The technology for photovoltaic

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1. Introduction

1.1 Photovoltaic History

The technology for Photovoltaic dates back to over 160 years. A French physicist, named Alexandre Edmond Becquerel, was the first to state his observations of the photovoltaic effect in the 19th century. Since then, many scientists have worked to develop energy technologies based on this effect.

The basic science was first discovered in 1839 but the pace of advancement really accelerated in three major thrusts in the 20th century.

1839 Experimenting with metal electrodes and electrolyte, nineteen-year-old French physicist Alexandre Edmond Becquerel observes a physical phenomenon allowing light-electricity conversion

1883 Charles Fritts, an American inventor, describes the first solar cells made from selenium wafers

1888 Edward Weston receives first US patent for "solar cell"

1901 Nikola Tesla receives US patent for "method of utilizing, and apparatus for the utlization of, radiant energy"

  1. Albert Einstein Makes His Mark
  2. It wasn't until Albert Einstein wrote his 1905 paper on the photoelectric effect: "On a Heuristic Viewpoint Concerning the Production and Transformation of Light".

    1905 Albert Einstein publishes paper on theory behind "photoelectric effect" along with paper on relativity theory

    1916 Robert Millikan provided experimental proof of Einstein's theory on photoelectric effect

    1922 Einstein wins Nobel prize for 1904 paper on photoelectric effect

  3. The Commercial Solar Age Begins
  4. Bell Laboratories, while working on silicon semiconductors, discovered silicon had photoelectric properties and quickly developed Si solar cells, achieving 6% efficiency and early satellites were the primary use for these first solar cells.

    1954 Bell Labs exhibits first high-power silicon PV cell. The New York Times forecasts that solar cells will eventually lead to a source of "limitless energy of the sun".

    1955 Western Electric sells commercial licenses for silicon PV technologies; early successful products include PV-powered dollar bill changers and devices that decoded computer punch cards and tape.

    1958 PV array powers radios on US Vanguard I space satellite

    1963 Sharp Corporation produces a viable photovoltaic module of silicon solar cells. Japan installs a 242-watt PV array on a lighthouse, the world's largest array at that time.

    1966 NASA launches Orbiting Astronomical Observatory with a 1-kilowatt PV array

    1970s Research drives PV costs down 80%, allowing for applications such as offshore navigation warning lights and horns lighthouses, railroad crossings, and remote use where utility-grid connections are too costly

    1973 Solarex Corp is founded by two ex-NASA scientists who worked on the development of satellite PV systems

    1974 Japan formulates "Project Sunshine" to fuel PV research and development

    1976 Kyocera Corp begins production of Silicon ribbon crystal solar modules

    1977 US Dept. of Energy establishes US Solar Energy Research Institute in Golden, CO

    1980s Continued improvements in efficiency and cost enables PV to become a popular power source for consumer electronic devices, such as calculators, watches, radios, lanterns and other small battery charging applications

  5. Progressive Governments Use Subsidies to Speed Adoption

To spur adoption, Germany and then Japan initiated considerable subsidy programs and now those markets exist largely without subsidies. In 2007, California leads the US with a similar 10-year program.

1990 Germany launches $500MM "100,000 Solar Roofs" program. The Cathedral of Magdeburg installs solar cells on the roof, marking the first installation on a church in East Germany

1991 President George H. W. Bush directs the U.S. Department of Energy to establish the National Renewable Energy Laboratory (transferring the existing Solar Energy Research Institute) in Sandia, NM

1994 Japan begins "70,000 Solar Roofs" PV subsidy program

1998 California initiates $112MM "Emerging Renewables Program" to fund rebates for <30 kW residential and commercial PV systems

2002 CA Public Utilities Commission begins $100MM "Self Generation Incentive Program" for >30 kW PV projects

2004 Five manufacturers - Sharp, Kyocera, Shell Solar, BP Solar and RWE SCHOTT Solar - account for 60 percent of the PV market. GE buys Astropower, the last remaining US independent PV manufacturer

2006 The CA PUC demonstrates leadership by outlining what will become the California Solar Initiative (CSI), a 10-year, $3 billion solar subsidy program.

2007 The CSI program begins and is well received by the market, with higher than expected application volume.

2008 Your company joins the fast-growing list of California business leaders who adopt solar power for their business with Sunlight Electric.

Sunlight Electric, LLC., 2002-2009)

1.2 Photovoltaic Basics and Working Principles

The term photovoltaic is derived by combining the Greek words - "photo", meaning light, and "voltaic", meaning producing electricity -means "electricity from light"

Photovoltaic which is abbreviated as PV is the term which is used to describe the solid state devices which are capable of direct conversion of sunlight into direct current electricity.

Sunlight is made up of photons which are discrete units of light energy. When these photons come in contact with a PV cell, some photons are absorbed by the semiconductor material and the energy is transferred to electrons. With this additional energy, the electrons can escape from their atoms and can flow as current in an electrical circuit.

PV systems are means of producing electricity on-site from the sun without any noise pollution and have no moving parts. These can therefore theoretically produce energy infinitely without requiring any maintenance. It is an established fact that in one hour the solar energy received by the earth if converted into electricity can generate energy which is equal to the total amount of energy consumed by all humans in one year.

The basic building blocks of PV modules are the PV cells. PV cells are made up of semi-conducting materials, which typically is silicon and is doped (doping is the process of intentionally introducing impurities into an extremely pure semiconductor to change its electrical properties) with special additives. The total amount of current that can be produced is directly proportional to the size of the cell, its conversion efficiency, and the intensity of sunlight received. PV cells are connected together to produce PV modules. PV modules can be connected in series and parallel to obtain the desired voltage and current respectively. When the PV modules are fixed together (in series or parallel) they are called an array.

(Eiffert and Kiss 2000)

PV arrays require very little maintenance no other than cleaning of the surfaces occasionally when and if they become soiled or if the PV arrays are being used in dusty locations. However for an efficient operation it is necessary to keep them clear of snow, weeds and any other sources which can shade a portion or whole of the array. As the PV cells are connected in series (especially to produces the desired voltage), so shading even one cell in a module will decrease the output of the entire module appreciably.

1.3 Types of PV Systems

Photovoltaic power systems are generally classified in accordance with their functional and operational requirements, the configuration of their components, and how these equipments are connected to other power sources and electrical loads.

The three main classifications are:

  • stand-alone systems
  • hybrid systems
  • grid-connected or utility-interactive systems

.Photovoltaic systems can be designed to provide either DC and/or AC power; these can operate interconnected with or independent of the utility grid, and can be connected with other energy sources and energy storage systems.

a) Stand Alone systems

Stand-alone PV systems are designed to such that they can operate independent of the electric utility grid. They are usually designed and sized to supply certain DC and/or AC electrical loads. These types of systems are powered by a PV array only. In many stand-alone PV systems, batteries are used to store energy during the day time when the sun shines to be used at night.

b) Hybrid Systems

These are an extended version of stand alone system as they consist of a combination of a PV array and a complementary means of electricity generation such as a diesel, gas or wind generator. In order for the operation of the two electricity generating systems to be optimum, hybrid systems typically require more sophisticated controls than any standalone PV systems. For example, in the case of PV/diesel system the diesel engine must be started when the battery reaches a given level of discharge, and then stopped again when the battery reaches an adequate level of charge.

When a hybrid system is being used it is possible to use a smaller PV array and smaller batteries than would be required for an equivalent sized stand-alone system. Hence the total cost of a hybrid system may more cheaper to install than a stand-alone system for some applications.

c) Grid or Utility Intertied Systems

Grid-connected or utility-interactive PV systems are designed such that they operate in parallel with and are interconnected with the electric utility grid.

The most important component in grid-connected PV systems is the inverter. The inverter is required to convert the DC power produced by the PV array into AC power which is in line with the voltage and power quality requirements of the utility grid and is capable of automatically stop supplying power to the grid when the utility grid is not energized. This system requires a bi-directional interface between the PV system AC output circuits and the electric utility network, typically at the on-site distribution panel or at the service entrance. This allows the AC power which is being produced by the PV system to either supply to the on-site electrical loads or to back-feed the grid when and if the PV system output is greater than the on-site load demand. At night and during other periods when the electrical loads required on-site are greater than the PV system output, the balance of power required by the loads is received from the electric utility. There is a safety feature built into all grid-connected PV systems, to ensure that the PV system will not continue to operate and feed back into the utility grid when the grid is down for service or repair.

1.4 Photovoltaic System Components

Typical Components required for a Photovoltaic System are:

  1. PV Array:
  2. A PV Array is made up of environmentally-sealed PV modules, which are collections of PV cells, the devices that convert sunlight to electricity.

  3. Balance of system equipment (BOS):
  4. BOS includes mounting and wiring systems which are used to integrate the solar modules into the structural and electrical systems. The wiring systems include all the isolation devices which are required for the dc and ac sides of the inverter, all the ground-fault protection equipment, and over current protections for the solar modules. Most systems also include a combiner board of some kind since most modules require fuses for each module source circuit. Some inverters include this fuse and combining function within the inverter enclosure.

  5. DC-AC inverter:
  6. An inverter is a device that takes the dc power from the PV array as an input and converts it into standard ac power which is required by the loads to which it is feeding.

  7. Batteries:
  8. This includes batteries and battery enclosures, battery charge controller and separate sub-panel(s) for critical load circuits.

  9. Metering:
  10. This includes meters to provide measurement of the system performance. Some meters can indicate the usage of energy.

  11. Other components:
  12. These include the utility switch and protections as required by the local utility department.

1.5 Definition - Building Integrated Photovoltaic

The acronym BiPV (Building integrated Photovoltaic) refers to systems and concepts in which photovoltaics are integrated within the building; they take on the role of building elements serving a secondary purpose such as roof, fa&ccedil;ade or a shading system as well as having the function of producing electricity. However existing buildings may be retrofitted by adding BIPV modules on the top of already constructed structures as well.

The main advantage of BiPV over the common non-integrated systems is that its initial cost can be offset by reducing the amount that had to be spent on building materials and labour normally that the BIPV modules replace. In addition, as BIPV are an integral part of the building design, they generally blend in better with the building and are more aesthetically more pleasing than other solar options

It means that they give best results if built/constructed along with a building/structure. They should also be planned together with the building. Yet, they could be built later on. They require working together of many different experts, such as architects, civil engineers, electrical engineers and PV system designers.

1.6 Application of Building Integrated Photovoltaic

The photovoltaics can be integrated with the buildings and structures as follows:

a) Facade systems

The BIPV system can be designed to act as an outer skin and weather barrier as part of the building envelope. BIPV systems are generally the glass products which are typically used as facade systems (laminated and patterned glass), spandrel glass panels, and curtain wall.

These can replace traditional construction materials. Laminated glass is the most common BIPV product used for the Fa&ccedil;ade systems. It is made up of two pieces of glass with PV solar cells sandwiched between these glass pieces, an encapsulant like ethylene-vinyl acetate (EVA) or another encapsulant material, and a translucent or coloured tedlar-coated polyester back-sheet. The architect can indicate the spacing between solar cells, which will determine the power supply and also permit the design of passive solar features by regulating the amount of day lighting allowed to enter into the building

The photovoltaics used as building facades have many advantages as they bring in natural light, visual contact with the nature and can contribute as an important element of passive solar energy. These make it possible to conjugate production of energy, aesthetics and thermal comfort. (Eiffert and Kiss 2000) and (Jesus, Manuela and Pereira 2005)

b) Atrium systems

In this system BIPV is a glass element joined with PV modules that provides different shading levels and can be designed to enhance indoor thermal comfort as well as use of natural daylight.

The semi-transparent PV modules are most quite often used within the commercial atria as these can be used to replace traditional shading solutions which generally have high maintenance costs associated with them. However, compared to standard double glazing systems, an element which incorporates either mono or poly crystalline PV cells in a glass-glass construction does come at a cost premium. But this cost premium can be offset as choosing PV laminates for the atrium roof has multiple benefits for the building users, such as electricity generation, solar shading, environmental and technology statements, enhanced comfort and prestigious office workspace.

Many researches have confirmed that the application of PV in atria is justified from both financial, environmental (CO2 emissions) and architectural perspectives. Using BIPV in the atria is perhaps the most appropriate use of PV today. As improvements happen in the cell efficiency and in particular the inverter reliability, it will further benefit the economics of PV atria and make its use far more common place. (Eiffert and Kiss 2000) and (James, Jentsch. and Bahaj 2008)

c) Awning and Shading systems

A variety of PV materials can be mounted onto a facade in aesthetic manner to serve as awnings.

d) Roofing systems

The BIPV roofing system replaces conventional roofing materials such as tiles, shingles, and metal roofing. This system can be applied to tilted roofs as well as plane coverings. This system has several advantages other than producing electricity such as reduction in maintenance costs, pays back the installation costs in shorter periods due to its privileged positioning for the reception of solar energy. BIPV applications in plane coverings have additional advantages like its capacity to extend the roof life through its property of protecting the insulation and membrane from ultraviolet rays and from degradation caused by rain. (Eiffert and Kiss 2000) and (Jesus, Manuela and Pereira 2005)

1.7 Design Issues

In order to obtain an optimum performance by the integration of a photovoltaic system into buildings it is required to give due consideration to its constructability and functionality, as its installation is different from the conventional PV installation method which only need supporting structures opened to air. The efficiency of BIPV system is determined by the method that is applied to the building envelope, as well as the efficiency of PV system itself. In addition to the general specifications of a PV system, there are various design factors that may decide the performance of the BIPV systems.

In any situation of BIPV integration, the following factors should be taken in consideration in all design and execution phase:

  • Environmental Factors - Climatic data - temperature, solar radiation - of the location must be known, this is because the solar access, the incidence of solar radiation that reaches a PV surface at any given time, determines the potential electrical output of a BIPV system.

It is also important to know the latitude of the place and the solar orientation (an inclination angle of the modules) as demonstrations have shown that a system installed at a tilt angle equivalent to the site latitude produces the greatest amount of electricity on an annual basis.

Care must be taken in order to avoid shading from the surroundings. If only a part of PV array is shaded the energy loss can be over-proportional compared to the loss of incident solar energy.

  • Structural Factors - These include the requested energy, weight and size of chosen module, ways of fixation and operating and maintenance strategies (ease of installation and accessibility of system components) of the BIPV system.

For choosing the type and size of BIPV three things which need to be considered are the energy required, architectural or aesthetic considerations, and economic factors.

In order to determine the desired power rating of a BIPV system for a building, the total electrical requirements of the building need to be evaluated. The optimum power rating of the BIPV system can then be calculated based on the portion of the building's electricity that will be supplied by this BIPV system.

Architecturally, the size of the BIPV system is physically limited to the dimensions of the building's available surface area. The balance between the amount of power required and the amount of surface area available can determine the type of PV technology that will be used. Each technology has an associated range of output in watts per square foot or per square meter and cost per watt.

  • Aesthetic and Economical Factors - The module should fit in the surroundings and must be harmonious with other construction materials. It should be multifunctional ad replace, whenever possible, other construction materials.
  • Electrical issues - Electrical issues primarily involve the performance and reliability of the inverters. BIPV systems include single inverters, master-slave inverter configurations, modular inverters, and parallel independent or string inverters.

A BIPV system is most vulnerable to a single-point failure where the power generated from the BIPV array must be transformed and synchronized through the inverter from DC to AC power and then fed into the building or an electric utility system. If the inverter fails, the entire system malfunctions.

A BIPV system must be designed so that multiple inverters work together ensures greater system reliability. If one inverter malfunctions or requires maintenance, it can be disconnected from the array and the BIPV system can still operate.

  • Safety Issues - With regards to the electrical safety issues, it is important to note that lightning, ground faults, and power line surges can all cause high voltages in otherwise low-voltage BIPV systems. The international electric codes, regulations and building codes are being amended to include PV technologies and address fire and safety issues concerning BIPV design, installation, and maintenance.

(Eiffert and Kiss 2000), (Jesus, Manuela and Pereira 2005) and (Moor, Borg, Boer and Oldenkamp 2004)

2. PV Technology

2.1 Current Status of technological Development of Photovoltaics

Photovoltaics industry has already become a billion dollar industry. This industry is experiencing rapid growth as there are concerns over fuel supplies and carbon emissions and this is leading the governments and individuals to ignore its current high costs. It will become truly mainstream when its costs are comparable to other energy sources. At the moment, it is around four times more expensive than other competitive commercial products.

Three generations of photovoltaics are being developed and these will take solar power into the mainstream.

  • First Generation PV

These include the following types:

Mono Crystalline Cells (c-Si)

Poly Crystalline Cells (mc-Si)

Wafer &eacute;quivalents (re-crystallisation etc)

These types of single-junction, silicon-wafer devices are now commonly referred to as the first- generation (1G) technology.

The First generation solar cells are crystalline based photovoltaic cells that have dominated and still dominate the solar module market. These solar cells use silicon wafers of between 4'' to 8'' size, and account for biggest share of the global PV market. They are dominant because of their high efficiency and proven technology. This is despite of the fact that their manufacturing costs are very high; a problem that will hopefully be resolved by the second generation cells. The manufacturing process of 1G solar cell involves high energy intensive production effort and is labour intensive; this has prevented significant cost reductions. 1st generation solar cells have the highest efficiency of all three generations, between 13% to 20% and approaching the theoretical limiting efficiency of around 30%.

  • Second Generation PV

The next step in the evolution of PV to reduced cost/W is to remove the unnecessary material from the cost equation by using thin-film devices. Second-generation (2G) technologies are also single-junction devices and are designed to use less material while trying to maintain the efficiencies of 1G PV. The main types in this category are:

Amorphous Silicon (a-Si)

Cadmium Telluride (CdTe)

Copper Indium Gallium Selenide - CuIn(Ga)Se2 -(CIGS)

Second generation cells, although significantly cheaper to produce than first generation cells have lower efficiencies of between 6%to 12%.

The main advantages of second generation, thin-film solar cells, are the lower manufacturing costs and their flexibility. Thin-film technology has led to the development of lightweight, aesthetically pleasing solar innovations such as solar shingles and solar panels that can be rolled out onto a roof or other surface. CdTe, CIGS and a-Si are applied in continuous roll to-roll or batch process to supporting substrates such as glass, stainless steel or polymer foil thus reducing material mass and therefore costs. It is becoming obvious that the second generation cells will dominate the residential and power utility solar applications, especially as new, higher-efficiency cells are being researched and produced.

It is now an accepted fact that as manufacturing techniques evolve the production of second generation technologies will gain significant market share in the next decade. Even among major manufacturers there is certainly a trend towards second generation technologies.

  • Third Generation PV

Third-generation (3G) approach to photovoltaics (PVs) aims to achieve high efficiency devices but still using thin-film, second-generation deposition methods. The concept is that this should be achieved only by a small increase in cost and hence reducing the cost per Watt peak. Increasing efficiency means lower costs because as smaller area is required for a given power this will also reduce the costs of balance-of-system equipment, and hence the efficiency values could dramatically decrease these costs per Watt peak.

In order to achieve efficiency improvements, devices have to overcome the limits for single-bandgap devices that limit efficiencies to either 31% or 41%, depending on concentration ratio (Figure 8). This requires multiple energy threshold devices.

Multiple energy threshold devices can be achieved in many different ways:

(a) By increasing the number of energy levels;

The concept of absorbing different sections of the solar spectrum, by means of multiple energy levels can be applied in many different device structures.

  • Tandem or multicolor cells

The tandem or multicolor cell is the easiest of all the configurations. Solar cells made up of p-n junctions in different semiconductor materials of increasing bandgap are placed on top of each other, such that the sunlight is first intercepted by the material of highest bandgap.

- III-V tandems

These are multi-junction cells that consist of multiple thin films produced using molecular beam epitaxy and / or metalorganic vapour phase epitaxy. Each type of semiconductor has a characteristic band gap energy which allows it to absorb light most efficiently over a portion of the spectrum. The choice of semiconductors is such that they absorb almost the entire solar spectrum, and generate electricity from as much of the solar energy as possible.

  • Concentrator systems

Concentrator cells consist of four- or even five-bandgap cells. These are not only higher in efficiencies but also have higher voltage and lower current than three-bandgap cells. This reduces the series resistance losses which is an important factor for concentrator cells.

Tandems suit the concentrator systems because as the number of cells increase in the stack, the voltage-to-current ratio also increases and this decreases the resistive losses in the high current densities of concentrator cells. However, concentrators do not work with an overcast sky and require direct sunlight for proper operation, unlike flat-plate cell modules.

  • Thin-film tandems - a-Si tandems, Si nanostructure tandems

A tandem thin-film silicon solar cell comprises of a transparent substrate, a first unit cell positioned on the transparent substrate, the first unit cell comprising a p-type window layer, an i-type absorber layer and an n-type layer, an intermediate reflection layer positioned on the first unit cell, the intermediate reflection layer including a hydrogenated n-type microcrystalline silicon oxide of which the oxygen concentration is profiled to be gradually increased and a second unit cell positioned on the intermediate reflection layer, the second unit cell comprising a p-type window layer, an i-type absorber layer and an n-type layer.

  • Intermediate-level cells: impurity PV and intermediate band solar cells

The approach adopted with these devices is to introduce one or more energy levels within the bandgap such that they absorb photons in parallel with the normal operation of a single-bandgap cell. This semi-parallel operation offers the potential to be much less spectrally sensitive but to still give high efficiencies.

(b) Multiple carrier pair generation per high energy photon or single carrier pair generation with multiple low energy photons;

Carriers generated from high-energy photons (at least twice the bandgap energy) absorbed in a semiconductor can undergo impact ionization events resulting in two or more carriers close to the bandgap energy. But impact ionization has a vanishingly small probability in bulk material. A device based on this approach requires a means of allowing the multiple electron-hole pairs to be separated, transported, and collected in a bulk structure. This is the subject of ongoing research.

(c) Capturing carriers before thermalization.

The final option for increasing efficiencies is to allow absorption of a wide range of photon energies but then to collect the photogenerated carriers before they have a chance to thermalize. A hot-carrier solar cell is just such a device that offers the possibility of very high efficiencies but with a structure that could be conceptually simple compared with other very high efficiency PV devices - such as multijunction monolithic tandem cells. For this reason, the approach lends itself to thin-film deposition techniques with their attendant low material and energy usage costs and the ability to use abundant, nontoxic elements.

Summary of Cell Efficiencies for 1G, 2G and 3G Photovoltaics

The Graph 3 shows a historic summary of cell efficiencies for various photovoltaic technologies. The multijunction solar cells have achieved the highest efficiencies, and these are increasing at a rate of almost 1% per year in recent years. The efficiencies of the Multijunction cell have the potential to approach 50% in the coming years. (Bagnall,D.M. and Boreland,M. (2008); Conibeer, G.,(2007); Ruoss,D.(2008))

2.2 Future Challenges and Developments

As we have discussed, progress in PV technology should be measured in $/W, and many scientific advances, as fascinating though they may be, will only be relevant to the industry if they can be implemented at affordable costs. In this sense, we can envisage two routes to cheaper photovoltaic energy that will be brought about by new science and 3G concepts. The first is based on the pragmatic use of new technology to improve the performance or decrease the cost of current devices. The second, more revolutionary, possibility might involve new whole-device concepts. Indeed, in recent years we have seen the emergence of dye-sensitised (Gratzel, 2001) and polymer-based solar cells (including organic/inorganic hybrids) (see Brabec and Sariciftci, 2001; Kanicki, 1986) as fundamentally new types of device, and although none of these have come close to outperforming wafer- based silicon devices in cost or efficiency, there is every chance that these devices could demonstrate step-change improvements or that new types of device may yet emerge. (Bagnall,D.M. and Boreland,M. 2008)

The PV industry is continuously putting effort towards cost reduction so that PV could become a self-sustained industry without the need for subsidies. Characteristic developments in solar industry are the following:

  • Strong investment in thin-film industry. Companies based on Si, such as QCells are investing in subsidiaries based on thin-film technology. Also LCD equipment manufacturers are developing equipment for solar industry and even complete lines for thin-film production (such as Oerlikon or Applied Materials); a diversity of technological innovations.
  • Reaching stability and device reliability for cheaper technologies, such as dye-sensitised cells.


  • Expansion of manufacturing volume and achievement of lower costs, such as the case of First Solar.
  • Silicon shortage is driving investments into poly-Si plants. Another trend is the production of metallurgical Si, which allows for less capital costs for production machinery and tools.
  • ribbon/sheet grown Si, capital costs and the amount of Si used can be diminished.
  • Thinner Si wafers and new poly-Si material supplies.
  • Faster processing/higher production volume.
  • Growth of the market for BIPV (Building Integrated PV) products and flexible PV products.
  • Concentrating technology could become attractive due to lower solar electricity costs in very sunny countries (Africa, USA, Middle East, India, China, Mexico and Australia).
  • Emerging of new PV technologies.
As the industry and the volumes produced are getting larger and larger, more attention will have to be paid to the following issues:
  • Raw materials bottlenecks for different technologies (cheap solar quality glass, tellurium and indium). Securing raw materials supply is necessary.
  • Reduce waste, both of raw materials and of resources used in production.
  • Being able to attract highly qualified and well trained personnel. (Jol,J.C., Mandoc, M.M.and Molenbroek, E.C. 2008)
  • 3. Costs and Benefits

    3.1 Costs of PV Systems

    3.2 Advantages, Disadvantages and limitations of BIPV Systems

    3.3 Future Costs

    4. Conclusions

    The solar market is booming. The solar market has shown average growth rate of more than 35% over the last ten years. The market value was estimated to be 13 billion Euros in 2007 and over 100,000 people have found employment in the solar business. The cost of solar panels continues to drop as well. Since the early years of solar panels, panel prices have dropped by 20% for each doubling in cumulative production. Important countries for the solar market are Germany, Japan, the US and not the least far Asian countries with China as a strong centre point.

    The renewable energy market is no longer a niche market. It was almost a $150 billion market in 2007. Almost 60% of this was spent on renewable power generation projects in asset finance, which accounts for 23% of all new power generation capacity worldwide in 2007. Solar investment really took off in 2007, when $ 28.6 billion of new investment flowed into solar, of which $ 18 billion (approx. € 13 billion) was spent on newly installed PV power. The annual growth is at an average rate of 254% since 2004. It is seen now as a mature market by financial institutions.

    The market share of the mainstay of the solar industry, crystalline PV modules, has still a market share of about 90% but the thin film modules are catching up. A lot of production facilities are coming into production the coming years. In an international perspective, it is expected that the solar market will continue its high growth rates (~30-40% per year) in the coming years. The coming years will show an expansion in the thin film production capacity. However, crystalline silicon will stay an important mainstay of the solar industry. Production is showing a shift toward Asia (China, Taiwan, Philippines). Nevertheless production capacity is also being built in Europe. In the short term, an oversupply situation could arise. In the longer term the market will be able to catch up with the expansion in production capacity that will materialize in the coming few years.

    From the financial market perspective solar is now seen as a mature market which is safe to invest in. International related investments funds and venture capitalists are investing more and more capital in solar companies and projects. Large investments are needed in the sector to allow for high growth rates in the coming years.

    On the technology side, In an international context, the relationship between a strong industry and a strong home market is well visible. The market in Japan 'collapsed' after subsidies were terminated and Japan lost it's international top position in production. At this moment, nowhere in the world can be found so many thin film start-up companies as in Germany, where currently the most PV modules are sold. A strong internal market also creates jobs in the installation sector. In terms of job Creation. Forexample: Germany has 40.000 jobs in PV, Grid parity may be reached in the Netherlands in 2015 or even earlier as well. It should be realized though that the volumes necessary to reach this low PV kWhprice will have to be realized and it will not happen if everybody starts waiting for grid parity. Also, it is not expected that the PV-consumer market will directly take off as soon as grid parity is reached. Grid parity is in fact already reached in South Italy by now, but the market is still small. However, a sufficiently interesting pay back time, awareness of the possibilities and willingness to pay up front for households and an infrastructure able to offer cost-effective rooftop PV-systems will have to be in place for this to happen. Last but not least, a lot will depend on the development of the conventional electricity prices in the years to come. (Jol,J.C., Mandoc, M.M.and Molenbroek, E.C. 2008)

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    6.0 BIPV Terminology

    Building-integrated photovoltaic (BIPV) is a relatively recent new application of photovoltaic (PV) energy technologies. These are some of the basic terms used in describing PV technologies, BIPV products, and their uses:

    Antireflection coating - a thin coating of a material that reduces light reflection and increases light transmission; it is applied to the surface of a photovoltaic cell.

    Balance of System (BOS) - Non-PV components of a BIPV system typically include wiring, switches, power conditioning units, meters, and battery storage equipment (if required).

    Bypass diode - a diode connected across one or more solar cells in a photovoltaic module to protect these cells from thermal destruction in case of total or partial shading of individual cells while other cells are exposed to full light.

    Conversion efficiency - Amount of electricity a PV device produces in relation to the amount of light shining on the device, expressed as a percentage.

    Curtain wall - an exterior wall that provides no structural support.

    Encapsulant - Plastic or other material around PV cells that protects them from environmental damage.

    Grid-connected - Inter-tied with an electric power utility.

    Inverter - Device that transforms direct-current (DC) electricity to alternating current (AC) electricity.

    Module - Commercial PV product containing interconnected solar cells; modules come in various standard sizes and can also be custom-made by the manufacturer.

    PV array - Group or string of connected PV modules operating as a single unit.

    PV laminate - Building component constructed of multilayers of glass, metal or plastic and a photovoltaic material.

    PV solar cell - Device made of semiconductor materials that convert direct or diffuse light into electricity; typical PV technologies are made from crystalline, polycrystalline, and amorphous silicon and other thin-film materials.

    Solar access - Insolation incidence of solar radiation that occurs on a PV system's surface at any given time; it determines the potential electrical output of a BIPV system.

    Stand-alone - Remote power source separate from an electric utility grid; a stand-alone system typically has a battery storage component.

    (Eiffert.P and Kiss.G.J. 2000)