Abstract
Reducing the operating temperature of photovoltaic modules increases their efficiency and lifetime. This can be achieved by reducing the production of waste heat or by improving the rejection of waste heat. We tested, using a combination of simulation and experiment, several thermal modifications in each category. To predict operating temperature and energy yield changes in response to changes to the module, we implemented a physics-based transient simulation framework based almost entirely on measured properties. The most effective thermal modifications reduced the production of waste heat by reflecting unusable light from the cell or the module. Consistent with previous results and verified in this work through year-long simulations, the ideal reflector resulted in an annual irradiance-weighted temperature reduction of 3.8 K for crystalline silicon (c-Si). Our results illustrate that more realistic reflector concepts must balance detrimental optical effects with the intended thermal effects to realize the optimal energy production advantage. Methods improving thermal conductivity or back-side emissivity showed only modest improvements of less than 1 K. We also studied a GaAs module, which uses high-efficiency and high-subbandgap reflectivity to operate at an annual irradiance-weighted temperature 12 K cooler than that of a c-Si module under the same conditions.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 532-540 |
| Number of pages | 9 |
| Journal | IEEE Journal of Photovoltaics |
| Volume | 8 |
| Issue number | 2 |
| DOIs | |
| State | Published - Mar 2018 |
| Externally published | Yes |
Bibliographical note
Funding Information:Manuscript received June 23, 2017; revised September 14, 2017 and October 27, 2017; accepted November 26, 2017. Date of publication January 9, 2018; date of current version February 16, 2018. This work was supported in part by the U.S. Department of Energy under Contract DE-AC36-08GO28308 with Alliance for Sustainable Energy, LLC, the Manager and Operator of the National Renewable Energy Laboratory and in part by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Solar Energy Technologies Office. The U.S. Government retains, and by accepting the article for publication, the publisher acknowledges that the U.S. Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes. (Corresponding author: Timothy J. Silverman.) T. J. Silverman, M. G. Deceglie, and I. Repins are with the National Center for Photovoltaics, National Renewable Energy Laboratory, Golden, CO 80401 USA (e-mail: timothy.silverman@nrel.gov; michael.deceglie@nrel.gov; ingrid.repins@nrel.gov).
Publisher Copyright:
© 2018 IEEE.
Keywords
- Computer simulation
- optics
- photovoltaic cells
- photovoltaic systems
- ray tracing
- solar energy
- solar panels
- thermal conductivity
- thermal management
