Open-circuit district heating nets exist only in Russia and in Central Asia. Other CIS or former USSR countries either had only closed-circuit systems (Belarus, Ukraine, Azerbaijan etc) or reconstructed open-circuit systems to closed-circuit ones (Baltic countries).

In Russia and in Central Asia 197 heat and power plants were identified and 163 of them were evaluated so far.

Roughly half of the identified heat and power plants have a closed-circuit system and were, thus, not further considered (cf. Figure 3). 38 of the open — and mix-systems are in operation in summer (cf. Figure 4) and are, therefore, in principle appropriate for solar water preheating. Since no information about the operation mode had been

Fig. 4. Number of identified heat and power plants with open (left) and mix (right) — circuit systems by

operation conditions

In this investigation only large heat and power plants with a possible potential for several thousand square meters of uncovered collector were identified and evaluated. Beside these, various small heat plants exist (without power generation). Some of them have cold water flow rates of 50..100 m3/h, which corresponds about 500 and 1000 m2 of collector. For example, the 6 largest heat plants out of 58 operating in Bishkek have a total potential of approx. 3000 m2 of uncovered collector.

Furthermore, large closed-circle district heating nets could benefit from solar preheating due to their water losses. E. g. the closed-circle in Moscow runs approximately 3 million m3 of water. Hourly water losses of 0.1 % of the net capacity correspond to 3000 m3/h in required feeding water, possibly offering an opportunity for solar preheating.

Estimation of annual heat gains is based on the local climate data as well as on the thermal performance of the uncovered collectors. For Bishkek, three sources of meteorological data are available [3]: the program “Meteonorm”, a local weather station “Frunze”, and measurements since 2004 on a pilot solar thermal system in Bishkek [2]. A commercial water preheating system will be working in the frost-free period, in Bishkek from May to September (5 months). Based on

simulation calculations with the program TRNSYS[3] with conservative climate data energy, solar heat gains of about 1000 kWh/m2a can be expected. The technical and economical potential for the heat and power plant TEZ in Bishkek is approx. 32 MWth (45000 m2 of uncovered collectors), which is more than two times larger than the currently largest solar thermal heat plant in the

world[4].

A promising option is thereby the recognition of the solar thermal plant as a so-called CDM project in the framework of the Kyoto protocol, which can lead to additional financial gains by the generation and selling of emission certificates. An average emission factor for TEZ Bishkek equals 0.282 t CO2/MWhth when calculated with the specific emission factors of the Intergovernmental Panel on Climate Change (IPCC) and fuel mix of the TEZ Bishkek. This corresponds to an annual emission reduction of 0.31 t CO2 per m2 collector area[5]. An economic calculation of an uncovered collector located in Bishkek was carried out with following assumptions:

• investment (system costs)[6] = 44 € per m2 of uncovered collectors

• solar energy gains = 1 MWh/m2a

• interest rate = 13 %/a

• maintenance = 1 % of system costs

• certificate price (CER) = 6 €/t CO2

• system size = 45000 m2 (corresponds to 2 million € investment)

• operation time =14 a

• fossil price increase rate = 2 %/a

For fuel prices in 2007 (e. g. gas 0.98 ct/kWh) a solar heat price of 0.5 ct/kWh and a payback period of 9 years are calculated. Thus, the heat price for solar thermal heat generation lies significantly below the price for fossil fuels. Without recognition as a CDM project a solar heat price of 0.7 ct/kWh and a payback period of 12 years are expected. If the uncovered collector loop and the district heating net must be separated with a heat exchanger, the solar heat price will rise by another 0.1 ct/kWh.

Furthermore, an economic study[7] for different locations in the CIS was carried out (cf. Figure 6). Energy gains are based on simulation calculations using climate data of the program Meteonorm 5.1. Here, the simulation period is Mai to September instead of the frost-free period to have better comparability between the different sites. The water inlet temperature was set to 12°C for all locations. Some locations, however, were also simulated with the water inlet temperature of 15 and 20°C. The specific flow rate of uncovered collectors in the simulations is 100 l/m2h.

Fig. 6. Solar and conventional heat costs for different locations in the CIS. (15) and (20) represents the water inlet temperature of 15°C and 20°C respectively. Otherwise an inlet temperature of 12°C was assumed.

2. Conclusions

Uncovered collectors can be effectively applied to preheat water for open-circuit district heating nets in cities of the Commonwealth of Independent States. In Russia and in Central Asia in total 197 heat and power plants were identified and 163 of them were evaluated. 38 heat and power plants seem to be technically suitable for solar preheating. Solar heat costs of less than 0.01 €/kWhth can be expected for many sites of the CIS. Large solar heating systems can be recognized as a CDM project to receive additional financial gains.

Acknowledgements

The authors would like to express their gratitude to the Volkswagen Foundation, Germany and Rudolf and Ursula Lieberum Foundation, Germany for the financial support, as well as to the Power Plants Inc., Kyrgyzstan and to the Almaty Power Consolidated, Kazakhstan for the opportunity to visit their heat and power plants.

References

[1] K. Vajen, M. Kramer, R. Orths, E. K. Boronbaev (1999): Solar Absorber System for Preheating Feeding Water for District Heating Nets, Proc. ISES Solar World Congress 1999

[2] E. Frank, K. Vajen, A. Obozov, V. Borodin (2006): Preheating for a District Heating Net with a Multicomponent Solar Thermal System, Proc. EuroSun 2006, Glasgow

[3] R. Botpaev, A. Obozov, C. Budig, J. Orozaliev, K. Vajen (2008), Comparison of meteorological data from different sources for Bishkek, Kyrgyzstan, Proceedings EuroSun, Lisbon

[4] E. Frank (2007): Modellierung und Auslegungsoptimierung unabgedeckter Solarkollektoren fur die Vorerwarmung offener Fernwarmenetze, Dissertation, Universitat Kassel

E. M. D. Pereira[16]*, A. S. de Andrade1, E. M. Duarte1, L. P. Carvalho1, C. V. T. Cabral1, L.
E. M. de Vasconcellos[17]*, E. Salvador2, G. C. dos Santos2, J. T. V. Pereira[18]*, J. T. Fantinelli3,

J. T. Pallottino[19]* and N. C. Guimaraes4

1GREEN — Grupo de Estudos em Energia — PUC-MG, Belo Horizonte, Brasil
2Eletrobras — Centrais Eletricas Brasileiras — Departamento de Desenvolvimento de Eficiencia Energetica
3NIPE — Universidade Estadual de Campinas, Brasil
4CEFEN — Universidade Estadual do Rio de Janeiro, Brasil
*E. M. Pereira, green@pucminas. br
*L. E. M. de Vasconcellos, menandro@eletrobras. com

Abstract

ELETROBRAS1 and GREEN2/PUC-MG3 are developing a project integrating actions with PROCEL4, to evaluate what is the real situation of the solar water heating systems in Brazil in the residential, service and industrial sectors. Therefore, 7 Brazilian cities were selected to be studied, then information will be collected and statistically treated leading to later field research. At that stage, the collected information are the real design conditions, installation, operation and life cycle of the systems and users’ satisfaction level. Technical questionnaires were developed to summarize all the required information, such as a website, designed to organize and manage the collected data, and a Matlab application that perform the dimensioning and F-chart systems evaluation. Quality indicators are being created through a full system monitoring, with thermographic analysis and evaluation of shading influence at the system’s efficiency, using the Ecotect software. Until now, more than 274 installations were visited of 800 intended to be studied. This article presents some results observed at 3 cities: Belo Horizonte, Campinas and Rio de Janeiro. This project, nationwide, is unprecedented and will get a list of recommendations geared to formulate a development plan for the sector, which could be used as a guideline for government policies.

Key words: Solar water heating, quality indicators for solar water heating systems, products quality, shading analysis.

Introduction

In 1997, Brazil had created a quality certification program for solar collectors and thermal storage tanks, coordinated by the National Metrology Standardization and Industrial Quality Institute (INMETRO) and ELETROBRAS/PROCEL, counting on the support of Energy Studies Group GREEN/PUC-MG and the Technology Research Institute of Sao Paulo/IPT. Currently,

85 active companies have joined this program, testing in this period 316 models of solar collectors and 281 of thermal storage tanks, presenting nowadays 22% of assays demand annual growth. Solar collectors total area installed in the country is 3,6 millions of square meters, expressing an insertion factor of only 19,2 m2/1000 inhabitants.

In order to create government policies to incentive the usage of solar heating, it is needed to evaluate the real impact of this technology into the national energy matrix with Demand

Management actions, through an estimation of final energy savings and the periods of higher energy demand peak displacement. These are important factors in a country where electric heaters devices participate at about 73% of households’ hot water production for sanitary usage. In the South and Southeast regions, this number reaches 98,6% and 91,1%, respectively [1].

However, the energy production of a solar system depends not only on the component’s quality and thermal performance, but also on their correct insertion in building, appropriated project’s design and quality, besides correct installation and maintenance executions. Therefore, an evaluation of in situ solar water heating systems program has been created in October 2006 in Brazil. The main goal of the finished research, which belongs to this actions program PROCEL integrated, was to characterize and evaluate solar water heating systems in 3 Brazilian cities: Belo Horizonte, Campinas and Rio de Janeiro. These 3 Southeast cities were chosen, among others, because they represent the major penetration of solar water heating in small, medium and large size systems applications in the residential sector, with inherent particularities of usage in different economic groups of population. In Rio de Janeiro, the low income households studied in this project were contemplated with solar water heating, whose all project stages, acquisition and installation were responsibility of the local energy distribution company — LIGHT RIO.

The high income households’ studies were performed at Campinas and Belo Horizonte, in the last of which buildings with central solar water heating were studied.

This project aims the definition of incentive plans to the users and suppliers of solar water heating, training programs to the production and installation companies and designers, the creation of quality marks, besides a statistic filtering about the current overview of this type of system in Brazil.

In 2001, the new energy efficient buildings of the Technology Center of FESTO AG in Berk- heim/Esslingen were completed. The area comprises 26,000 m2 of air-conditioned office and computer services area and additionally moderately air-conditioned atria area. In order to use waste heat from the production facility nearby, three thermally driven chillers are installed with a rated chilling capacity of 350 kW each (total: 1.05 MW), to supply cold for slab cooling and supply air cooling of the Tech­nology Center. The installed cooling technology are adsorption chillers from the Japanese manufac­turer Mayekawa. At rated conditions, the total heat input for the chillers is approx. 1.7 MW. However, during operation of the plant it turned out that less than the originally expected 0.8 MW of waste heat was available. Remaining heat input for the chiller operation is provided by gas boilers. Figure 4 shows the Technology Center and one of the adsorption chillers.

Within Solarthermie 2000plus, a vacuum-tube collector system is added as third heat production sys­tem to assist the chiller operation in summer and for heating support in winter. The collector system consists of 1218 m2 aperture area of CPC Star Azurro collectors from Paradigma. At present, this col­lector is the largest system operated with pure water as collector fluid. At low collector temperatures with danger of freezing, a special control allows periodically circulation of the collector fluid for some seconds in order to transport heat at a low temperature level into the collector. In winter, solar pro­duced heat is used for slab heating at temperatures < 50°C in a new office building of the company. The collector went into operation in the end of 2007; the monitoring system was installed and is operated by the University for the applied sciences Offenburg. Figure 5 provides a scheme of the system.

Electrical generation is from a combination of a 40Wp PV donated by Solar Century Ltd and located on the roof of the van cab and a 100Wp wind turbine donated by Ampair Ltd located on the roof of the van on a hinged frame so it can be lowered when the van is being driven. Electricity from both these sources goes via controllers into a twin battery pack(total 120Wh), lead-acid type, located on the floor of the technical compartment. Some appliances are driven by the 12V direct current from the battery but most are powered by 230V AC from an an invertor driven by the battery.

3. Van body

The van body is divided into two compartments. The larger is the public/living room which is nicely furnished with carpets, a table and chairs and pictures on the wall. A mural painted by a local artist showing all renewables is on one wall and an array of leaflets and brochures on all renewables is on another. This compartment has underfloor heating fed from the solar storage tank. It has a translucent roof to maximise daylight and its window to the rear is double glazed with low-e glass and an argon infill. Access to this compartment from outdoors is via a set of aluminium steps with handrails which can all be folded up for transport.

The second, smaller compartment is forward of the larger compartment and is the technical/sleeping compartment. It houses the thermal and electrical storage systems, the control and display systems, a sink for washing and a shower. It also has a bunk bed for the driver.

All wastewater (grey water) is treated, through a process of filtration, aeration and ionization to be reused for gardens in a way that such water eventually percolates into the open wells and so completing the loop of use and generation. This treated water is also used in the toilets.

Kitchen wastes are segregated into organic /inorganic wastes. Organic waste goes to the vermicomposting pits where they are converted into Vermicompost, a nutrient-rich natural fertilizer and soil conditioner to be used for the garden.

3.6 Energy management through innovative interventions

Intelligent lighting systems blend motion sensors, ambient light sensors and timers to ensure that lights are switched off when not needed. Compact Fluorescent Lamp (CFL) and Light Emitting Diode (LED) based bulbs serve as highly efficient illuminating systems reducing CO2 emissions (1 CFL saves 0.1 tonnes of CO2 per year) and reduces power consumption by up to 80 per cent while protecting lighting efficiency. Nano-technology based solar lighting system (like quantum dots) for dwelling houses is expected to be close to 100% efficiency, energy and economy too.

The first thermal regulation was adopted in 2000 and now is going to be published the second phase concerning the thermal requirements of the building envelope elements (windows, walls and roofs). Although the existence of the thermal regulation, the social houses in Chile, have enormous deficiencies related with the thermal insulation application, ventilation and condensation [2]. In this context a proposal was prepared, to start in 2006, with the principles and the design guidelines for the social houses rehabilitation [2]. One of the measures proposed consists on the improvement of the envelope thermal quality: roof thermal insulation replacement, inclusion of thermal insulation on the external walls, replacement of single glass by double glass windows. In what concerns the passive solar systems the interventions will focus on solar walls for heating with and without ventilation, solar collectors and accumulator collectors for water heating.

Miguel C. Brito7*, Joao M. Serra7, Jorge Maia Alves7, Killian Lobato7, Ivo Costa7, Antonio
Vallera7, Carlos Rodrigues2, Susana Viana2, Antonio Joyce2

1 SESUL, Faculty of Sciences of University of Lisbon, Campo Grande, 1749-016, Lisbon, Portugal
2INETI, Department of Renewable Energies, Campus do Lumiar do INETI, 1649-038 Lisbon, Portugal

* Corresponding Author, mcbrito@fc. ul. pt

Abstract

The deployment of photovoltaics in large scale, in particular PV microgeneration, requires the development of a numerous workforce trained for PV systems installation and maintenance. Since there is an obvious lack of local training opportunities for PV professionals, the University of Lisbon and INETI have promoted a new Training Course for PV System Installation with special emphasis on hands-on practical experience and safety issues.

Keywords: PV systems, training, installation

1. Introduction

The full potential of photovoltaics, as microgeneration in residential urban context as well as in off-grid stand alone systems, can only be successfully achieved through the appropriate training of the PV installation professionals. In Portugal, where a recent law has defined the framework for the development of microgeneration, it is expected that this sector will witness a fast increase. However, if these systems are improperly designed, incorrectly installed, not properly maintained or if the users are not instructed in the proper use and routine maintenance, they will fail to meet performance expectations, or they might fail altogether.

Since there is an obvious lack of local training opportunities for professionals in this field, we have developed a training course on PV Systems Installation. The non-availability of similar training courses, certified or non-certified, required that the proposed training course should fulfil two objectives: i) prepare the participants for the installation of PV systems; ii) set a quality standard for other training courses expected to be organized in the future.

For the moment, the PV System Installation Training Course is open to professional electricians (Level III) only. In the foreseeable future, however, and as a result of partnerships to be developed with professional schools, it is expected that the training course might be offered within a broader context as a Professional Course of PV Systems Installation.

This training course was developed in a partnership between University of Lisbon and the Renewable Energy Department of INETI and tries to combine a solid theoretical preparation with hands-on practical experience.

At the Faculty of Electrical Engineering of the CTU in Prague a course on Solar Energy Exploitation Systems, mostly oriented in the field of photovoltaics, was introduced in 1995 as an optional course. The course was developed to give undergraduate students information about the full set of important problems connected with photovoltaics from photovoltaic effect, cell construction and technology to applications, including operating conditions and economical and ecological problems. Details about the course were published in [3]. Since the school year 2006/7, a course in Photovoltaic Systems, dealing with PV system technology (28 hours of lectures, 28 hours of exercises) forms part of the master study programme in Electrical Engineering and Information Technology. Synopsis of lectures on Photovoltaic Systems is shown in Table 1. Education in Photovoltaics at the CTU in Prague has been in more details described in [4].

2. Exercises

Exercises are a very important part of the course orienting the course in a particular direction. The developed laboratory exercises deal with photovoltaic system applications, and are adapted to the requirements of electrical engineers. The exercises have been divided into three blocks. The first block deals with detailed measurements of PV cell characteristics and the influence of important external parameters (light intensity and temperature) and internal parameters (series and parallel resistance) on the shape of these characteristics and on cell efficiency. PV cell measurements are performed on square (102 mm x 102 mm) silicon cells (both single-crystalline and poly-crystalline) using

illumination with a halogen bulb. The basic circuit used for measuring I-V characteristics in all four tasks is schematically shown in Fig.1. From measured characteristics parameters VOC and ISC and the maximum power point characterised by Vmp and Imp are extracted. Results of measurements are dependences of VOC, ISC, fill factor FF and maximum power Pmp on given parameters [6].

The second block consists of three laboratory tasks concerned with measuring the

• measurements on a solar module — dc/dc — dc/ac system

For measurements on modules are used 26 Wp standard (12 V) modules and they were performed in last courses in front of the building using natural sunshine. The measurements outside of building were relatively strongly influenced by the temporary weather. Even from one viewpoint it gives students a sample of real applications, from another viewpoint it complicates the exercise programme that should be performed in accordance with a given timetable. For this reasons there have been prepared laboratory measurements on PV modules using set of halogen lamps and reflecting walls as a solar source, as shown in Fig 2. The homogeneity of irradiance on the module area is very good, differences from the mean value are less than 5%, as demonstrated in Fig.3. A disadvantage of using halogen bulb is, that the PV modules must be cooled (a van below the PV module can be seen in Fig.2.).

One of the circuits used (for measurements on an off-grid PV system with battery and inverter) is shown in Fig.4.

At measurements, problems with connection of PV modules in parallel and in series, influence of partial shading on I-V characteristics are also demonstrated.

The third block of tasks analyses data obtained from an on-grid demonstration PV system, and includes a small, simple photovoltaic system project (both off-grid and on-grid). To demonstrate the function of photovoltaic systems in real operating conditions, a 3kWp demonstration, on-grid connected photovoltaic system has been built at the Czech Technical University in Prague on the roof of the Faculty of Electrical Engineering. (This installation has been supported by the State Fond of Environmental Policy of the Czech Republic and has been realised by the company Solartec s. r.o,

Roznov p Radostem.) The block diagram of the system is shown in Fig.5. The photovoltaic modules are situated at the flat roof of the Czech Technical University, Faculty of Electrical Engineering with the aim of demonstration a photovoltaic system (on-grid connected) and of evaluating the potential of using roof top photovoltaic systems under conditions of real urban utilization. This system allows monitoring of data about performance of three photovoltaic fields with different tilt angle. Collected data give important information about system performance in both fa? ade and on-roof applications. Input and output data (dc voltage, dc current, ac voltage, ac current, instant power and energy produced) supplemented by PV field temperature and intensity of solar radiation are available online at http://andrea. feld. cvut. cz/fvs.

Synopsis of laboratory exercise on Phtovoltaic Systems is shown in Table 2.

4. Conclusions

The course on Photovoltaic Systems oriented in the field of photovoltaics performed at the Faculty of Electrical Engineering of the Czech Technical University in Prague at the undergraduate level has been discussed. The course gives information on both device and application approach with application oriented laboratory measurement tasks. Laboratory measurements are prepared to give student practical knowledge about cell characteristics, module characteristics and system behaviour. The course has become suitable for all branches of study in the field of electrical engineering.

References

[1] Hirshman W., Herring G. and Schmels M.: Gigawarts — the measure of things to come, Photon International, No.3, 136 — 166, (2007)

[2] Jager-Waldau A., PV Status Report 2006 (Research, Solar Cell Production and Market Implementation of Photovoltaics), Office for Official Publications of the European Communities, Luxembourg (2006)

[3] Benda, V, Development of a Course on Photovoltaic Systems. Solid State Phenomena. no. 97-98, pp. 133- 138.(2004)

[4] Benda, V., Education in the Field of Photovoltaics at the Czech TechnicalUniversity in Prague, this Proceedings, paper #269 (2008)

[5] Goetberger, A., Knobloch, J. and Voss, B.: Crystalline Silicon Solar Cells, J. Wiley & Sons., Chichester, 1998

Platforms

Volker Wittwer

Fraunhofer Institute for Solar Energy Systems, Heidenhofstr. 2, 79110 Freiburg, Germany

Abstract

In this paper, an overview of the content of the strategic research agenda of the European Solar Thermal Technology Platform in the area of active solar buildings will be given. The vision for a sustainable energy supply of our buildings based mainly on solar energy will be presented as well as a review on short-term, medium-term and long-term research. In addition, the integration of this vision into the framework of the other technology platforms in the area of renewable energy is shown. Beside some competition, many synergetic effects are possible, which will help us to create a sustainable energy supply system for the future.

Keywords: energy-efficient buildings, solar collector, energy supply system,

1. Introduction

The decision of the European governments to reduce the energy demand by 20% by 2020 and to supply 20% of the energy demand 20% by renewable energy forces all countries to strengthen their activities in the field of renewables. If the worldwide potential of renewables is analysed, solar energy is found to have the highest potential (figure 1). Therefore solar energy should be used wherever it is possible. Of course there might be some places, where geothermal or available district heating systems might be preferred or combined with solar systems but in general solar energy could be our main resource in future.

If the final energy demand is examined in detail, the result for Europe is that heat is the dominating component with roughly 50 %, followed by energy for transport with 30 % and electricity with 20%.

The total heat demand is dominated by the heating demand of our buildings followed by the process heat demand of the industry. Thinking about the European goals of 20% reduction and a 20% contribution by renewables by 2020, the reduction of the heating demand in buildings and the increased integration of solar systems are fundamental approaches to reach these goals.

In 2005 a preliminary steering committee for the European Solar Thermal Technology Platform was founded by researchers and industry under the administrative leadership of ESTIF and EUREC to work out a vision paper and a strategic research agenda, which should show how we can reach this goal.

The major advantage of involving users in the innovation process is the convergence of ideas and efforts to match exactly buyer’s needs. The specification of certain characteristics in some products allows manufacturers to develop and improve, products that capture common users attention and also users whose needs are based in more detailed products and for whom specific products are not easy to find. In this way a more demanding parcel of the market is addressed and captured.

Although designed to satisfy a rather strict community of users, to whom the strategy of “few sizes fit all” does not adequate (Von Hipel, 2006), user product innovations are expected to benefit directly their developers, while manufacturers only expect to benefit by selling their products, a fact that increases innovators impel to create novel products. Directly involving users in the product design process can be seen as an advantage, as customer ideas can complement the R&D performed in the company, improving productivity of new products. Users can also be good allies in establishing the optimum price/performance combination and, if the relations established with the customer at an early stage are good, the interaction manufacturer-customer may extend throw the life cycle of the introduced innovation. In fact several studies have found that commercially viable products tend to be developed by “lead-users” that anticipate market needs and develop products from which they expect to benefit greatly. (Baldwin, Hiernerth and Von Hippel, 2005)