Photovoltaic Cells: Quick Guide to PV Photovoltaic Tech

he world increasingly shifts towards clean energy. Photovoltaic technology is already the cornerstone of sustainable development in many countries, especially sun-rich ones. This article will cover the main aspects of photovoltaic solar energy and explain what makes it unique.

Is there any difference between solar and photovoltaic?

All photovoltaic systems can be called solar, but not all solar systems are photovoltaic. Solar power can be used either to produce electrical or thermal energy. Solar thermal technologies convert solar radiation into heat, while photovoltaic panels transform sunlight into electricity (as the name implies: photo = light, voltaic = electricity).

Photovoltaic solar cells as the basic unit of a PV module

Photovoltaic cells, also known as solar cells, are electrical components that absorb the sun’s energy and use it to create an electrical current. A standard residential solar panel is usually composed of 60 cells. Large commercial solar panels have 72 cells, as the additional 12 photovoltaic cells increase the total energy output.

Photovoltaic solar cells are made of semiconductors – materials with intermediate electrical conductivity. Today, the most popular semiconductor material for solar panels (and for most other electronic devices) is silicon - the second most abundant element on Earth after oxygen. It is valued for its availability, efficiency, and reasonable cost.

How do solar photovoltaic panels work?

Photovoltaic solar technology is based on the photovoltaic effect. This term is used to define the process of turning sunlight into electricity.

Silicon crystalline solar technology

Silicon solar cells consist of two layers of silicon. The top layer contains an excess of electrons and is negatively charged, and the bottom layer has an excess of so-called holes, or missing electrons, and is positively charged. Each layer of the solar cell is connected to the ends of a circuit.

The sunlight in the form of photons hits and penetrates the solar cells. Thanks to the photovaoltaic effect, these photons cause electrons to “come loose” from atoms. The loose electrons are forced to jump out of the top layer, flow around the circuit, and combine with the holes in the bottom layer. The electrons move in one constant direction, which creates a direct current flow.

Then, a solar system com ponent called an inverter converts the generated direct current (DC) electricity into alternating (AC) current electricity, which flows from the photovoltaic panels to your home and powers your appliances.

Crystalline PV panels can be monocrystalline or polycrystalline. Monocrystalline cells are manufactured from a single crystal. Such PV solar modules convert solar energy into electric energy with higher efficiency than polycrystalline photovoltaic solar cells that consist of multiple silicon crystals.

Alternatives to conventional solar modules

While silicon is the most common semiconductor used worldwide in solar panels, there are some alternative photovoltaic solar options. Let’s take a quick look at some other PV solar products.

• Thin-film photovoltaic panels are made up of electricity-producing layers that are hundreds of times thinner than those made of silicon. As a result, thin-film solar panels are very light and flexible. Usually, they are less expensive but also less efficient than silicon models.
• Whereas PV photovoltaic panels are attached to the part of your house, most often on rooftops, building-integrated photovoltaic systems (BIPV) are seamlessly integrated into the house's vital exterior elements, like facades, roofs, or windows. Being a promising innovation in the photovotaic market, BIPV products remain more expensive than traditional solar systems.
• Unlike conventional PV systems, concentration photovoltaics (CPV for short) uses optical light collectors such as lenses or mirrors to focus a large area of sunlight onto a small area of high-efficient multi-junction photovoltaic cells. CPV needs less PV solar material, therefore, it is less expensive. However, concentrating light requires direct sunlight, limiting this technology to extremely sunny locations, for example, the desert Southwest of the United States.

The history of photovoltaic systems

Photovoltaic technology was born in the United States in the 1950s. Throughout the 1960s, the first conventional photovoltaic solar cells were principally used to provide electrical power for satellites. The U.S. energy crisis of the 1970s forced American leaders and scientists to develop PV systems further. Improvements in the performance of solar cells opened up many opportunities to produce electric energy for powering homes and businesses. Still, at that time, photovoltaic solar energy was not cost-competitive with existing energy sources such as fossil fuels.

Nowadays, the cost of PV solar energy products is about 100 times cheaper than in the mid-1970s, in particular thanks to the technological advancements in PV and declines in manufacturing costs. Over the past few decades, governments began incentivizing the use of solar, offering grants and subsidies. PV solar equipment is getting less expensive and more efficient yearly.

Current trends in solar energy

As photovoltaic solar technology advances, its application is becoming more widespread. For example, solar powered LED streetlights reduce carbon emissions in many urban areas. PV noise barriers along highways mitigate noise levels while producing clean, renewable energy. Floating photovoltaic solar panels generate massive amounts of energy without taking up land or real estate.

The future of solar power

Although many successful steps have already been taken, further advances and investments will be necessary for the development of the PV solar industry. By constantly reducing manufacturing costs while simultaneously increasing the efficiency of photovoltatic cells, solar producers will ensure the ongoing rise of the industry. Another technical issue for photovoltaics is increasing storage capacity. Last but not least, the challenge is not limited to the technology itself – the development of the solar industry should be supported by policymakers.