Tag Archives: Solar Panels

Cleaning Solar Panels without Water

Most installations of solar panels are in desert areas that provide plentiful amounts of sunshine. While the desert property is cheap, winds are also common. When the wind blows, it carries a huge amount of dust, which forms a layer on the solar panels. Dust on the solar panel reduces their performance, and the electrical output from the panel can reduce by about 30% with only a month of exposure to the elements.

For a 150 MW solar panel installation, even a 1% drop in the output could translate to a loss in yearly revenue to the tune of US$200,000. According to researchers, a reduction of 3 to 4% power output from solar plants all over the world could lead to an annual loss of nearly US$3.3 billion to US$5.5 billion. Therefore, it is essential to keep solar panels clean, and the most common technique presently is by using water.

However, keeping solar panels clean presently requires an annual supply of nearly 10 billion gallons of water. This is enough water necessary for a million people in developing countries. Cleaning solar panels without water is a labor-intensive task, and carries with it the high risk of scratching and damaging the surface of the panels, which also leads to a reduction in the efficiency of the cells.

MIT researchers have come up with an innovative method of cleaning the surface of solar panels. The method does not require the use of water, is contactless, and is automatic.

This innovative new method from MIT uses electrostatic repulsion. This makes the dust particles jump off the panels and does not require water or brushes. When activated, the system runs an electrode just above the surface of the panel. This results in the dust particles acquiring an electrical charge. The solar panels have a transparent conductive layer on top of their glass covering, and this is only a few nanometers thick. The system applies the same electric charge to this transparent conductive layer.

The same charge on the conductive layer and the dust particles makes them repel each other. As the conductive layer cannot move, the dust particles fall off the panel because of the repulsion. The researchers had to change the voltage until they found a range that overcame the adhesion forces and the pull of gravity and allowed the dust to lift away. They then automated the system using guide rails on the sides of the panel and an electric motor.

This is not the first time that engineers have tried to use an electrostatics-based approach to keeping solar panels clean. However, most approaches used electrodynamic screens and interdigitated electrodes. The problem with such screens is they allow ingress of moisture that can damage the electronics. If the atmosphere is dry, and moisture is not an issue, such as on the surface of Mars, the arrangement could be useful. However, on Earth, this can be a serious problem, because even the desert has ample amounts of moisture.

The researchers have found that as long as the humidity is more than 30%, dust removal was easy. However, the process of dust removal got increasingly more difficult with a decrease in humidity. 

Butterfly Technology Boosts Solar Panel Output

We normally do not relate butterflies to solar panels. After all, bees and butterflies are good for pollinating flowers and transforming them to fruits so that nature can propagate. On the other hand, solar panels are human creations that collect energy from the sun for the use of humankind. The link between the two seems rather distant, apart from the fact that the sun is the basic force that drives all life on our planet. However, science finds the humble butterfly could be holding the key to unlock new techniques for making solar energy cheaper and more efficient.

Cabbage White butterflies need to heat up their flight muscles before they can take off. Researchers at the University of Exeter have observed that the butterflies adopt a specific posture to maximize solar heat capture. The butterflies position their wings in a V-shape, which, when the researchers adapted for their solar panels, increased the power-to-weight ratio of the panels by about 17 times, making them more efficient.

Scientific Reports, a leading scientific journal has published the research. The research team contained members from both the Centre for Ecology and Conservation and the Environment and Sustainability Institute, based at the University of Exeter in the Penryn Campus in Cornwall. According to Tapas Mallick, the lead author of the research, although bio mimicry is popular in engineering, such unparalleled multidisciplinary research is opening pathways for developing low cost solar panels.

Butterflies usually depend on the sun to heat up their flight muscles before they can take off. However, researchers found the Cabbage White butterflies taking flight before other butterflies did, even on cloudy days. The energy from the sun is limited on cloudy days, forcing insects to make maximum use of the available energy to heat up their flight muscles.

Researchers observed that Cabbage White butterflies adopted a v-shaped posture, known as reflectance basking. That allows the butterflies to maximize the concentration of solar energy onto their thorax, so necessary for fast heating up the flight muscles. The wings of the butterflies have a specific sub-structure that allows maximum light from the sun to be most efficiently reflected onto their muscles, which warm up to the optimal temperature as quickly as possible.

The scientists then investigated the process of replication of the butterfly wings for developing a new, lightweight reflective material solar energy products could use. They found that by replicating the simple monolayer of scale cells on the butterfly wings, they could optimize the power-to weight ration of solar concentrators. That made the solar cells lighter and more efficient.

The team also found the optimal angle at which the butterfly held its wings. When the butterflies tilted their wings by about 17 degrees to the body, they were able to increase the temperature of their bodies by 7.3°C more than when they held their wings flat. By positioning the reflectors at 17 degrees within the solar cells, researchers found the output from the solar cells increased by 50 times.

Therefore, by studying the manner in which the lowly butterfly maximized its use of solar energy, scientists could not only double the output of their solar cells. They were also able to improve its power-to-weight ratio significantly.

Is Your Solar Panel Installed the Right Way?

Although few people would have noticed, the costs of solar photovoltaic cells have been dropping over the years. As the technology took off, costs plummeted in the first 12 years. However, between 2005 and 2009, global market demand surged, making it difficult for supply to keep up. As manufacturing picked up post 2009, solar PV cell prices have continued their downward trend steadily. Now, it makes sense for companies to switch to PV cells purely based on economics.

As solar grows to become a more attractive option, we see a clear preference in its adoption over adding new wind capacity. Navigant Research has predicted in their recent report that declining prices will result in the global solar PV market exceed $134 billion by 2020 – a phenomenal increase of 50% from this year. That means a solar capacity addition of nearly 435 Gigawatts.

However, getting the maximum benefit from solar PV cells requires mounting them the right way. As the sun traverses the sky in the daytime, the PV cells must either follow the trajectory of the sun or be mounted in the most optimum way for them to catch most of the sunlight. Automatically turning the PV cells to face the sun requires elaborate sensing and expensive movement mechanisms. Therefore, most people prefer fixed installations that are simple to put up and maintain.

Another thing to consider is the latitude tilt of the location where you intend to install the solar cells. If your location is below the 25 degrees latitude, tilt the solar panel towards the sun the same amount as the latitude number. At 25 degrees latitude, your panel must tilt by 25 degrees. Above 25 degrees, you will need to add five degrees for each additional five degrees of latitude up to 40 degrees. At and beyond 40 degrees latitude, add 20 degrees of tilt to the latitude number. The above is the general thumb rule people follow for solar PV panel installation. Consequently, most installations have the solar panels facing south to catch the maximum amount of sunlight.

Researchers at the Pecan Street Research Institute have discovered ways to additionally fine-tune the positioning and tilt of the solar panels to extract somewhat more power. During their research on impact of residential solar power on the power grid, they discovered that if the solar panels faced west rather than the customary south, they could generate about 2% more power.

So long, homeowners, utilities and architects believed that in the northern hemisphere, solar panels directed south would receive the maximum exposure from the sun. However, when studying home installations in Austin, Texas, Pecan Street researchers found that this was not true. In fact, they noticed south-facing panels generating less energy. They found west-facing panels generated more power in the afternoon, when the energy demand peaked.

As energy demand peaks, a typical home in Austin using solar panels reduces its reliance on the power grid by as much as 54%. However, for homes with west-facing panels, this number shot up to 65% – a significant power saving. Therefore, by merely shifting the angle, you may be able to achieve significant gain in solar power generation.

Can a Solar Cell Store Its Own Power?

Can a Solar Cell Store Its Own Power?

Researchers at Ohio State University have invented a device that looks like a solar cell but has the ability to store the power it generates. The patent-pending device is the world’s first solar battery. On October 3, 2014, the researchers reported in the journal – Nature Communication – that they have succeeded in combining a solar cell and a battery into a single hybrid device.

The innovation is a special solar panel in the form of a mesh that allows entry of air into the battery. Another unique process allows electrons to be transferred between the solar panel and the electrodes of the battery. Light and oxygen entering the device enable chemical reactions to charge the battery.

According to Yiying Wu, Professor of chemistry and biochemistry at the Ohio State University, they will license the new solar battery to industry. Wu expects that the solar battery will tame the costs of renewable energy.

A solar panel is typically used to capture light for converting it to electricity, which is then stored in a cheap battery for later use. By integrating the two functions into a single device, installation becomes simpler and costs go down. The new solar battery may typically bring down the costs by about 25 percent.

The invention also has another advantage. The long interconnections between solar panels and its battery introduce ohmic resistance that reduces the solar energy efficiency because of heat generation when charging. Typically, about 20 percent of the electricity generated by the solar cells is wasted as heat when charging the battery. With the new design, nearly all the electricity generated reaches the battery.

Wu and his students have also developed a high-efficiency battery for use with their solar cells. An earlier designed battery, invented by Wu and his research team, won them the 2014 clean energy prize of $100,000 from the US Department of Energy. The researchers have created a technology spinoff – KAir Energy Systems, LLC – to develop the battery.

The high-efficiency battery is air-powered, meaning it breathes in air when discharging and breathes out when charging. The battery discharges by the chemical reaction of potassium and oxygen. The researchers faced a formidable challenge when trying to combine a solar panel with the KAir type of battery. Typical solar cells are solid panels of semiconductor material and this would prevent air from entering the battery.

Wu and his research team had to redesign the solar panel to make it permeable. They did this by using titanium gauze, a flexible fabric. They grew vertical rods of titanium dioxide on the fabric, similar to blades of grass growing on soil. The rods capture sunlight, while air passes freely through them and the gauze.

Normally, interconnecting a solar cell and a battery requires four electrodes – two on the solar panel and two on the battery. The hybrid design of the researchers has reduced the number of electrodes required to three.

The mesh in the solar panel forms the first electrode. Under this, a thin sheet of porous carbon forms the second electrode, while a lithium plate forms the third. Layers of electrolyte sandwiched between the electrodes forms the battery to store electricity.

What is stretchable electronics?

Imagine carrying your solar panel rolled up like a grapefruit while going camping and stretching it to the size of a room on the spot. It will not break, since it is made from fracture-proof electronics that is super compliant. Well, for the moment, that is the dream of Professor Darren Lipomi, department of Nano engineering, University of California at San Diego.

Darren has a vision of self-repairing skins for sensors. A special super-thin layer of organic material will make up the stretchable skin, very similar to a thin layer of plastic. As this will be as pliable as foil, it will allow the semiconductor to conform to the object and stretch with movement. Such a new phase of bendable materials will influence change in the supply chain by turning flexible electronics into a layer similar to skin. Not only will this give a new meaning to the current phrase – mobile technology, to accommodate to the transition, OEMs will have to alter their manufacturing processes.

Darren is exploring different materials and types of electronics that have molecular structures for allowing conductive materials to function even when deformed or contorted in any direction for long durations. Of importance here, is the molecular level structural details of organic semiconductors. According to the scientists at the University of California, the super-thin film-like material, sometimes as thin as 100 nanometers, could be made to stretch without any loss in its electronic functions. Display light emitters need only be about one hundred billionth of a meter thick, according to Darren.

The professor is interested in solar panels, which he plans on making in the form of a thin, stretchable film on any object such as a piece of clothing or a tent. He describes this as an extremely large solar module that is fracture proof while generating electricity. He also envisions flexible commercial displays used in wearable devices such clothing and watches from Microsoft, Samsung, LG, Google, Apple and many others.

The professor’s research has identified several types of electronic materials that can stretch. However, he feels the major challenge here is to understand the way in which the molecular structure of the flexible materials influences the mechanical and electrical properties. This is especially true when moving from the laboratory material to a commercial product. Depending on the acceptance of the industry towards development of new processes and technology, Darren expects stretchable organic materials will find use in about 10-20 years.

The research is proceeding in two directions. One way is trying to obtain working electronic properties from films of highly amorphous nature. The other is trying to prepare stretchable fabrics or nanowires from processing solutions or by electro spinning. According to the researchers, the latter path forms the middle ground between molecular and composite approaches to elastic semiconductors.

This presents a challenge of representing high-performance molecular semiconductors that have predictable mechanical properties. A tight collaboration will be required from materials scientists, device engineers, synthetic chemists along with theorists – specializing in both the mechanical behavior of soft materials and the electronic structure calculations.

Energy Harvesting – How & Why

What Is Energy Harvesting – Why Is It Needed?

The process of extracting small quantities of energy from one or more natural, inexhaustible sources, accumulation and storage for subsequent use at an affordable cost is called Energy Harvesting. Specially developed electronic devices that enable this task are termed Energy Harvesting Devices.

The world is facing acute energy crisis and global warming, stemming from rapid depletion of the traditional sources of energy such as oil, coal, fossil fuels, etc., which are on the verge of exhaustion. Not only is the global economy nose-diving, but the damage to the environment is also threatening our very existence. Natural calamities like earthquakes, tsunamis, droughts, floods, storms, etc., have become the order of the day. Economic growth is generating a spiraling demand for energy, goading us to tap alternative sources of energy on a war footing. Our very existence on the planet Earth is at stake, and we must find immediate solutions to meet the energy needs for survival.

Alternative Energy Sources Available

There are many, almost inexhaustible, sources of energy in nature. In addition, these energy forms are available almost free, if available close to the place where required. Sources include: Solar Energy, Wind Energy, Tidal Energy, Energy from the waves of the ocean, Bio Energy, Electromagnetic Energy, Chemical Energy, and so on.

Recent Advances in Technology

The sources listed above provide miniscule quantities of energy. The challenge before us is to gather the miniscule amounts and generate meaningful quantities of energy at affordable cost. Until very recently, this has remained an unfulfilled challenge.

Today, research and innovation has resulted in creation of more efficient devices to capture minute amounts of energy from these sources and convert them into electrical energy. Besides, better technology has led to lower power consumption, and hence higher power efficiency. These have been the major propelling factors for better, more efficient energy harvesting techniques, making it a viable solution. These solutions are considered to be more reliable and relatively maintenance free compared to traditional wall sockets, expensive batteries, etc.

Basic Building Blocks of an Energy Harvesting System

An Energy Harvesting System essentially consists of:

a) One or more sources of renewable energy (solar, wind, ocean or other type of energy)
b) An appropriate transducer to capture the energy and to convert it into electrical energy (such as solar cells for use in conjunction with solar power, a windmill for wind power, a turbine for hydro power, etc.)
c) An energy harvesting module to accumulate, store and control electrical power
d) A means of conveying the power to the user application (such as a transmission line)
e) The user application that consumes the power

With advancement in technology, various interface modules are commercially available at affordable prices. Combined with the enhanced awareness of the efficacy of Energy Harvesting, more and more applications and utilities are progressively using alternative sources of energy, which is a definite sign of progress to effectively deal with the global energy crisis.

Optional addition of power conditioning systems like voltage boosters, etc., can enhance the applications, but one must remember that such devices also consume power, which again brings down the efficiency and adds to cost.

How about a solar energy bikini for this summer?

We thought we’d seen just about everything powered by solar panels or solar film until we came across this bikini. Made by Solarcoterie, this bathing suit is made of photovoltaic film strips sewn together in series with conductive thread! With a USB connection, you could be laying on the beach and powering your iPod at the same time. The suit is constructed of 1″ x 4″ solar strips which terminate in a 5V regulator and a female USB connector – perfect for powering your iPod.

The downside is that the bathing suit is a currently custom made offering only so this is not something readily available at your local store. And, we don’t have the power specs but wonder if this also wouldn’t be a great solution for charging other small appliances needed at the beach – like most smartphones and iPads. Of course, this got us thinking about our dream ideas of powering a small cooler (imagine never needing ice at the beach!) or a small fan for cooling off while you’re baking in the sun. The biggest item on our wishlist is always a blender but we’ve got that covered with our battery operated one!

No matter what, we think this use of solar technology is genius.

Solar Energy – a beginner’s look

Solar energy is an exciting field for both scientific study and home and office use, representing the modern drive to find clean, sustainable ways to power everyday life while protecting the planet for generations to come. Solar energy is created by the sun, which plays host to constant explosions of heat and energy. This energy radiates light that eventually reaches Earth, where water, land, and the clouds in the atmosphere absorb a portion.

This light manifests as heat and helps to regulate the planet’s water cycles, including rainfall. Solar energy is converted into food for trees and plants via photosynthesis, and in turn provides the Earth with oxygen and the natural materials necessary for human habitation.

With the many intrinsic and ancient benefits of solar energy we’ve enjoyed over the centuries, it is perhaps unsurprising that modern man has taken it upon himself to truly harness the potential of this natural power source. Solar power is fast becoming a popular way for businesses and homeowners to cut down on energy costs while making a commitment to the health of the environment.

Solar power itself can take many forms, operating for instance through the means of solar panels, which convert radiation from the sun to practical electric energy suitable for a variety of uses, and can store this energy in batteries.

Other common applications for solar power include pumps, switches, and fans for various industrial purposes, greenhouse and other thermal agricultural uses, and special technologies employed in space, such as those used to operate satellites.

Taking advantage of natural solar energy is not only an efficient way to power machines, houses, and more, but is cost-effective as well. Many entrepreneurs and environmentally savvy homeowners find that using solar power greatly diminishes their average monthly electricity expenditures, adding a welcome benefit to the clean and green energy source.

As oil prices fluctuate, and we become more aware of our impact on the global ecosystem, it is becoming imperative that we search for and use renewable sources of energy, and seek to live in a sustainable fashion, so that future generations can enjoy a happy and healthy planet. The use of solar energy through solar power panels and other technologies is an important step in reducing your overall energy footprint, and can give you — and your wallet — a sincere sense of peace and well being.

IKEA completes solar installation in Tempe; 8 more planned

Yesterday, IKEA announced it had flipped the switch on newly installed dual rooftop solar units at its Tempe, Arizona store. The new system is one of the largest solar systems in the Phoenix area and the third such solar energy system for the Swedish home furnishings retailer; they have similar units already in place in Brooklyn, NY and Pittsburgh, PA.

The 300 kW solar energy system will generate 960,000 kWh of electricity annually from 2600 solar panels. It is the equivalent of reducing at least 760 tons of (C02) – which equals the emissions of 133 cars or powering 84 homes annually.

IKEA has other renewable energy initiatives in place. Already operating is solar water heating in stores in Charlotte, N.C.; Draper, Utah; Orlando, Florida; and Tampa, Florida. In addition, a geothermal system is being installed in a store under construction in Centennial, Colorado.

It was also announced that eight California locations are on deck for solar systems. In all, IKEA will be installing nearly 20,000 solar panels at eight of its California locations. IKEA expects the panels to generate 6.65 million kilowatt hours of electricity annually which is enough to power 580 homes for a year. Pending governmental approval, it will begin installing the renewable energy systems later this fall at existing stores in East Palo Alto, Emeryville, West Sacramento, Burbank, Costa Mesa, Covina and San Diego along with its large distribution center in Tejon.

The New York Jets are green on and off the field

With the installation of an array of 3000 solar panels, the New York Jets have really set themselves apart from other professional sports teams. Their team headquarters and 120,000 square foot training facility will be powered by the solar panels that will generate an estimated 750,000 kilo-watt hours of electricity.

Other sports teams have installed alternative energy systems at their training camps and stadiums, but the system at the Jets facility is the largest to date.

The New York Jets can wear their long-time green jerseys proudly – their commitment to providing a source of green energy at their training camp is an inspiration for the rest of the league.