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Triple-Junction Concentrator Photovoltaic-Thermoelectric Hybrid Receivers:
Robustness, Validation and Preliminary Reliability Studies
Matthew Rolley [1, a], Tracy Sweet [1, b], Vasil Stoichkov[2], Jeff Kettle[2], Gao Min [1, c]
1.
Cardiff School of Engineering, a. [email protected] , b. [email protected] , c. [email protected]
Abstract:
A novel Concentrator Photovoltaic-Thermoelectric (CPV-TE)
hybrid receiver prototype was electrically characterised at
Cardiff, Loughborough and Bangor Universities. Through an
independent test centre (CREST) accurate I-V data was
obtained and experimental methods at Cardiff validated.
Reliability testing showed no significant sign of degradation
on any of the receiver’s key performance properties over a
216 hour test at 65oC under AM1.5G (1 sun). These results
confirm the receiver’s robustness, repeatability, reliability
and hence the future potential of the CPV-TE hybrid design.
Introduction:
Concentrator photovoltaics combine high-efficiency multijunction solar cells with low-cost optical concentrators to
enable economical large-scale power generation.
Thermoelectrics are semiconductors built into module
configurations, that can either generate power when
operating in Seebeck mode or create a temperature
differential in Peltier mode. CPV-TE hybrids can use
spectrum splitting techniques to target specific spectral
ranges, monolithic integration for linear heat flow through
the structure or capitalise on the positive temperature coefficients of organic solar technologies such as Perovskites
or Dye Sensitized Solar Cells. Many theoretical and
computational simulations exist that evaluate different
optimisation criteria for designing parameters of
monolithic, hybrid CPV-TE devices. The feasibility of such
device hybrids has been investigated in literature with
increases in overall device conversion efficiency being
reported through simulations. Currently, there exist very
limited work regarding experimental multi-junction CPV-TE
hybrids, and their measured device performances. This
work expands on previous efforts to develop a hybrid CPVTE receiver design, and considers the accuracy and
repeatability of such a device (Sweet et al. 2016).
Preliminary lifetime and reliability testing was undertaken
and the data obtained to-date is included.
Experimental Method and Results:
The receiver used in this work was a
generation IV PCB design named “ALPHA”
(Figure 1). The receiver was tested at
Figure 1. "ALPHA"
Cardiff University using a LOT Oriel ABB
-2
class solar simulator. The 1000Wm
incident irradiance plane was calibrated with multiple
devices, including a Spectroradiometer, pyranometer and
silicon reference cell to ensure confidence in the data
obtained. The temperature was precisely controlled to 25 oC
using the thermoelectric and current-voltage (I-V) data was
measured using an AUTOLAB system. The same receiver
was then sent to Loughborough University’ s Centre for
Renewable Energy Systems Technology (CREST) as part of a
link with the SUPERGEN Supersolar Hub for independent
device performance validation. The I-V data obtained from
Figure 2. I-V Data from Cardiff and Loughborough CREST
CREST agreed with data measured in-house at Cardiff
University within 2% of the short-circuit current (Isc) and
matched the measured open-circuit voltage (Voc) to six
decimal places (Figure 2). With this, the functionality and
repeatability of the ‘Generation IV’ CPV-TE hybrid receiver
design has been demonstrated, simultaneously validating
the experimental equipment and methods used at Cardiff.
Figure 3. Reliability and Degradation Data from Bangor CLARET
The receiver was then re-measured at Cardiff as a posttravel evaluation with no significant change in the data.
“ALPHA” was then sent to Bangor University’s Centre for
Lifetime and Reliability Testing (CLARET) to undergo
preliminary reliability testing to establish a benchmark for
future investigations on hybrid receivers. The data obtained
showed that no substantial degradation (<2%) of the Isc,
Voc, Fill factor (FF) or Photon Conversion Efficiency (PCE)
was exhibited by the receiver over a 216 hour light-soaking
test at AM1.5G and at the elevated temperature of 65oC
(Figure 3). Further testing is currently ongoing with
increased temperature and irradiance to increase the
degradation rate of the CPV module.
Acknowledgements:
The authors would like to thank the Sêr Cymru National
Research Network (NRN) for financial support, Cardiff
school of Physics and Astronomy for use of the cleanroom
and manufacture, Loughborough’s CREST and the
Supersolar hub for characterisation, and Bangor’s CLARET
for the reliability testing.
References:
Sweet, T. K. N. et al. eds. 2016. Scalable solar thermoelectrics and photovoltaics (SUNTRAP). AIP Conference Proceedings.
AIP Publishing. DOI: http://dx.doi.org/10.1063/1.4962105