Solar panels have emerged as a transformative technology, not only in the field of sustainable energy but also in reshaping the way we harness power from the sun. These sleek and unassuming arrays of photovoltaic cells have a complex engineering foundation, seamlessly converting sunlight into electricity.
At the heart of a solar panel lies the principle of photovoltaics. Photovoltaic cells, often referred to as PV cells or solar cells, are the workhorses of solar panels. These cells are typically made of semiconductor materials, such as silicon, which have the unique ability to convert sunlight into electrical energy. The process begins when photons from the sun’s rays strike the surface of the PV cells, knocking electrons loose from their atoms and creating an electric current.
Solar panels primarily come in two types: crystalline and thin-film solar cells. Crystalline cells are made from slices of single-crystal or multi-crystal silicon. These are more efficient and have a longer lifespan but can be costlier to manufacture. Thin-film cells, on the other hand, are created by depositing thin layers of semiconductor material onto a substrate. While they are less efficient and durable, thin-film panels offer more flexibility and lower production costs. Engineers must carefully select the appropriate type of solar cell based on the intended application and budget.
The core engineering principle behind solar panels is the photovoltaic effect, discovered by French physicist Edmond Becquerel in 1839. It describes the process of converting light into electricity using semiconductors. When photons strike the surface of the solar cell, they transfer their energy to electrons, allowing them to escape from their atomic bonds. This creates an electron-hole pair, generating an electric current. Engineers have refined this concept over the years to develop highly efficient solar cells.
To maximise the efficiency of solar panels, engineers have designed various structures and configurations for solar cells. The most common design is the p-n junction solar cell. In this setup, one side of the cell is doped with elements that provide excess electrons (n-type), while the other side has elements that create electron deficiencies (p-type). When photons are absorbed, they create an electric field at the junction, which drives the electrons toward the positively charged side, generating electricity.
One of the key engineering challenges in solar panel design is ensuring that the panels receive the maximum possible sunlight throughout the day. This is achieved through solar tracking systems, which adjust the angle and orientation of the panels to follow the sun’s path. These systems can significantly improve energy generation by ensuring that the panels always face the sun at an optimal angle.
Solar panels produce direct current (DC) electricity, but most of our household appliances and the electrical grid operate on alternating current (AC). Engineers integrate inverters into the solar panel systems to convert the DC electricity into AC, making it compatible with our electrical systems. This critical component ensures that the energy generated by solar panels can be effectively used in homes and businesses.
Solar panels are designed to withstand various environmental conditions. Engineers select materials that can endure harsh weather, extreme temperatures, and UV radiation. The external glass covering of solar panels is tempered to resist hail and other impacts, and the frame is often made of durable materials like aluminium. Ensuring the long-term durability of solar panels is crucial for their economic and environmental viability.
Innovative engineering solutions go beyond the solar cells themselves. Optics and reflectors are sometimes incorporated into solar panel designs to concentrate sunlight onto the cells. Concentrated photovoltaic systems use lenses or mirrors to focus sunlight onto a smaller area of highly efficient solar cells. This concentration can greatly increase energy output, but it requires precise tracking and cooling systems to manage the increased heat generated.
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