Solar energy: from the photovoltaic effect to energy communities

03 April 2025

solar panels

You don’t need to consult the stars to understand this energy: just look up at the sun to see things clearly. Let’s begin a journey that starts with a single ray of sunlight and leads to self-produced, shared energy, exploring a technology that brings people together and drives the energy transition.

A century of light: the long road to photovoltaic cells

The history of solar energy and electricity intertwines between the 18th and 19th centuries. While scientists like Faraday and Volta unveiled the secrets of electricity and electromagnetism, French physicist Antoine Cesar Becquerel, in 1839, observed an extraordinary phenomenon: some materials, when exposed to sunlight, generated a weak electric current. Without fully realizing it, he had discovered the photoelectric effect, later defined as such by Italian professor Antonio Pacinotti, who, together with his student Augusto Righi, paved the way for studies conducted at the beginning of the century by Albert Einstein. It was not until the mid-20th century, with the development of semiconductors and transistors, that solar energy started transitioning from scientific curiosity to a tangible energy source. In 1953, Bell Laboratories introduced the first photovoltaic cell.

The photovoltaic system: how it works

Whether in a large solar park or on a home’s rooftop, a photovoltaic system is based on a complex technology that converts solar energy into immediately usable electricity. The process starts with solar panels, each composed of multiple interconnected photovoltaic cells. When these cells are struck by sunlight, the photovoltaic effect generates direct current electricity. This current is then transferred to an inverter, an electronic device that converts it into alternating current, making it compatible with household or industrial power grids. The generated energy can be consumed in real-time, fed into the power grid, or stored in batteries for later use, such as at night. To track this energy flow, a bidirectional meter measures the energy produced by the system, the energy consumed, and any energy injected into the grid. A monitoring system continuously checks the system’s production and operational status.

From podcast "Solar": "The three essential elements for capturing energy are photovoltaic cells, inverters, and storage batteries"

Learn more in the podcast Reflecting on Light.

Listen to it here

From the Sun to the switch, the journey of solar energy

Solar panels

Not all solar panels are the same; the differences lie in the semiconductor material used and the underlying technology, which determine costs and efficiency. The vast majority use silicon, whether monocrystalline or polycrystalline. Among today’s photovoltaic technologies, monocrystalline n-type silicon stands out for its advantageous balance between conversion efficiency and lower degradation over time, making it one of the most efficient technologies available. In the future of semiconductors, another material with a difficult name to remember, perovskite, shows promise for high performance. Research is focused on durability and stability over time—key elements for making this technology viable for large-scale adoption.

The produced energy can be consumed in real-time, fed into the national power grid, or stored in batteries for later use.

Photovoltaic at the plural

Solar parks, photovoltaic parks, solar power plants, or solar farms. Different names for the same thing: utility-scale facilities that generate electricity to feed into the grid. These facilities cover vast areas, often in rural or industrial zones with high solar irradiation.

A photovoltaic park results from careful planning, considering not only solar potential but also land integration and local activities. It consists of thousands of interconnected solar panels linked to high-power centralized inverters. The panels can be fixed or equipped with trackers that rotate according to sunlight exposure. The generated energy is fed into the national power grid via transformer stations that increase voltage for faster distribution.

A photovoltaic park is designed with consideration not only for production factors but also for the land and integration with local activities

Photovoltaics and territory: agricultural integration and industrial redevelopment

Agriculture and solar energy: a winning combination

Agrivoltaics is the term used to describe the installation of solar parks on cultivated land, allowing the two activities to integrate. The panels are mounted high to minimize invasiveness or can be used to create shaded areas beneficial for certain crops. They can also be equipped with sensors to monitor soil and plant conditions, optimizing irrigation and fertilization. In Villarino De Los Aires, in the province of Salamanca, Plenitude has started the construction of a photovoltaic plant with a future installed capacity of 220 MW. Covering an area of approximately 286 hectares, it will be one of the largest in the Castilla y León region.

Photovoltaics to enhance abandoned areas

Photovoltaic parks can also be used to revitalize a decommissioned industrial area, which in this way becomes a resource for the local economy. Plenitude was involved in the reclamation of an 11-hectare industrial site in Ravenna Ponticelle, owned by Eni. Over 10,000 solar panels were installed here, with a total capacity of 6 MW. The bifacial monocrystalline silicon panels also use the rear side for energy production and are mounted on special solar tracking structures fixed on ballasts placed on an impermeable capping, created as part of the permanent safety measures outlined in the Reclamation Action Plan for the industrial area.

Photovoltaics and self-consumption

Alongside utility-scale photovoltaics, which produce energy for the grid, there is a rapidly growing model focused on self-consumption. These are smaller systems used to meet part of the energy needs of industrial facilities or, more commonly, homes. According to GSE statistics, the vast majority of photovoltaic systems installed in Italy have a capacity of less than 20 kW. These systems are mainly for household self-consumption, typically installed on rooftops or nearby properties and sized according to the user’s energy demand. Smart energy management systems can optimize consumption based on production. Additionally, integrating storage batteries allows surplus energy to be stored during the day for use at night or during periods of low production, increasing self-consumption (read here our detailed insight).

Self-consumption, or the direct use of energy produced by the system, gives rise to a new type of consumer, the prosumer (producer + consumer)

Here, we have outlined its profile

Energy communities

Energy communities represent an innovative model of energy production and consumption based on collaboration and resource sharing. Technically, they function as a virtual network connecting multiple production and consumption units, involving both public and private entities. Those with their own photovoltaic systems can consume their generated energy directly or share surplus energy with other community members, receiving financial incentives. However, their significance extends beyond technical and administrative aspects; energy communities embody values of sharing, education, and change.

Watch the video

Matilde Scandroglio, Head of Energy Services Development & Go to Market, and Roberto Gatti, Head of Energy Technologies and Solutions at Plenitude, explain what an energy community is and how it works.

The Future of solar energy

The electrification of consumption is a hallmark of the ongoing energy transition. This process requires a mix of different energy sources, with photovoltaics playing an increasingly important role. Its scalability and ability to be deployed in both utility-scale and residential settings make it one of the most versatile technologies. Additionally, digitalization in energy management, including sensors, software, and digital platforms, enables real-time monitoring and control of energy production and consumption. Artificial intelligence (AI) opens new frontiers, developing services and technologies that optimize consumption, load distribution, and demand management. AI-driven intelligent storage systems can analyze consumption habits and weather conditions, storing energy at optimal times and releasing it when demand is highest. Moreover, AI will enhance smart, efficient, and automated power grids, promoting integration among different energy sources and facilitating energy exchanges among prosumers, fostering increasingly complex virtual energy communities.
The future of solar energy is shaping up as a deeply interconnected and digitalized energy ecosystem where production, distribution, and consumption are seamlessly integrated and intelligently managed.

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