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Increased Energy Yield for Bosch´s n-Type Solar Cells in Bifacial ApplicationSolar Cells in Bifacial ApplicationJan Lossen, Tim Böscke, Hans-Joachim Krokoszinski
Figures.: EQE, Reflection and IQE measured form front and rear side: All data are measured in an area including fingers, IQE is calculated as EQE/(1-R) without further corrections
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Increased Energy Yield of Bifacial n-Type Solar Cells
Unbiased IV-measurement of bifacial cells?Unbiased IV measurement of bifacial cells?Measurement on golden chuck Chuck Jsc
Additionally the irradiance, temperature and wind are logged.
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Increased Energy Yield of Bifacial n-Type Solar Cells
Variation of mounting conditions
The albedo is varied bymanipulation of mounting:The albedo is varied bymanipulation of mounting:The albedo is varied bymanipulation of mounting:
Variation of mounting conditions
RefThe albedo is varied bymanipulation of mounting:manipulation of mounting:1. covered rear side, upper rowmanipulation of mounting:1. covered rear side, upper row2. open rear side above grass
manipulation of mounting:1. covered rear side, upper row2. open rear side above grass3 open rear side above foil
Bifacial
Ref
manipulation of mounting:1. covered rear side, upper row2. open rear side above grass3 open rear side above foil3. open rear side above foil Ref
Bifacial
3. open rear side above foil
4. covered rear side, lower row5 open rear side above grass5. open rear side above grass6. open rear side above foil
E h i ti i k t f Each variation is kept for some days, containing at least one (almost) sunny day
Additional gain for very low irradiation angles, due to free standing rack
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Increased Energy Yield of Bifacial n-Type Solar Cells
Bifacial gain on a day with white clouds (28.05.)Bifacial gain on a day with white clouds (28.05.)
2.29Bifacial
Configuration: Open rear side, white ground, upper rack
1 41.61.82
5678
A]
Bifacial
Reference
ratio
0.811.21.4
2345
Isc
[A
0.40.60.8
012
06:00 09:00 12:00 15:00 18:00
Noisy signal, due to slight time difference between measurments Very high absolute values for both modules Increased bifacial gain due to increased albedo
Increased Energy Yield of Bifacial n-Type Solar Cells
Conclusions from the outdoor evaluationConclusions from the outdoor evaluationDoes it make sense to use Bosch cells in bifacial modules?
Technical:Technical: Module integration with transparent back sheet causes 3-5% additional
embedding losses In appropriated systems this loss can by far be compensated by a higher In appropriated systems, this loss can by far be compensated by a higher
energy yield due to bifacial gain. Above grass +10%, above bright surfaces >20% seem realistic.
CommerciallyCommercially: Today´s PV market prices products only on Wp, but not on energy yield
Proposal to solve the dilemma: p If the community could agree on Standard Bifacial Test Condition (SBTC),
including certain amount of albedo (e.g. 10%), modules might be sold with higher power rating, reflecting better their real value.
higher power rating, reflecting better their real value.
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Increased Energy Yield of Bifacial n-Type Solar Cells
Acknowledgments:Acknowledgments:Matthias Kugler and Philipp Schinköthe of
CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbHfor operating the test site
Bosch´s R&D Team for excellent work, especially:Daniel Kania, Anke Helbig, Thomas Roth, Claus Schöllhorn, Martin Dupke, Patrick Sadler, Matthias Braun, Daniel Stichtenoth, Tobias Wütherich, Reik Jesswein, Dennis Fiedler, Robert Carl, Karsten Meyer
ISC Konstanz for fruitful cooperation on n-Type solar cells in the p ypprojects enSol and hoch-n-Solar
BMU for funding of hoch-n-Solar under the contract FK 0325369B