How Does Photovoltaic Energy Work?

How Does Photovoltaic Energy Work?

Once restricted to space stations and satellites, photovoltaics are now gaining popularity and becoming an increasingly viable option. Every day, the sun releases an enormous amount of energy, far more than the entire population consumes. Being that the sun is a sustainable, renewable, and inexhaustible source for generating electricity, not using it seems almost counter-intuitive, especially considering the social and environmental impacts of other forms of energy generation. But the technology to create electricity from the sun is by no means simple and still has some limitations, the most significant being price. The following article attempts to explain some basic concepts about this process, and to highlight important considerations for designing a solar energy system. 

Austrian Embassy Bangkok / HOLODECK architects. Image © Ketsiree Wongwan

The process of turning the sun's rays into electrical energy all starts in the so-called photovoltaic cell. These cells are produced with two chemically altered silicon layers of which one is missing elections and the other is electron-overloaded. When the photons from the sunlight reach the surface, these electrons gain the ability to move, generating a flow that creates an electric current. Each cell generates a small amount of energy and a panel is usually made of between 36 and 72 photovoltaic cells. By connecting several panels together, a photovoltaic system is created. Eight to ten panels is enough to power a small house. Evidently, however, this statistic is influenced by some factors, such as the efficiency of the panels, the amount of sunshine in the region, and the energy demand of the residence itself.

Importantly, photovoltaic solar panels produce electricity in the form of direct current, meaning the electricity must pass through an inverter to transform it into alternating current - which is what is normally used in buildings, appliances, sockets, and light bulbs.

Jenson-DeLeeuw NZE House / Paul Lukez Architecture. Image © Greg Premru

Photovoltaic systems can facilitate energy generation in remote locations where infrastructural networks do not reach. In these cases, the system uses batteries to store electricity when less energy is used than is consumed, such as at night or on very cloudy days. However, it is also possible to use photovoltaics in systems connected to the power grid. In these cases, the excess energy goes to the electricity grid, creating energy “credits” for the building in question. In some countries, it is even possible to sell surplus energy, making the building a power plant for neighbors and method of paying off the investment more quickly.

Hackney Backhouse / Guttfield Architecture. Image © Will Scott

Panel Types

Research on the subject is advancing rapidly, and there are already transparent and even flexible prototypes for photovoltaic solar panels being developed. But today there are two main types of these panels, which can be easily identified visually. They include Monocrystalline Silicon Cells (mono-Si) and Polycrystalline Silicon Cells (multi-Si).

Cortesia de Flickr / LillyAndersen via University of British Columbia

Simply put, the efficiency of a solar panel is the percentage of sunlight energy that the panel converts to electrical energy per square meter. Monocrystalline solar panels are more efficient, reaching between 15 and 20%, and are made from a single ultrapure silicon crystal (cylindrical silicon ingots). As this is a more complex process, they are also more expensive. In the case of polycrystalline panels, instead of one crystal, there are several crystals. Its manufacture produces less waste and is cheaper. Because it is more affordable, despite lower efficiency, it is the most widely used type.

Cortesia de Ciclo Vivo

Because these panels are an important technology in the field of sustainability, several countries are already creating incentives for the implementation of a cleaner energy matrix. The industry is rapidly evolving to make panels increasingly efficient, smaller, more affordable, sustainable, and more effectively embedded in the architecture housing it. Investing in applied research is indescribably important to increasingly incorporate this technology into everyday life.

About this author
Cite: Souza, Eduardo. "How Does Photovoltaic Energy Work?" [Como a energia fotovoltaica funciona?] 15 Oct 2019. ArchDaily. Accessed . <> ISSN 0719-8884

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