El empleo de técnicas de posifivado

The original intention had been to have several different SWH systems tested by the Centre for Renewable and Sustainable Energy Studies (CRSES) at their testing facility on the roof of

85Particularly useful interviews were those with Izak van Gass, a researcher working for Eskom, Helmut Hertzog of Atlantic Solar, Carl Wesselink, project manager of the City of Cape Town Kuyasa project, Professor Ben Sebitosi of the Department of Mechanical Engineering at Stellenbosch University and Riaan Meyer and Duncan Scott of the Centre for Renewable and Sustainable Energy Studies

86 For a justification of why Stellenbosch Municipality was chosen as a focus area please refer to the document entitled Selecting Stellenbosch Municipality as a Focus Area on the attached CD

the Engineering Faculty. The idea was to do a technical analysis of which low-cost systems would provide the most reliable source of hot water in Stellenbosch’s climatic conditions.

Such a study would be valuable as there is some debate in the available literature about the different performance of flat-plate collectors vs. evacuated tube collectors. Unfortunately, after discussions with the CRSES and the funding partners for the research (Unilever and the Royal Society of Chemistry) it was decided that such a comparative technical test would be too expensive and not entirely relevant to the research question posed in this thesis. It was instead decided that the research could offer more valuable insights into the performance of SWH systems if they could be tested in real-life settings where the experience of residents with the technology could be monitored. The reduced financial costs of this approach also made it feasible within the budget of the study.

Tasol Solar donated a 100l, low-pressure, direct, evacuated tube SWH system. A 80l 200kPa direct flat-plate collector system was bought from Atlantic Solar and the Royal Society of Chemistry provided a third system, manufactured by Celsius Solar in Scotland, which was installed with the help of the inventor David Osborne. Tasol are the only providers of SABS certified low-pressure evacuated tube collectors in South Africa and have been involved in the Nelson Mandela Bay SWH rollout. Atlantic Solar was selected as a key partner for the research as they supplied and installed the SWHs for the Western Cape Solar Water Heating project in KwaNokuthula. The Celsius Solar system is an alternative new extremely low-cost design made of moulded plastic and an aluminium collector plate.

After securing the SWH systems the next step was to identify three suitable houses for the installation of the systems. Community leaders in both Kayamandi and Cloetesville were contacted to assist with the selection of households. They were Songo Fipaza, who had orchestrated the development of several youth development programmes in Kayamandi and Joanne Manuel, the local leader of the FEDUP NGO and a church outreach programme in Cloetesville. With the help of these individuals three households were identified for the study. Each, at the time of initiating the research, had five permanent residents, consisting of two adults and three children/young adults. The houses had to have North-facing roofs and the residents had to be willing to cooperate in a research project over a few months.

Both the flat plate and evacuated tube systems achieved excellent water heating results as shown in Figure 41 but the Celsius Solar system was deemed to be unsuitable for further study due to very low levels of efficiency. There were also some problems with the evacuated

tube collector system due to leakage from the feeder tank. A team came out from Tasol on three separate occasions to fix the problem. After the final call-back an extra tap was installed that would enable the residents to stop the inlet of water if the overflow became too great. This seems to be a satisfactory solution and the family have mentioned no further problems with the system. Tasol (Van Zyl 2010) believes that the leakages occurred due to slight damage to the feeder tank, possibly caused by rocks thrown at the system. After the modifications, which could be done very cheaply, the system did not experience any further problems. If the system was, damaged by vandalism, it illustrates the necessity that larger SWH rollout programmes should not be completed without encouraging community participation in the planning process. Because this installation consisted of a single isolated system it created the potential for envy and jealousy that could lead to vandalism. In the Kuyasa CDM project no incidents of vandalism have been reported as the rollout programme only commenced after much time was taken to include the local community in the planning process (Wesselink 2009).

The Celsius Solar system was tested as an example of alternative very low-cost technologies.

Further testing of the systems was suspended after it failed to heat water during personal tests or during a trial installation on a low-income home in Cloetesville⁸⁷.The example served to

87 Nothing could be found in the specific installation that would explain the poor performance as the system was installed North facing on a roof out of the shade. The installed system had been monitored for a few weeks during autumn and despite ideal climatic conditions with daytime temperatures reaching higher than 30°C the system produced water that was only lukewarm to the touch BB Commercial, a manufacturing plant in Johannesburg, were also interested in the (footnote continued)

Figure 38 Tasol Evacuated Tube Installation

Figure 39 Celsius Solar Alternative Low-Cost Installation

Figure 37 Atlantic Solar Flat-Plate Installation

illustrate the dangers of installing sub-standard systems in low-income community rollouts.

Poor technology will only be a waste of valuable resources and harm the perception of renewable energy technologies. The SWH industry in South Africa is well established and years of experience have shown that the existing commercially available systems are the most cost efficient configurations (Hertzog 2008, Bester 2010). Before alternative technologies are recommended for mass rollout they need to be thoroughly tested, not only in laboratory tests but also in case study projects such as was conducted as part of this thesis. It is likely that the Celsius Solar system failed due to a lack of sufficient insulation around the water storage tank and a collector area that is too small given the large amount of water in the tank that has to be heated. The area under the collector is even more poorly insulated and, despite having a Perspex cover, the collector plate remains in contact with air from the surrounding environment. These poor insulation properties mean that most of the heat collected is lost again to the atmosphere rather than transferred and retained in the water stored in the tank.

The initial objective had been to monitor the systems during the winter but due to delays in sourcing the systems monitoring could only start in spring. In retrospect this enforced delay was an advantage in that it allowed the systems’ hot water output to be monitored during the variable weather of early spring rather than only during the cold, cloudy winter period. In order to assemble some quantifiable data on the performance of the installed SWH systems two Toptronic T500K Thermometers⁸⁸ with liquid temperature probes were purchased and used to measure the water temperatures delivered by the SWH systems at different times of the day between 17 September and 17 November. Before purchasing the thermometers their specifications were checked with the staff of the CRSES to verify that they were of sufficient quality to monitor the temperatures. The objective was not to develop an accurate, detailed model of the temperatures achieved by the SWH systems but rather to have quantifiable indication of the achieved water temperatures that is more descriptive than how the water felt to the touch. Data on solar radiation levels during the monitoring period were obtained from the Stellenbosch University’s Department of Mechanical Engineering via the internet (Stellenbosch University 2009) and through direct consultation by e-mail with JP Meiers (2009) who works at the weather station.

Unfortunately the thermometers require that temperature measurements be taken manually.

After visiting each case study household three times in one week to take temperature measurements it became clear that the research was becoming intrusive and that such frequent visits could influence water usage patterns and might affect the trustworthiness of information provided by the households. It was thus decided to train one person in each household in the use of the thermometers and to ask them to take regular temperature measurements at certain times of the day. This approach was feasible as the thermometers are extremely simple to operate. It was also explained that the water temperature had to be measured after it had been running for longer than 30 seconds in order to ensure that water from the storage tank and not from connecting pipes should be measured. The temperature measurements were recorded on a calendar and checked on a twice weekly basis by the author.

technology and they conducted their own temperature tests in Johannesburg which failed to achieving significant water heating results (Beukes 2009).

88 Rated to be accurate to within 0.3%rdg +/- 1ºC

Unfortunately, residents were not always able to measure the water temperatures three times per day as instructed and often only one reading per day was taken. This meant that during the research period the readings were often taken at different times of the day in the different households making them useless for comparative purposes. This led to a flaw in the research process due to the low numbers of comparable data assembled. A study with better equipment where a thermometer was installed on the outside of the house to measure the temperature within the hot water storage tank would have been a better approach but few other options were available under the budget constraints of the project. Though flawed, the data does provide a few valuable indications as discussed under 4.1.1.1.

The provision of hot water services combined with frequent visits enabled the researcher to build a strong collaborative relationship with the households and this allowed for the completion of in-depth qualitative research into the benefits that SWHs provide to low-income households. The primary output of the case-study is thus qualitative data on the poverty-alleviating potential of SWH technology with some quantifiable data used to provide an indication of the water temperatures achieved by the SWH systems. As with any case study research it is dangerous to inductively make assumptions about wider populations based on just one or two instances. The value of this study lies therein that it can be used to inform future wider research and that it allowed the researcher to develop a deeper understanding of the impacts of an the installation of a SWH in a low-income household.

Such insights are particularly valuable in understanding the synergic benefits of SWH as many of the more indirect benefits such as improved senses of “freedom” or “pride” can only be observed through close interaction. In order to balance this case study with quantitative findings, a wider demand-side survey was conducted to determine what existing hot water usage patterns are in low-income communities in Stellenbosch.