# Overview and Perspectives for Vehicle-Integrated Photovoltaics
## 2 Results and Discussions
#### 2.1.2 Car-Integrated Photovoltaics and Constraints Related to the Automotive Sector  
It was found that the number of car-integrated photovoltaic (CIPV) projects has increased since 2015 (Figure 3). This increase may be linked to the reduction in PV price and increase in EV sales. Advantages such as increased range or lower recharge frequency, especially in summer, have led to a decrease in cost and increased market share.  
For these developments, the following regulatory constraints are demanding [58; 59; 60; 61; 62; 63; 64; 65]:  
* The safety of the vehicle, verified through mechanical calculations, crash tests, static mechanical tests, impact, electrostatic discharge safety, and vibration or fatigue tests.
* Acoustic emissions, in order to limit noise pollution, particularly in cities. They can be limited by the choice of vibration-absorbing materials, the development of quieter engines, etc.
* Particle and greenhouse gas emissions, which can be reduced by developing fuel-efficient engines and particle filters or even eliminated in the case of electric vehicles, at least during the vehicle's use phase [66].
* Recycling of the vehicle, with a recovery rate of 85% by weight, including a minimum recycling and reuse rate of 80% (European Directive on end-of-life vehicles (ELV); Directive 2000/53/EC of the European Parliament and of the Council of 18 September 2000).  
In addition to these competitive and regulatory requirements, a car manufacturer must meet the following expectations of its end-users, which can be broken down according to different criteria:  
* Safety: normally assured by standards, in addition to a feeling of safety. The interior must be protective, and the vehicle must be reliable in case of an accident. PV modules integrated in the roof and/or car body need to meet the relevant automotive safety standards.
* Reliability, robustness, durability: the purchase of a vehicle is an investment for 10 to 15 years [67]. It must remain in good condition in terms of performance and aesthetics without excessive maintenance throughout its life. If maintenance is required, it must be at an acceptable cost.  
Figure 3: Number of CIPV projects over time.  
* Purchase cost or lifetime profitability of the product: If the vehicle has a particular technology that increases the cost of the vehicle, it must have an important functionality for the user or pay back its cost in the long run. For example, for a solar panel, one could set a constraint that the additional cost of the technology should be translated into fuel savings, which would pay back the technology in a few years.
* Functionality: every user expects a product to fulfill certain functionalities. For example, for a photovoltaic module, the functionality is provided by the production of energy used either to propel the vehicle or to supply on-board equipment. We can also expect ease of use and a limitation of the constraints linked to its use (PV allows for example to reduce the time or the number of charging sessions on the grid, in addition to range extension). Another functionality could be the possibility to power auxiliary functions.
* Aesthetics for passenger cars similarly to building-integrated photovoltaics (BIPV) is critical although existing coloring technologies will reduce performance, leading to a tradeoff.