Team training and field research

Each work group was composed by 01 professor and 04 Engineering and/or Physics students. The training course had included solar geometry concepts, solar collectors and storage tanks, small, medium and large systems functioning characteristics, attending to variable factors found at each location. With practice classes, students had learned how to use the field research Kit, composed by GPS, tape measure, compassing, turn indicator and digital cameras used to register the visited systems.

All data observed were registered by filling technical and behavioral questionnaires, and by producing two sketches: architectonic and hydraulic. These sketches included verification of collectors orientation, tilt angles, array scheme and distance, main characteristics and identification — also verified for storage tanks -, accessibility and safety conditions, obstacles around solar collectors and auxiliary system’ characteristics. Figure 4 illustrates the field research.

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Figure 4 — Field research

4. Obtained results

The concluded part of this project, in which three cities were studied, had summed a number of 274 visited systems, containing 4105 solar collectors. About 8777m2 of collector area were observed for a total hot water storage volume of 492m3. Also, this research had evaluated systems of different functioning period that were divided into 4 groups. This evaluation can be observed at Figure 5 for Belo Horizonte and Campinas cities.

Подпись: Visited installations' age
Подпись: 40 -| 36 36 > 15 years 10 < years < 15 5 < years < 10 < 5 years Unidentified

Belo Horizonte □ Campinas

Figure 5 — Visited installations’ visited

This comparative evaluation is not performed for Rio de Janeiro because there were no low — income households solar systems installed more than 5 years ago; therefore these data were not included in this analysis.

System sizing

The characteristic consumption of the studied buildings was estimated relating the total solar collector areas and volumes for each location. Campinas, where medium and high income households with 1 or 2 storey buildings were visited, presented an average collector area of 8m2/household, storage volume of 600 liters/household and an average hot water consumption of 150 liters/person. The average storage volume found at Belo Horizonte’s systems is 7500 liters/building, 240 liters/household and nearly 60 liters/person. This last number is considered low if compared to high-income households consumption observed at Campinas. This fact was linked to the consumption compensation between the apartments and the small available area to install solar systems that can cause reductions over the f-chart value and increase the auxiliary system consumption. Moreover, there’s a tiny use of hot water in kitchens, which can also raise significantly the systems sizing prediction. At Rio de Janeiro, the average consumption for low — income households studied is 58 liters/person.

Products Quality

The solar collectors inspection had displayed the presence of oxidation, infiltration, painting and insulator deterioration and broken or damaged glasses. At 10 to 15 storey buildings’ systems visited, 12% presented infiltration, 10% painting deterioration and 5% oxidation, showing these three problems as the most common ones. Thus, the infiltration problem can be considered as the most critical, since, in most of the cases, it is the main actor that causes other problems, such as painting deterioration and oxidation.

It is reasonable to associate those problems with low incidence of systems maintenance, proved by the great number of dirty solar collectors: nearly 30% at large and 67% at small systems for medium and high-income households.

Large systems storage tanks presented good functioning, although oxidation problems were detected at the structural base: low (22%), medium (13%) and high (9%). Again, this problem can be a lack of periodic maintenance consequence.

The observed results about equipments approved by INMETRO market, point to an interest growth demonstrated by specialized stores. At Rio de Janeiro nearly 45% commercialize only these products, while at Belo Horizonte this value raises up to 70%. For these stores, 80% of products have the PROCEL Stamp, which is considered the best quality product, classified as “A”.

Auxiliary Heating Systems

Basically, LPG gas predominates at large systems in Belo Horizonte, where 74% of them use this kind of auxiliary heating. Meanwhile, at Campinas, where small residential systems were analyzed, the electric auxiliary heating is the most used, reaching 66% of studied households. At low-income households visited at Rio de Janeiro, which integrated a special program of the electric energy company, all the auxiliary systems are electric, represented by the resistance installed into the storage tank or the electric shower.

Safety, accessibility, monitoring and system’s maintenance

Another problem noticed is the bad conditions of systems accessibility (Figure 6). In large systems, 30% presented elevated and risky access, whereas in small systems this number corresponds to 46%. The lack of monitoring and maintenance might be associated to accessibility difficulties, since this problem obstructs the necessary equipment maintenance.

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Figure 6. Solar heating systems accessibility examples

It was detected a general absence of monitoring systems and consumption control of hot water and gas or electric energy. In 90% of small systems, and 71% of large ones this occurrence were presented.

5. Conclusions

Preliminary data results observed in this research demonstrate the need of creation of a Solar Water Heating Systems evaluation program, through quality indicators definition. This strategy would evaluate essential aspects for proper functioning of the solar system, which include: hydraulic array, products quality, auxiliary systems, collectors’ orientation and tilt angles, shading occurrence, accessibility, safety, monitoring and system’s maintenance. At the same time, a Good Practices Manual for Solar Water Heating in Brazil should be developed, with the creation of formal training programs focused on design, installation, operation and maintenance of solar systems. This new program, along with the equipment certification, already established in Brazil, will help the Brazilian solar heating market to grow with sustainability and will contribute for its current national’s scene changing.

References

[1] PROGRAMA NACIONAL DE CONSERVACAO DE ENERGIA ELETRICA. “Avaliagao do Mercado de Eficiencia Energetica no Brasil: Pesquisa de Posse de Equipamentos e Habitos de Uso da Classe Residencial no Ano Base 2005”.

[2] LEITE, H. G. Consideragoes sobre amostragem. Departamento de Engenharia Florestal, Universidade Federal de Vigosa. 2004.

[3] MINGOTI, S. A.; Analise de Dados Atraves de Metodos de Estatistica Multivariada — Uma Abordagem Aplicada. Editora UFMG, Belo Horizonte, 2005.

[4] DUFFIE, J. A., BECKMAN W. A., Solar Engineering of Thermal Processes, John Wiley & Sons,

INC, 2a Edigao, 1991.

[5] INSTITUTO NACIONAL DE METEOROLOGIA — INMET — pelo site www. inmet. gov. br acessado em junho de 2007.

[6] INSTITUTO BRASILEIRO DE GEOGRAFIA E ESTATISTICA — IBGE — Banco de Dados,

Cidades, Belo Horizonte — MG, pelo site www. ibge. gov. br Accessed on: Jun. 2007.

[7] MESQUITA, L, PEREIRA, E. M.D. ESTEC 2007