The Sun emits enough power onto Earth each second to satisfy the entire human energy demand for over two hours. Given that it is readily available and renewable, solar power is an attractive source of energy. However, as of today, only two percent of the world’s energy comes from solar. Historically, solar energy harvesting has been expensive and relatively inefficient. Even this meager solar usage, though, is an improvement over the previous two decades, as the amount of power collected from solar energy worldwide increased over 300-fold from 2000 to 2019. New technological advances over the last twenty years have driven this increased reliance on solar by decreasing costs, and new technological developments promise to augment this solar usage by further decreasing costs and increasing solar panel efficiency.

Over the past 20 years, the costs associated with solar cells, the structures capable of converting light energy into electricity, have been steadily decreasing. 

Silicon based

Because solar cells are used to convert light into electricity, they need to be composed of some material that’s good at capturing energy from light. Historically, silicon has been the most popular material for solar cells. Theoretically, about 32% of light energy could be converted into electric energy with a silicon solar cell. Additionally, silicon is also inexpensive. It is one of the most abundant elements on earth, and the cost of refining it has decreased dramatically since 1980. The solar cell and electronics industries have driven the decrease in purification cost as they have learned better bulk purification techniques to drive the demand of solar cells and consumer electronics.

In addition to decreasing material costs, clever engineering tricks are pushing the efficiency of silicon solar cells closer to their theoretical maximum. 

Currently, the cost of silicon-based solar cells continues to decrease, and, despite predictions to the contrary, the cost of silicon itself continues to decrease. Silicon solar cells are likely to remain popular for the next few years. Alternatives to silicon solar cells have been developed but aren’t far enough along to be commercially viable.

To outpace current solar cells, a new design would need to be able to capture more light, transform light energy to electricity more efficiently, and/or be less expensive to build than current designs. Energy producers and consumers are more likely to adopt solar power if the energy it produces is equally or less expensive than other, often non-renewable, forms of electricity, so any improvement to current solar cell designs must bring down overall costs to become widely used.

The first option, adding hardware that allows the solar cells to capture more light, does not actually require that we abandon current solar cell designs. Electronics can be installed with the solar cell that let the cell track the sun as it moves through the daytime sky. If the solar cell is always pointing at the sun, it will be hit by many more photons than if it was only pointing towards the sun around midday. Currently, designing electronics that can track the position of the sun accurately and consistently for several decades at a reasonable cost is an ongoing challenge, but innovation on this front continues. An alternative to making the solar cell itself move is to use mirrors to focus light on a smaller, and therefore cheaper solar cell.

Another route to improving the performance of solar cells is to target their efficiency so they are better at converting energy in sunlight to electricity. Solar cells with more than one layer of light-capturing material can capture more photons than solar cells with only a single layer. Recently, lab-tested solar cells with four layers can capture 46% of the incoming light energy that hit them. These cells are still mostly too expensive and difficult to make for commercial use, but ongoing research may one day make implementing these super-efficient cells possible.

The alternative to improving the efficiency of solar cells is simply decreasing their cost. Even though processing silicon has become cheaper over the past few decades, it still contributes significantly to the cost of solar cell installation. By using thinner solar cells, material costs decrease. These “thin-film solar cells” use a layer of material to harvest light energy that is only 2 to 8 micrometers thick, only about 1% of what is used to make a traditional solar cell. Much like cells with multiple layers, thin-film solar cells are a bit tricky to manufacture, which limits their application, but research is ongoing.Source: Emily Kerr, Harvard University

According to recent research from BloombergNEF, wind and solar energy are now the least expensive forms of power in two-thirds of the world, and advancements in technology are pushing it towards an even brighter future.

What the future has in store

The DNV GL energy transition outlook provides an outlook of 33 percent of all electricity being generated from solar by 2050, with all renewables totaling 80 percent of electricity generation.

According to the International Renewable Energy Agency (IRENA) First generation technologies remain the principal driver of solar industry development and still hold the majority of the market value. Tandem and perovskite technologies also offer interesting perspectives, albeit in the longer term several barriers still need to be overcome. The emergence of new cell architectures has enabled higher efficiency levels. In particular, the most important market shift in cell architecture has resulted from bifacial cells and modules, driven by the increased adoption of advanced cell architecture, such as passive emitter and rear cell (PERC), and by its compatibility with other emerging innovations, such as half-cut cells and others.

Bifacial systems

Bifacial PV modules and the expanding application of single-axis trackers are helping to fuel this growth. Bifacial modules provide additional energy as they can absorb and convert light into electricity from both sides of the module, capturing energy that reflects from the ground.

Recent projects have been announced that take advantage of bifacial modules to increase the output beyond that of traditional mono-facial systems. DNV GL are working with customers across Egypt, Brazil, Mexico and the US, all of whom are deploying bifacial modules, to drive down costs and increase the value of these PV assets.

Combining these systems with single axis-trackers designed for bifacial applications can also increase the total energy output. However, bifacial systems require additional simulations and measurements to estimate and optimize the output. The industry is making progress toward reducing the uncertainty with a growing collection of performance data from the field, which is helping us validate models and demonstrate the added value of these assets. (Source: Renewable energy world)

New generation photovoltaics: Perovskite

In recent years the innovation of perovskite solar cells may very well revolutionize solar energy. Perovskites, third-generation solar cells, are composed of a calcium titanium oxide mineral which is composed of calcium titanate (CaTiO3) on a man-made material that can be produced at a low cost. 

One of the most exciting parts of perovskites is their high efficiencies. Based on lab calculations, scientists believe that perovskite solar cells are capable of beating the efficiencies of traditional mono- or poly-crystalline silicon cells. Although they have been in development for far less time than silicon cells, perovskite cells are already reaching lab efficiencies above 20 percent. Researchers hope that perovskite solar cells can exceed the efficiency limits of traditional panels once more lab development is done.

Another advantage of perovskite solar cells is that they are based on a man-made material that can be produced at a low cost. Standard solar PV cells are made with crystalline silicon, which has to be extracted from the earth and processed before it can be used to make high-quality solar cells. Perovskite cells are made through a process called “solution processing” which is the same practice used when printing out newspapers.

Thanks to solution processing, perovskite manufacturing is highly scalable, and production costs have the potential to be very low compared to other solar panel technologies. Lower production costs translate to low costs for consumers looking to go solar, and lowering the cost of installing solar makes it easier for anyone to take advantage of solar energy.

Like other thin-film technologies, perovskite solar cells have unique properties that make them attractive for reasons beyond their low-cost potential and energy production capabilities. Thin-film panels are typically flexible, lightweight, and semi-transparent. From a design perspective, this makes perovskites highly appealing, as they appear much lower-profile than traditional silicon solar panels and can be incorporated into parts of buildings besides just the roof. Additionally, their lightweight nature means less physical stress on roofs, walls, or wherever they may be installed.

Perovskites are currently still in the development phase as scientists try to work out the roadblocks to the technology becoming widely available. Some issues that still need lab time to fix are the toxicity of cell components and the durability of the solar cells. Specifically, a toxic substance called Pbl is produced when perovskite breaks down, and there are some concerns that it may be carcinogenic as well. 

We may still see perovskite solar cells become available in the near future. It has taken over 60 years of development and improvements for consumers to be able to purchase silicon solar cells with efficiencies over 20 percent, and perovskites have already reached those numbers in the laboratory. At the current rate of progress, some scientists predict that perovskites will be ready for solar installations within several years (source: Jacob Marsh, EnergySage’s).

 Floating solar farms

Silicon panels are becoming cheaper and more efficient day-by-day. According to experts, if photovoltaic panels are placed on reservoirs and other water bodies, they offer even greater efficiency as well as a plethora of other benefits.

“Floatovoltaics” are photovoltaic solar power systems created for floating on reservoirs, dams, and other water bodies.Floating solar farms can generate huge amounts of electricity without using valuable land or real estate. The installation costs of floating photovoltaic panels are less than land-based photovoltaic panels. Also, research showed that the power production of floating solar panels is greater by up to 10% due to the cooling effect of water. Besides producing clean solar power, floating solar farms can help with water management. They reduce the loss of water to evaporation as they limit air circulation and block sunlight from the surface of the water. Also, floating solar farms prevent noxious algae production, lowering water treatment costs. Furthermore, the water beneath keeps solar panels clean and minimizes energy waste.In 2008, the first commercial 175 kWh floating panel system was installed in California at the Far Niente winery in Napa Valley.Source: Jagpreet Sandhu | SolarReviews 

Solar power: Ideal solution for airport operators?

Airport interest in solar energy is growing rapidly as a way to reduce airport operating costs and to demonstrate a commitment to sustainable development. Airport owners and operators are interested in solar energy for many reasons. Solar technology has matured and is now a reliable way to reduce airport operating costs. Environmentally, solar energy shows a commitment to environmental stewardship, especially when the panels are visible to the traveling public. Among the environmental benefits are cleaner air and fewer greenhouse gases that contribute to climate change. 

Airports are large users of electricity. For instance Schiphol Airport uses more than 175 million kWh in electricity yearly. This is the equivalent of a small city.

Solar farming is particularly well-suited to airports because of the available space at airports, unobstructed terrain, and energy demand and because the largest energy demand for an Airport is during daytime, the captured solar energy can be used directly, powering the Terminal operation and the ground handling operation efficently. In a growing number of locations, solar farming can provide a cost-effective and stable long-term energy supply for airports. If implemented smart and power usage across the airport operation has been optimized, Investing in solar farming can be hugely profitable, generally seeing significant return on investment within 7 years. 

Solar electricity performance is affected on-site by geographic, meteorological, and technical conditions. Electricity production is dependent on the amount of solar irradiance (i.e., sunshine intensity) at any one location, cloud cover, and other environmental factors such as smog and dust. The amount of energy available also changes daily and seasonally depending on the position of the sun in the sky. For any location, the maximum solar irradiance will occur at 12:00 noon on the summer solstice. Solar irradiance is typically measured in “peak sun hours” which defines the number of hours (on average) where a location can produce 1 kWh/m2 (kilowatt-hour per meter squared). (source: FAA)

Growth of the solar energy industry has led developers to approach airports with a business prospect of locating solar facilities on airport due to the availability of cleared open space and high energy and electricity use. More indirectly, private developers have proposed large-scale solar developments off airport in areas utilized by aviation either near airports or along common flight paths. These interactions have caused the aviation community to question in a broad sense whether solar energy generation is compatible with aviation due specifically to issues such as glare, radar interference, and physical penetration of airspace. 

Given the large amount of new information being created by the solar industry, a brief overview of ins and outs, do’s and dont’s  will help Airport owners and operators make the right choices. ENADT can provide airport owners and operators with a quick scan! Feel free to contact us and see what we can do for your airport.