A closer look at solar panels and the technologies that are driving us to a sustainable future.
Solar power is one of the fastest growing industries in the world, largely due to the emergence of new technologies focused on making harnessing the sun’s energy more efficient and affordable. This of course begins with solar panels.
What are solar panels?
We all know what solar panels or modules look like, but if we had to break them down, we would say they consisted of a glass casing, insulation and an anti-reflective coating. All of these are designed to protect and enhance the most important component which is the photovoltaic solar cells. These cells are made of semiconductors with positive and negatively charged layers sandwiched together to create an electric field. They are responsible for initiating the process of power generation the moment sunlight hits them. The more panels you have, the more power you can generate.
Solar panels are usually wired together in an array and laid on rooftops or the ground, – and more recently over water – angled in a direction for optimum exposure or fitted with a tracking system. Most solar panels come with a 10-15 year manufacturer warranty with a 25-30 year performance warranty and the installation process is relatively hassle-free. Though it is always advisable to work with a reliable retailer and installer for the best outcomes.
A matter of efficiency
Simply put, efficiency of a solar panel or cell is a measure of the amount of sunlight hitting its surface converted into energy. This factor varies from panel to panel, manufacturer to manufacturer, but the technology behind it is constantly evolving, always targeting a higher efficiency. However, there are a few factors that affect even the most highly efficient panel. These include:
- The intensity of the sun during the course of the day and shading.
- The rise in temperature and consequent heat build-up, which can reduce efficiency by 10-15%.
- Irregular maintenance which can lead to accumulation of dust or other issues that can reduce light absorption ability.
Materials make a difference
Solar cells are predominantly made of crystalline silicon and are available in two cell formations: monocrystalline which are made up of a single silicon crystal; and polycrystalline cells which are made up of fragments or shards of silicon. These can be quite expensive and some researchers point out that they max out at converting around 22% of harnessed sunlight into electricity.
That being said, efforts are being made to increase the efficiency of crystalline silicon. One such effort is being driven by the National Renewable Energy Laboratory in the U.S. Their work is focused on III-V multijunction materials and hybrid tandem III-V/Si solar cells and their six junction III-V cells have reached 47.1% efficiency under concentrated light.
Also among next generation solar cells are those crafted of a hybrid metal halide perovskite. These cells are garnering a lot of attention for their low price, low temperature processing, excellent light absorption properties and thinner design. Researchers at Oxford PV also found that silicon coated in perovskite increased cell efficiency by 28% with the potential of reaching up to 40%. In an interview, a co-founder of Oxford PV stated that if we are to make a complete shift to solar power, we need to keep driving the price down and one way to do that is to push the efficiency of modules up.
Shaping the future
Simultaneously, innovation in overall solar panel design to enhance efficiency continues. For instance, bifacial solar modules which offer many advantages. Since power can be produced from both sides, the total energy generated is greater. The array footprint is also smaller, thereby reducing Balance of System (BOS) costs.
Some manufacturers are also experimenting with hexagonal lenses to concentrate light and boost efficiency. While Saudi researchers have recently developed a spherical solar cell prototype that is the size of a ping pong ball. Tests under a simulator lamp revealed a 24% higher output than a flat solar cell and 39% after both cells heated up and suffered loss in efficiency.
Thin film solar cells, because of their narrow design, are changing the way solar panels are being integrated into buildings. Solar shingles, for instance, are designed to function as regular roofing materials that generate power. Solar skins on the other hand are a type of PV technology that are flexible, transparent and can even be printed on, allowing for a variety of applications.
And there’s so much more which we will explore in greater detail in upcoming stories. But know that the rapid development of low-cost, high-performance semiconducting materials, space-saving thin films and easily installable technologies means that when it comes to solar power the possibilities are endless.