Exploring the 5 Main Types of Solar Energy: PV, STE, CSP, Passive Solar, BIPV

Solar energy is a renewable energy source that has gained immense popularity in recent years as a cleaner, more sustainable alternative to traditional fossil fuels. With advancements in technology, solar energy has become more efficient, affordable, and accessible to people all over the world. In this article, we will explore the four main types of solar energy that are commonly used today.

The 5 main types of solar energy are Photovoltaic (PV) Solar Energy, Solar Thermal Energy (STE), Concentrated Solar Power (CSP), Passive Solar Energy, and Building-integrated Photovoltaics (BIPV).

#1 Photovoltaic (PV) Solar Energy

Photovoltaic (PV) solar energy is obtained by converting sunlight (solar radiation) into electricity through the use of solar panels, a technology based on the photoelectric effect. The solar panels contain photovoltaic cells that convert sunlight into direct current (DC) electricity, which is then converted into alternating current (AC) electricity for use in homes and businesses. A photovoltaic cell can be made of monocrystalline, polycrystalline, amorphous silicon, or other thin-film semiconductor materials.

It is modular, so it can be used in installations ranging from huge photovoltaic plants on the ground to small roof panels. Owing to this trait, Solar PV has become the dominant type of solar energy in use in recent years, accounting for over 95 per cent of total installations.

#2 Solar Thermal Energy (STE)

Solar thermal energy is the energy created by converting solar energy into heat and is one of the most cost-effective forms of using solar energy. There are several ways solar thermal energy can be used to make commercial and industrial buildings sustainable and more energy efficient. The applications may range from but are not limited to, solar space heating, solar water heating, and solar thermal cooling.

Using STE requires special arrangement. For instance, space heating is done in a solar ventilation system that uses transpired collector, which consists of a thin, black metal panel mounted on a sun-facing wall to absorb the sun’s heat. Air passes through the many small holes in the panel. A space behind the perforated wall allows the air streams from the holes to mix. The heated air is then sucked out from the top of the space into the ventilation system.

Using other mechanisms, such as solar collectors and thermally activated cooling systems (TACS), STE is also used in solar water-heating systems and space cooling systems to provide large quantities of hot water for nonresidential buildings and to cool the air, respectively.

While concentrated solar power (CSP) technology also uses the thermal energy of the sun to obtain power, the process and scale of power generated differ significantly. Further, regular solar thermal energy systems need the sun and go useless once the sun has set. However, Concentrating solar power systems can store thermal energy in molten salts, allowing them to continue generating electricity even after the sun has set.

#3 Concentrated Solar Power (CSP)

Concentrated Solar Power (CSP) is a type of solar thermal energy that uses mirrors or lenses to focus solar radiation onto a small area to generate high-temperature heat. The mirrors or lenses focus sunlight onto a receiver, heating a fluid that is then used to produce steam and drive a turbine. The heat is then used to create steam, which drives a turbine to generate electrical power. The process can be repeated continuously because CSP technology can store the heat produced. It can therefore be used on days where there is no sun, or before sunrise and after sunset.

CSP systems can be combined with other power sources to create hybrid power plants. For example, it can be integrated with thermal-fired power plants that use fuels like coal, natural gas, and biofuel.

Located in the Moroccan city of Ouarzazate, the Noor Ouarzazate Solar Complex, a 580MW solar power project, is one of the world’s biggest concentrated solar power facilities.

#4 Passive Solar Energy

Passive solar energy refers to the use of natural light and heat from the sun to warm a building or space without the use of any active mechanical systems or technologies (like TACS and collectors in STE systems). It utilizes favourable architecture.

Passive Solar Heating is often used in the design of buildings, through the use of large windows that allow for maximum sun exposure, sun-facing glass, and the use thermal mass materials that absorb and store heat during the day. Similarly, Passive solar cooling systems use shading, thermal mass, and natural ventilation to reduce unwanted daytime heat and store cool night air to moderate temperatures.

#5 Building-integrated Photovoltaics (BIPV)

This includes the integration of photovoltaic (PV) panels into the building components, such as the roof, walls, or windows. This type of solar energy is used to generate electricity for the building, reducing the need for traditional power sources. Apart from increasing the energy efficiency and sustainability of buildings, BIPV also serves as an attractive design feature.

Further, the initial installation cost is also offset by reducing the number of building materials and labour work – overall cost saving. The Copenhagen International School is one of the most shining examples of buildings with the BIPV system. The BIPV solar energy system not only looks great, but it provides half of the annual electricity needs for the school. With a total capacity of 700 kW, the system produces 500,000 kWh annually.