The sun can deliver enough energy to the earth every second to meet human energy needs for over two hours. Solar energy is an attractive energy source because it is readily available and renewable. However, as of 2018, less than 2% of his global energy comes from solar power. Until now, collecting solar energy has been expensive and relatively inefficient. But even this modest use of sunlight has improved over the past two decades, with the amount of electricity generated worldwide from solar energy increasing 300-fold from 2000 to 2019. Recent technological advances over the past two decades have increased our reliance on solar energy through lower costs, and new technological developments will increase the use of this solar energy through further cost reductions and improved solar panel efficiency.
Over the past two decades, the cost of solar cells, structures that can convert light energy into electricity, has steadily declined. The National Renewable Energy Laboratory, a U.S. government laboratory that studies solar cell technology, estimates the factors contributing to the increasing affordability of solar cells. They estimate that the hard costs, which are the costs of the physical solar cell hardware, and the soft costs, which include the associated labour force or the cost of obtaining necessary government permits, are about the same. With more potential consumers and more professionals installing new solar cells, soft costs have fallen, allowing companies to mass produce solar cells and install them easily. Hard costs are less than half what they were in 2000, mainly due to lower material costs and increased light-trapping ability of cells. In addition to innovative design, the development of cheaper and more efficient solar cells required careful consideration of the physics of solar radiation.
Solar cells are used to convert light into electricity, so they must be made of materials that can efficiently capture energy from light. This material can be sandwiched between two metal plates and can carry electricity generated from light energy to wherever it is needed, such as home lighting or factory machinery. Choosing the right material to capture light requires measuring the difference between two energy levels called the valence and conduction bands. The low-energy valence band is filled with many small negatively charged particles called electrons, while the high-energy conduction band is mostly empty. When an electron collides with a light particle called a photon, it can absorb enough energy to jump from the low-energy conduction band to the high-energy valence band. Once in the valence band, the electron's excess energy is harvested as electricity. It's as if an electron is sitting at the bottom of a hill (the conduction band) and hits a photon (the valence band) that gives the electron jumping energy.
The amount of energy required for an electron to jump into the valence band depends on the type of material. Basically, the size of the figurative mound depends on the properties of the particular material. The size of this energy gap is important because it affects the efficiency with which a solar cell converts light into electricity. In particular, if a photon hits an electron with less energy than the energy required for the electron to jump from the valence band to the conduction band, no light energy is captured. Alternatively, if the light has more energy than is needed to fill this gap, the electrons will absorb exactly the energy they need and waste the rest.
Previously, silicon was the most common material for solar cells. One reason for this popularity is the large gap between the conduction and valence bands of silicon. This is because the energy of most photons is very close to the energy required for electrons in silicon to jump over the energy gap.
In addition to falling material costs, clever technical tricks bring silicon solar cell efficiencies closer to their theoretical maximums. In order for a photon to be converted to energy, it must first collide with an electron. One trick to increasing the likelihood of photon/electron collisions is to pattern the silicon of solar cells into tiny pyramidal shapes. As light is absorbed by the pyramids, it travels further and has a greater chance of colliding with electrons in the silicon before it leaves the cell.
In a similar tactic, chemists and materials scientists have developed anti-reflection coatings applied to the front surface of solar cells to prevent useful light from reflecting into space without impinging on the solar cell's electrons. Similarly, more light can be collected by attaching a reflector to the back of the solar cell. The light that reaches the solar cell and is transmitted to the back without hitting electrons is reflected back to the front of the cell, giving the cell another chance to collect light.
Currently, the cost of silicon-based solar cells continues to fall, and despite predictions to the contrary, the cost of silicon itself continues to fall. Silicon solar cells may continue to be popular in the future. Alternatives to silicon solar cells are being developed, but not sufficiently developed to be commercially viable.
To outperform today's solar cells, new designs will capture more light, convert light energy into electricity more efficiently, and be cheaper to manufacture than current designs. Is required. Producers and consumers of energy are more likely to choose solar energy if the energy it produces is comparable to or cheaper than other forms of electricity, which are often non-renewable. Therefore, to improve current solar cell designs, it is necessary to reduce overall costs and find broader applications.
The first option of adding hardware to allow the solar cell to capture more light doesn't really have to abandon the current solar cell design. Solar cells can be attached to electronic devices so that they can track the sun as it travels through the daylight. If the solar cell is pointed at the sun all the time, more photons will hit the solar cell than if it is pointed at the sun only at noon. Today, developing electronics that can accurately and consistently track the position of the sun over decades is an ongoing challenge, but innovation in the field continues. Instead of moving the solar cells themselves, mirrors can be used to focus the light onto smaller and therefore cheaper solar cells.
Another way to improve the performance of solar cells is to tune the efficiency of the solar cells to convert more of the sun's energy into electricity. A solar cell with multiple layers of light-trapping materials can capture more photons than a solar cell with only a single layer. A four-layer solar cell recently tested in the lab can capture 46% of the incident light energy. These cells are typically still expensive and difficult to manufacture for commercial use, but ongoing research may one day implement these ultra-efficient cells.
An alternative way to improve the efficiency of solar cells is simply to lower the cost. Although silicon has become cheaper to process in recent decades, it still contributes significantly to the installation cost of solar cells. Using thinner solar cells reduces material costs. These "thin film solar cells" use layers of material that are only 2 to 8 microns thick to collect light energy. This is only about 1% of the thickness used to manufacture conventional solar cells.
You can also read: 10 Strong Reasons – Why solar energy is important for the future
WAAREE RTL (WRTL) is Waaree Energies’ EPC arm which is also a listed company in India. It has an experience of more than 600MWp of Solar power plant installations across several countries including projects like ‘50MW in 100 Days – Vietnam’, while embarking on a successful competence in Ground mounted, Rooftop, and Floating Solar power projects. WRTL has helped numerous clients with their transition to clean energy and helped reduce their carbon footprint with SOLAR POWER. Step on to your cleaner journey by contacting us at 18002121321 or mail us at waaree@waaree.com
