# Overview and Perspectives for Vehicle-Integrated Photovoltaics
## 4 Perspectives  
VIPV development will also need to meet other challenges not discussed here, such as energy production forecast, energy management, low environmental impact, and recycling.  
The forecasting of PV production for a typical year is possible through tools such as PVGIS [106] of PVSYST [107]. The mean annual energy is, thus, pretty well known and helps the development of photovoltaics. On-board photovoltaics in vehicles usually involve curved PV modules, and the vehicles are, by definition, at different locations, as well as both static and non-static. The mean annual energy production also depends on the use cases, and there is a lack of data available for both irradiance and associated products.  
The optimal energy harvesting of photovoltaic requires day-long operation. This situation may imply a significant energy loss from the vehicle system that is required to be partially awake. The optimization of vehicle system energy consumption may, thus, be a significant way to improve on-board photovoltaics. Additionally, cases with more system energy consumption than production must be avoided, for example, via a system shut down.  
Other promising applications of EVs, including PHEV, are V2X (vehicle-to-everything) applications, such as vehicle-to-home [108], V2V (vehicle-to-vehicle), V2B (vehicle-to-building), or V2G (vehicle-to-grid). Such functionalities allow using the photovoltaicenergy generated in homes and others, which is beneficial for the photovoltaic energy utilization ratio.  
A need for new standards has to be highlighted. To the best of the authors' knowledge, the measurement of curved PV modules is not yet addressed by existing standards [4]. It might be more relevant to indicate a calculated power label value from a mixture of measurements at different angles of incidence using direct/diffuse light. Indeed, curved modules can be more sensitive to changes in yield depending on the angle of irradiance and the use of direct or diffuse sunshine.  
Standards do exist for photovoltaic modules in automotive applications; however, to the best of the authors' knowledge, they are neither dedicated to on-board PV application nor ensure the compatibility of requirements of both domain standards.  
A third point is the need for a standardized calculation of the energy produced. Moreover, in the case of the energy being used for solar kilometers, their calculation requires a standard approach.  
Finally, calculation of the impact of CO2 emissions from on-board vehicle-integrated PV, such as HEV or PHEV, needs to be fully defined and approved as an eco-innovation [2].  
Investigation, V.M.; writing--original draft preparation, B.C.; writing--review and editing, T.D. and J.G.; supervision, F.C. and E.V. All authors have read and agreed to the published version of the manuscript.  
This research received funding from ADEME, grant number 1905C0043. This project was realized with the participation from members of INES.2S and received funding from the French State under its investment for the future program with reference ANR-10-IEED-0014-01.  
Not applicable.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.