PVMirror: A New Concept for Tandem Solar Cells and Hybrid Solar Converters

Zhengshan Yu, Kathryn C. Fisher, Brian M. Wheelwright, Roger P. Angel, Zachary Holman

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


As the solar electricity market has matured, energy conversion efficiency and storage have joined installed system cost as significant market drivers. In response, manufacturers of flat-plate silicon photovoltaic (PV) cells have pushed cell efficiencies above 25% - nearing the 29.4% detailed-balance efficiency limit - and both solar thermal and battery storage technologies have been deployed at utility scale. This paper introduces a new tandem solar collector employing a 'PVMirror' that has the potential to both increase energy conversion efficiency and provide thermal storage. A PVMirror is a concentrating mirror, spectrum splitter, and light-to-electricity converter all in one: It consists of a curved arrangement of PV cells that absorb part of the solar spectrum and reflect the remainder to their shared focus, at which a second solar converter is placed. A strength of the design is that the solar converter at the focus can be of a radically different technology than the PV cells in the PVMirror; another is that the PVMirror converts a portion of the diffuse light to electricity in addition to the direct light. We consider two case studies - a PV cell located at the focus of the PVMirror to form a four-terminal PV-PV tandem, and a thermal receiver located at the focus to form a PV-CSP (concentrating solar thermal power) tandem - and compare the outdoor energy outputs to those of competing technologies. PVMirrors can outperform (idealized) monolithic PV-PV tandems that are under concentration, and they can also generate nearly as much energy as silicon flat-plate PV while simultaneously providing the full energy storage benefit of CSP.

Original languageEnglish (US)
Article number7222375
Pages (from-to)1791-1799
Number of pages9
JournalIEEE Journal of Photovoltaics
Issue number6
StatePublished - Aug 25 2015


  • Concentrating solar power
  • concentrator
  • multi-junction
  • photovoltaic cells
  • solar energy
  • solar thermal
  • tandem

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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