This research explores currents and under developed methods to improve Solar energy assimilation to confront most of today mankind needles. Solar energy is not available at night, and energy storage is an important issue because modern energy systems usually assume continuous availability of energy. This is one of the research object of this paper. Curently, when using solar energy is so expensive (see Figure 1), it is very important to reduce solar energy production costs and to develop it in purpose to create more efficiency methods growing theefficiency value. This is an another research object of this paper.
Today solar energy is used in a couple different manners. First is the photovoltaic conversion format, which most people know as solar panels. These panels are used to create electricity directly from the sun. These panels can be used alone or can be used in conjunction with other power resources. The second type of solar power that is used today is thermal solar power, which is where the sun is used to heat fluids, which then powers turbines or other types of machinery.
Since the middle of the 20th century, the ability to harness and utilize solar energy has greatly increased, making it possible for homes and businesses to make use of the renewal energy source rather than rely on more conventional means of generating power. Research into the applications of solar energy continue, along with the development of more costeffective ways to capture and store the energy for future use, .
The efficiency of solar energy exists primarily because it takes advantage of renewable energy – the sun – unlike typical energy solutions which use fossil fuels. The efficiency of solar energy harnesses the energy received from the sun and channels it into existing electrical grids, .
Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favourable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies, .
In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating climate change, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments, .
Already, the sun’s contribution to human energy needs is substantial — worldwide, solar electricity generation is a growing, multibillion dollar industry. But solar’s share of the total energy market remains rather small, well below 1 percent of total energy consumption, compared with roughly 85 percent from oil, natural gas, and coal, .
Reasons why Solar Energy cost is expensive
There are many reasons why solar energy is so expensive. There could be different reasons influences the cost, some of these are:
- competition is minimal. Government regulations will not allow house owners to install their own systems. Architects are reluctant to approve innovative unproven solar house designs. Builders find that it is not profitable for them to spend excessive architectural fees on designs that are not mainstream and salable;
- our government, who should be demonstrating a leadership position in the promotion and use of solar energy, is the primary offender of energy
conservation and has no interest in the promotion of a sustainable culture that might threaten the aristocracy;
- The price of oil is maintained at an artificially low price by government subsidies and special interest groups;
- Most people are too busy dealing with the problems of day to day survival to be concerned with the headache of a long range investment like solar energy;
- Fossil fuel oil corporations, who control our economy are doing all they can to discourage the proliferation of alternative energies.
Global prevalence of sollar collectors
Figure 1 clearly shows solar collectors prevalence around the world. It is clear that solar collector has most meaningful value in USA and in countries where sunlight is shining on suitable angle in comparison with other countries long term per year.
Figure 1 The Global prevalence of solar collectors performance
In the case of U.S. Solar Energy applying ammount, the growth of this energy type in megawatts is shown in the Figure 2.
Figure 2 Rapid Growth of Solar Power in U.S.
Figure 3 clearly shows comparision between most popular renewable energy sources in the world Global renewable power capacities (2004-2010).
Figure 3 Global renewable power capacities
Understanding the Costs of Solar Energy
In comparison to conventional hydrocarbon fuels such as coal or oil in generating electricity, the cost of solar energy is significantly higher. To compare energy cost, a common equivalent is required. For example, a ton of coal on the average produces approximately 6,182 kWh of electric at a cost of about €27,1 per short ton (934 kg). Under this measure coal cost less than €0.0075 per kWh. In comparison, a barrel of oil at €52,7/barrel produces 1,700 kWh at a cost approximately €0.038 per kWh.
Only 20 Years ago, solar energy cost 7 times as much. Advanced technologies have contributed to the enormous decrease in price, but it is mainly due to the increase in manufacturing volumes, as more and more people realise the benefits of solar energy, . In comparison to solar energy, the hydrocarbon fuel costs are significantly lower without rebates, tax benefits nor the cost of carbon emissions. A two– Kilowatt (kW) solar energy system costs about €33,880 and covers roughly half of a typical American household’s energy needs. At €33,880, a solar energy system equates to €6,780 a kilowatt. The €6,780 per kW for solar is not very helpful in comparing electric generation costs to other fuels like coal or gas. Since coal, oil, and gas can be measured on a cost per kWh, we should measure solar costs on a kWh basis.
Some of the considerations for a solar energy system include the 20-to-30 year lifespan of the system and the hours of available sunlight. The hours of available sunlight depends on latitude, climate, unblocked exposure to the sun, ability to tilt panels towards the sun, seasonality, and temperature. On the average, approximately 3.6 peak sunlight hours per day serves as a reasonable proxy to calculate the average annual output of electric from solar energy panels.
1 ton of coal - 6,128 kWh
1 barrel of oil - 1,699 kWh
1 cubic foot of gas - 0,3 kWh
1 ton of coal - €27,1 = 0,006 per kWh
1 barrel of oil - €52,7 = 0,05 per kWh
1 cubic foot of gas - €0,006 = 0,03 per kWh
Solar energy efficiency depending on various parameters
One way of measuring the efficiency of solar panels is to calculate the percentage of the solar energy that a panel converts into electricity. Most solar panels convert around 15% of the sun's energy into electricity. More experimental photovoltaic panels, like concentrating solar panels, can convert 40% of incident solar energy into electricity. These panels utilize varying band gaps and mirror arrays and are used more for large-scale solar power generation. There are 5 efficiency tiers in the clasification of modules based on efficiency percentage value (seeTable 1), .
Solar modules efficiency tiers
There are 3 main types of solar efficiency.
1. Module Efficiency measures how well a solar module (aka panel) converts the Sun’s energy into usable energy. If the Sun dumps 100 Watts of energy onto the module and the module spits out 15 Watts, the the module is said to have 15% module efficiency, see formula 1: 15W/100W =0.15 = 15% (1).
2. Area Efficiency (Density) measures how much usable energy a module produces in a given area. It’s Watts per square foot, so the more Watts, the more energy you’ll get from a specific area (or available space on your roof). Normally one square foot gives 14 Watts of energy so in this way fifteen square foots of module area gives 210 Watts. According to this rule in the case of having limited area roof it would be the best decision toset the module of highest density;
3. Cell Efficiency is measured the same way as module efficiency, but only with a single cell. This is the number news media and blogs love to tout in their headlines as ‘record breaking’ and ‘highest efficiency achieved’. This number is generally not useful for the average consumer, .
There are two most often occurs questions: “Which panels have the highest efficiency?” and, “Which solar PV panels are the best?” The answer to these question can be based on the solar power panel comparison chart below (see Table 1) compares the density and module efficiency of the most popular 200 W solar panels. All of the modules on this chart are label rated at 200 Watts, which means in strict laboratory conditions, they produce the same output.
In the Table 2 is present different types of modules which has been measured with the worst efficiency per area of all the panels because it’s not crystalline, but thin-film.
Solar power panel (200 W) comparison table
Solar panel efficiency is obviously poor when it comes to lighting up our homes. Using the sunlight directly through daylighting techniques would use approximately 80% of the sunlight available – clearly much more efficient than first converting the solar energy into electricity. The most intelligent way to utilize solar energy is to make use of direct sunlight through daylighting and passive solar heating technologies and then using the highest efficiency solar panels for the rest of our energy needs.
Solar power panel (220 W) comparison table
Chart key of the table is present below:
- Manufacturer - Solar Company or Brand;
- ID - Specific solar module identification code; module name;
- STC (W) - Standard Testing Conditions Rating; nameplate rating under laboratory conditions;
- Density (W) - Efficiency per area; realistic output per area, the higher the more output in a given area;
- Efficiency (%) - Output per input light irradiance using STC; energy conversion efficiency; module efficiency;
- Tier - Solar Panel Efficiency Tier. 1 is highest, 5 is lowest, .
Scientists who work on solar panel efficiency believe that the 40% level is the highest efficiency that can be achieved with the standard silicon materials in most solar cells. Instead of focusing on making them more efficient, the current focus is on how to manufacture PV panels less expensively. However, new technologies have recently been developed that may make solar panels that are much less expensive while achieving an incredible 80% efficiency.
Solar energy costs
Average system costs equals to €71,5 per square foot;
Average solar panel output equals to 10.6 watts per square foot;
Average solar energy system costs equals to €6,73 per watt. 
For 5-kW solar energy system costing €33,880, the conversion to kWh is as follows in Table 4:
Solar energy conversion to kWh
So a €33,880 5KW solar energy system produces about 119,246 kWh of electric over its lifespan meaning the average cost equals €0.29 per kWh. (€33,880 divided by 119,246 kWh), .
Figure 4 Energy costs per Kilowatt Hour
Solar energy component costs
The relatively high solar energy costs in comparison to conventional fuels should improve with utility rebates and government tax incentives. In addition, solar panel prices should continue to decline as volume production increases. Solar cell manufacturers employ similar production methods as semiconductor suppliers and benefit from economies of scale, .
The single largest cost is the solar panels themselves. The following figure provides an overview of the components of a solar energy system. Sharp Solar provides a very useful calculator for system costs and electric generation by geographical location along with utility rebates for your area.
Figure 5 Solar Energy component costs
Ways to reduce cost of Solar energy production
Most solar cells are made from silicon — the same semiconductor material that is at the heart of computers. The cells are expensive to produce because it takes a great deal of energy to purify the silicon. And, while the computer industry has made enormous strides in making cheaper silicon devices, those advancements don’t translate to the solar industry.
It’s kind of comparing apples and oranges. The semiconductor industry makes minutely patterned silicon. The one way to see the intricate structure is to look at it under an electron. Their advancements have been about how to design and fabricate that intricate structure cheaply. And the solar cell: That is completely not intricate. It is simply a few layers of semiconductor. It changes the economics dramatically since the manufacturing cost is more closely tied to the cost of the material, not the patterning.
What may really help to lower the cost of solar are new materials — especially semiconductors made from the compound cadmium telluride (see Figure 6). It is cheaper to make “thin-film solar cells” with cadmium telluride than with silicon. But that still leaves what experts call “soft costs,” everything from permitting fees to the hardware that mounts solar panels onto a roof. Even though there is disagreement over how much of the price of solar is tied up in these soft costs, they are clearly an important factor. In fact, the solar array itself accounts for only half the cost of a solar system today.
Innovations that could cut both hard and soft costs are being made all the time, but they don’t necessarily reach customers quickly. For one thing, not every great idea that works in a lab can be replicated on a mass production scale. And it can take a long time to iron out technological kinks on an apparatus that the manufacturer wants to be sure will last a long time.
Figure 6 compound cadmium telluride priciples of operating
Different industries have different speeds from discovery to marketing. Consumer electronics is relatively quick. But it can be seven or eight years for the auto industry. With solar, you have 20-year warrantees. You want it to work and be durable. And that means you have to spend a long time testing it, .
Low cost manufacturing using Cadmium Telluride (CdTe)
CdTe technology has been in development at First Solar since 1990 and is now the low cost panel leader in the solar field. In a typical CdTe panel, the top layer is p-type cadmium sulfide (CdS) and the bottom layer is n-type CdTe. These layers are extremely thin, deposited in a vacuum chamber molecule by molecule on glass. Hence very little semiconductor material (about 2% compared to crystalline silicon cells) is used which greatly reduces product costs.
Cadmium telluride (CdTe) is a photovoltaic (PV) technology based on the use of a thin film of CdTe to absorb and convert sunlight into electricity. CdTe is growing rapidly in acceptance and now represents the second most utilized solar cell material in the world. The first is still silicon.  Basic structure of a silicon PV cell is shown in Figure 7 and the layers of the Figure is describes in Table 5. 
Layers of a Silicon PV cell
History says that Research in Cadmium telluride dates back to the 1950's because it is almost perfectly matched to the distribution of photons in the solar spectrum in terms of optimal conversion to electricity. Early leaders in CdS/CdTe cell efficiencies were General Electric in the 1960s, and then Kodak, Monosolar, Matsushita, and AMETEK.
Figure 7 Basic Structure of a Silicon PV cell
Some experts believe it will be possible to get the solar cell costs down to around €0.38 per watt. With commodity-like margins and combined with balanceof- system (BOS) costs, installed systems near €1.1/W seem achievable. With sufficient levels of sunlight – this would allow such systems to produce electricity in the €0.045 to €0.06 / kWh range – or for less than fuel based electricity costs, . 90% of materials are re-used to build the next generation of modules.
It is necessary to keep in mind that Telluride is rather rare element global. Most of it comes as a by-product of copper, with smaller by product amounts from lead and gold. One gigawatt (GW) of CdTe PV modules would require about 93 metric tons (at current efficiencies and thicknesses), so the availability of tellurium will eventually limited how many panels can be produced with this material.
Solar Panels cost could be reduced by 40 %
Typically solar panels are created by cutting large sheets of silicon into small wafers. This process wastes nearly half of the silicon. “1366tech” (U.S.) uses a different approach, making their silicon wafers at directly at the the small size used in solar panels (6 inches by 6 inches), and thereby eliminating excess
Their technique however, has not yet been commercialized, meaning it has not yet been proven in the marketplace, where it needs to happen to be a real-world breakthrough. Still, their work is very promising. They also have made some changes to the wafers themselves which they say have increased their electricity generating capacity, .
Metal layer increases solar efficiencies by using gold nanoparticles
By adding gold nanoparticles to organic photovoltaic panels, a research team from UCLA, China, and Japan have increased the solar efficiency. By using the plasmonic effect, where the metal helps absorb more sunlight, the team pushed the overall light to energy output efficiently from 5.22 to 6.24, for a 20% increase. The construction places a gold layer between two light absorbing subcells, called a tandem polymer solar cell. Their method of layering has sidestepped all past difficulties of adding metal nanostructures into devices.
The success of the plasmonic effect of gold nanoparticles will lead to future development of polymer solar cells. The interlayer structure is being considered for other materials and "opening up opportunities" for higher efficiency, milt-stack, tandem solar cells, .
Fiber Optics in Solar Energy
In a solar farm power generation system, large amounts of current are generated from the heat of the sun. In order to protect the equipment from huge current leakage, galvanic insulation becomes important to ensure the power system’s quality and reliability. Fiber optics offer insulation protection from high-voltage/current glitches and unwanted signals into power equipment controls and communication. It is also feasible to use fiber optics to control the tracking capabilities of the solar panels.
Fiber optics communication can cover longer link distance connections compared to copper wire (Basic scheme is shown in Figure 8). As the solar farms grow in size, monitoring and controlling all the solar panels requires long link distance connections, which is only possible with fiber optics cable.
Figure 8 Power generation Block Diagram
Solar panels collect solar energy and convert it into electrical energy through photovoltaic modules or solar thermal collectors. In order to integrate the power generated from solar panels to the power transmission lines, the power needs to be converted into utility-grade AC power (see Figure 8).
Fiber optic components are commonly used to control a high voltage and current switching device, with reliable control and feedback signals.
Key applications for fiber optic components in solar
energy systems include:
- Power electronic gate drivers for inverters
- Sun tracking control and communication boards
- Solar farm substation automation and protection relays,.
New method for connecting solar panels may increase efficiency
Solar arrays of the future may be more energy efficient and reliable, thanks to efforts to reconfigure the way panels are connected. If one of the panels is shaded, dirty or damaged, it affects them all. The conventional approach to solar arrays inherently limits the amount of power they produce if there's any variation in the panels.
Rather than connecting solar panels in a series - where the electrical current must flow from one panel to get to the next, the better decision would be parallel wiring for the panels. The parallel approach would connect each panel to its own power converter instead of sending the electrical current through a
series of panels to a single converter, .
What there are ways to make solar energy more economical?
Other new materials for solar cells may help reduce fabrication costs. “This area is where breakthroughs in the science and technology of solar cell materials can give the greatest impact on the cost and widespread implementation of solar electricity,” Caltech chemist Nathan Lewis writes in Science.
A key issue is material purity. Current solar cell designs require high-purity, and therefore expensive, materials, because impurities block the flow of electric charge. That problem would be diminished if charges had to travel only a short distance, through a thin layer of material. But thin layers would not absorb as much sunlight to begin with.
One way around that dilemma would be to use materials thick in one dimension, for absorbing sunlight, and thin in another direction, through which charges could travel. One such strategy envisions cells made with tiny cylinders, or nanorods. Light could be absorbed down the length of the rods, while charges could travel across the rods’ narrow width.
Another approach involves a combination of dye molecules to absorb sunlight with titanium dioxide molecules to collect electric charges. But large improvements in efficiency will be needed to make such systems competitive.
Variations of Solar Energy storage ways
Although advanced solar cells become at generating electricity cheaply and efficiently, a major barrier to widespread use of the sun’s energy remains: the need for storage. Cloudy weather and night time darkness interrupt solar energy’s availability. At times and locations where sunlight is plentiful, its energy must be captured and stored for use at other times and places.
Many technologies offer mass-storage opportunities. Pumping water (for recovery as hydroelectric power) or large banks of batteries are proven methods of energy storage, but they face serious problems when scaled up to power-grid proportions. New materials could greatly enhance the effectiveness of capacitors, superconducting magnets, or flyweels, all of which could provide convenient power storage in many applications. [Ranjan et al., 2007]
Another possible solution to the storage problem would mimic the biological capture of sunshine by photosynthesis in plants, which stores the sun’s energy in the chemical bonds of molecules that can be used as food. The plant’s way of using sunlight to produce food could be duplicated by people to produce fuel.
For example, sunlight could power the electrolysis of water, generating hydrogen as a fuel. Hydrogen could then power fuel cells, electricity-generating devices that produce virtually no polluting by products, as the hydrogen combines with oxygen to produce water again. But splitting water efficiently will require advances in chemical reaction efficiencies, perhaps through engineering new catalysts. Nature’s catalysts, enzymes, can produce hydrogen from water with a much higher efficiency than current industrial catalysts. Developing catalysts that can match those found in living cells would dramatically enhance the attractiveness of a solar production-fuel cell storage system for a solar energy economy.
Fuel cells have other advantages. They could be distributed widely, avoiding the vulnerabilities of
centralized power generation.
If the engineering challenges can be met for improving solar cells, reducing their costs, and providing efficient ways to use their electricity to create storable fuel, solar power will assert its superiority to fossil fuels as a sustainable motive force for civilization’s continued prosperity, .
Solar Panels Control and Monitoring System
There are two main ways to maximize electrical power conversion from solar energy. One is to use the most efficient solar panel. The other is to track the sun’s movements throughout the day. It has been shown that solar panels with tracking systems have higher electrical output compared to a fixed system.
While solar farms become larger to generate more power for utilities, they are equipped with intelligent features to monitor the performance of each solar panel. For example, to monitor the panels’ electrical output and temperature to maximize the electrical output, controlling the angle and direction of the solar panels is very important. In the commercial solar farm that generates a few megawatts of power, the solar panels should be installed in huge areas, where reliable controlling and monitoring networks are only possible with fiber optic networks, .
Artificial photosynthesis process
While Hydrogen generated via the electrolysis of water is not a new concept and is a frequent object of high school science classroom experiments and demonstrations, Massachusetts Institute of Technology (MIT) researchers have taken photosynthesis storage method to an entirely new level, splitting water to create what can be described as an artificial photosynthesis process. The process at the heart of the system splits water into hydrogen and oxygen, storing them in their own respective tanks and recombining them to generate electricity within the hydrogen fuel cell. The technology is promising, but large-scale projects will have to determine how energy efficient the entire process is. If this new artificial photosynthesis process proves economically viable, it could revolutionize the energy market, .
Using Superconductor Solar Collectors
Solar Thermal collector (see Figure 9) is exceptionally suitable for the UK climate. Specifically Designed for the Northern European Climate, this model converts solar energy into heat from temperatures as low as –50°C, even under cloudy conditions.
Figure 9 Superconductor Solar Collector
The Superconductor incorporates the latest technology in selective absorptive coatings. AL/Ni/AL. This coating converts a much wider spectrum of daylight directly into heat energy.
Wind, snow, rain, hail and cold resistant, durable and easily maintained, the tubes are manufactured from high quality borosilicate glass capable of withstanding hailstones up to 35mm in size. Wind resistant to 80 Mph gales. By design, the panel is easy to install and reduces the amount of time spent working at height. The tubes simply plug into the manifold casing. The frame and manifold are constructed out of stainless steel and extruded anodised aluminium.
Working temperature –50°C to 100°C. Stagnation temperature of 220°C. Very Fast Warm-up and Low thermal capacity enables the tubes to release their energy within only 2 minutes of recieving sunshine.
Night-time Solar Energy
Devices employing billions of heat collecting nanoantennas (“nantennas”) are under development, which may eventually provide a solar energy collector that is amenable to mass-production using flexible sheets, and will produce electricity at night. It is not presently possible to convert the energy collected to electricity but it is envisaged that once this hurdle is overcome, lightweight "skins" could be made to power all kinds of electrical devices from i-Pods to electric cars, at a higher efficiency than is possible with traditional PV cells. The nanoantennas also have the potential to cool buildings or electronics by collecting background infra-red (heat) energy which could be used to make electricity that could provide further cooling by powering airconditioning units. Since they target mid-infrared rays, which the Earth continuously radiates as heat after absorbing energy from the sun during the day they could be used to produce electricity at night, in contrast with PV cells which are useless after dark. I.R.-driven PV cells are another route to providing night time solar electricity.
Figure 10 An array of nantennas, printed in gold and imaged with a scanning electron microscope. The deposited wire is roughly a thousand atoms thick.
A nantenna is an electromagnetic collector designed to absorb specific wavelengths that are proportional to the size of the nantenna. Currently, Idaho National Laboratories has designed a nantenna to absorb wavelengths in the range of 3-15 μm. Since around 85% of the solar radiation spectrum contains light with shorter than infra-red wavelengths, in the range 0.4-1.6 μm it would be ideal to make nantennas of these dimensions to harvest more energy than is possible with PV, .
According to research by a team led by a University of Missouri professor, however, newly developed nantenna-equipped solar sheets can reap more than 90 percent of the sun's bounty - which is more than double the efficiency of existing solar technologies (today solar panels only collect about 20 percents of available light), .
Nantennas work in practically the same way as rectifying antennas: namely that Incident light drags electrons in the antenna material back and forth at the same frequency as the incoming light, in consequence of the oscillating electric field component of the electromagnetic light wave. The refractive index of a material has a similar origin, .
Different methods for Solar energy harvesting comparison
There are rough comparison of couple of methods to convert Solar Energy to heat in Table 6.
Solar Thermal is called Concentrated Solar Power or C.S.P. The idea is simple; no complex chemistry or fancy silicon wafers required. Glorified mirrors shaped like satellite dishes direct the sun‘s rays towards a reservoir. The concentrated solar heat boils water into steam, and steam powers a turbine. When the water cools off it is collected and cycled back through the system. The mirrors can even track the sun across the sky to maximize efficiency. Water is not the only fluid that can be used, but its unique properties have made it popular.
Comparison of Solar Power Conversion methods 
According to above described methods and improvement ways to get Solar Energy efficiency as much high as possible, it can be excepted these mains
benefits of The Efficiency of Solar Energy:
- The efficiency of solar energy exists because solar energy is renewable; it doesn't deplete our earth's natural resources;
- the efficiency of solar energy exists because it is dependable, affordable and easy to distribute, and simple to connect to existing electrical grids;
- the efficiency of solar energy exists because you can lock in long-term electricity rates, putting you in control even if on-grid utility prices soar.
Today, when the average efficience of Solar Panel (200÷220W) is between 20 and 30 percents and 1 kWh cost roughtly 0,29 €, there are some ways how to increase the Solar energy efficiency:
- using gold nanoparticles;
- reconfigure the way panels are connected (the parallel connection throught each panel to it‘s own power converter instead of sending the electrical current throught a series of panels to a single converter;
Another important point about applying Solar energy is storage. There was described these tools and ways to storage Solar Energy:
- use superconducting magnets or flywheels (all of which could provide convenient power storage in many applications)‘;
- mimic the biological capture of sunshine by photosynthesis in plants (which stores the sun’s energy in the chemical bonds of molecules).
Moreover, in order to broad the abilities of Solar Energy storage in Night-time, there are recommend to use nantennas which are suitable to convert infrared Sunlight into Electricity with High Efficiency.
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19. Chris Rhodes, 2009. „Night-time Solar Energy“, Great Britain.
20. WesTech UK, 2011. “Superconductor Solar Energy”, http://www.westechsolar.co.uk/superconductor.html
PREPARED BY: Vytautas Bielinskas
ORIGINAL FILE: http://www.mesg.nl/wiki/images/f/fd/Paper_VGTU_03.pdf (Materials, Energy and Sustainable Growth : The Netherlands, Leewarden, 2012)