Photovoltaic Characterization under Artificial Low Irradiance Conditions Using Reference Solar Cells

Area of Science:

• Photovoltaics and Renewable Energy
• Metrology and Measurement Science

Background:

• Growing interest in indoor energy harvesting for Internet-of-Things (IoT) devices necessitates accurate characterization of light-harvesting solar cells.
• Current methods for measuring indoor light irradiance, such as illuminance meters, exhibit significant inter-laboratory discrepancies.
• Standardized testing conditions are lacking for indoor photovoltaic (PV) devices, unlike well-established outdoor solar module rating conditions.

Purpose of the Study:

• To establish a more accurate and reproducible method for measuring irradiance from indoor ambient lighting for solar cell characterization.
• To propose a standardized approach that facilitates inter-laboratory comparisons and accurate power conversion efficiency calculations.
• To initiate a dialogue among National Metrology Institutes for drafting standards for indoor solar cell testing.

Main Methods:

• Utilizing a calibrated reference solar cell to measure the total irradiance of the test light source.
• Establishing multiple reference indoor lighting spectra with defined illuminance and precise spectral irradiance profiles.
• Employing the reference solar cell to set the test light level before and during the collection of current-voltage (I-V) characterization data.

Main Results:

• Demonstrated a method for creating reference indoor lighting spectra that meet specific illuminance and spectral profile requirements.
• The proposed method provides a more accurate measure of irradiance compared to traditional illuminance meters.
• The approach enables consistent and reliable measurements across different laboratories.

Conclusions:

• The developed method offers a viable solution for accurate irradiance measurement in indoor solar cell testing.
• This approach is crucial for reliable power conversion efficiency calculations and inter-laboratory data comparability.
• The proposed methodology serves as a foundation for developing international standards for indoor PV device characterization.