Optimizing limited solar roof access by exergy analysis of solar thermal, photovoltaic, and hybrid photovoltaic thermal systems/Literature review part II

Performance Analysis of a Double Pass Thermoelectric Solar Air Collector 2008[edit | edit source]

"Over the last few years, different PVT systems, based on air and water as heat carrying fluid, have been studied, developed and reported in literature. For example, Kalogirou [3] has studied experimentally an unglazed hybrid PVT system under the force mode of operation for climatic condition of Cyprus. He observed an increase in the mean annual efficiency of a PV solar system from 2.8% to 7.7% with a thermal efficiency of 49%. Hagazy [4] and Sopian et al. [5] investigated a glazed PVT air system for a single and double-pass air heater for space heating and drying purposes. They have also developed a thermal model of each system. Thermal energy for the glazed PVT system is increased with lower electrical efficiency due to high operating temperature. However, there is another technology for combined electrical and thermal energies namely: thermoelectric (TE) technology. The term TE refers to solar thermal collectors that use TE devices as an integral part of the absorber plate. The system generates both thermal and electrical energy simultaneously. A TE device for power generation consists of n and p semiconductors connected electrically in series and thermally in parallel. Heat is supplied at one end of the TE, while the other end is maintained at a lower temperature with a heat sink [6]. As a result of the temperature difference, a current flows through an external load resistance. TE has the advantage that it can operate from a low grade heat source such as waste heat energy. It is also attractive as a means of converting solar energy into electricity. A number of simulations as well as experimental studies have been reported on solar-driven TE power generators. Chen [7] derived a thermodynamic analysis of solar-driven TE power generator based on a well-insulated flat plate collector. A thermodynamic model including four irreversibilities is used to investigate the optimum performance of a solar-driven TE generator. The example discussed by Chen is based on an extremely well-insulated flat plate collector, which, in practice, may be difficult to achieve. Gunter et al. [8] constructed a prototype of a solar thermoelectric water heater. The hot side of TE module was heated by solar hot water. Meanwhile, the heat was released at the cold side of TE module via a heat sink. Three vacuum tubes with heat pipes, each with a

1. 1m2 absorber area and with water as the heat pipe medium,

were connected via a specially designed heat exchanger to a fluid circuit acting as a heat sink. Test result showed that the electrical efficiency reached a maximum value of 1.1% of the incoming solar radiation, which is around 2.8% of the transferred heat. Scherrer et al. [9] presented a series of mathematical models based on the optimal control theory to assess the electric performance of a skutterudites-based solar TE generator as a function of sunspacecraft distance, and optimized its design parameters (such as dimensions, weight and so on) when operating at a distance of

1. 45 a.u. from the sun, for 400Welectrical output power and for a

required load voltage of 30 VCD. The simulation results indicated that the skutterudites-based solar TE generator offered attractive performance features as primary or auxiliary power source for spacecraft in near-Sun missions. Maneewan et al. [10] studied a thermoelectric roof solar collector (TE-RSC) to reduce roof heat gain and improve indoor thermal comfort. Maneewan's TE-RSC combined the advantages of a roof solar collector and TE to act as a power generator. The electric current produced by the TE modules was used to run a fan for cooling the modules and improve the indoor thermal conditions. The subsequent simulation results, using a real house configuration, showed that a TERSC unit with a 0.0525m2 surface area could generate about 1.2W under solar radiation intensity of about 800W/m2 and at ambient temperatures varying between 30 and 35 1C. The induced air change rate varied between 20 and 45 ACH (number of air changes per hour) and the corresponding ceiling heat transfer rate reduction was about 3–5W/m2. The electrical conversion efficiency of the proposed TE-RSC system is 1–4%." - Paper

This paper is about the testing and development of TE solar air heater to determine its performance in Thailand. The theoretical model and testing were within experimental error of each other. The results showed that with an air flow-rate of.123 kg/s the overall efficiency was 80.3% with the electrical efficiency of around 5.7%.

TE uses the same idea of thermocouples, ie. the higher the difference in temperture, the higher the voltage. So by cooling one side of the TE and collecting that warmer air, the thermal and electrical efficiency goes up. see thermoelectricity

File:09 05 28 performance analysis of a double pass thermoelectric solar air collector.pdf

& 2008 Elsevier B.V. All rights reserved. Performance analysis of a double-pass thermoelectric solar air collector. C. Lertsatitthanakorn, N. Khasee, S. Atthajariyakul and S. Soponronnarit. A. Therdyothin b, Ryosuke O. Suzukihttp://ci.nii.ac.jp/naid/120000947350/

5mjmp 19:06, 10 June 2009 (UTC)

Performance Analysis of a Photovoltaic-Thermal Integrated System 2008[edit | edit source]

This is a very good paper going over PV/T's.

This paper is an overall summary of PV/T's and it talks about why PV/T's are more practical. PV/T's is designed to remove the unwanted heat from PV's and collect the excess heat, thus making them more efficient than PV's. You can not compare them to a thermal system since PV/T's produce heat and electricity which is more useful than just heat. The paper talks about the use of exergy efficiency as a means to determine the PV/T's efficiency since exergy takes more variables such as heat into the efficiency. Exergy help determine the magnitude, location and the sources of the thermodynamic inefficiencies in a system. This allows for the optimization of a system efficiency.

"The exergy efficiency can be defined to describe the quality difference between electricity and heat" - Paper

Exergy analysis is a tool that can help determine the amount of exergy required for a process and the avaible exergy which can then be used to utilize the exergy more efficiently. The exergy efficiency decreases with decreasing heat harvest (ie. heat transfer medium flow rate fast therefore medium isn't as hot and therefore heat harvest lower).

Many advantages to PV/T systems:

• "increase of the electric output power,
• improvement of conversion efficiency of solar cells,
• heat transfer from the module to the cooling medium" -Paper

"The exergy analysis of the hybrid system allows evaluating influence of every particular process on the efficiency of the system, eliminating the profitless components of the system, and identifying the maximum efficiency of the system." - Paper

File:09 05 28 performance analysis of a photovoltaic-thermal integrated system.pdf

80-952 Gdansk, POLAND, G. Narutowicza 11/12 e-mail: ewarad@chem.pg.gda.pl, tel/fax +48 58 347 18 74 PERFORMANCE ANALYSIS OF A PHOTOVOLTAIC-THERMAL INTEGRATED SYSTEM. Ewa Radziemska. Chemical Faculty, Gdansk University of Technology. http://66.102.1.104/scholar?hl=en&lr=&q=cache:NJNQCrv6m98J:hindawi.com/RecentlyAcceptedArticlePDF.aspx%3Fjournal%3Dijp%26number%3D732093+Performance+Analysis+of+a+Photovoltaic-Thermal+Integrated+System+Ewa+Radziemska

5mjmp 20:26, 10 June 2009 (UTC)

Nanodiagnostics of Concentrator Solar Cells with Vertical p-n-Junctions for PV/T Systems 2008[edit | edit source]

Eurosun 2008

Not very useful. The following is the conclusion.

"Concentrator PV/T technologies are prospective alternative of traditional solar thermal collectors and PV modules. First results of diagnostic of solar cells with vertical p-n-junctions show high informative and useful data obtained with the help of modern methods of investigation of semiconductors. As for thickness of inter-layers connecting p-n- junction structures in developing SCs with vertical p-n junctions we have a definite reserve i.e. decreasing thickness of inter-layers it is possible to increase sensitive surface of SCs. It is necessary to improve quality of the surface on the cutting stage of bonded (soldered) structures for improving technology and quality of solar cells and potential using scanning capacitance microscopy for detailed study of carrier's distribution." -Paper

5mjmp 18:53, 10 September 2009 (UTC)

489 - Nanodiagnostics of Concentrator Solar Cells with Vertical p-n- Junctions for PV/T Systems Corresponding Author, ityukhov@yahoo.com 5mjmp 18:59, 16 June 2009 (UTC)

Study on Thermal Performance of Hybrid Photovoltaic Thermal 2008[edit | edit source]

Eurosun 2008

"Many researchers and institution have attempted to develop and evaluate the hybrid PV/T collector performance experimentally and analytically. Ito and Miura, experimentally and analytically studied the thermal performance of a PV/T collector that used a partially transparent PV module as a cover [2], [3]. Ito and Miura also reported that the collector efficiency was slightly less while generating power than while not generating power [4]. Othman et al. [5], studied theoretically and experimentally hybrid PV/T solar collector regarding its thermal and electrical performance, used air as a flowing fluid to extract heat from the photovoltaic cells and keep electrical efficiency of it a satisfactory level by the reduction of its operating temperature. The conclusion of this work this work is that is important to use fins as an integral part of the absorber surface in order to achieve meaningful efficiencies for both thermal and electrical output of the hybrid PV/T solar collector. Santbergen and Zolingen simulated various crystalline silicon solar cell configurations found that a standard untextured solar cell with a silver back contact has an absorption factor of only 74%. If a semi transparent solar cell is used in combination with second absorber the total absorption factor can increase to 87%, and if irradiance is absorbed in the back contact, the absorption factor can increase to 85%. They suggested to apply the rough interface in combination with a non standard metal as back contact [6]." - Paper

This paper experimentally tested whether having PV panels on a thermal collector greatly affected the thermal efficiencies. From the results, the PV panels do not reduce the efficiency significantly.

5mjmp 20:00, 10 September 2009 (UTC)

(PV/T) Collectors with and without Electricity Generation 041 - Study on Thermal Performance of Hybrid Photovoltaic Thermal (PV/T) Collectors with and without Electricity Generation *Corresponding Author, yandri@ctr.kanagawa-it.ac.jp 5mjmp 18:59, 16 June 2009 (UTC)

Improvement of the performance of PVT Collectors 2008[edit | edit source]

Written: 2008

This paper looks at the application of anti-reflective (AR) coatings adn low-emissivity (low-e) coatings. It was found that the AR coating improved the anual thermal and electrical efficiency by 10% and 5% relatively. The low-e coating reduces the electrical efficiency by 10% but increaes the thermal efficiency by 10%. Overall AR coating is much better than the low-e coating.

"In table 4 results are given for PVT collectors with amorphous silicon solar cells (with an efficiency of 6.3% at STC) in stead of crystalline silicon solar cells. In case a low-e coating is used, the drop in annual electrical efficiency is only 6.7% (5.02% versus 5.38%), because of the lower temperature coefficient of the efficiency of single junction amorphous silicon solar cells (-0.18%/ºC relative versus -0.45%/ ºC for crystalline silicon solar cells)." - Paper

09_06_16_Improvement of the performance of PVT Collectors

5th European Thermal-Sciences Conference, The Netherlands, 2008. IMPROVEMENT OF THE PERFORMANCE OF PVT COLLECTORS. R. Santbergen, C.C.M. Rindt and R.J.Ch. van Zolingen. http://www.eurotherm2008.tue.nl/Proceedings_Eurotherm2008/papers/Thermal_Solar_Energy/TSE_2.pdf 5mjmp 18:59, 16 June 2009 (UTC)

Development and characterization of semitransparent double skin PV Façades 2008[edit | edit source]

Eurosun 2008

"Some European funded projects have been actively supporting this work, PASSLINK, PV-HYBRIDPAS and IMPACT [18].Between 1999 and 2000, the Centre for Applied Research at the University of Applied Sciences Of Stuttgart [7,11] undertook the theoretical analysis and monitoring of the Mataro's public library building, which had the first PV ventilated façade in Europe. More recently, the treatment of the induced flow and the heat transfer at the air gap and the surfaces of a natural ventilated double skin façade has been progressively refined by Brinkworth [3,4]. Concerning to the mathematical model to define the energy performance 2 of such façades, sophisticated models for double skin façades were developed by Saelens [15]." - Paper

"Although these detailed studies have lead to an increase in the knowledge of the heat transfer processes, there are still many unclear fields such as: the convective heat transfer coefficients definition; the evaluation of the direct solar radiation absorbed by the solid parts; the evaluation of the mass flow rate in non-developing turbulent flows and, the coupling with the HVAC systems." - Paper

This paper deals with Facades which are basically wall PVTs. In this paper it deals with air as the coolent with the air flowing from the bottom on the PVT (close to the ground facing the ground) and the exhaust air exits from the top which can then enter the building as a preheat. There are several Nussel equations and TRNSYS simulations. This paper deals more witht the convection heat transfer and simulations rather than the PV.

156 - Development and characterization of semitransparent double skin PV Façades. Eurosun 2008. J.Cipriano, C. Lodi, D.Chemisana, G.Houzeaux, O. Perpiñán. http://web.archive.org/web/20160413014208/http://www.inive.org/members_area/medias/pdf/Inive%5CPalencAIVC2007%5CVolume1%5CPalencAIVC2007_043.pdf 5mjmp 18:59, 16 June 2009 (UTC)

Multi Solar (PVT) Co-Generation Power Station 2008[edit | edit source]

Eurosun 2008

Patent No 5522944

This power plant has a 85% solar efficiency (15% electrical and 70% thermal [35% hot water, 35% hot air]). Each square meter of the Multi Solar System (MSS) produce 150 W DC electricity from PV panels and 700 W of thermal energy. Using low pressure steam generators the thermal energy mass can be converted into electrical energy with a 20-25% efficiency. The temperature of the steam gets to 135 C. This is done by first using cold water to cold the PV panels and extracting that heat. The water exiting this array is about 55 C. Next this 55 C is further heated by solar thermal panels to 85 and then the second flow get the water to 135 C. This steam is then sent to a boiler and then to the turbine. This PVT/air technology has been developed for 16 years in a variety of projects in Isreal.

5mjmp 02:19, 22 July 2009 (UTC)

079 Multi Solar (PVT) Co-Generation Power Station http://web.archive.org/web/20160804081500/http://ct-si.org/publications/proceedings/procs/cleantech2009/2/10038 5mjmp 18:59, 16 June 2009 (UTC)

PV Thermal Systems - Capturing the Untapped Energy 2008[edit | edit source]

Eurosun 2008 This is TASK 35 Canadian Results

It was found that it is possible to collect 2-3 times as much thermal energy as electrical energy. Typically, PV modules operate 50 C above ambient temperatures but with water/air coolants the temperature can be lowers and the electrical efficiency improved. Two problems that arise from the high temperatures is the stress that are produced on the PV panels and that the PV panel efficiency decreases. The total effiecient (thermal and electrical) ranged from 25-50% which is significantly higher than just the PV which had an efficiency of 6-12%. It was stated that covering a roof with just PV panels only utilizes 10-15% of solar potential. In this test air was used as a coolant. The testing was done indoors at Canada's National Solar Test Facility in Mississauga and three different PV panels were used. The three companies were; BP Solar, Evergreen Solar and UniSolar.

"

• Evergreen supplied six of their new 170 Watt panels. Two rows of three panels covered 90% of the 10 m2 test panel.
• BP Solar supplied six of their 160 Watt panels which when placed onto the test panel covered

approximately 76% of the test panel surface leaving 24% of the transpired panel exposed to the sun.

• UniSolar supplied eight of their peel and stick 68 Watt modules which fit onto the test panel in a horizontal configuration and covered 90% of the test panel.

" -Paper

"It was decided to perform two sets of tests at two flow rates for each panel, one set at NOCT conditions and the other at the solar thermal conditions. The air flow heat removal rates selected were 36 m3/h. m2 (2 cfm/ft2) and 108 m3/h.m2 (6 cfm/ft2) of gross collector surface which represent low and medium air flows typical for heating ventilation air." - Paper

Four systems were tested for each companies PV panel: "System 1: SolarWall with two PV modules on top, variable flow (high) System 2: SolarWall with two PV modules on top, variable flow (low) System 3: SolarWall alone, variable flow (thermal reference) System 4: PV module alone, natural ventilation (electrical reference)" - Paper

"According to the SolarWall supplier, the additional cost for including the thermal component is about 25% of the cost of the PV system but the additional energy delivered is 150% to 400%." -paper

In conclusion, the Evergreen and BP PVT setup produce the highest electrical efficiency of 10.3% compared to Unisolar of 6.7%. However, because the Unisolar panel became hotter the thermal efficiency was the highest at 50% and therefore the overall highest efficiency goes to Unisolar. But looking at it from an exergy point of view, BP was the best since it had the second highest overall efficiency of 51.6%.

5mjmp 15:46, 23 July 2009 (UTC) 5mjmp 17:26, 24 July 2009 (UTC)

018 - PV Thermal Systems - Capturing the Untapped Energy http://web.archive.org/web/20081120220702/http://solarwall.com/media/images-articles/ASESPaper-PVThermalSystems-theUntappedEnergy175A3.pdf 5mjmp 18:59, 16 June 2009 (UTC)

Multi Solar (PVT) Air Conditioning System 2008[edit | edit source]

189 - Multi Solar (PVT) Air Conditioning System

Eurosun 2008

This article is about the MSS (Multi Solar System) that combines PV panels cooled by air and water. (see another article on the details) This article is explains some of the technical notes of the MSS such as its use of lithium cloride as part of the heat exchanger. According to the article this material in environmental friendly. MSS is patented with it's number PATENT NO 5522944. The MSS claims to be 85% efficient and that it's the best PVT system currently. This MSS is designed for large scale electrical generation rather than for single homes.

5mjmp 17:14, 4 August 2009 (UTC)

http://www.nsti.org/procs/Nanotech2009v3/3/W63.115 5mjmp 18:59, 16 June 2009 (UTC)

An Experimental Study of Air Flow and Heat Transfer in an inclined Rectangular Channel with Wood Strips on the Bottom Plate 2008[edit | edit source]

Eurosun 2008

This article deals with thermal heat transfer using air as a medium and the testing of natural convenction with different inclines. It was found that the natural convection does not reduce the temperature reduction of the PV panels. A flat plate thermal collector had 24 thermal couples placed in 3 rows of 8 along it to record the temperatures. The heat transfer was also modelled and the equations used can be found in the article. The purpose of this research is to help improve BIPVT (Building Integrated PVT). PIV (Particle Image Velocity) system was used to understand the air flow within the system.

5mjmp 19:29, 4 August 2009 (UTC)

252 - An Experimental Study of Air Flow and Heat Transfer in an inclined Rectangular Channel with Wood Strips on the Bottom Plate Dr. Harrison 5mjmp 18:59, 16 June 2009 (UTC)

The Active Solar Building – Overview of the SRA of the ESTTP and Synergy with other Technology Platforms 2008[edit | edit source]

Eurosun 2008

This article talks about the steps required in reaching Europes 2030 goals to have 50% of their thermal energy produced from solar. According to the article, Europe plans to have its energy demands reduced by 20% and to have 20% of its energy demands renewable and that solar has a very good potential.

Areas that need further research to the 2030 goals are the following: "

• Selective coatings for absorbers
• Advanced collector production methods (e.g. laser welding)
• Advanced flat-plate collector technology
• High-quality vacuum tube collectors
• Process heat collectors
• Stratified hot water storage tanks
• Electronic controllers
• System technology (e.g. solar combined systems for domestic hot water and space heating, with a burner directly integrated into the storage unit)
• Large-scale ST systems combined with seasonal heat storage
• Advanced applications (cooling, combined systems and industrial applications)

"-Paper

Sweden, Austria, Denmark and Germany are the leading countries in low-energy building technology.

Areas which need to be improve on the manufacturing stages of the solar collectors are the following.

"Major efforts are needed in the following areas:

• More efficient ways to use conventional collector materials (metals, glass, insulation), especially with a view to developing multifunctional building components, which simultaneously act as an element of the building envelope and a solar collector.
• Evolution in the optical properties of collector components. In particular, a more systematic use of optical films to enhance heat/light transmission through glass covers and reduce this transmission during excessive exposure; and the use of colours in absorbers or covers to achieve more flexible integration concepts.
• Alternative materials for collector production: the use of polymers or plastics, the coating of absorbers optimised to resist stagnation temperatures and new materials to prevent deterioration resulting from UV exposure.
• Improvement in the recycling potential of collector components and materials in view of lifecycle cost reduction, and overall sustainability of materials.
• Special topics will include issues such as: The control of solar energy delivered by entire facades, in particular the aspects related to fault detection and the consequences of stagnation temperatures when a prolonged no-load situation coincides with peak solar radiation;
• New component testing and evaluation methods; and
• A dedicated concept for the automation of manufacturing processes and assembly techniques." -Paper

The paper also talks about different types of thermal storage; sensible, latent, sorption and thermochemical. Currently concrete, molten salt and pressurised liquid water are used for sensible storage. Latent storage (water) used for low temperature storage for small buildings. Sorption is still in the development stages. Thermochemical storage could be salts and hydrates combined together to produce a thermal storage capacity 8 to 10 times higher than water. However, further research is needed in all 4 fields to better improve the solar thermal systems.

5mjmp 23:28, 4 August 2009 (UTC)

313 - The Active Solar Building – Overview of the SRA of the ESTTP and Synergy with other Technology Platforms http://books.google.ca/books?hl=en&lr=&id=4SbqvDzIIw4C&oi=fnd&pg=PA175&dq=The+Active+Solar+Building+Wittwer&ots=lcYfm4XBlF&sig=Hm1jQ3T46GUYbkb9W-K6P9VLo44 5mjmp 18:59, 16 June 2009 (UTC)

A COOLING SYSTEM FOR A HYBRID PV/THERMAL LINEAR CONCENTRATOR 2008[edit | edit source]

Eurosun 2008

This article is about using a finite volume 3D numerical computations to study the thermal characteristics of a rectangular cross section aluminum pipe to determine the performance of a PVT collector using several laminar flow rates.

1981 Florschuetz [4] determined that due to air's low diffusivity and thermal capacity, air would not be a great coolant. He decided water would be a better choice. Even if water is used as the coolant, very few use the warm water.

Two systems that are currently being worked on:

• "CHAPS (Combined Heat And Power Solar), developed at the Australian National University. It

consists of a parabolic concentrator with a ratio of 37X which focuses radiation onto a PVT module. The module converts the radiation into thermal and electrical energy with efficiencies of 57% and 11% respectively. The prototype was initially designed as a photovoltaic system with active cooling, the idea later evolved to use the water to capture the thermal energy. Reference data of the thermal gain achieved by the collector is not mentioned in any of the reference publications for the system [5].

• BIFRES, developed at the University of Lleida, is a system which concentrates radiation by

Fresnel reflection to a concentration factor of 22X. The hybrid module operates with a nominal thermal efficiency of 59%, permitting the c-Si photovoltaic cells to operate at an optimum efficiency of 11.9% [2]. "- Paper

Both achieve efficiencies greater than 50% but both are complicated systems... CHAPS uses an alumimum heat sink and BIFRES uses copper. BIFRES also uses furrowed tubes to improve convection of the liquid. Rectangle tubes are used for higher Nusselt numbers and greater heat exchange.

General Specs of the PVT system

"The configuration of the PVT module consists of a row of photovoltaic cells with a rectangular surface area of 1cm x 1m, placed at the top of the aluminium heat sink. The encapsulation can be divided into various elements.

1. In the surface at which concentrated radiation is received, an EVA film is applied to the cells, and

high absorption glass with low iron content is used as an outer skin. This reduces deterioration of the cells and minimises the thermal losses through the top of the module.

1. Between the cell and the heat sink a strip of electrical insulation is inserted using a double sided

adhesion (Chomerics Thermattach T404). This method considerably simplifies the adhesion process, as it simultaneously serves to insulate the cell and to fix it in right position.

1. Finally, the lateral and underneath faces of the heat sink are thermally insulated with a plate of

temperature resistant polypropylene." -Paper

CONSIDER PRESSURE DROP ACROSS PIPES. The paper contains the pressure equations needed to determine the pumps power. Contains values and equations on the thermal resistance of the system.

Conclusion

"The heat exchange properties of the aluminium improve increasing the aspect ratio of its cross section, in addition the pressure drop or in consequence the pumping power is higher when the hydraulic diameter (which is directly related with the cross section) is lower. Nevertheless, a big aspect ratio implies a much more difficult mechanical procedures, suck as hydraulic connections, isolation. Moreover, is necessary to mention that the main aluminium factories don't manufacture pipes of one centimetre width with aspect ratios higher than 2.43. Attending to this explanations, the pipe selected to be include in the PVT systems under concentration is with a cross section of 20x10cm2 (α = 2.43)." - Paper

5mjmp 19:03, 2 September 2009 (UTC)

174 - A COOLING SYSTEM FOR A HYBRID PV/THERMAL LINEAR CONCENTRATOR * Daniel Chemisana, daniel.chemisana@macs.udl.cat 5mjmp 18:59, 16 June 2009 (UTC)

Modelling the Energy Contributions of a PVT System to a Low Energy House in Sydney 2008[edit | edit source]

Eurosun 2008

084 - Modelling the Energy Contributions of a PVT System to a Low Energy House in Sydney * Corresponding Author, s.bambrook@student.unsw.edu.au 5mjmp 18:59, 16 June 2009 (UTC)

Building Integrated Concentrating PV and PV/T Systems 2008[edit | edit source]

Eurosun 2008

This paper looks at concentrated PV (CPV), PV/T and CPV/T and how they can be integrated into building designs / retro fitted.

"The performed works can be grouped in systems with V-trough reflectors [1-4], achieving concentration ratios up to two with east-west or north-south orientated reflectors, CPC (Compound Parabolic Concentrator) type reflectors [5-10], which are usually static and CR<2.5, refractive concentrators of 3D acrylic lens [11-13] and linear Fresnel lenses [14-16]. Comparison results give an idea about the benefits of concentrating photovoltaics and point-focus concentrating systems with a fixed flat plate PV module [17-19] show that the concentrating systems produces 37% greater electrical energy than the flat PV modules. In the University of Patras, research works on low concentration photovoltaics have been performed last years [20-25]." -Paper

5mjmp 13:18, 4 September 2009 (UTC)

241 - Building Integrated Concentrating PV and PV/T Systems Corresponding Author, yiantrip@physics.upatras.gr 5mjmp 18:59, 16 June 2009 (UTC)

Modelling and Performance of a Solar Demonstration House with Integrated Storage and BIPV/T System 2008[edit | edit source]

Eurosun 2008

This article deals with creating a zero net energy consumption house. The house was built in 2007 and uses a wide range of renewable sources / energy efficient building materials to reduce the energy consumption of the house. It uses a BIPV/T but does not go into the specifics of the make and materials.

5mjmp 13:44, 4 September 2009 (UTC)

288 - Modelling and Performance of a Solar Demonstration House with Integrated Storage and BIPV/T System *Corresponding Author: yuxia_ch@alcor.concordia.ca 5mjmp 18:59, 16 June 2009 (UTC)

Evaluation of a Parabolic Concentrating PVT System 2008[edit | edit source]

Eurosun 2008

The article is nicely summarized in it's conclusion.

Solar8 is a PV/T system created by a Swedish company called Arontis. The tests were simulated using Sweden,Portugal and Zambia climates. The results are the following.

"With this study several conclusions can be taken not only for Solar8 but also perhaps to the general photovoltaic/thermal concentrating hybrids being developed:

1. Solar8 can be replaced by a traditional side-by-side system using less space and producing the same electric and thermal output.
2. Local diodes installed in each cell can be able to bypass the current over the poorest cells and help reducing the problem with uneven radiation.
3. One axis tracking around North-South direction is considerably better than tracking around an axis placed on East-West direction.
4. The global irradiation on a static surface is higher when compared with the beam irradiation towards a tracking concentrating surface.
5. The ratio between electric and thermal output decreases when Solar8 is moved to the equator where the beam irradiation values are higher.
6. This PV/T combination still present lower outputs when compared with the traditional side-by-side system for the same glazed area. It is possible to say that there is chain efficiency around the most important components in Solar8. If every part of this chain works accurately and perfectly integrated in the system, higher efficiencies can be achieved in future models." -Paper

5mjmp 14:39, 4 September 2009 (UTC)

321 – Evaluation of a Parabolic Concentrating PVT System Corresponding Author, Ricardo.Bernardo@ebd.lth.se 5mjmp 18:59, 16 June 2009 (UTC)

Photovolatic-Thermal System for Stand-Alone Operation 2008[edit | edit source]

Written: 2008

• Thermal systems have low costs and high efficiencies
• Solar panels have high costs and moderate efficiencies (long payback period)
• Thermocouples have low efficiencies and therefore combining them with thermal systems not a great way to get electicity
• Big issue with solar is roof area

This paper demostrates a PV/T stand alone system and tests it out. The theoretical calculations confirm the experimental results. This sytem uses Maximum power point tracking (MPPT) and pc-silicon panels.

5mjmp 15:59, 4 September 2009 (UTC)

09_06_16_Photovolatic-Thermal System for Stand-Alone Operation

Photovoltaic / Thermal System for Stand-Alone Operation. Rafael K. Jardan, Istvan Nagy, Angel Cid-Pastor, Ramon Leyva, Abdelali El Aroudi and Luis Martinez-Salamero ©2008 IEEE. http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=04592568 5mjmp 18:59, 16 June 2009 (UTC)

Experimental Investigation of Single Pass, Double Duct Photovoltaic Thermal Air Collector with CPC and Fins 2008[edit | edit source]

Written: 2008

This paper is the same as 09_05_23_the effect of flow rates on teh performance of finned single pass, double duct photovoltaic thermal solar air heaters and the conclusion is the same. 'Fins are crucial in the improvement of the efficiency of the PV/T.'

"A number of researches and development programs have been carried out to improve the applications of solar energy systems. Several design of photovoltaic thermal solar air collector has been proposed in the past. Among the first, Kern and Russel[1] are the first who give main concept of photovoltaic thermal collector using water or air as the working fluid. Florschuetz[2] has extended the Hottel-Willer model to analysis steady state combined photovoltaic/thermal collector with simple modification of the conventional parameters of the original model by assuming that a liner correlation between efficiency of solar cell array and its temperature over its operating temperature range. Hendrie and Raghuraman[3] have been made a comparative experimental study in (pv/t) collectors with liquid and air as the heat removal fluid (working fluid). Cox and Raghuraman[4] suggested air type photovoltaic thermal system by analysis the effect of various design variables on the performance of the system. Lalovic et al.[5] fabricated photovoltaic thermal collector using amorphous Silicon pv cell and its performance was tested. Garg et al.[6] presented the theoretical study of (pv/t) collector with reflectors; they found that the system is well suited for solar drying applications. Bharagava et al.[7] and Prakash[8] reported the effect of air mass flow rate, air channel depth and packing factor. Sopain[9] have successfully demonstrated the improved performance of steady state double pass collector over the single pass collector due to efficient cooling of pv cells. Bergene and Lovvik[10] found that the thermal efficiency may increase only by a factor of 0.1 if flow rate increase from 0.001 to 0.075 kg-1 s. Sopian et al.[11] developed and tested a double pass photovoltaic collector suitable for solar drying applications and they comparison between theoretical and experimental results. Tripanagnotopoulos et al.[12] built and tested various photovoltaic thermal collector models with both water and air as the working fluids. Zondag et al.[13] compared the efficiency of seven different design types photovoltaic thermal collectors. Othman et al.[14] investigate the performance of double pass (pv/t) air heater with fins fixed in the bottom of absorber, the system theoretically under steady state conditions and experimentally was studied. They conclude that it is important to use fins as integral part of the absorber surface in order to achieve meaningful efficiencies for both thermal and electrical output of photovoltaic solar collector. Y. B. Assoa[15] developed simplified steady state 1-D mathematical model of (pv/t) bi-fluid (air and water) collector with a metal absorber. A Parametric study (numerically and experimentally) to determine the effect of various factors such as the water mass flow rate and thermal performance was studied. Simulation results were compared with the experimental results." -Paper

File:09 05 28 experimental investigation of single pass, double duct phtovoltaic thermal air collector with CPC and fins.pdf

American Journal of Applied Sciences 5 (7): 866-871, 2008. Experimental Investigation of Single Pass, Double Duct Photovoltaic Thermal (PV/T) Air Collector with CPC and Fins. M. Ebrahim Ali Alfegi, Kamaruzzaman Sopian, Mohd Yusof Hj Othman and Baharudin Bin Yatim. http://scipub.org/fulltext/ajas/ajas57866-871.pdf

5mjmp 15:16, 8 June 2009 (UTC)

Parametric Study of an Active and Passive Solar Distillation System: Energy and Exergy Analysis 2009[edit | edit source]

This article deals with solar stills instead of PVT however, it has some useful equations to help solve some of the heat problems. In this paper two models are looked at. One model assumes that the inner and outer walls of the glass cover are the same while the other does not. These models use mass and energy balance equations. The conclusion was that the temperature of the inner and outer glass does effect the yield of the solar stills.

File:09 05 23 parametric study of an active and passive solar distillation system, Energy and exergy analysis.pdf

Desalination 242 (2009) 1–18. Parametric study of an active and passive solar distillation system: Energy and exergy analysis. G.N. Tiwari, Vimal Dimri and Arvind Chel. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFX-4W3HPH2-3&_user=1025668&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050549&_version=1&_urlVersion=0&_userid=1025668&md5=7acf18855d8866aa699e11975ce5b025

5mjmp 20:18, 4 June 2009 (UTC)

The Effect of Flow Rates on the Performance of finned single pass, double duct PVT solar air heaters 2009[edit | edit source]

In this article, the PV panels were pasted directly onto the absorber with fins attached to the back of the absorber. The solar radiation was set at 400-700 W/${\displaystyle m^{2}}$ from 23 halogen lights rated at 500 W. The flow rate was varied rom 0.0316-0.09 kg/s and it was found that the greater the flow rate, the higher the efficiencies. The total efficiencies ranged from 49.135%-62.823%. Air flows above and below the absorber plate. The fins were 0.025 cm high, 0.001 thick, density of 0.384 fin/ cm and there were 29 fins. The inlet air temperature varied from 30 - 35 C.

File:09 05 23 the effect of flow rates on teh performance of finned single pass, double duct photovoltaic thermal solar air heaters.pdf

European Journal of Scientific Research ISSN 1450-216X Vol.25 No.2 (2009), pp.339-344. The Effect of Flow Rates on the Performance of Finned Single Pass, Double Duct Photovoltaic Thermal Solar Air Heaters. E. Ali Alfegi, K. Sopian, M. Othman and B. Yatim.

5mjmp 17:28, 5 June 2009 (UTC)

Indoor Simulation and Testing of Photovoltaic Thermal Air Collectors 2009[edit | edit source]

"Several designs of hybrid PV/T solar air heater had been proposed in the past. Kern and Russed [1] were the first who gave the main concept of PV/T collector using water or air as the working fluid. Cox and Raghuraman [2] have performed computer simulation to optimize the design of flat plate PV/T solar air collector in order to increase the solar absorptance and reducing the infrared emittance (IR). Bhargava et al. [3] have analyzed a hybrid system which is a combination of an air heater and photovoltaic system parameters such as channel depth, length of the collector, and air mass flow rate. Garg et al. [4] have presented a theoretical study of PV/T collector using plane booster reflectors. The system consists of a flat plate solar air heater mounted with photovoltaic cells and two plan reflectors above and below the collector unit. Sopian et al. [5] have proposed at University of Miami a new design of double pass PV/T collector which can produce more heat, while simultaneously having a productive cooling effect on the cell. Garg and Adhikar [6] have developed a computer simulation model for predicting the transient performance of PV/T air heating collector with single and double glass configurations. Hagazy [7] has investigated glazed photovoltaic/ thermal air system for a single and a double pass air heater for space heating and the drying purposes. Kalogirou [8] has carried out monthly performance of an unglazed hybrid PV/T system under forced mode of operation for climatic condition of the Cyprus. Lee et al. [9] and Chow et al. [10] have described interesting modelling results on air cooled PV modules. They have found that the overall electrical efficiency of PV/T system in the year is around 10.2% and reduce the space heat gain by 48%. Tiwari et al. [11] have validated the theoretical and experimental results for photovoltaic (PV) module integrated with air duct for composite climate of India and concluded that an overall thermal efficiency of PV/T system is significantly increased (18%) due to utilization of thermal energy from PV module. Annual performance of building-integrated photovoltaic/ water-heating system for Hong Kong climates have presented by Chow et al. [12] and found that annual thermal and cell conversion efficiencies are 37.5% and 9.39%, respectively. Nayak and Tiwari [13] have presented performance of PV integrated greenhouse system for New Delhi climatic condition and reported that the exergy efficiency of the system is 4%. Dubey et al. [14] have derived the expression for temperature dependent electrical efficiency considering glass to glass and glass to tedlar type PV modules." - Paper

In this article a PVT system was set-up and tested under different operating conditions. 16 halogen lamps each rated at 500 W.

The following parameters were tested in the experiment:

1. 1. Inlet air temperature.
2. 2. Outlet air temperature for all the ducts.
3. 3. Room temperature.
4. 4. Solar cell temperature.
5. 5. Air velocity.
6. 6. Solar intensity.
7. 7. Load current (IL) and load voltage (VL).
8. 8. Short circuit current (Isc) and open circuit voltage (Voc).

In the theoretical model the following assumptions were made:

One dimensional heat conduction is good approximation for the present study.

• The glass cover is at uniform temperature due to no temperature

gradients along the thickness of glass.

• There is stream line flow of air through the duct at small flow

rate.

• The transmittivity of EVA is approximately 100% due to thickness

of EVA is less than 0.0003 m.

• The system is in quasi-steady state.
• The ohmic losses in the solar cell and PV module are negligible.

Solar Intensities (400-900 W/${\displaystyle m^{2}}$) and mass flow rates (0.01- 0.15 kg/s) were varied and results were graphed. The electrical, thermal and total efficiency found were 8.4%, 42% and 50%.

Future considerations suggested in the paper:

• Use of more halogen lamps of low capacities (or voltage) for uniform

insolation and temperature distribution, so that the each PV panel gets equal insolation and the output from the PV panels will be uniform.

• Automatic arrangement for varying the distance between lamps

and PV module. This will save the testing time and desired insolation can be obtained easily.

• Use of adhesive paste around PV/T air collector to further minimize

air leakage. This will helpful to get the optimum flow rate and uniform temperature can be obtained accurately.

File:09 05 28 indoor simulation and testing of photovoltaic thermal air collectors.pdf

Applied Energy 86 (2009) 2421–2428. Indoor simulation and testing of photovoltaic thermal (PV/T) air collectors. S.C. Solanki, Swapnil Dubey and Arvind Tiwari. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V1T-4W207K3-3&_user=1025668&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050549&_version=1&_urlVersion=0&_userid=1025668&md5=150e40b6e74eb9a952595c14603cbeea

5mjmp 21:12, 9 June 2009 (UTC)

Life Cycle Cost Analysis of Single Slope Hybrid (PVT) Active Solar Still 2009[edit | edit source]

"More than 80% of the solar radiation falling on photovoltaic (PV) cells is not converted to electricity, but either reflected or converted to thermal energy. In view of this, hybrid photovoltaic and thermal (PV/T) collectors are introduced to simultaneously generate electricity and thermal power [5]. Chow [6] has analyzed the PV/T water collector with single glazing in transient conditions, consisting of tubes, in contact with the flat plate, reported an increase of electric efficiency by 2%, and obtained the thermal efficiency of 60% at 0.01 kg/s flow rate of water. Further, Zakharchenko et al. [7] have studied the unglazed hybrid (PV/T) system with suitable thermal contact between the PV module and the collector and reported that the area of module and collector in the PV/T system need not to be equal for higher overall efficiency. To operate the PV module at low temperature, the PV module should be fixed at lower temperature part of the collector (i.e. at the inlet of feed water). The parametric study of different configuration of hybrid (PV/T) air collector has also carried out by Tiwari and Sodha [8]. Kumar and Tiwari [9] have reported that daily yield obtained from hybrid (PV/T) active solar still is 3.5 times of the passive solar still. Tiwari et al. [10] have validated the theoretical and experimental results for photovoltaic (PV) module integrated with air duct for composite climate of India and concluded that an overall thermal efficiency of PV/T system is significantly increased due to utilization of thermal energy from PV module. Recently, Dubey et al. [11] have reported the higher annual average efficiency of glass to glass type PV module with and without air duct as 10.41% and 9.75%, respectively." - Paper

This article is about the life-cycle analysis of passive and active PV/T solar stills. The purpose is to determine if which solar stills are better at producing potable water. It was found that the payback period for the passive and active solar stills were 1.1-6.2 years and 3.3-23.9 years. The active PV/T solar still is 2.8 the cost of the passive solar still. The paper also states the because of the continual development of the PV the PV/T active solar still will become feasible in the growing years.

File:09 05 28 Life cycle cost analysis of single slope hybrid (pvt) acticve solar still.pdf

Applied Energy 86 (2009) 1995–2004. Life cycle cost analysis of single slope hybrid (PV/T) active solar still. Shiv Kumar and G.N. Tiwari. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V1T-4W034CH-3&_user=1025668&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050549&_version=1&_urlVersion=0&_userid=1025668&md5=0754dcf50bea79ad3103ff87311f7bf9

5mjmp 13:59, 10 June 2009 (UTC)

Thin Film Silicon Photovoltaics, Architectural Perspectives and Technological Issues 2009[edit | edit source]

Written: 2009

This article talks about thin film cells and their advantages. According to the article thin films can be integrated onto buildings such that they do not appear visible. Buildings in europe account for 40% of the energy consuming in Europe and the belief is that if the solar panels are added this will reduce the load. The other focus of this article is on the processing steps and how the thin films are made. It talks about transparent and conductive oxide (TCO) and thin film amorphous and microcrystalline silicon solar cells and the pros and cons with them. It has some technical and facts about the above. Useful if interested about thin films.

5mjmp 19:45, 31 July 2009 (UTC)

File:09 05 28 thin film silicon photovoltaics, architectural persepcitives and technological issues.pdf

5mjmp 20:23, 1 June 2009 (UTC)

Applied Energy 86 (2009) 1836–1844. Thin film silicon photovoltaics: Architectural perspectives and technological issues. Lucia Vittoria Mercaldo, Maria Luisa Addonizio, Marco Della Noce and Paola Delli Veneri, Alessandra Scognamiglio, Carlo Privato. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V1T-4VDSJRB-2&_user=1025668&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050549&_version=1&_urlVersion=0&_userid=1025668&md5=4e09fe1b4208f26a6bd1299bf2f1687d

Amorphous Silicon PV/T[edit | edit source]

The Following are articles that deal with Amporphous Silicon panels in a PV/T system.

Effects on Amorphous Silicon Photovoltaic Performance from High-temperature Annealing Pulses in Photovoltaic Thermal Hybrid Devices[edit | edit source]

Abstract:

There is a renewed interest in photovoltaic solar thermal (PVT) hybrid systems, which harvest solar energy for heat and electricity. Typically, a main focus of a PVT system is to cool the photovoltaic (PV) cells to improve the electrical performance; however, this causes the thermal component to under-perform compared to a solar thermal collector. The low temperature coefficients of amorphous silicon (a-Si:H) allow the PV cells to be operated at high temperatures, which are a potential candidate for a more symbiotic PVT system. The fundamental challenge of a-Si:H PV is light-induced degradation known as the Staebler–Wronski effect (SWE). Fortunately, SWE is reversible and the a-Si:H PV efficiency can be returned to its initial state if the cell is annealed. Thus an opportunity exists to deposit a-Si:H directly on the solar thermal absorber plate where the cells could reach the high temperatures required for annealing.

In this study, this opportunity is explored experimentally. First a-Si:H PV cells were annealed for 1 h at 100 °C on a 12 h cycle and for the remaining time the cells were degraded at 50 °C in order to simulate stagnation of a PVT system for 1 h once a day. It was found when comparing the cells after stabilization at normal 50 °C degradation that this annealing sequence resulted in a 10.6% energy gain when compared to a cell that was only degraded at 50 °C.

Source: M.J.M. Pathak, J.M. Pearce and, S.J. Harrison, "Effects on Amorphous Silicon Photovoltaic Performance from High-temperature Annealing Pulses in Photovoltaic Thermal Hybrid Devices" Solar Energy Materials and Solar Cells, 100, pp. 199-203 (2012). arXiv

The Effect of Hybrid Photovoltaic Thermal Device Operating Conditions on Intrinsic Layer Thickness Optimization of Hydrogenated Amorphous Silicon Solar Cells[edit | edit source]

Abstract:

Historically, the design of hybrid solar photovoltaic thermal (PVT) systems has focused on cooling crystalline silicon (c-Si)-based photovoltaic (PV) devices to avoid temperature-related losses. This approach neglects the associated performance losses in the thermal system and leads to a decrease in the overall exergy of the system. Consequently, this paper explores the use of hydrogenated amorphous silicon (a-Si:H) as an absorber material for PVT in an effort to maintain higher and more favourable operating temperatures for the thermal system. Amorphous silicon not only has a smaller temperature coefficient than c-Si, but also can display improved PV performance over extended periods of higher temperatures by annealing out defect states from the Staebler-Wronski effect. In order to determine the potential improvements in a-Si:H PV performance associated with increased thicknesses of the i-layers made possible by higher operating temperatures, a-Si:H PV cells were tested under 1 sun illumination (AM1.5) at temperatures of 25oC (STC), 50oC (representative PV operating conditions), and 90oC (representative PVT operating conditions). PV cells with an i-layer thicknesses of 420, 630 and 840 nm were evaluated at each temperature. Results show that operating a-Si:H-based PV at 90oC, with thicker i-layers than the cells currently used in commercial production, provided a greater power output compared to the thinner cells operating at either PV or PVT operating temperatures. These results indicate that incorporating a-Si:H as the absorber material in a PVT system can improve the thermal performance, while simultaneously improving the electrical performance of a-Si:H-based PV.

Source: M.J.M Pathak, K. Girotra, S.J. Harrison and J.M. Pearce, "The Effect of Hybrid Photovoltaic Thermal Device Operating Conditions on Intrinsic Layer Thickness Optimization of Hydrogenated Amorphous Silicon Solar Cells" Solar Energy (in press). DOI: http://dx.doi.org/10.1016/j.solener.2012.06.002 open access

The effects of dispatch strategy on electrical performance of amorphous silicon-based solar photovoltaic-thermal systems[edit | edit source]

J. Rozario, A.H. Vora, S.K. Debnath, M.J.M. Pathak, J.M. Pearce, The effects of dispatch strategy on electrical performance of amorphous silicon-based solar photovoltaic-thermal systems, Renewable Energy 68, pp. 459–465 (2014). open access