Posts Tagged ‘def’

Costs for Thermo-photovoltaic Cells Significantly Reduced

Thermo-photovoltaic (TPV) cells are important for changing radiation from any heat source to power. These cells can generate power from the wasted heat which gets released when glass or steel is developed. Adding these TPV cells to domestic power systems can help generate power along with heating water. TPV systems are also overly complex for everyday use. Both of these reasons have made the TPV systems beyond industrial and domestic consumer routine set-up.

Prohibitive cost:

Though TPV cells can be used to enhance the domestic heating system efficiency, the price is a daunting factor in deploying cated on epi-ready substrates, these cells were commercialized for III-V layered epitaxial growth.

Unique new processing technique:

But IMEC has been researching more original and better methods. IMEC has used amorphous Si by diffusion and passivation to form the emitter. Ge substrates specially designed were produced and tested. Ge substrates defined (germanium-based) TPV cells had better quantum efficiency as compared to epi-ready started traditional TPV cells.

Benefits of new method:

The increased efficiency of the germanium-based TPV cells can means more electricity generation from waste heat. An addition in cell performance and reduction in price are the direct result of the surface passivation techniques and the new contacting technologies that had been uniquely formulated by IMEC. The new TPV cells will be crafted up on the special germanium substrate designed and produced just for this.

IMEC’s contribution:

Jef Poortmans, Director Photovoltaics, IMEC, claimed, “IMEC’s research into photovoltaics aims at finding techniques to fabricate cost-efficient and more efficient solar cells.” IMEC has had a long innings in making silicon solar cells and this has been instrumental in the success of their TPV research.

Better future:

As band-gap of the germanium is very near the emission height of the TPV system emitters, germanium-based photovoltaic devices can be found as the appropriate receivers for these kinds of systems. Now with the decreased cell price because of the better processing methods, the future of the market for thermo-photovoltaic applications looks brighter.

Searched Solar Info

Light-driven Nanomotor

How we see things around us without noticing it! We know the unusual habit of the sunflower. How it moves with the movement of the sun each day. But if we want to move anything with the help of sunlight we are not as fortunate as the sunflower is. We first have to convert sunlight into heat or electricity and then convert any of this into mechanical energy. Scientists are trying to copy the action of the sunflower at nanoscale right now. It is no less than a miracle but scientists are the greatest magicians on this earth. Coming generations will reap the benefits of their hard work. A team of the University of Florida chemists is trying a new mechanism to transform light straight into motion – albeit at a very, very, very tiny scale.

Their paper will look soon in the online edition of the journal Nano Letters. The UF team produced a new type of “molecular nanomotor” driven only by photons. Photons are also known as particles of light. While this is not the first photon-driven nanomotor, but what differentiates this nanomotor with others is that this almost microscopic device is totally made up of a single molecule of DNA. This feature makes this photon nanometer special because this simplicity heightens the flexibility of the device. When we are going to use this photon nanomotor in the real world we can easily upgrade, modify, alter the existing one for development, manufacture and real-world applications. It is said that this technology can be used for various purposes and it ranges from medicine to manufacturing.

Huaizhi Kang, who is the doctoral student in chemistry at UF and the first author of the paper said, “It is easy to assemble, has fewer parts and theoretically should be more efficient.”

We have to stress the point again and again that the scale of the nanomotor is almost vanishingly small but its implications are not.

In its clasped, or closed, form, the nanomotor measures 2 to 5 billionths of a meter. When it is unclasped, it extends as long as 10 to 12 nanometers. According to the apparent scientific calculations the nanomotor uses substantially more of the energy in light than traditional solar cells, the amount of force it exerts is proportional to its small size. But it should be clear that size is not going to be a limiting factor.

If we try to glance into the future the nanomotor will successfully be implemented to microscopic devices. It can mend a defunct cell or fight viruses or bacteria. Nanomotor is made up of DNA, so it is biocompatible. While in the conceptual stage, those devices, like much bigger ones, will require a power source to function. One more advantage of the nanomotor is it leaves no waste when it converts light energy into motion.

Preparation of DNA molecules is relatively easy and reproducible, and the material is very safe,” said Yan Chen, a UF chemistry doctoral student and one of the authors of the paper.

But the practical world applications don’t seem easy. If we want to run an assembly line production or drive a vehicle by using nanomotors we would need trillions of those. They have to work together in harmony. Weihong Tan, a UF professor of chemistry and physiology, author of the paper and the leader of the research group reporting the findings, acknowledged, “The major difficulty lies ahead that is how to collect the molecular level force into a coherent accumulated force that can do real work when the motor absorbs sunlight.”

Tan is quite optimistic that the group has already started working on the problem and they would find an answer. He said, “Some prototype DNA nanostructures incorporating single photo-switchable motors are in the making which will synchronize molecular motions to accumulate forces.”

How idi the team make the nanomotor? The research team combined a laboratory-created DNA molecule with azobenzene. Azobenzene is a chemical compounds that reacts to light. A high-energy photon prompts one response, lower energy, another. The researchers attached a fluorophore, or light-emitter, to one end of the nanomotor to demonstrate the movement. At another end they had a quencher, which can quench the emitting light. Their instruments recorded emitted light intensity that corresponded to the motor movement. The research is being funded by the National Institutes of Health and the National Science Foundation.

Radiation does cause things to move from the spinning of radiometer wheels to the turning of sunflowers and other plants toward the sun,” said Richard Zare, distinguished professor and chairman of chemistry at Stanford University. “What Professor Tan and co-workers have done is to create a clever light-actuated nanomotor involving a single DNA molecule. I believe it is the first of its type.”

Solar Powered Wi-Fi Bus Stops

What a pleasing combination for environmentalists! While you are waiting for your bus to come you can happily stay in touch with the cyber world. San Francisco bus stops create solar electricity and offer Wi-Fi connectivity as well. By 2013, San Francisco is planning to have 1100 such solar-powered bus shelters put in throughout the city. This project can act as a catalyst for other states and even countries to follow. They have taken care of the bus stops at the grass root level also. They have used recycled materials to produce these bus stops. The bus stops’ roofs will have solar panels. The underutilized energy of these bus shelters will be directed back to the grids.

The shelter will capture the solar energy with a rolling red top of photovoltaic panels to power the LEDs, the Wi-Fi routers and the intercom. When all the 1100 shelters are installed and in working order these routers will provide Wi-Fi connectivity, probably throughout the state.

San Francisco Mayor Gavin Newsom recently introduced the first solar powered bus shelters designed by Lundberg Design. This solar bus stop is located at Geary and Arguello boulevards in the Richmond District. This new bus shelter boasts of an undulating solar roof that resembles both the hills of San Francisco and a seismic wave. San Francisco falls in the seismic zone. 40% post-industrial recycled polycarbonate material is used in the structure of the roof. In between thin-film photovoltaic cells are embedded. The steel used in the bus shelter is of 75% recycled material. Another advantage of using the recycled material is the reduction in maintenance price. These materials will not be graffiti and etching friendly. “We’re going to see a very stringent maintenance schedule adopted and implemented,” Newsom opined. “I’m looking forward to seeing this shelter looking like this four, five, ten years from now. I’ll be driving by — and riding by, because little do you know I take Muni in spite of some of those who wish I didn’t so they’d have another reason to criticize me.”

The shelter also features a pushbutton update system, more room for transit information, and is expected to feed the energy into the city’s electrical grid.

Though the site of the first shelter is in the foggiest parts of town, but it definitely proclaims to have a clear vision and set great standard for things to come. The current color is ruby red but they will soon utilize amber as more shelters are installed along Market Street and throughout San Francisco. Mayor Newsom proudly proclaimed: “Transit shelters that use photovoltaics, LEDS, and WiFi are going to be standard in the future and I’m proud that San Francisco is once again acting like the pace car for other cities by trying and implementing these technologies.”

The polycarbonate roof structure was configured by 3form Materials Solutions. The photovoltaic laminates were supplied by Konarka Power Plastic. None of the two companies had any experience in implanting photovoltaic cells into a polycarbonate base. But they had produced a technology that realizes negligible electricity loss, and subsequently patented the procedure.

The MTA and Clear Channel didn’t go for a predesigned solution. They held a design competition and selected a local architect, Olle Lundberg of Lundberg Design. Olle Lundberg confirmed that this was his first civic project. His firm designed and built restaurants.

It’s been fun to leave your signature on the city,” said Lundberg. “We’ve done some really beautiful buildings in the city, but honestly nothing will have the same impact as [1100] of these will. These are going to be everywhere and are going to be this kind of icon. I do hope that they become part of the street vocabulary of San Francisco.”

New Concentration Solar Power Modules

The alternative sources of energy are perpetually evolving. Scientists and manufacturers are trying to come up with more beneficial products that are user friendly and efficient. Government is drawing policies that promote use of alternative sources of energy. Researchers, entrepreneurs and common people are devising their own ways to use clean and green sources of energy. We are reading nearly each day about some innovation in the area of alternative energy by one university or another. Newly, University of Lleida has designed a concentration solar power module that creates heat, cold and electricity. The unique feature of these solar power modules is that they can be integrated to façades or building roofs. People instrumental in this project are Daniel Chemisana who is a member of the research group in Agrometeorology and Energy for Environment, Manel Ibáñez and Joan Ignasi Rosell. Both Manel Ibáñez and Joan Ignasi Rosell are lecturers in University of Lleida.

The team has formulated a thermal-photovoltaic modular system having a solar concentration of ten suns. Solar concentration of ten suns implies only a tenth part of a standard system’s active surface is needed to create the same energy. This energy can be in the form of electricity, heat, or both at the same time. It is understood that the reduction in the surface of used solar cells can lead to reduction in price of solar panels. The added advantage is this new technology can generate cold by connecting a heat pump to the system. They have already requested a worldwide patent for this system.

How this research team was able to reduce the surface area without compromising on the amount of power generation? A stationary lens and a linear absorber plate are the main components of the concentrator system. Lens and a linear absorber plate help in concentrating the sunlight to generate energy. This concentration system is responsible for reducing the space that until now was needed with traditional plates. It is to be known that traditional plates move around in search of sunlight.

Rosell also emphasized about the architectural integration that is the USP of this module. These modules can be installed either on roofs or in façades, which will definitely cut down their visual impact. You can set up these plates on roofs, on the closure of concrete or brick blocks. They will act as a curtain wall in the façades or as a part of the railings in terraces. You can term them as your “building’s second skin”. This module is useful for residential buildings, companies or farms.

Why one should go for this model? According to Rosell aside from making a second skin for a building, this device also demonstrates the global efficiency of energy conversion. The conversion rate could rise above 60%. Researchers at University of Lleida are hoping that the product could be manufactured at commercial scale in a year if companies show positive response for this technology. The prototype has been funded by CIDEM and has the support of the University of Lleida Technological Springboard.

Solar Water Heater

Solar Water Heaters

Solar water heaters can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use (sunshine) is free.

solar water heating

Solar water heating is water heated by the use of solar energy. Solar heating systems are generally composed of solar thermal collectors, a water storage tank or another point of usage, interconnecting pipes and a fluid system to move the heat from the collector to the tank. This thermodynamic approach is distinct from semiconductor photovoltaic (PV) cells that generate electricity from light; solar water heating deals with the direct heating of liquids by the sun where no electricity is directly generated. A solar water heating system may use electricity for pumping the fluid, and have a reservoir or tank for heat storage and subsequent use. The water can be heated for a wide variety of uses, including home, business and industrial uses. Heating swimming pools, under floor heating or energy input for space heating or cooling are common examples of solar water heating. A solar water heating system can form part of a solar thermal cooling system, promoting efficient temperature control of buildings or parts thereof. During cool conditions, the same system can provide hot water.

solar water heater

In order to heat water using solar energy, a collector, often fastened to a roof or a wall facing the sun, heats working fluid that is either pumped (active system) or driven by natural convection (passive system) through it. The collector could be made of a simple glass topped insulated box with a flat solar absorber made of sheet metal attached to copper pipes and painted black, or a set of metal tubes surrounded by an evacuated (near vacuum) glass cylinder. In industrial cases a parabolic mirror can concentrate sunlight on the tube. Heat is stored in a hot water storage tank. The volume of this tank needs to be larger with solar heating systems in order to allow for bad weather, and because the optimum final temperature for the solar collector is lower than a typical immersion or combustion heater. The heat transfer fluid (HTF) for the absorber may be the hot water from the tank, but more commonly (at least in active systems) is a separate loop of fluid containing anti-freeze and a corrosion inhibitor, which delivers heat to the tank through a heat exchanger (commonly a coil of copper tubing within the tank).

Residential solar thermal installations fall into two groups: passive (sometimes called “compact”) and active (sometimes called “pumped”) systems. Both typically include an auxiliary energy source (electric heating element or connection to a gas or fuel oil central heating system) that is activated when the water in the tank falls below a minimum temperature setting such as 55°C. Hence, hot water is always available. The combination of solar water heating and using the back-up heat from a wood stove chimney to heat water can enable a hot water system to work all year round in cooler climates, without the supplemental heat requirement of a solar water heating system being met with fossil fuels or electricity.

Passive solar water heating systems are typically less expensive than active systems, but they’re usually not as efficient. However, passive systems can be more reliable and may last longer.

There are two basic types of passive systems:

Integral collector-storage passive systems

These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot water needs.

Thermosyphon systems

Water flows through the system when warm water rises as cooler water sinks. The collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable, but contractors must pay careful attention to the roof design because of the heavy storage tank. They are usually more expensive than integral collector-storage passive systems.

There are two types of active solar water heating systems:

Direct circulation systems

Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.

Indirect circulation systems

Pumps circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.

Other Considerations

Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a demand (tankless or instantaneous) water heater for backup.

When a solar water heating and hot-water central heating system are used in conjunction, solar heat will either be concentrated in a pre-heating tank that feeds into the tank heated by the central heating, or the solar heat exchanger will replace the lower heating element and the upper element will remain in place to provide for any heating that solar cannot provide. However, the primary need for central heating is at night and in winter when solar gain is lower. Therefore, solar water heating for washing and bathing is often a better application than central heating because supply and demand are better matched. In many climates, a solar hot water system can provide up to 85% of domestic hot water energy. This can include domestic non-electric concentrating solar thermal systems. In many northern European countries, combined hot water and space heating systems are used to provide 15 to 25% of home heating energy.

Selecting a Solar Water Heater

Before you purchase and install a solar water heating system, you want to consider the following:

The Economics of a Solar Water Heater

Solar water heating systems usually cost more to purchase and install than conventional water heating systems. However, a solar water heater can usually save you money in the long run.

How much money you save depends on the following:

  • The amount of hot water you use
  • Your system’s performance
  • Your geographic location and solar resource
  • Available financing and incentives
  • The cost of conventional fuels (natural gas, oil, and electricity)
  • The cost of the fuel you use for your backup water heating system, if you have one.

On average, if you install a solar water heater, your water heating bills should drop 50%–80%. Also, because the sun is free, you’re protected from future fuel shortages and price hikes.

If you’re building a new home or refinancing, the economics are even more attractive. Including the price of a solar water heater in a new 30-year mortgage usually amounts to between $13 and $20 per month. The federal income tax deduction for mortgage interest attributable to the solar system reduces that by about $3–$5 per month. So if your fuel savings are more than $15 per month, the solar investment is profitable immediately. On a monthly basis, you’re saving more than you’re paying.

Evaluating Your Site’s Solar Resource for Solar Water Heating

Before you buy and install a solar water heating system, you need to first consider your site’s solar resource. The efficiency and design of a solar water heating system depends on how much of the sun’s energy reaches your building site.

Solar water heating systems use both direct and diffuse solar radiation. Even if you don’t live in a climate that’s warm and sunny most of the time—like the southwestern United States—your site still might have an adequate solar resource. If your building site has unshaded areas and generally faces south, it’s a good candidate for a solar water heating system.

Your local solar system supplier or installer can perform a solar site analysis.

Sizing a Solar Water Heating System

Sizing your solar water heating system basically involves determining the total collector area and the storage volume you’ll need to meet 90%–100% of your household’s hot water needs during the summer. Solar system contractors use worksheets and computer programs to help determine system requirements and collector sizing.

Collector Area

Contractors usually follow a guideline of around 20 square feet (2 square meters) of collector area for each of the first two family members. For every additional person, add 8 square feet (0.7 square meters) if you live in the U.S. Sun Belt area or 12–14 square feet if you live in the northern United States.

Storage Volume

A small (50- to 60-gallon) storage tank is usually sufficient for one to two three people. A medium (80-gallon) storage tank works well for three to four people. A large tank is appropriate for four to six people.

For active systems, the size of the solar storage tank increases with the size of the collector—typically 1.5 gallons per square foot of collector. This helps prevent the system from overheating when the demand for hot water is low. In very warm, sunny climates, some experts suggest that the ratio should be increased to as much as 2 gallons of storage to 1 square foot of collector area.

Solar Water Heater Energy Efficiency

For a solar water heating system, use the solar energy factor (SEF) and solar fraction (SF) to determine its energy efficiency.

The solar energy factor is defined as the energy delivered by the system divided by the electrical or gas energy put into the system. The higher the number, the more energy efficient. Solar energy factors range from 1.0 to 11. Systems with solar energy factors of 2 or 3 are the most common.

Another solar water heater performance metric is the solar fraction. The solar fraction is the portion of the total conventional hot water heating load (delivered energy and tank standby losses). The higher the solar fraction, the greater the solar contribution to water heating, which reduces the energy required by the backup water heater. The solar fraction varies from 0 to 1.0. Typical solar factors are 0.5–0.75.

Estimating a Solar Water Heater System’s Cost

Before purchasing a solar water heating system, you can estimate its annual operating cost and compare it with other more and/or less efficient systems. This will help you determine the energy savings and payback period of investing in a more energy-efficient system, which will probably have a higher purchase price.

Calculating Annual Operating Cost

To estimate the annual operating cost of a solar water heating system, you need the following:

  • The system’s solar energy factor (SEF)
  • The auxiliary tank fuel type (gas or electric) and costs (your local utility can provide current rates).

Then, use the following calculations.

With a gas auxiliary tank system:

You need to know the unit cost of fuel by Btu (British thermal unit) or therm. (1 therm = 100,000 Btu)

365 × 41,045/SEF × Fuel Cost (Btu) = estimated annual cost of operation


365 × 0.4105/SEF × Fuel Cost (therm) = estimated annual operating cost

Example: Assuming the SEF is 1.1 and the gas costs $1.10/therm

365 × 0.4105/1.1 × $1.10 = $149.83

With an electric auxiliary tank system:

You need to know or convert the unit cost of electricity by kilowatt-hour (kWh).

365 × 12.03/SEF × Electricity Cost (kWh)= estimated annual operating cost

Example: Assuming the SEF is 2.0 and the electricity costs $0.08/kWh

365 X 12.03/2.0 X $0.08 = $175.64

Building Codes, Covenants, and Regulations for Solar Water Heating Systems

Before installing a solar water heating system, you should investigate local building codes, zoning ordinances, and subdivision covenants, as well as any special regulations pertaining to the site. You will probably need a building permit to install a solar energy system onto an existing building.

Not every community or municipality initially welcomes residential renewable energy installations. Although this is often due to ignorance or the comparative novelty of renewable energy systems, you must comply with existing building and permit procedures to install your system.

The matter of building code and zoning compliance for a solar system installation is typically a local issue. Even if a statewide building code is in effect, your city, county, or parish usually enforces it locally. Common problems homeowners have encountered with building codes include the following:

  • Exceeding roof load
  • Unacceptable heat exchangers
  • Improper wiring
  • Unlawful tampering with potable water supplies.

Potential zoning issues include the following:

  • Obstructing side yards
  • Erecting unlawful protrusions on roofs
  • Sitting the system too close to streets or lot boundaries.

Special area regulations—such as local community, subdivision, or homeowner’s association covenants—also demand compliance. These covenants, historic district regulations, and flood-plain provisions can easily be overlooked.

To find out what’s needed for local compliance, contact the following:

  • Your local jurisdiction’s zoning and building enforcement divisions
  • Briefly describe your intended construction, asking for other relevant ordinances/codes that might be in effect.
  • Find out if there are any additional local amendments or modifications to the regulations in effect.
  • Ask how to determine whether you are located in a historic district, flood-plain area, or any other special category regulated by a government body.
  • Ask where you may find pertinent ordinances/codes (local library, government office, etc.).
  • Read pertinent sections of the regulations, making photocopies of information you wish to file for future review and design/installation analysis.
  • Ask if they have any ordinances, provisions, or covenants that may affect the design and installation of the system.
  • Copy and file pertinent sections for reference.
  • Homeowner’s, subdivision, neighborhood, and/or community association(s)

Installing and Maintaining the System

The proper installation of solar water heaters depends on many factors. These factors include solar resource, climate, local building code requirements, and safety issues; therefore, it’s best to have a qualified, solar thermal systems contractor install your system.

After installation, properly maintaining your system will keep it running smoothly. Passive systems don’t require much maintenance. For active systems, discuss the maintenance requirements with your system provider, and consult the system’s owner’s manual. Plumbing and other conventional water heating components require the same maintenance as conventional systems. Glazing may need to be cleaned in dry climates where rainwater doesn’t provide a natural rinse.

Regular maintenance on simple systems can be as infrequent as every 3–5 years, preferably by a solar contractor. Systems with electrical components usually require a replacement part or two after 10 years.

When screening potential contractors for installation and/or maintenance, ask the following questions:

  • Does your company have experience installing and maintaining solar water heating systems?
    Choose a company that has experience installing the type of system you want and servicing the applications you select.
  • How many years of experience does your company have with solar heating installation and maintenance?
    The more experience the better. Request a list of past customers who can provide references.
  • Is your company licensed or certified?
    Having a valid plumber’s and/or solar contractor’s license is required in some states. Contact your city and county for more information. Confirm licensing with your state’s contractor licensing board. The licensing board can also tell you about any complaints against state-licensed contractors.

Searched Solar Info

PV Cell Prototype Generates Electricity from IR and UV Light

Solar energy is existing in abundance around us. The trouble is how to harness a substantial portion of it for human use. How to raise the efficiency bar of solar transition into electricity? Scientists are endlessly engaged in finding a way out for this problem. Lately scientists at the Kyoto Institute of Technology have deviated from the regular path and tried to trap the visible as well as invisible rays of sun for electricity. They tried to produce a new photovoltaic cell that can capture visible, infrared and ultraviolet light of the sun. The team now thinks that this photovoltaic will be extremely efficient for solar power transition.

In March, 2010 a meeting was held by the Japan Society of Applied Physics. In this meeting a research group from the Kyoto Institute of Technology talked about their new photovoltaic cell that is capable of generating electricity not only from visible light, but from ultraviolet and infrared light as well. The research group is headed by the associate professor Saki Sonoda. The research group presented a 90-minute lecture on the cell under the title “Nitride Semiconductor Added With Transition Metals as a Photoelectric Conversion Material for Ultraviolet, Visible and Infrared Lights ~ In the Aim of Realizing the Next-generation Super-efficient PV Cell With a Simple Element Structure.”

Saki Sonoda is quite hopeful that his team’s work would lead towards a more effective PV cell that can be single-junction instead of the more conventional multi-junction. A multi-junction PV cell has multiple thin films of varying absorption capabilities. This will help in capturing the entire spectrum of light. But with a single-junction cell all that light can be absorbed using a single junction cell.

These new PV cells were comprised of gallium nitride (GaN) semiconductor. This new photovoltaic cell is produced by ‘doping’ a wide bandgap transparent composite semiconductor i.e. gallium nitride (GaN) with a 3d transition metal such as manganese. Gallium belongs to the family of scandium, titanium, vanadium, chrome, iron, cobalt, nickel, copper, and zinc. Sonoda explained that his team has gone for those additive elements. He said that even aluminum nitride (AlN), which has a very large bandgap, can perhaps have an absorbing region in the visible light range,

If we view the stats we can see that the short-circuit current density of the PV cell is about 10?A/cm2, which is nearly 1/1,000 that of a normal crystalline silicon PV cell. Sonoda explained that typically the cell and electrodes are separated, therefore the electric resistance of the p-type GaN connecting them is very large. Now we can hope that the findings of the research group are anticipated to pave the way to a GaN-based PV cell with a entirely different mechanism.

Solar Energy Facts


General facts

  • Solar Energy production is better for the environment than conventional forms of energy production.
  • Solar energy has many uses other than electricity production. For instance heating of water with solar thermal energy, water treatment through solar distillation and chemical production through solar reaction.
  • Solar energy can be used to heat swimming pools, power cars, power phones, radios and other small appliances.
  • You can cook food with solar energy.
  • Solar Energy is becoming more popular each day. The world demand for Solar Energy is currently greater than the supply.

Facts about Solar Energy usage:

  • Solar Energy is measured in kilowatt-hour. 1 kilowatt = 1000 watts.
  • 1 kilowatt-hour (kWh) = the amount of electricity required to power a 100 watt light bulb for 10 hours.
  • According to the US Department of Energy, an average American household used approximately 888-kilowatt hours per month in 2009 costing them $94.26.
  • About 30% of our total energy consumption is used to heat water.

Facts about Solar Energy systems:

  • A typical home solar system is made up of solar panels, an inverter, a battery, a charge controller, wiring and support structure.
  • A 1-kilowatt home solar system takes about 1-2 days to install and costs around $10,000 USD, but can vary greatly and does not take into account any incentives offered by the government.
  • A 1-kilowatt home solar system consists of about 10-12 solar panels and requires about 100 square feet of installation area.
  • A 1-kilowatt home solar system will generate approximately 1,600 kilowatt hours per year in a sunny climate (receiving 5.5 hours of sunshine per day) and approximately 750 kilowatt hours per year in a cloudy climate (receiving 2.5 hours of sunshine per day).
  • A 1-kilowatt home solar system will prevent approximately 170 lbs. of coal from being burned, 300 lbs of CO2 from being released into the atmosphere and 105 gallons of water from being consumed each month!
  • About 40 solar cells are usually combined into a solar panel and around 10-12 panels mounted in an array facing due North to receive maximum sunlight.
  • An average solar system usually comes with a 5-year warranty, although the solar panels are warranted for 20.
  • Relying on the battery back up, a solar energy system can provide electricity 24×7, even on cloudy days and at night.
  • Solar panels come in various colors.
  • Solar energy can be collected and stored in batteries, reflected, insulated, absorbed and transmitted.

Sun related Facts about Solar Energy:

  • Sunlight travels to the earth in approximately 8 minutes from 93,000,000 miles away, at 671,000,000 miles per hour.
  • Our sun is also the main source of non-renewable fossil fuels (coal, gas and petroleum), their energy was originally converted from sunlight by photosynthesis over millions of years.
  • Solar energy is responsible for weather patterns and ocean currents.
  • Clouds, pollution and wind can prevent the sun’s rays from reaching the earth.
  • The sun accounts for about 99.86% of the total mass of our Solar System.
  • Sunlight on the surface of the Earth is attenuated by the Earth’s atmosphere so we receive only 1,000 watts per square meter of its power in clear conditions.

Other Interesting Facts about Solar Energy:

  • In one hour more sunlight falls on the earth than what is used by the entire population in one year.
  • A world record was set in 1990 when a solar powered aircraft flew 2522 miles across the United States, using no fuel.
  • Fierce weather cost the world a record $130 Billion in the first eleven months of 1998- more money than was lost from weather related disasters from 1980 to 1990 ($82 Billion).
  • Researchers from the Worldwatch Institute and Munich Re blame deforestation and climate change from Earth warming for much of the loss. The previous one-year record was $90 Billion in 1996. Source – Associated Press, November 28,1998.
  • About 2 billion people in the world are currently without electricity.
  • Accounting for only 5 percent of the world’s population, Americans consume 26 percent of the world’s energy.
  • Electric ovens consume the most amount of electricity, followed by microwaves and central air conditioning.
  • Third world countries with an abundance of sunlight and a population currently without electricity, represents the fastest growing market for solar energy, with the largest domestic market being the utilities sector.
  • Shell Oil predicts that 50% of the world’s energy will come from renewable sources by 2040.

High-Tech Thin-Film

You can think of it as origami — very high-tech origami. Researchers at the University of Illinois are working on the same great old silicon but they are taking a completely different path. They are working on thin films of silicon using two processes one is photolithography and another is self-folding process driven by capillary interactions. This process results in the three-dimensional, single-crystalline silicon structures. Their films are only a few microns thick. Their biggest strength is mechanical bendability that is not possible with thicker pieces of the same material.

Ralph G. Nuzzo who is the G. L. Clark Professor of Chemistry at Illinois. Nuzzo is also the co-author of a paper accepted for publication in the Proceedings of the National Academy of Sciences. He explains, “This is a completely different approach to making three-dimensional structures. We are opening a new window into what can be done in self-assembly processes.”

Nuzzo and his co-workers produced spherical and cylindrical shaped silicon solar cells and assessed their performance. They have also gone for a prophetic model that analyzes the type of thin film to be used, the film’s mechanical properties and the desired structural shape. Armed with these facts, researchers must offer us something good and make life easier for those willing to live easy on this earth.

K. Jimmy Hsia is the mechanical science and engineering professor. He tells us, “The model identifies the critical conditions for self-folding of different geometric shapes. Using the model, we can improve the folding process, select the best material to achieve certain goals, and predict how the structure will behave for a given material, thickness and shape.”

Researchers wanted to fabricate their free-standing solar cells. They had to begin from someplace. So they preferred using photolithography to define the desired geometric shape on a thin film of single-crystalline silicon. This crystalline silicon was sitting on a thicker, insulated silicon wafer. Next few steps again required lots of steps and to say the least lots of hard work and thinking. They took out the exposed silicon with etchant. Further they undercut the remaining silicon foil with acid. This resulted in letting go of the foil from the wafer. Finally they placed a minute drop of water at the center of the foil pattern. What will occur when the water evaporates? Capillary forces will come into action. These forces pulled the edges of the foil together, causing the foil to wrap around the water droplet.

Researchers wanted to hold the desired shape after the water had fully evaporated. They accomplished this goal by placing a tiny piece of glass, coated with an adhesive, at the center of the foil pattern. The glass acted as a framework and “froze” the three-dimensional structure in place, once it had achieved the desired folded state.

Jennifer A. Lewis, the Thurnauer is the Professor of Materials Science and Engineering and director of the university’s Frederick Seitz Materials Research Laboratory. She says, “The resulting photovoltaic structures, not yet optimized for electrical performance, offer a promising approach for efficiently harvesting solar energy with thin films.”

The curved three-dimensional structures have an edge over the conventional, flat solar cells. They serve as passive tracking optics by absorbing light from almost all directions. Lewis explains further, “We can look forward from this benchmark demonstration to photovoltaic structures made from thin films that behave as though they are optically dense, and much more efficient.”

There is one more advantage. The new self-assembly procedure is not limited to the silicon only. It can be used by an assortment of thin-film materials.

Fiber Optics Could Provide New Options For Photovoltaics

When we think about going solar we make a mental picture of big weighted panels adorning one’s rooftop. But researchers are trying to get rid of bulky solar panels. They are aiming to accomplish this feat with the help of zinc oxide nanostructures grown on optical fibers and coated with dye-sensitized solar cell materials. Researchers at the Georgia Institute of Technology have built up a new kind of three-dimensional photovoltaic system. This three-dimensional photovoltaic system will not be heavy and it will not occupy a place of prominence on rooftops; it can be hidden from the view.

This project is supported by the Defense Advanced Research Projects Agency (DARPA), the KAUST Global Research Partnership and the National Science Foundation (NSF). Zhong Lin Wang, who is a Regents professor in the Georgia Tech School of Materials Science and Engineering, shares his views, “Using this technology, we can make photovoltaic generators that are foldable, concealed and mobile. Optical fiber could conduct sunlight into a building’s walls where the nanostructures would convert it to electricity. This is truly a three dimensional solar cell.”

Dye-sensitized solar cells have certain distinct rewards over traditional solar panels. They utilize a photochemical system to produce energy. Manufacturer can develop dye-sensitized solar cells cheaply. They are flexible and also mechanically robust. But they have their disadvantages too. Their conversion efficiency is lower than that of silicon-based cells. But this hurdle can be overcome. Nanostructure arrays can be increased enlarge the surface area. This enlarged surface area can trap a lot of sunlight to change it into energy. This feature could assist in cutting down the efficiency disadvantage. Presently the largest advantage of Dye-sensitized solar cells is it can be gelled into anything, be it buildings, vehicles or military equipments.

Dye-sensitized solar cells are inspired by the optical fiber of the type used by the telecommunications industry to transport data. Researchers improved upon the previous model by taking away the cladding layer. In the next step they went for a conductive coating to the surface of the fiber before seeding the surface with zinc oxide. Now scientists utilized solution-based methods to grow aligned zinc oxide nanowires around the fiber. It shaped up like the bristles of a bottle brush. These nanowires are ultimately covered with the dye-sensitized materials that do the ultimate work, i.e. convert light to electricity.

How this whole system works? Wang is forthcoming with a good explanation, “In each reflection within the fiber, the light has the opportunity to interact with the nanostructures that are coated with the dye molecules, You have multiple light reflections within the fiber, and multiple reflections within the nanostructures. These interactions increase the likelihood that the light will interact with the dye molecules, and that increases the efficiency.” First sunlight passes through the optical fiber and into the nanowires. When sunlight is trapped inside the nanowires here it acts jointly with the dye molecules to generate electricity. A liquid electrolyte is present between the nanowires. This electrolyte collects the electrical charges. The ultimate outcome is a hybrid nanowire/optical fiber system which is six times as efficient as planar zinc oxide cells with the equivalent surface area.

Presently Wang and his research team have accomplished an efficiency of 3.3%. But they are aiming for the 7-8% percent after surface modifications. This level of efficiency is distinctly lower than silicon solar cells. But it will prove to be a good source of practical energy harvesting. Its cheaper prices will makes its penetration deep into the market.

The researchers are trying to overcome the lack of conversion rates by utilizing other options such as furnishing a larger area for gathering light. This method would lead to maximize the amount of energy produced from strong sunlight. It will also generate decent power levels even in weak light. The amount of light entering the optical fiber could be manipulated as well. It could be amplified by using lenses to focus the inward bound light, and the fiber-based solar cell have very high saturation intensity.

Wang elaborates on some added points, “This will really provide some new options for photovoltaic systems. We could eliminate the aesthetic issues of PV arrays on building. We can also envision PV systems for providing energy to parked vehicles, and for charging mobile military equipment where traditional arrays aren’t practical or you wouldn’t want to use them.”

Solar Energy System for Google Headquarters

Google Inc. plans to build a massive solar-electricity system to help power parts of its Mountain View, Calif., campus that it says will benefit both the environment and its bottom line. The system, to be built by EI Solutions, a unit of Energy Innovations Inc., of Pasadena, Calif., will apply 9,212 solar panels and have a total capacity of 1.6 megawatts, or plenty electricity to supply 1,000 average California homes. That will satisfy 30% of the campus’ peak electricity needs. The installation at Google’s headquarters, known as the Googleplex, will start next month and will be finished in the spring. It will be the biggest solar-power system ever constructed at a U.S. corporate campus and one of the largest on any corporate site in the world, EI Solutions said.

The solar panels, which cover an area equal to approximately four acres, will be installed on the roofs of some campus buildings and double as shading for cars in parking lots. Most of the panels will be made by Sharp Electronics, a unit of Japan’s Sharp Corp.

Google refused to say how much money it would spend to build the system. Nevertheless, the company estimates the savings it expects to realize on its electricity bills will pay for the cost of the panels before leases expire on its leased campus buildings, which will hold some of the panels. EI Solutions said panels generally last for 20 to 25 years and pay for themselves within five to 10 years.

It’s good for Google, the Earth and for shareholders,” said Google’s vice president of real estate, David Radcliffe. “If we can dispel the myth that you can’t be both green and profitable, then we’ll be happy about that.”

Google also expects to see some savings in air-conditioning costs because the panels on the building roofs, by absorbing sunlight, will cut back the amount of heat absorbed into their top floors.

The system will work seamlessly with the power grid, allowing Google to draw more energy from the grid when the panels aren’t supplying enough power due to a lack of sun. But it will also allow Google to sell the utility power at times when the panels generate too much energy.

Andrew Beebe, president of EI Solutions, said companies are becoming increasingly interested in solar power as their electricity bills mount and the costs of solar power decline. Corporate America is reaching a tipping point where “people are making these decisions on an economic basis,” he said.

Google is looking for other ways to make its campus more environmentally friendly. “This is definitely just the tip of the iceberg,” Radcliffe said, but declined to discuss other possible initiatives.