The Science and Invention of Solar Panels

What is a solar panel?

Solar panels turn sunlight into electricity using photovoltaic (PV) cells. These cells consist of semiconductors like silicon that can generate an electrical current when exposed to light. The panels are installed on the roof of a building or a solar farm or ground to collect sunlight and generate energy. You can also find solar panels on carports, canopies, and on the sides of buildings. Solar panels can be classified based on the type of photovoltaic semiconductor used - single-crystalline silicon, polycrystalline silicon, amorphous silicon, or non-silicon materials. The most common materials used to make solar panels are crystalline silicon, mono-crystalline silicon, and amorphous silicon. Silicon is used because it is abundant, cheap, stable, and has high electron mobility. A silicon solar cell generates about a third more power than a cell made from an alternative semiconductor.

How does a solar panel work?

Solar panels contain photovoltaic cells that convert sunlight into electricity. These cells are made from a material called silicon, which can generate an electrical current when exposed to light. A solar panel contains many silicon photovoltaic cells connected. When sunlight falls on these cells, it generates a flow of electrons. The electrons then flow through a wire from the photovoltaic cells and into your home’s electrical grid. Solar panels also come with an inverter, which converts the direct current (DC) produced by the solar panels into alternating current (AC) that can be fed into the grid. The AC generated by the solar panels is the same current that is supplied by the grid. The only difference is that the source of the power has now been changed from an AC cord coming from the grid to a DC cord coming from the solar panels.

How was the problem of limited daylight hours solved?

The silicon photovoltaic cells used in solar panels are not very efficient. That is, they only convert a small percentage of the sunlight they receive into electricity. This low efficiency is because silicon is a poor conductor of electricity. There are several ways in which the efficiency of silicon photovoltaic cells can be increased. The most effective method is to use a larger silicon wafer. Using a silicon wafer that is about 10 times thicker than the standard silicon wafer increases the efficiency of silicon photovoltaic cells. The larger silicon wafer can also be cut into smaller pieces and stacked together, forming a solar panel. This way, a larger surface area of silicon is exposed to sunlight, leading to higher efficiency in generating electricity. The silicon wafer can also be combined with materials like cadmium or indium which are better conductors of electricity, to improve the overall efficiency of silicon photovoltaic cells.

How was the problem of low light intensity solved?

Silicon photovoltaic cells are efficient when exposed to light with a wavelength of about 900 nanometers. But lower wavelengths are also reflected by clouds and dense forests, thereby reducing the intensity of light reaching the silicon photovoltaic cells. The intensity of light falling on silicon photovoltaic cells has to be very high to generate a substantial flow of electrons. This creates a challenge since sunlight intensity falls as the distance from the sun increases. One way to solve this problem is by adding a reflective coating to silicon photovoltaic cells. This coating reflects light at a wavelength of fewer than 900 nanometers, thereby increasing the intensity of light falling on silicon photovoltaic cells and increasing their efficiency. Silicon photovoltaic cells can also be stacked together to form a solar panel. This increases the surface area of silicon photovoltaic cells and hence the intensity of light falling on them.

How was the problem of high installation cost solved?

Silicon photovoltaic cells are made from pure silicon crystals that have to be grown in a laboratory. Growing silicon crystals is a time-consuming and energy-intensive process that requires large amounts of money. This high cost of silicon photovoltaic cells is a major challenge to their wide adoption in the energy sector. One solution to this problem is to use thin silicon wafers that can be economically produced from raw materials like sand or quartz. Growing silicon crystals from these less expensive materials can reduce the cost of silicon photovoltaic cells. Silicon photovoltaic cells grown from less expensive materials can be stacked together to form a solar panel. This reduces the overall cost of silicon photovoltaic cells, making solar energy more affordable.

Conclusion

The invention of solar panels brought solar power into homes across the globe. Solar panels are made from silicon photovoltaic cells that have been engineered to increase their efficiency. Higher efficiency in generating electricity has been achieved by increasing the thickness of silicon wafers, adding reflective coatings, and stacking silicon photovoltaic cells together to increase the surface area of silicon exposed to sunlight. The challenge of low light intensity has been addressed by using a more reflective coating. This has been made economically possible by growing silicon photovoltaic cells from less expensive materials like quartz sand. The invention of solar panels has solved the problems hindering the use of solar power as an alternate source of electricity.