Photovoltaic electricity and energy transition: From sunlight to PV generator

The scientific observation that our modern development is profoundly disrupting several planetary balances, particularly biodiversity and climate, has a profound impact on the current global context and points to the need for a transition to a more sustainable development model. The energy sector, fundamental to all forms of development, is a major contributor to this global disruption. Confronted with the climate emergency that has now gained consensus since the Paris Agreement adopted in December 2015, humanity has high expectations of an "energy transition" that effectively meets these challenges.

Against this backdrop, photovoltaic solar power is a key technology in the ongoing realization of an age-old utopia: to rebuild the energy supply of human societies, like the food chains of life on Earth, on the only low-entropy energy source outside the Earth: the Sun. In this remarkable thermo-dynamic situation, several renewable energy sources of solar origin with very high potential are called upon: solar radiation, wind power on land and at sea, hydropower, biomass, etc. Photovoltaic electricity makes it possible to generate electricity from the sun's rays. Photovoltaic electricity makes direct use of the most important of these energy potentials, solar radiation, and has taken the lead in terms of new installed capacity. It can supply large public electricity grids as well as micro-grids and isolated sites. When combined with electrochemical storage - batteries or green hydrogen and power-to-gas, which are also the focus of major global programs - it can compensate for daily intermittency and seasonal variations in sunlight, as well as indirectly meeting the needs of autonomous and mobile systems. But, like any technology, it is not without environmental impact: densifying the energy provided by solar radiation requires large collector surfaces and the mobilization of significant mineral resources, which are exhaustible if not recycled. The aim of this article is to present these elements and the physical properties of photovoltaic electricity in a unified way, by placing them precisely in the above-mentioned socio-technical context of transition, with the aim of providing engineers with a set of scientific and technical elements enabling them to develop relevant solutions for the design and/or operation of photovoltaic systems in all their diversity.

In this document, we begin with an analysis of the energy transition, including the thermodynamic situation of the Sun-Earth system; this serves as a framework to which we can explicitly relate one or more of the physical properties specific to photovoltaics, as presented later. Next, the properties of solar radiation and the principles of photovoltaic conversion are described, along with the technological devices...