Photovoltaic systems are one of the most widely used ways of harnessing solar energy. These systems have the ability to capture energy from the sun and convert it into electricity. This form of energy has become widely recognized and has developed significantly, particularly over the past century. It is considered a Renewable Energy Source (RES) because it does not cause environmental pollution and generates electricity without using conventional fuels.
How Do Photovoltaic Systems Work?
Photovoltaic systems operate based on a natural phenomenon known as the “photovoltaic effect.” This occurs when sunlight falls on specific materials, such as silicon, causing electrons to be released. These electrons then begin moving through the material, generating electrical energy. The electricity produced can subsequently be directed into an electrical circuit and used to power electrical appliances or supply energy to homes and businesses.
For example, a two-axis photovoltaic tracking system can generate approximately 25–30% more energy annually in Greece, although its cost is around 10–15% higher than that of photovoltaic systems installed on fixed structures. An important consideration is the reliability and maintenance cost of solar tracking systems, as well as their impact on electricity production and the overall sustainability of the investment. To meet the energy requirements of a household, approximately 2–3 kWp of photovoltaic capacity and an installation area of around 30–50 square meters are required, depending on the photovoltaic technology selected.
Historical Background of Photovoltaic Systems
Photovoltaic technology was first discovered in the 19th century, when French physicist Alexandre-Edmond Becquerel identified the photovoltaic effect in 1839. He observed that certain materials could generate electricity when exposed to light. Several decades later, in 1877, scientists discovered that selenium behaved in a similar way when exposed to light. However, a major breakthrough in the development of photovoltaic technology came in 1954, when the first practical silicon photovoltaic cells were manufactured at Bell Laboratories. Since then, this technology has continued to evolve, and its applications have expanded into various sectors. Today, photovoltaic systems are used in numerous countries around the world.
Photovoltaic Systems Today
Nowadays, photovoltaic systems continue to rely on the photovoltaic effect while incorporating advanced technologies that meet modern energy requirements. The central component of a photovoltaic system is the photovoltaic cell, also known as a solar cell. Essentially, this is an electronic device manufactured from semiconductor materials such as silicon. When sunlight reaches its surface, the photovoltaic effect is activated, converting solar energy into electrical current. This process takes place because photons from sunlight transfer energy to the electrons within the material, causing them to move and generate an electrical voltage.
A photovoltaic system consists of solar panels and several other components. Individual photovoltaic cells are connected to form photovoltaic panels, which are installed either on the ground using special mounting structures or on rooftops. These panels initially generate direct current (DC) electricity, which is then converted into alternating current (AC) with the help of an inverter. This allows the electricity to be used by household appliances or supplied to the electricity grid. Generally, these installations also include cables, fuses, charge controllers, and photovoltaic batteries for energy storage, depending on the system’s configuration and purpose.
Regarding the operation of photovoltaic systems, most types are based on silicon technology. In this process, silicon is refined to achieve a very high level of purity and formed into large crystals, which are then cut into thin sheets known as wafers. Photovoltaic cells are manufactured from these wafers and form the foundation of photovoltaic panels. In addition to crystalline silicon technology, other manufacturing methods are also used to produce photovoltaic panels, such as thin-film photovoltaic technology, which uses very thin layers of materials deposited onto surfaces such as glass or metal. These technological developments have contributed significantly to improving the efficiency of photovoltaic systems while reducing production costs.
Where Are Photovoltaic Systems Used?
Residential Use
Over recent decades, many homeowners have chosen to install photovoltaic systems for residential use. In these cases, photovoltaic panels are usually installed on the rooftops of houses or in small outdoor spaces. In this way, households can generate part or even all of the electricity they consume. The energy produced can be used for household lighting, operating electrical appliances, heating water, and meeting other everyday needs. As a result, homeowners benefit financially because household electricity costs can be significantly reduced. At the same time, the use of more environmentally friendly energy sources is encouraged.
Commercial Use
The use of photovoltaic systems in the commercial sector is even more widespread. Photovoltaic Systems are frequently installed by businesses, industrial facilities, and agricultural units to meet their substantial electricity requirements. In these cases, photovoltaic panels are installed on the rooftops of large buildings and warehouses or in specially prepared areas on the ground. There are also large-scale photovoltaic installations, commonly known as solar parks, where hundreds of photovoltaic panels are installed to generate significant amounts of electricity.
When used in the commercial sector, photovoltaic panels offer several important benefits. Reduced operating costs and greater energy independence are among the most significant advantages. Furthermore, since large businesses and industrial facilities have substantial energy requirements, photovoltaic systems help reduce pollutant emissions and contribute to environmental protection.
Basic Requirements for Installing Photovoltaic Systems
For photovoltaic systems to be installed at a particular location, several basic requirements must be met to ensure compliance with safety regulations and efficient operation.
First, the location where the photovoltaic panels will be installed must be carefully evaluated. Sufficient space and proper orientation are necessary, with a south-facing direction generally being recommended. The installation area should also remain unobstructed by trees or taller buildings that could block sunlight. In addition, the structural stability of the building must be assessed because the photovoltaic panels add extra weight to the existing structure. An assessment by a qualified engineer is therefore an important step before any such installation.
Furthermore, compliance with the applicable legal framework governing these installations is necessary. For residential photovoltaic installations in Greece, a full building permit is generally not required, although approval for small-scale construction work may be necessary. However, larger or commercial projects may require electricity generation permits, environmental approvals, and a grid connection agreement with the relevant network operator.
In addition, the electrical connection of the system is essential. The photovoltaic installation must be connected to the electricity network and comply with the required technical and safety specifications. This includes installing a suitable inverter and appropriate protection systems. For self-consumption systems using energy netting, a specific agreement with the electricity supplier is also required.
Regarding commercial photovoltaic installations, additional approvals may be necessary, including environmental assessments or land-use permits. Overall, proper preparation and compliance with all the necessary requirements are essential for the legal and efficient use of solar energy.
Why Choose Photovoltaic Systems?
Harnessing solar energy offers several advantages compared to other renewable energy sources. First, solar energy can be generated easily, even on a relatively small scale, which is why photovoltaic systems are frequently recommended for residential use. In addition, their installation can be relatively straightforward when carried out with proper guidance from specialists. As for their location, photovoltaic panels can be installed even in urban areas, including on the rooftops of high-rise buildings. Their maintenance costs are negligible, and they have a relatively long lifespan. Overall, they represent a cost-effective investment that benefits both the finances of individuals and businesses and the environment. This is because they do not produce direct pollutant emissions or noise during normal operation.
Subsidy Programs & Rooftop Photovoltaic Systems
From time to time, government initiatives provide subsidies for the installation of photovoltaic systems, allowing households and farmers to generate their own green energy. These programs offer significant financial assistance, covering part of the installation costs, in some cases reaching up to 60%. One such initiative is the Photovoltaics on the Roof program, which aims to encourage the installation of photovoltaic systems for electricity self-consumption in combination with electrical energy storage systems (photovoltaic batteries). These systems contribute to energy savings and support the goal of bringing the building stock closer to nearly zero-energy consumption standards by 2050, while also helping reduce living expenses.
The Photovoltaics on the Roof program provides subsidies to households for installing photovoltaic systems with energy storage facilities (photovoltaic batteries). It also supports farmers in installing photovoltaic systems with or without energy storage for self-consumption through an energy netting arrangement.
Photovoltaic Systems in Greece
Considering the high levels of sunshine in Greece, the country undoubtedly offers favorable conditions for the development and installation of photovoltaic systems. Solar energy is available in abundance and is certainly one of the most widely available natural energy resources. Installing photovoltaic systems can contribute positively to the growth of this industry and benefit individual consumers who are looking for reliable and more cost-effective alternatives to oil and gasoline. This is particularly relevant nowadays, as demand for electric vehicles continues to increase.
In conclusion, photovoltaic systems represent a sustainable solution that supports both financial savings and environmental protection, contributing to a greener and more resilient energy future.
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