**5. Conclusions**

This study introduced a new approach to FPV using a flexible crystalline silicon module backed with foam, which is less expensive than conventional pontoon-based FPV racking and land-based PV racking. The results show that the foam-backed FPV had a lower operating temperature than conventional pontoon-based fixed tilt out-of-water FPV and thus a higher energy output per unit power because of the modules' close proximity to the water. Thus, because PV costs are now normally the least costly method of new electricity production, the hypothetical large-scale foam-based FPV provides a potentially profitable means of reducing water evaporation in the world's at-risk bodies of fresh water.

The case study of Lake Mead found that if 10% of the lake was covered with foam-backed FPV, there would be more than enough solar electricity generated to power the homes in Las Vegas, Henderson and Reno combined and enough water savings for Las Vegas and Reno. At 50% lake coverage, the foam-backed FPV would provide over 127 TWh of clean solar electricity and 633.2 million m3 of water savings, which would provide enough electricity to retire 11% of the polluting coal-fired plants in the U.S. and water for over five million Americans, annually.

**Author Contributions:** Conceptualization, J.M.P.; methodology, K.S.H., P.M. and R.K.K.; software, K.S.H.; validation, K.S.H. and R.K.K.; formal analysis, K.S.H., P.M., R.K.K. and J.M.P.; investigation, K.S.H. and R.K.K.; resources, J.M.P.; data curation, K.S.H. and P.M.; writing—original draft preparation, K.S.H., P.M., R.K.K. and J.M.P.; writing—review and editing, K.S.H., P.M., R.K.K. and J.M.P.; visualization, K.S.H. and P.M.; supervision, J.M.P.; project administration, J.M.P.; funding acquisition, J.M.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Witte endowment.

**Acknowledgments:** The authors would like to acknowledge technical support from Shane Oberloier, helpful conversations with Nelson Sommerfeldt, as well as the support of SOLCAST who provided historical solar data for the simulations performed in the study.

**Conflicts of Interest:** The authors declare no conflict of interest.
