@article{li_chen_liu_2012, 
  title={Research on a Stand-alone Photovoltaic System with a Supercapacitor as the Energy Storage Device}, 
  volume={16}, 
  DOI={10.1016/j.egypro.2012.01.262}, 
  publisher={Elsevier BV}, 
  author={Li and Chen and Liu}, 
  year={2012}
  }