Energy Saving By Using Solar Panels Engineering Essay
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Climate change concerns, coupled with high oil prices, peak oil, and increasing government support, are driving increasing renewable energy legislation, incentives and commercialization. New government spending, regulation and policies helped the industry weather the global financial crisis better than many other sectors. Renewable energy is energy that comes from natural resources such as sunlight, wind, rain, tides, waves and geothermal heat, which are renewable because they are naturally replenished at a constant rate. About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from hydroelectricity. New renewables (small hydro, modern biomass, wind, solar, geothermal, and biofuels) accounted for another 3% and are growing very rapidly. The share of renewables in electricity generation is around 19%, with 16% of global electricity coming from hydroelectricity and 3% from new renewables. Since its emergence; renewable energy has come a long way.
In was not until the 1970s that environmentalists promoted the development of alternative energy both as a replacement for the eventual depletion of oil, as well as for an escape from dependence on oil; it was at that stage that the first wind turbines appeared. On the other hand, solar had always been used for heating and cooling, but solar panels were too costly to build solar farms, until 1980.
The reason why have chosen the topic of solar heating systems; solar energy for my dissertation is because among the various renewable energy sources, solar energy is one of the crucial energy sources, if not the most crucial. According to a 2011 projection by the International Energy Agency, solar power generators may produce most of the world's electricity within 50 years, dramatically reducing the emissions of greenhouse gases that harm the environment. Before doing this report, I have to admit that the knowledge that I had regarding solar energy or solar energy systems was minimal. But since starting working on this report, I think, I have come a long way; yet, I have to admit, there has been done so much research in this field, in the past couple of decade that I would still have to go a long way before I would consider myself a specialist. This report should cater towards any individual who had heard of the solar energy, solar energy systems and how they could benefit from it. This report also gives a brief insight into, where solar energy system (solar energy) is headed in the future.
A far as the structure of my report is concerned, I will be looking into the history of solar energy, the solar energy itself, solar energy collectors solar panels; Furthermore, I would also be looking at the benefits of solar energy systems for us and the consequences, if any. On the other hand, I would also be analysing economic issues related to solar energy systems such as: the cost of heating a house or a building by the means of solar energy contra to contemporary means. Last but not the least I would be summarizing the advantages that I have discussed as well as look at some disadvantages, if there are any. I will sum up the whole report with a conclusion, thanks beforehand.
History of solar energy
Before we delve into the discussion of why solar energy is so needed in the world today, we'll first look into what solar energy really is. By definition, solar energy is that beaming light and heat that is generated from the sun. Solar energy has been used by human beings since time immemorial.
The radiation that comes from solar energy along with the resultant solar energized resources such as wave power, wind, biomass and hydroelectricity all give an explanation for most of the accessible renewable energy that is present on earth. However, only an infinitesimal portion of the existing solar energy is used.
Solar energy has been used by humans for thousands of years. For example, ancient cultures used energy from the sun to keep warm by starting fires with it.
Ancient Egyptians built places to live that allowed stored energy from the sun during the day, and a heat release during the night. This kind of architecture: heated homes at night while keeping the temperature low during the day; buildings were designed so that, walls and floors collected solar heat during the day, that was released at night to keep them warm. If you have ever stood in the sun to get warm then you too have utilized solar thermal energy. Egyptians also used the sun as part of their mummification process, using the sun to dry dead bodies. The Egyptians used a form of passive solar power.
3rd Century B.C., Greek soldiers with the help of Archimedes, focused light on a Roman fleet by using mirrors. The Romans were invading a port city that did not have defenses ready for the attack. The mirrors were used to concentrate the energy of the sun, and cause the fleet's sails to burn. The Romans retreated and the Greeks were able to prevent the invasion. The Greeks used passive solar power.
100 A.D. a historical writer by the name of Pliny the Younger, built a house in the northern part of Italy that had mica windows in one room. This one particular room demonstrated solar heating in that its mica windows stored heat, and later gave it off. This room was useful because the added heat it generated lessened the amount of wood that had to be burnt, to maintain heat.
Roman bath houses had famous south facing windows that heated the rooms.
Native Americans also built houses that used passive solar power. Houses were built into the side of cliffs or hills to allow storage of heat during the day, and a release of heat at night.
In 1767, the world's first solar collector was built by Swiss scientist Horace de Saussare.
They also kept their homes warm through passive solar energy designs
The discovery of photovoltaic happened in 1839 when the French physicist Edmond Becquerel first showed photovoltaic activity. Edmond had found that electrical current in certain materials could be increased when exposed to light. 66 years later, in 1905, we gained an understanding of Edmonds' work, when the famous physicist Albert Einstein clearly described the photoelectric effect, the principle on which photovoltaic are based. In 1921 Einstein received the Nobel Prize for his theories on the photoelectric effect.
Solar cells of practical use have been available since the mid 1950's when AT&T Labs first developed 6% efficient silicon solar cells. By 1960 Hoffman Electronics increased commercial solar cell efficiencies to as much as 14% and today, researchers have developed cells with more than 20% efficiencies. 20% efficient means that out of the total energy that hits the surface of a solar cell; about 20% is converted into usable electricity.
The first long-term practical application of PV cells was in satellite systems. In 1958 the Vanguard I, was launched into space. It was the first orbiting vehicle to be powered by solar energy. Photovoltaic silicon solar cells provided the electrical power to the satellite until 1964 when the system was shut down. The solar power system was so successful that PV's have been a part of world-wide satellite space programs ever since. The sun provides endless nonpolluting energy to the satellite power systems and demand for solar cells has risen as a result of the telecommunications revolution and need for satellites.
The energy crisis and oil embargos of the 1970's made many nations aware of their dependency on controlled non-renewable energy sources and this fueled exploration of alternative energy sources. This included further research into renewable sources such as solar power, wind power and geothermal power.
An economic breakthrough occurred in the 1970's when Dr. Elliot Berman was able to design a less expensive solar cell bringing the price down from $100 per watt to $20 per watt. This huge cost savings opened up a large number of applications that were not considered before because of high costs. These applications included railroads, lighthouses, off-shore oil rigs, buoys, and remote homes. For some countries and many applications, solar energy is now considered a primary energy source, not an alternative.
Solar energy is the energy derived from the sun through the form of solar radiation. Solar powered electrical generation relies on photovoltaic and heat engines. A partial list of other solar applications includes space heating and cooling through solar architecture, day lighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes. In my report, I would only be looking into a few of the above mentioned solar power harnessing techniques, due to the fact that there is a limitation towards, how much material I can present in my dissertation.
A solar cell (also called a photovoltaic cell) is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect. It is a form of photoelectric cell (in that its electrical characteristics-- e.g. current, voltage, or resistance-- vary when light is incident upon it) which, when exposed to light, can generate and support an electric current without being attached to any external voltage source.
Passive solar or active solar
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate.
The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere .Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet.
Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C. By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.
Yearly Solar fluxes & Human Energy Consumption
Primary energy use (2005)
The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year. In 2002, this was more energy in one hour than the world used in one year. Photosynthesis captures approximately 3,000 EJ per year in biomass. The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth's non-renewable resources of coal, oil, natural gas, and mined uranium combined Solar energy can be harnessed at different levels around the world, mostly depending on distance from the equator.
How solar power works
Light (photons) striking certain compounds, in particular metals, causes the surface of the material to emit electrons. Light striking other compounds causes the material to accept electrons. It is the combination of these two compounds that can be made use of to cause electrons to flow through a conductor, and thereby create electricity. This phenomenon is called the photo-electric effect. Photovoltaic means sunlight converted into a flow of electrons (electricity).
Passive solar heating
In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design or climatic design because, unlike active solar heating systems, it doesn't involve the use of mechanical and electrical devices.
The key to designing a passive solar building is to best take advantage of the local climate. Elements to be considered include window placement and glazing type, thermal insulation, thermal mass, and shading. Passive solar design techniques can be applied most easily to new buildings, but existing buildings can be adapted or "retrofitted".
Passive energy gain
Passive solar technologies use sunlight without active mechanical systems (as contrasted to active solar). Such technologies convert sunlight into usable heat (water, air, and thermal mass), cause air-movement for ventilating, or future use, with little use of other energy sources. A common example is a solarium on the equator-side of a building. Passive cooling is the use of the same design principles to reduce summer cooling requirements.
Some passive systems use a small amount of conventional energy to control dampers, shutters, night insulation, and other devices that enhance solar energy collection, storage, and use, and reduce undesirable heat transfer.
Passive solar technologies include direct and indirect solar gain for space heating, solar water heating systems based on the thermo siphon or geyser pump, use of thermal mass and phase-change materials for slowing indoor air temperature swings, solar cookers, the solar chimney for enhancing natural ventilation, and earth sheltering.
More widely, passive solar technologies include the solar furnace and solar forge, but these typically require some external energy for aligning their concentrating mirrors or receivers, and historically have not proven to be practical or cost effective for widespread use. 'Low-grade' energy needs, such as space and water heating, have proven, over time, to be better applications for passive use of solar energy.
Pragmatic approach to a productive passive solar energy
Many detached suburban houses can achieve reductions in heating expense without obvious changes to their appearance, comfort or usability. This is done using good siting and window positioning, small amounts of thermal mass, with good-but-conventional insulation, weatherization, and an occasional supplementary heat source, such as a central radiator connected to a (solar) water heater. Sunrays may fall on a wall during the daytime and raise the temperature of its thermal mass. This will then radiate heat into the building in the evening. This can be a problem in the summer, especially on western walls in areas with high degree day cooling requirements. External shading, or a radiant barrier plus air gap, may be used to reduce undesirable summer solar gain.
Active solar heating systems
Active solar technologies are employed to convert solar energy into another more useful form of energy. This would normally be a conversion to heat or electrical energy. Inside a building this energy would be used for heating, cooling, or off-setting other energy use or costs. Active solar uses electrical or mechanical equipment for this conversion. Solar energy collection and utilization systems that do not use external energy, such as a solar chimney, are classified as passive solar technologies. Passive solar relies on the inherent thermo-dynamic properties of the system or materials to operate. They do not need external energy sources.
Solar hot water systems, except those based on the thermo siphon, use pumps or fans to circulate fluid (often a mixture of water and glycol to prevent freezing during winter periods) or air, through solar collectors, and are therefore classified under active solar technology.
The basic benefit of active systems is that controls (usually electrical) can be used to maximize their effectiveness. For example a passive solar thermal array which does not rely on pumps and sensors will only start circulating when a certain amount of internal energy has built up in the system. Using sensors and pumps, a relatively small amount of energy (i.e. that used to power a pump and controller) can harvest a far larger amount of available thermal energy by switching on as soon as a useful temperature differential becomes present. Controls also allow a greater variety of choices for utilizing the energy that becomes available. For example a solar thermal array could heat a swimming pool on a relatively cool morning where heating a domestic hot water cylinder was impractical due to the different stored water temperatures. Later in the day as the temperature rises the controls could be used to switch the solar heated water over to the cylinder instead.
The downside to Active Solar systems is that the external power sources can fail (probably rendering them useless), and the controls need maintenance.
How to buy solar panels solar water heating
Solar water heating can meet about a third of your hot water needs, research conducted by a UK research magazine.
A solar water heating system (also known as solar thermal system) uses panels fitted to your roof to heat water for use around the home.
A typical solar hot water system is able to meet around a third of a household's hot water needs - a saving of £55 to £80 on your annual water-heating bills, based on a three-bedroom semi-detached house.
Householders installing solar water heating systems can get £300 through the government's Renewable Heat Incentive Premium Payment scheme.
Choosing a solar water heating system
When choosing a solar water heating system, you'll need to consider four major factors:
your average hot water use
the area of south-facing roof available
your existing water heating system
You'll need roughly one square meter of collector area per person in the household. Each metre of panel area will need between 30 and 60 litres of water tank volume.
If you use a less efficient collector (such as flat-plate solar water heating panels), you'll need to cover a larger area than if you use a more efficient collector (such as evacuated tubes).
You'll also need to select system components (such as a hot water cylinder, controls and pipe work) and choose the location for your solar panels, considering shade, pipe runs, roof pitch and future access.
Solar water heating installation
There are plenty of solar panel installers out there, so I recommend that you always collect a range of quotes to compare.
Cost effectiveness of solar water heating systems
In my opinion developing common industry standards and offering public incentives is important. He emphasizes that creating public awareness programs is the key to having success in this industry, including a cleaner environment and more jobs as a consequence.
It is clear that installing the application is easy for households since the technology is less complicated and cheaper than PV. According to The Solar Guide, the payback period for an investment in a solar water heating system is 3 to 5 years, although it may vary a lot in different countries due to national standards and differences in manufacturing quality.
The return of investment depends on the system and the current fuel source that is being used to heat the water. It makes more sense to install a combi-system (hot water+space heating) whereby a 12-20 sq-m would completely cover a household's water heating demand and a substantial part of its space heating demand in spring and in autumn.
Solar trackers may be driven by active or passive solar technology
Most solar collectors are fixed in their array position mounting, but can have a higher performance if they track the path of the sun through the sky (however it is unusual for thermal collectors to be mounted in this way). Solar trackers, used to orient solar arrays may be driven by either passive or active technology, and can have a significant gain in energy yield over the course of a year when compared to a fixed array. Again passive solar tracking would rely on the inherent thermo-dynamic properties of the materials used in the system rather than an external power source to generate its tracking movement. Active Solar Tracking would utilize sensors and motors track the path of the sun across the sky. This action can be caused by geographical and time data being programmed into the controls. However, some systems actually track the brightest point in the sky using light sensors, and manufacturers claim this can add a significant extra yield over and above geographical tracking.
How does Solar Thermal work?
The basic mechanism of solar thermal energy is to collect the solar radiation and transfer the heat directly or indirectly to its final destination via a heat transfer medium - usually a fluid.
The most commonly used applications are Domestic Hot water (DHW), Combined DHW and Space Heating, District Heating, Solar Cooling and Air-Conditioning. High Temperature Solar Thermal Electricity Generation is also among solar thermal applications. (e.g. solar tower and parabolic through applications).
The key component of the solar thermal systems is the collectors which can be divided into two groups:
Unglazed collectors have been used in the industry for a long time, mainly for heating open-air swimming pools. There is no heat exchanger in the system, and the water is flowing directly through long thin tubes. It is cheap and easy to install. Due to the simplicity of unglazed collectors, they cannot fulfill the needs for delivering full-time energy. Unglazed collectors are mainly used in the USA and in Australia.
Glazed collectors are much more efficient in supplying continuous heating and achieving higher temperatures than unglazed ones. Glazed collectors are usually rectangular boxes covered by glass, containing little pipes and tubes and a heat absorbing material inside. There are different types of collectors for different means of use. Glazed collectors are commonly used in China, Europe and the Middle East.
Solar thermal collector
A solar thermal collector is a solar collector designed to collect heat by absorbing sunlight. The term is applied to solar hot water panels, but may also be used to denote more complex installations such as solar parabolic, solar trough and solar towers or simpler installations such as solar air heat. The more complex collectors are generally used in solar power plants where solar heat is used to generate electricity by heating water to produce steam which drives a turbine connected to an electrical generator. The simpler collectors are typically used for supplemental space heating in residential and commercial buildings. A collector is a device for converting the energy in solar radiation into a more usable or storable form. The energy in sunlight is in the form of electromagnetic radiation from the infrared (long) to the ultraviolet (short) wavelengths. The solar energy striking the Earth's surface depends on weather conditions, as well as location and orientation of the surface, but overall, it averages about 1,000 watts per square meter under clear skies with the surface directly perpendicular to the sun's rays.
A solar collector works to convert and concentrate solar energy into a more usable form. For example, a thermal collector may use a parabolic array of mirrors to focus, direct, and reflect the light of the sun to a smaller point where the heat can be used to drive some sort of turbine engine by heating the driving fluid. Another type of collector may use a flat panel array of solar photovoltaic cells to convert solar energy directly into electricity. Some metals exhibit a photoelectric property whereby when the metal is exposed to light, it causes electrons to be emitted. These metals may be arranged in a valence-covalence band configuration which generates the actual voltage within the array.
Types of solar collectors for heat
Solar collectors fall into two general categories: non-concentrating and concentrating. In the non-concentrating type, the collector area (i.e., the area that intercepts the solar radiation) is the same as the absorber area (i.e., the area absorbing the radiation). In these types the whole solar panel absorbs the light.
Flat-plate and evacuated-tube solar collectors are used to collect heat for space heating, domestic hot water or cooling with an absorption chiller.
Types of solar collectors for electricity generation
Parabolic troughs, dishes and towers described in this section are used almost exclusively in solar power generating stations or for research purposes. Although simple, these solar concentrators are quite far from the theoretical maximum concentration. For example, the parabolic trough concentration is about 1/3 of the theoretical maximum for the same acceptance angle, that is, for the same overall tolerances for the system. Approaching the theoretical maximum may be achieved by using more elaborate concentrators based on non-imaging optics.
This type of collector is generally used in solar power plants. A trough-shaped parabolic reflector is used to concentrate sunlight on an insulated tube (Dewar tube) or heat pipe, placed at the focal point, containing coolant which transfers heat from the collectors to the boilers in the power station.
Solar Parabolic dish
It is the most powerful type of collector. One or more parabolic dishes concentrate solar energy at a single focal point, -similar to a reflecting telescope which focuses starlight, or to a dish antenna used to focus radio waves. This geometry may be used in solar furnaces and solar power plants.
There are two key phenomena to understand in order to comprehend the design of a parabolic dish. One is that the shape of a parabola is defined such that incoming rays which are parallel to the dish's axis will be reflected toward the focus, no matter where on the dish they arrive. The second key is that the light rays from the sun arriving at the Earth's surface are almost completely parallel. So if the dish can be aligned with its axis pointing at the sun, almost all of the incoming radiation will be reflected towards the focal point of the dish-most losses are due to imperfections in the parabolic shape and imperfect reflection.
Losses due to atmosphere between the dish and its focal point are minimal, as the dish is generally designed specifically to be small enough that this factor is insignificant on a clear, sunny day. Compare this though with some other designs, and you will see that this could be an important factor, and if the local weather is hazy, or foggy, it may reduce the efficiency of a parabolic dish significantly.
In dish-stirling power plant designs, a Stirling engine coupled to a dynamo is placed at the focus of the dish, which absorbs the heat of the incident solar radiation, and converts it into electricity.
(Solar) Power tower
A power tower is a large tower surrounded by tracking mirrors called heliostats. These mirrors align themselves and focus sunlight on the receiver at the top of tower, collected heat is transferred to a power station below.
Very high temperatures reached. High temperatures are suitable for electricity generation using conventional methods like steam turbine or some direct high temperature chemical reaction.
Good efficiency. By concentrating sunlight current systems can get better efficiency than simple solar cells.
A larger area can be covered by using relatively inexpensive mirrors rather than using expensive.
Concentrated light can be redirected to a suitable location via. For example illuminating buildings.
Heat storage for power production during cloudy and overnight conditions can be accomplished, often by underground tank storage of heated fluids. Molten salts have been used to good effect.
Concentrating systems require sun tracking to maintain Sunlight focus at the collector.
Inability to provide power in diffused light conditions. Solar Cells are able to provide some output even if the sky becomes a little bit cloudy, but power output from concentrating systems drop drastically in cloudy conditions as diffused light cannot be concentrated passively.
A solar panel (also solar module, photovoltaic module or photovoltaic panel) is a packaged, connected assembly of photovoltaic cells. The solar panel can be used as a component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications. Each panel is rated by its DC output power under standard test conditions, and typically ranges from 100 to 320 watts. The efficiency of a panel determines the area of a panel given the same rated output - an 8% efficient 230 watt panel will have twice the area of a 16% efficient 230 watt panel. Because a single solar panel can produce only a limited amount of power, most installations contain multiple panels. A photovoltaic system typically includes an array of solar panels, an inverter, and sometimes a battery and or solar tracker and interconnection wiring.
Theory and construction
Solar panels use light energy (photons) from the sun to generate electricity through the photovoltaic effect. The majority of modules use wafer-based crystalline silicon cells or thin-film cells based on cadmium telluride or silicon. The structural (load carrying) member of a module can either be the top layer or the back layer. Cells must also be protected from mechanical damage and moisture. Most solar panels are rigid, but semi-flexible ones are available, based on thin-film cells.
Electrical connections are made in series to achieve a desired output voltage and/or in parallel to provide a desired current capability. The conducting wires that take the current off the panels may contain silver, copper or other non-magnetic conductive transition metals. The cells must be connected electrically to one another and to the rest of the system. Externally, popular terrestrial usage photovoltaic panels use MC3 (older) or MC4 connectors to facilitate easy weatherproof connections to the rest of the system.
Bypass diodes may be incorporated or used externally, in case of partial panel shading, to maximize the output of panel sections still illuminated. The p-n junctions of mono-crystalline silicon cells may have adequate reverse voltage characteristics to prevent damaging panel section reverse current. Reverse currents could lead to overheating of shaded cells. Solar cells become less efficient at higher temperatures and installers try to provide good ventilation behind solar panels.
Some recent solar panel designs include concentrators in which light is focused by lenses or mirrors onto an array of smaller cells. This enables the use of cells with a high cost per unit area (such as gallium arsenide) in a cost-effective way.
Depending on construction, photovoltaic panels can produce electricity from a range of frequencies of light, but usually cannot cover the entire solar range (specifically, ultraviolet, infrared and low or diffused light). Hence much of the incident sunlight energy is wasted by solar panels, and they can give far higher efficiencies if illuminated with monochromatic light. Therefore, another design concept is to split the light into different wavelength ranges and direct the beams onto different cells tuned to those ranges. This has been projected to be capable of raising efficiency by 50%.
Currently the best achieved sunlight conversion rate (solar panel efficiency) is around 21% in commercial products, typically lower than the efficiencies of their cells in isolation. The energy density of a solar panel is the efficiency described in terms of peak power output per unit of surface area, commonly expressed in units of watts per square foot (W/ft2). The most efficient mass-produced solar panels have energy density values of greater than 13 W/ft2 (140 W/m2).
Crystalline silicon modules
Most solar modules are currently produced from silicon photovoltaic cells. These are typically categorized as monocrystalline or polycrystalline modules.
Third generation solar cells are advanced thin-film cells. They produce high-efficiency conversion at low cost
Rigid thin-film modules
In rigid thin film modules, the cell and the module are manufactured in the same production line.
The cell is created on a glass substrate or superstrate, and the electrical connections are created in situ, a so called "monolithic integration". The substrate or superstrate is laminated with an encapsulant to a front or back sheet, usually another sheet of glass.
The main cell technologies in this category are CdTe, or a-Si, or a-Si+uc-Si tandem, or CIGS (or variant). Amorphous silicon has a sunlight conversion rate of 6-12%.
Flexible thin-film modules
Flexible thin film cells and modules are created on the same production line by depositing the photoactive layer and other necessary layers on a flexible substrate.
If the substrate is an insulator (e.g. polyester or polyimide film) then monolithic integration can be used.
If it is a conductor then another technique for electrical connection must be used.
The cells are assembled into modules by laminating them to a transparent colourless fluoropolymer on the front side (typically ETFE or FEP) and a polymer suitable for bonding to the final substrate on the other side. The only commercially available (in MW quantities) flexible module uses amorphous silicon triple junction (from Unisolar).
So-called inverted metamorphic (IMM) multijunction solar cells made on compound-semiconductor technology are just becoming commercialized in July 2008. The University of Michigan's solar car that won the North American Solar Challenge in July 2008 used IMM thin-film flexible solar cells.
The requirements for residential and commercial are different in that the residential needs are simple and can be packaged so that as solar cell technology progresses, the other base line equipment such as the battery, inverter and voltage sensing transfer switch still need to be compacted and unitized for residential use. Commercial use, depending on the size of the service will be limited in the photovoltaic cell arena, and more complex parabolic reflectors and solar concentrators are becoming the dominant technology.
The global flexible and thin-film photovoltaic (PV) market, despite caution in the overall PV industry, is expected to experience a CAGR of over 35% to 2019, surpassing 32 GW according to a major new study by IntertechPira.
Module embedded electronics
Several companies have begun embedding electronics into PV modules. This enables performing maximum power point tracking (MPPT) for each module individually, and the measurement of performance data for monitoring and fault detection at module level. Some of these solutions make use of power optimizers, a DC-to-DC converter technology developed to maximize the power harvest from solar photovoltaic systems. As of about 2010, such electronics can also compensate for shading effects, wherein a shadow falling across a section of a panel causes the electrical output of one or more strings of cells in the panel to fall to zero, but not having the output of the entire panel fall to zero.
Module performance and aging
Module performance is generally rated under standard test conditions (STC): irradiance of 1,000 W/m², solar spectrum of AM 1.5 and module temperature at 25°C.
Electrical characteristics include nominal power (PMAX, measured in W), open circuit voltage (VOC), short circuit current (ISC, measured in amperes), maximum power voltage (VMPP), maximum power current (IMPP), peak power, Wp, and module efficiency (%).
Nominal voltage refers to the voltage of the battery that the module is best suited to charge; this is a leftover term from the days when solar panels were only used to charge batteries. The actual voltage output of the panel changes as lighting, temperature and load conditions change, so there is never one specific voltage at which the panel operates. Nominal voltage allows users, at a glance, to make sure the panel is compatible with a given system.
Open circuit voltage or VOC is the maximum voltage that the panel can produce when not connected to an electrical circuit or system. VOC can be measured with a meter directly on an illuminated panel's terminals or on its disconnected cable.
The peak power rating, Wp, is the maximum output according under standard test conditions (not the maximum possible output). Typical panels, which could measure approximately 1x2 meters or 2x4 feet, will be rated from as low as 75 Watts to as high as 350 Watts, depending on their efficiency. At test panels are binned by their test results, and a typical manufacturer might rate their panels in 5 Watt increments, and either rate them at +/- 3%, +/-5%, +3/-0% or +5/-0%.
Solar panels must withstand rain, hail, and cycles of heat and cold for many years. Many crystalline silicon module manufacturers offer a warranty that guarantees electrical production for 10 years at 90% of rated power output and 25 years at 80%. The output power of many panels slowly degrades at about 0.5%/year.
Most parts of a solar module can be recycled including up to 95% of certain semiconductor materials or the glass as well as large amounts of ferrous and non-ferrous metals. Some private companies and non-profit organizations are currently engaged in take-back and recycling operations for end-of-life modules.
Recycling possibilities depend on the kind of technology used in the modules:
Silicon based modules: aluminum frames and junction boxes are dismantled manually at the beginning of the process. The module is then crushed in a mill and the different fractions are separated - glass, plastics and metals. It is possible to recover more than 80% of the incoming weight. This process can be performed by flat glass recyclers since morphology and composition of a PV module is similar to those flat glasses used in the building and automotive industry. The recovered glass for example is readily accepted by the glass foam and glass insulation industry.
Non-silicon based modules: they require specific recycling technologies such as the use of chemical baths in order to separate the different semiconductor materials. For cadmium telluride panels, the recycling process begins by crushing the module and subsequently separating the different fractions. This recycling process is designed to recover up to 90% of the glass and 95% of the semiconductor materials contained. Some commercial-scale recycling facilities have been created in recent years by private companies.
Since 2010, there is an annual European conference bringing together manufacturers, recyclers and researchers to look at the future of PV module recycling.
The "solar tree", a symbol of Gleisdorf, Austria
In 2010, 15.9 GW of solar PV system installations were completed, with solar PV pricing survey and market research Company PVinsights reporting growth of 117.8% in solar PV installation on a year-on-year basis. With over 100% year-on-year growth in PV system installation, PV module makers dramatically increased their shipments of solar panels in 2010. They actively expanded their capacity and turned themselves into gigawatt GW players. According to PVinsights, five of the top ten PV module companies in 2010 are GW players. Suntech, First Solar, Sharp, Yingli and Trina Solar are GW producers now, and most of them doubled their shipments in 2010.
Top ten producers
The top ten solar panel producers (by MW shipments) in 2011 were:
Renewable Energy Corporation
Average pricing information divides in three pricing categories: those buying small quantities (modules of all sizes in the kilowatt range annually), mid-range buyers (typically up to 10 MWp annually), and large quantity buyers (self-explanatory-and with access to the lowest prices). Over the long term-and only in the long-term-there is clearly a systematic reduction in the price of cells and modules. For example in 1998 it was estimated that the quantity cost per watt was about $4.50, which was 33 times lower than the cost in 1970 of $150.
In the real world, prices depend a great deal on local weather conditions. In a cloudy country such as the United Kingdom, price per installed kW is higher than in sunnier countries like Spain.
Following to RMI, Balance-of-System (BoS) elements, this is, non-module cost of non-microinverter solar panels (as wiring, converters, racking systems and various components) make up about half of the total costs of installations. Also, standardizing technologies could encourage greater adoption of solar panels and, in turn, economies of scale.
Despite the cost of solar panels, one of the main selling points of them is their return on investment, which can be as high as 6.8% in some areas of the United Kingdom, where a typical 4 kWp panel would take about 15 years to be paid off.
Solar trackers increase the amount of energy produced per panel at a cost of mechanical complexity and need for maintenance. They sense the direction of the Sun and tilt the panels as needed for maximum exposure to the light.
Fixed racks hold panels stationary as the sun moves across the sky. The fixed rack sets the angle at which the panel is held. Tilt angles equivalent to an installation's latitude are common.
Ground mounted solar power systems consist of solar panels held in place by racks or frames that are attached to ground based mounting supports.
Ground based mounting supports include:
Pole mounts, which are driven directly into the ground or embedded in concrete.
Foundation mounts, such as concrete slabs or poured footings
Ballasted footing mounts, such as concrete or steel bases that use weight to secure the solar panel system in position and do not require ground penetration. This type of mounting system is well suited for sites where excavation is not possible such as capped landfills and simplifies decommissioning or relocation of solar panel systems.
Roof mounted solar power systems consist of solar panels held in place by racks or frames attached to roof based mounting supports.
Roof based mounting supports include:
Pole mounts, which are attached directly to the roof structure and may use additional rails for attaching the panel racking or frames.
Ballasted footing mounts, such as concrete or steel bases that use weight to secure the panel system in position and do not require through penetration. This mounting method allows for decommissioning or relocation of solar panel systems with no adverse effect on the roof structure.
Technicians installing photovoltaic panels on a roof mounted rack.
A roof mounted solar panel system installed on a sloped roof using pole mounts and rails.
The state of solar power in Europe
Europe contains nine of the largest 15 solar markets in the world. In 2011, new European PV installations amounted to 20.9 GW, over 75% of the global total (27.7 GW). Germany has long held the crown within Europe as the clear leader in installed solar power capacity and now has a total of 24.7 GW of capacity installed, generating approximately 3% of its electricity.
Why has Germany been such a long way in front? The Renewable Energy Act introduced in 2000 was one of the first of its kind in the world. It introduced guaranteed feed-in tariffs, lasting for 20 years at a fixed price. The rates decrease gradually for new installations, exerting downward pressure on manufacturers to drive innovation. The stability of the scheme, and it's popularity, has lead to great confidence in solar as an investment option; solar panels are a common sight on a German roof. For this reason, Germany has seen exponential growth in solar installations:
However, Germany is not alone in this rapid year-on-year growth. Italy is the world's second largest installer, and is closing the gap on Germany. A study by GSE showed Italian installations tripling in capacity from 2009 to 2010 (from about 1 GW to over 3 GW) and then almost tripling again in 2011 after an additional 9 GW of solar were installed (the world-leading amount in 2011).
This surge is due to changes made to the solar power subsidies in Italy in 2010 - there was a feed-in tariff introduced, in addition to a generous grants system. Italy has some of the most favorable weather conditions in Europe for solar, and so it seems logical that it has the most beneficial grants structure.
Solar in the UK - a Roller Coaster Ride
Unfortunately, not every country can keep up with these prime examples; the UK solar industry has recently been in outrage. After introducing a feed-in tariff in April 2010, the number of installations rocketed. However, as installed panel prices fell by 30% from 2010 to 2011, due to a dramatic increase in competition that accompanied the increasing demand for residential solar, the popularity of the scheme was underestimated. Whilst the rate of adoption was impressive, the Department of Energy and Climate Change (DECC) panicked due to the cost of the scheme. The DECC subsequently tried to cut the feed-in tariff rates without holding a complete official consultation, which resulted in an extended court case from several large solar companies. The government's decision to cut the rate by more than 50% was ruled as illegal. This led to the following:
The scheme was remarkably popular throughout the year, with the boom caused by the announcement that installations from the 3rd of December would receive a much lower rate - $0.33/kWh rather than $0.68c/kWh. Although the figures are not yet released, following the court decision to reinstate the tariff at the higher level, our (nation-wide) company's data show installations are likely at a near all-time high. The tariff will fall in March, and so there will be another slump at that point. This instability is very bad for the industry - it puts off investors in solar power, and it has led to thousands of job losses.
Solar in Other Parts of Europe
Solar also hasn't yet had much of an impact in Eastern Europe. Latvia, Estonia, and Lithuania each have under 0.1 MW of installed solar power capacity, and none of them have any government funding specifically for solar panels. Hopefully, the success of solar seen in other countries may be replicated. For example, Lithuania opened its first solar panel production site last year, primarily targeting surrounding countries.
Parts of Europe have struggled economically in 2011, of course, especially from the Greek financial crisis, but hopefully priorities will switch to longer term tasks soon, such as developing renewable energy from 2012.
Currently under construction in the Sahara, the Desertec project will be the world's largest solar power farm (or collection of farms), and parts of it will be producing electricity for use in Europe by as soon as 2015. The aim is to meet between 15 and 20% of Europe's energy demand by 2050, meaning German levels of solar power across every member state!
Whilst this will all provide a boost to Europe's renewable energy use, it's worth noting that other countries are working hard to close the gap - the USA is seeing record levels of solar installations, China is also engaged in a big solar power push, as are India and Japan. The consensus is that the German model is the most sustainable solution to replicate, and we'll likely see feed-in tariff schemes adopted in most economically developed countries in the months and years to come, both within Europe and worldwide.
Latvia has limited domestic energy resources. Peat land areas cover 9.9% of the country's territory. Renewable energy sources accounted for roughly 31% of the primary energy share in 2008, predominantly from biomass.
With the exception of peat and timber, Latvia had no significant domestic energy resources and received 93% of its imported energy from Soviet republics in 2007.s sources.
The solar energy resource potential in Latvia is small compared to other European countries due to the geographic location and to the climatic conditions. The average irradiance per year is 2.6 kWh/m2. There are although other renewable energy solutions available in Latvia, e.g. wind and geo thermal but that is a different discussion. And it is therefor because of this reason; Latvia government at this point has plans only to invest in the renewable energy resources that are available in abundance. Their neighbors on the other hand are willing to swim against the current.
Baltic States' largest solar energy station to be opened in South East Estonia
The Baltic States largest solar energy station, a 100 KW one, will soon start operating in the Võrumaa County, South East Estonia, LETA/Pubic Broadcasting reports.
11 concrete foundations and metal poles have already been installed in the Keema village near Kurenurme. Now prepartions for installing equipment and cables is under way.
The solar panels will turn towards the light automatically and the station produces energy even in a cloudy day in winter, gathering light that is reflected from snow, for example. It is possible to cattle farm under the solar panels, thus the land can also be utilised.
"There was like an agreement that there just isn't any sun in Estonia," said Energy Smart board member Viido Polikarpus. Soon Energy Smart intends to refute that misconception in practice.
"We don't have to live in oil shale diesel, here in Estonia - this is yesterday's technology. Let us embrace tomorrow, let us embrace solar energy," says Polikarpus.
Once the solar panels are up it will be Baltic States' largest solar power station and also the first business enterprise of that field.
Lithuania to open first solar panel production site
Just because you don't have abundance of sun-light does not necessarily means that you cannot play your part in help catering for the worlds energy needs and cutting down of co2 gas emissions.
Lithuania is to see its first solar panel production site opened this spring. Initial capacity will be 38 megawatts (MW), however, there will room to ramp up to 65 MW.
Meyer Burger knowledge pic with 2 men talking
The facility was sold together with know-how transfer and a training package. Image: Meyer Burger.
The news comes as Switzerland-based Meyer Burger subsidiary, 3S Modultec, announces it will be supplying MG AB Precizika with an integrated manufacturing facility. The financial terms were not disclosed, but it has been said that crystalline solar panels, primarily for the Eastern and Southeastern European market, will be produced.
"We are the first company to manufacture solar panels in Lithuania. With the high-class production equipment from Switzerland, we can manufacture top-quality panels and are very confident that we can open up a good local and regional market," commented Tomas Kovera, CEO of MG AB Precizika.
The 38 MW production line is scheduled to be delivered this spring. The facility can reportedly be upgraded up to 65 MW, and was sold together with know-how transfer and a training package.
According to 3S Modultec, the Lithuanian company will also benefit from the Fast-Track Certification service that it, together with the TÜV Rheinland, implements for its customers. In a statement, it explains: "With the rapid certification process and a service package tailored specifically to the company, MG AB Precizika will be able to quickly set up production and start supplying panels to customers as early as the beginning of summer."
Solar Thermal Energy - cheaper & easier than Photovoltaics
Solar thermal energy, which is the oldest way of tapping power from the sun, has been used for years in heating applications for households. Although its counterpart solar photovoltaic seems to be getting more attraction, according to European Solar Thermal Industry Federation (ESTIF), solar thermal energy industry in Europe has grown over 60% in 2008.
In a recent interview broadcasted by RenewableEnergyWorld.Com, Olivier Drücke, president of ESTIF, mentions that the solar thermal potential in Europe can meet 15% of heating and cooling demand in 2030 and up to 50% in 2050. That is particularly significant given that heating and cooling demand represents 50% of the final energy consumption in Europe (with the remaining 20% for electricity generation and 30% for transportation).
solar thermal collectors capacity
According to ESTIF statistics, the fastest growing European solar thermal market in 2008 was in Germany. Germans have reached 11 million sq-m of solar panel surface area (7,765 MWt) by installing a record number of 2.1 mil sq.-m in 2008.
China is reported to have almost 130 mil sq-m collectors already installed, making it the biggest market in the world (too big for the graph as well). Turkey, still one of the biggest markets in the world, installs around 500,000 sq-m each year.
Cyprus, Israel and Austria have developed their markets significantly in recent years, consequently positioning themselves as the global leaders in installed capacity per capita. Austrian manufacturers are dominating 40% of the solar thermal market in Europe.
Japan installs around 300,000 sq.-m every year, and roughly 15% of Japanese households are equipped with solar water heating systems. The USA is one of the biggest markets for low temperature systems, accounting for 11 mil sq.-m. However, as can be observed from the graph, the market development in medium and high temperature systems has been negligible when taking into account the country's potential.
Growth of renewables
From the end of 2004, worldwide renewable energy capacity grew at rates of 10-60% annually for many technologies. For wind power and many other renewable technologies, growth accelerated in 2009 relative to the previous four years. More wind power capacity was added during 2009 than any other renewable technology. However, grid-connected PV increased the fastest of all renewables technologies, with a 60% annual average growth rate. In 2010, renewable power constituted about a third of the newly built power generation capacities. By 2014 the installed capacity of photovoltaic will likely exceed that of wind, but due to the lower of solar, the energy generated from photovoltaic is not expected to exceed that of wind until 2015.
Renewable power generation and capacity as a proportion of change in global power supply.
Selected renewable energy indicators
Selected global indicators
Investment in new renewable capacity (annual) (109 USD)
Renewables power capacity (existing) (GWe)
Hydropower capacity (existing) (GWe)
Wind power capacity (existing) (GWe)
Solar PV capacity (grid-connected) (GWe)
Solar hot water capacity (existing) (GWth)
Ethanol production (annual) (109 litres)
Biodiesel production (annual) (109 litres)
Countries with policy targets
for renewable energy use
When it comes to deciding on the type of alternative energy to use, many people are not sure if they should opt for wind power or solar power systems.
The short answer is that solar power systems are more efficient and convenient in residential locations and commercial enterprises. The prices of both systems have come down dramatically, and the payback periods of both have decreased. But most houses don't have the room for a wind turbine, whereas solar panels and geysers just sit on top of the roof.
Solar power systems also have less restrictive operating conditions - even weak sunlight will do - and tend to deliver better value in terms of energy generated.
Once you've made the decision to make the sun work for you, there are other factors to consider.
According to a 2011 projection by the International Energy Agency, solar power generators may produce most of the world's electricity within 50 years, dramatically reducing the emissions of greenhouse gases that harm the environment. Cedric Philibert, senior analyst in the renewable energy division at the IEA said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 -- and half of all energy needs -- with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity," Philibert said
Projections vary, but scientists have advanced a plan to power 100% of the world's energy with wind, hydroelectric, and solar power by the year 2030.
All forms of energy are expensive, but as time progresses; renewable energy generally gets cheaper, while fossil fuels generally get more expensive. A 2011 IEA report said: "A portfolio of renewable energy technologies is becoming cost-competitive in an increasingly broad range of circumstances, in some cases providing investment opportunities without the need for specific economic support," and added that "cost reductions in critical technologies, such as wind and solar, are set to continue."
The International Solar Energy Society argues that renewable energy technologies and economics will continue to improve with time, and that they are "sufficiently advanced at present to allow for major penetrations of renewable energy into the mainstream energy and societal infrastructures".
How Much Money Can Be Saved From Using Solar Panels?
Solar energy is a buzzword in home improvement and solar panels are a "hot" item to install in a home. Harnessing the sun's energy is ecologically sound, and saving money doesn't hurt too much. But while the claim that using solar panels to supply electricity in a home is easily substantiated, with the high costs of purchase and installation, the claim that it saves money is more difficult to prove.
When determining whether or not solar panels are a cost-effective investment, there are several factors to consider. First, what is the sun like where you live? If it shines down pretty often, you're likely to get a better return on your investment than if it doesn't. You can use a neat little calculator to assess how much sun you get where you live (see Resource.) Next, what's the scope of your project? A smaller panel meant for limited use is likely to be very efficient, while a full house outfit will cost much more and take much longer to prove its worthiness.
The government supports the use of solar energy as it preserves our precious, natural resources. You may be able to get a rebate to cover some of the cost of installing solar panels in your home, and your solar panel supplier will be able to direct you toward the appropriate agency and help you complete any necessary paperwork in order to apply.
If you are building a home from scratch, you may be able to bundle the cost of your solar panel system into your mortgages payments. The total cost split into monthly payments over a number of years will make it much easier to swallow. If you are installing a system into an existing home, you may be able to refinance your home loan to add in the solar panel cost or take out an equity line of credit.
Over time, whatever you pay for your solar panel system will almost certainly be paid for by the reduction in your electricity bills. Anecdotal evidence points to a savings for homeowners of 50 to 90 percent in monthly electricity bills. Obviously, the more expensive the system, the longer it will take to see the savings. With full-house solar panel installation running into the mid five digits, it will certainly take a number of years to be paid off. But once it is, you'll have a reduced electricity bill the remainder of time you stay in that house; and if you decide to sell, the system increases the value of your home.
Solar energy savings over a long term period (research conducted in the USA)
The average household today pays nearly $170 each month in home energy costs. Some estimates have energy costs pegged at almost $200 per month, a cost of $2,400 for the entire year.
It's important to look at the long term pi
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