This project proposes a new technology for primary standard cells. The goal is to demonstrate the practical accuracy and stability of this new primary standard and have it accepted by standard committees. The new procedure relies on the fabrication of cells whose internal quantum efficiency approaches unity over a range of wavelengths. Such cells are today technologically possible through recent developments in the fabrication of high efficiency silicon cells.
The internal quantum efficiency is the ratio between the current produced in the cell and the number of the photons at a monochromatic radiation entering the semiconductor.
In practice most methods of calibrating solar cells are based on the assumption that the calibration current of the cell under the standard irradiance can be calculated from the cell spectral response to monochromatic radiation by superposition. The measurement of the spectral response is done by illuminating the cell with an apparatus that provides monochromatic radiation at variable wavelengths such that the power in each wavelength is the same.
The calibration of the cell under test is given by:
I(R,T) = I(S,T) * I(R,R) / (I(S,R)*M)
where I(R,T) is the calibration current of the test cell under the standard spectrum, I(S,T) is the current when illuminated with the simulator, I(R,R) is the calibration current of the reference cell (under the standard spectrum) and I(S,R) is the measured current of this cell under the simulator. M is the spectral mis-match correction factor.
- Know-how for production of high efficiency PV solar cells
- Examination of possibilities for series production of primary irradiance reference device
- Decrease of costs of primary irradiance reference devices and high a wide dissemination and availability of reliable standards
Expected Achievements and Exploitation
The goals of this project are to establish a new method for the production of primary reference cells with a defined consistency of internal quantum efficiency due to accurate definition of the production process and determination of physical parameters, to determine its capacity for producing reference cells, to compare with other reference cells and to explore the guarantees needed before reference institutions can accept the method.
Each producer and end user of photovoltaic devices will really have available a high-precision, absolute reference, which will contribute to harmonisation of measurements and improve the credibility of data-sheet values.
Funding SchemeCSC - Cost-sharing contracts
21020 Ispra - Varese