economic value of PV power relative to the average market price, while the second metric measures how much pollution the PV system reduces by producing clean energy instead of using fossil fuels. The last indicator refers to the degree of integration of the PV system with the grid and the extent to which local energy needs are met.

The analysis shows that the South, East and West PV zones reduce CO2 emissions by 1,725, 1,492 and 1,335 kg per kW, while the reference zone with optimized PV module settings reduces CO2 emissions by 2,434 kg per kW. The value factor for the optimized PV zone drops to 0.73 in 2023 compared to 2018 levels, while the value factors for the east and west PV zones are 0.87 and 0.84, respectively.

“We do see a decline in the value factor of PV over time, although this decline is slower than predicted in the scientific literature,” the scientists said. “Interestingly, eastern and western farade PV show lower rates of decline and are therefore more economically efficient compared to optimally oriented PV. This suggests that deviations from the optimal direction are becoming increasingly attractive.”

The scientists conclude that public incentives for solar should be considered to deploy a more optimal mix of PV tilt and orientation. They said, “Integrating solar panels on panels reduces the stress on the grid because it has a higher self-consumption ratio and lower peak feed-in compared to optimally oriented PV.”

Their findings were published in the journal Energy and Buildings in “Photovoltaics on buildings: a financial, technical and environmental assessment.”

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