Nicholas Riedel

Luminescence imaging strategies for drone-based PV array inspection

The goal of this work is to perform outdoor defect detection imaging that will be used in a fast, accurate and automatic drone-based survey system for PV power plants. The imaging development focuses on techniques that do not require electrical contact, permitting automatic drone inspections to be perform quicker and with less manpower. The final inspection method will combine several techniques such as, infrared (IR), electroluminescence (EL), photoluminescence (PL), and visual imaging. Solar plant inspection in the future can be restricted only by imaging speed requirements, allowing an entire new perspective in large-scale PV inspection.

Bifacial PV cell with reflector for stand-alone mast for sensor powering purposes

Reflectors to bifacial PV-cells are simulated and prototyped in this work. The aim is to optimize the reflector to specific latitudes, and particularly northern latitudes. Specifically, by using minimum semiconductor area the reflector must be able to deliver the electrical power required at the condition of minimum solar travel above the horizon, worst weather condition etc. We will test a bifacial PV-module with a retroreflector, and compare the output with simulations combined with local solar data.

The components of variance for calibration methods of thin film CdTe photovoltaic modules

Methods for qualifying the performance of thin film CdTe modules are compared. The authors characterize short circuit current (Isc) of two spectrally unique CdTe modules at STC using a class AAA indoor solar flash simulator and two calibration methods. In the first calibration method, two spectrally unique CdTe reference modules are established based on outdoor testing at STC and are used to calibrate the indoor flasher. In the second method, the spectral responses of two monitor cells and the two spectrally unique CdTe modules are used to calculate a total of four spectral mismatch factors per IEC 60904-7. Using the outdoor transfer calibration method, the authors find that regardless of which CdTe module is used to calibrate the indoor simulator the Isc measurements deviate by 0.5% or less. The data from the mismatch factor approach show that the measured Isc values deviate by an average of 1.1% depending on whether a KG3-filtered or an HOQ-unfiltered c-Si reference cell is used. Finally, the authors demonstrate that the largest source of variance between the two calibration methods is correlated to the primary reference cell calibration traceability.