1 Scope
This Technical Report summarises present perspectives on the performance evaluation
of emerging PV technologies, specifically OPV, DSC and PSC devices. These devices
present some challenges for accurate measurement under the existing IEC 60904 series of standards, which were developed in the context of silicon wafer solar cells.
These challenges can be different for different devices, but in general they arise
due to one or more of the following: instability in performance over time; unusual
spectral responsivity; small device size; difficulty in measuring temperature; a transient
response to external stimulus; optical interference effects; and a non-linear current
response to irradiance. These challenges can lead to the cell output in laboratory
testing being significantly different to the output that would be observed in a real
application.
The primary focus of the report is measurement of the current-voltage (I-V) relationship under illumination for the purpose of determining the device output
power, or power conversion efficiency. Where appropriate, the report makes reference
to the IEC 60904 series which describes the standard approach to measuring the performance of all
PV devices. The report also references existing published standards that seek to accommodate
OPV, DSC or PSC devices.
The report does not seek to find consensus on measurement protocols at this stage.
A lot of work has been done by the community toward that aim, but more work is needed.
The report therefore seeks to document current knowledge and practices, hence serving
as a reference and a tool for conducting further discussion. It is hoped that by identifying
the issues that remain unresolved, the report will focus efforts toward resolving
those issues, such that a guiding Technical Specification can be prepared in the near
future. A robust Technical Specification will bring clarity and confidence to the
markets for these PV products as they develop.