Category Archives: EuroSun2008-9

There is a wise solution

Currently the contribution of renewable energy resource in Armenia is negligible. A number of small hydro power plants and one pilot wind power plant are under operation with less than 2% of contribution in total electricity generation. At the same time, the electricity generation potential only from small hydro and wind power plants in Armenia is estimated over 2 billion kWh/year. Having said that one should expect that contribution of small hydro power plants (with 10MW capacity and less) and wind power plants in Armenia can contribute about 20% of total electricity generation by 2025. The potential of solar energy in Armenian is significant. The average solar irradiation in Armenian is assessed at 1,760 kWh/sq. m. Thus, solar thermal energy applications can contribute in heat and hot water supply sufficiently.

1.2 Challenges renewables face with

Despite some undertakings have been taken by the government of Armenia to promote renewable energy development in Armenia since 2001, realization of renewable energy projects face with real challenges. In grid connected projects the major obstacle for private and foreign investments are tariffs which are not attractive to finance projects; this is especially true in case of wind energy. In thermal energy applications, such as solar energy, the main obstacles are subsidized natural gas prices and nuclear energy. Finally, one of the real obstacles is the lack of public awareness and proper education in renewable energy and benefits it can offer to the public and the state such as reliance on own energy resources, independency on imported fuel and international prices, environmentally friendly technologies and increased energy security. Moreover, there is a lack of familiarity in terms renewable energy, green energy and clean energy.

Approach in teaching RES

The results of Bg Ministry of Education’s decision to patronize the SSF project were as follow:

• an initial fax from Ministry of Education to all Bg schools recommending them to join the SSF project (December, 2004);

• attendance and open addresses to all our six SSF official events — SSF opening ceremony — SunDay04; National SSF exhibition,2005; 4 seminars, including several media attendances;

• confirmation of the importance of SSF ideas and work by the Exclusive award for two Bg schools, (each EU 100,000 for their EE reconstruction), distinguished by the Bg SSF jury;

• distinguish SSF First winners with honorary diploma for the SSF Bg National Exhibition, 2005;

Below are given the result which follow from the Ministry’ patronizing of SSF project.

Teachers, together with students succeeded to organize local Days of Energy celebration and to select 276 entries to participate in SSF Bg National exhibition (26-28 June 2004), where two Ministries, 22 Bg firms and 3 German ones offered their individual awards for Bg SSF national winners. Moreover all that happened with schools most without internet access;

Participating in local, national or international RES/EE exhibitions or competitions.

Invite Pantomime/Actors Body at school celebration with Etudes, dedicated to RES/EE/sustainable Bg reality and this way bringing laugh and pleasure across.

Most of the more experienced teachers in Bg have once weekly an hour to be with his/her class. Ministry patronizing of SSF project encouraged these teachers to dedicate this hour to the topic of environmental protection through RES/EE. Our SSF team supplied them with suitable training RES aids.

Partnership between teachers, students ( schools) and RES firms, agencies, etc.

Partnership between teachers, students ( schools) and RES experience of officials from national and international institutions;

Partnership between teachers, students ( schools) and RES issues of different media;

More detailed collaboration with existing international teams;

In the frame of official school schedule, keeping in accordance with governmental educational requirements the students could be well informed in interesting and attractive way with RES. Programs, such as “Man and Nature”, “Household and Techniques”, “Household and Economy” — allow the pupils to get skills in collecting and distributing RES information; to know objects and events, to compare them, to look for their interrelations and at the end to form own relation to the environment and its protection. *)2.

Developed different games with environmental content and results;

2. Conclusion

• Indirect study of RES could also inform pupils in global environmental problems, enough to get stable position, when graduated;

• RES skill and knowledge could serve as a good ground in further team work;

• The RES knowledge itself are not enough — the pupils need their interest to be aroused and they to be stimulated to look for solutions —

References

Dobrinova A., Shtrakov St., Marinov N., — “RES-what has it to do with you”, Proceedings, NorthSun2007, Riga, Latvia;

Eneva J., XXXVI National Conference in physics education; Physics and Energetics;

3-6 April 2008; Sofia

ITALY’S ARCHIVE ON THE HISTORY OF SOLAR ENERGY

C. Silvi

Gruppo per la storia dell’energia solare (GSES) — Via Nemorense, 18 — 00199 Rome, Italy

E-mail: csilvi@gses. it

Abstract

This paper reviews research and organizational activities for the creation of the Italy’s Archive on the History of Solar Energy, a project started in 2003. The project’s main purpose is to preserve the Italian heritage of solar energy use, creating a digital archive accessible via the Internet. The first branch of what will be a geographically distributed archive has been taking shape over the past years at the Luigi Micheletti Foundation and the Eugenio Battisti Museum of Industry and Work (www. musil. bs. it) in Brescia, in northern Italy. An important step forward came in 2006, when the “Italian National Committee ‘The History of Solar Energy’” (CONASES), a multidisciplinary non-profit entity, was established by the Italian Ministry for Cultural Heritage and Activities, following a proposal by the Group for the History of Solar Energy (GSES, www. gses. it). In 2008, a cooperation agreement on a nationwide survey of sources on solar energy, signed between the State Archives Department and GSES, opened up new prospects for further development of the Archive. Examples of archives and documents already collected and under study are provided. The paper also shows that the Solar Archive project is already rewriting Italian solar energy history.

Keywords: solar archive, solar history, solar pioneers, solar architecture, solar cities,

1. Introduction

It often happens that we think of solar energy (its direct and indirect forms, wind, hydro, forests and other biomass) as an aspect of our modern world, although it had powered everything on earth until 150-200 years ago, when its fossilized forms — coal, oil and gas — began to gain sway.

For thousands and thousands of years the use of solar energy shaped human settlements and cities, farming and forestry, architecture and buildings, landscapes and territories, religious beliefs and cultures, social relations and lifestyles on Earth — in a word, whole civilizations. The use of solar energy is thus an age-old experience marked by milestones on the path that led human beings to artificially convert it into other useful forms of energy and goods: food, construction materials, heat, fuel, daylight and, more recently, electricity, which has been, is and will continue to be a fundamental part of modern life.

Discoveries in the field of solar energy use, made during what I would propose to call the primitive or ancient solar age — when solar was the sole source of energy — still have a major role in our daily lives. This is well exemplified by the Romans’ discovery of windowpane glass in the first century A. D., to bring daylight inside buildings and at the same time prevent cold and winds from entering. Today millions upon millions of windows provide daylight to homes and workplaces all over the world, thereby saving on artificial light produced with electricity generated by fossil and nuclear fuels.

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An additional example is provided by farming and agriculture. From the earliest civilizations they were powered, and continue to be powered today, by solar energy as the primary and principal energy source.

These technologies and discoveries, which have evolved throughout the centuries, are still of greatest importance in our daily lives. It is as if an ancient renewable-solar-energy soul were an essential part of our modern world, taken for granted and not accounted for in official energy-use and economic statistics. Therefore, the history of solar energy can hold important lessons for our own times, when humanity is beset by a growing number of problems, closely related to the use and availability of energy.

Since 2000 GSES, a volunteer not-profit organization formed by experts and scholars from various technical fields, has been promoting and organizing initiatives aimed at producing a systematic history of the use of solar energy. In this paper, the focus is on modern or future solar age, currently sprouting from the pioneering work on solar energy done over the last centuries, in particular during the last 150-200 years.

Renewable energy education in Armenia: going for imperative

1.3 How educated we are

The availability of educated and trained people at all levels and in all engineering disciplines is a crucial factor for the successful implementation of any programme towards sustainable use of energy, as well as preserving the environment. Unfortunately, at current stage the universities of Armenia are not involved in specific education programmes to prepare specialists and professionals in renewable energy field. Some disciplines within the general power engineering programmes though incorporate basics for renewable energy. An introductory and non-mandatory renewable energy classes are incorporated in very few universities’ curricula. However, no

institution is actively pursuing teaching activities in this area at both bachelor and master degrees. Few universities are engaged in education and research and development in solar energy, such as State Engineering University, State University, and American University of Armenia. Despite the fact that with increasing pressures of fossil fuel scarcity and adverse environmental impacts of their use, more countries make efforts towards providing renewable energy and environmental education, Armenia has not been taken this seriously and no real efforts have been made to provide renewable energy and environmental education.

Education as a way to get public (not only academic institutions and students) to understand and be aware about the benefits renewable energy can offer is a crucial component. In this regard, a few efforts have been taken to bring attention of general public and schools community on renewable energy basics. A number of programs to promote renewable energy in Armenia were implemented since mid 1990s. Specifically the education and public awareness projects included small scale publications for general public [1], [2] and workshops or seminars under donor funded projects [3]. In 2004 SolarEn, LLC in association with UNDP, ASE/USAID, Armenia Tree Project NGO and Ministry of Education has developed and implemented a project that included preparation of Renewable Energy Poster and Instruction Manual for teachers [4]. The posters and manuals were distributed to all state schools in Armenia (over 1400). The project envisaged provision of general information on renewable energy technologies as well as the specific technologies applicable for Armenia. It also indicated renewable energy projects already implemented in Armenia. The poster is easily understandable to pupils, while the teachers’ manual provides key information in technical and economic aspects as well as environmental benefits. The project was unique in terms of the approach — delivery of basic knowledge to young generation and teaching teachers through the all state schools. Measurement of results was not envisaged under the project. It was agreed with the Ministry of Education to include provision of basic knowledge through school curricula under “General Physics” classes. However, non-mandatory nature of such introductory approach did not ensure the classes be successful. Finally, general public and potential consumers as well as communities, businesses and decision makers at state agencies are unfamiliar with the benefits of renewable energy.

Development of an educational kit for teaching photovoltaic. generators interconnection modes and reverse bias effect

M. Perez-Garci’a1* , J. L. Bosch1 and A. Fernandez2

1 University of Almeria (UAL), Department of Applied Physics, E-04120 Almeria, Spain
2 CIEMAT-PSA E-04200 Tabernas (Almeria), Spain
Corresponding Author, mperez@ual. es

Abstract

This work describes the configuration and the performance of a small scale device aimed to be used as educational tool to support the contents related to the interconnection modes in a PV generator as well as to visualize the effect caused by the partial shading of one or several of its cells. The device consists of three main components: a set of m-Si cells, a variable light source and a load simulator connected to general purpose electrical meter. All the elements of the device are low cost and easily available in electricity and electronics laboratories. The performance of the device allows to draw I-V curves for each one of the cells and their parallel — series combinations under controllable illumination levels. This educational kit has been developed for its use in the Laboratory of Energy and Environment of the Department of Applied Physics of the University of Almeria.

Keywords: solar cells, interconnection, mismatch, hotspot

1. Introduction

The understanding of the solar cells characteristics as electricity generators is one of the key topics in any course on photovoltaic solar energy fundamentals or applications. In this sense, the students might get used to the solar radiation and temperature dependence of the solar cells parameters and, as consequence, their energy yield in function of local climate as well as they should be also able to extract complementary information from the shape of I-V curves as, for example, that requested for optimizing PV systems performance by the application of the maximum power tracking concept.

The step from individual cells characteristics to PV modules, arrays or plants characteristics is immediate because it consists essentially in the series-parallel combination of single elements until matching the voltage and/or current levels requested for the inverters or any other final PV system component. This combination, although in practice is not usually further analyzed by the students once PV system design is concluded, must however be still carefully studied because the lack of equilibrium between interconnected parts or strings can cause a serious problem in the whole PV generator under certain conditions. The above is provoked by two main reasons [1]. The first one, intrinsic, is the finite manufacturer’s tolerance in cell characteristics and, consequently, the eventual interconnection of non exactly identical elements. In an PV array, in these circumstances, the output power of the combination is less than the sum of maximum output power of its constituents. The second reason arises due to external causes as accidental impacts provoking the partial or full opening of a string due to cell

cracking and, especially, the shadowing of a certain fraction of the generator because predictable (near buildings, trees, mast,…) or unpredictable (bird droppings or fallen leaves) sun radiation blocking.

All the losses in the PV generator performance caused by the above are called mismatch losses As greater the difference between mismatched parts in regard to the rest of the generator elements, the higher losses because the output of the entire PV generator is determined by the solar cell with the lowest output. In addition to this undesired effect, when the difference exceeds certain level, the unbalanced elements in the generator become reverse biased, acting as loads instead of generators and, if not appropriate protection exists, overheating of these parts (hot-spot effect) can arise and, in severe cases, the system can be irreversibly damaged [2].

The methods for correcting fault tolerance for the electrical mismatch consist on limiting of component malfunctions by redundant circuit design together to on site extensive modules checking. This increase the installation time and costs, specially in multi-MWp plants, but, usually, the retrieved energy justify this extra effort. On the other hand, the hot spot effect in the partially shadowed solar cell arrays is minimized considerably by installing bypass diodes connected in parallel, but with opposite polarity, to the eventually affected solar cell. Many studies have been done to optimize the number and configuration of these diodes in PV modules and generators [3-4]. The performance of by-pass diodes is based on the following: under normal operation, each solar cell will be forward biased and therefore the bypass diode will be reverse biased and will effectively be an open circuit. However, if a solar cell is reverse biased due to the a mismatch in short-circuit current between several series connected cells, then the bypass diode conducts, thereby allowing the current from the good solar cells to flow in the external circuit rather than forward biasing each good cell. Although modules manufacturers and PV systems designers are used on hot spot prevention, the new needs as bigger modules for grid connected applications and the requirement of the absence of connection box for architecturally integrated PV applications in windows or roofs, make necessary case specific configurations to protect the systems against this risk.

The effect of unbalanced cells in PV generators curves can be easily visualized by a simple a procedure and its study can provide to the students a large amount of specific skills on cells electrical performance. The equipment proposed in this work consists of a) a set of cells prepared to be manually interconnected by leads in different modes c) a set of controllable light sources, each one linked to specific cell and d) a load simulator able to provide corresponding I-V pairs to draw characteristic curve of each cell.

2. Theoretical basis