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  1. 1. Sponsored by the Department of Science & TechnologyThis journal is accredited by the South African Department ofEducation for university subsidy purposes. It is abstracted andindexed in Environment Abstract, Index to South AfricanPeriodicals, and the Nexus Database System.The journal has also been selected into the Science CitationIndex Expanded by Thomson Reuters, and coverage begins Volume 22 Number 3 • August 2011from Volume 19 No 1.Editor CONTENTSRichard DrummondEditorial board 2 Dissemination of solar water heaters inMr J A Basson South AfricaEnergy consultant Keh-Chin Chang, Wei-Min Lin, Greg RossProfesor K F Bennett and Kung-Ming ChungEnergy Research Centre, University of Cape TownProfessor A A Eberhard 8 The challenges and potential options toGraduate School of Business, University of Cape Town meet the peak electricity demand inDr S Lennon MauritiusManaging Director (Resources & Strategy Division), Eskom Khalil ElaheeMr P W Schaberg 16 Outdoor testing of amorphous andSasol Oil Research and Development crystalline silicon solar panels at ThohoyandouAdministration and subscriptionsMs Ann Steiner Eric Maluta and Vaithianathaswami SankaranAnnual subscriptions 2011 (four issues) 23 Renewable energy, poverty alleviation andIndividuals (Africa): R160 (single copy R51)Individuals (beyond Africa): US$109 (single copy US$39) developing nations: Evidence from SenegalCorporate (Africa): R321 (single copy R103) Djiby Racine ThiamCorporate (beyond Africa): US$218 (single copy US$77) 35 The impact of health behaviour changeCost includes VAT and airmail postage. intervention on indoor air pollutionCheques should be made payable to the University of CapeTown and sent to the address given below. indicators in the rural North West Province, South AfricaEnquiries may be directed to:The Editor, Journal of Energy in Southern Africa, Brendon Barnes, Angela Mathee andEnergy Research Centre, University of Cape Town, Elizabeth ThomasPrivate Bag, Rondebosch 7701, South AfricaTel: +27 (021) 650 3894 45 Experimental study on heat and massFax: +27 (021) 650 2830 transfer for heating milkE-mail: Mahesh Kumar, K S Kasana, Sudhir KumarWebsite: and Om PrakashIt is the policy of the Journal to publish papers covering thetechnical, economic, policy, environmental and social aspectsof energy research and development carried out in, or relevantto, South Africa. Only previously unpublished work will be 54 Details of authorsaccepted; conference papers delivered but not published 56 Forthcoming energy and energy-relatedelsewhere are also welcomed. Short comments, not conferences and courses: 2011–2012exceeding 500 words, on articles appearing in the Journal areinvited. Relevant items of general interest, news, statistics,technical notes, reviews and research results will also beincluded, as will announcements of recent publications,reviews, conferences, seminars and meetings.Those wishing to submit contributions should refer to theguidelines given on the inside back cover.The Editorial Committee does not accept responsibility forviewpoints or opinions expressed here, or the correctness offacts and figures.© Energy Research Centre ISSN 1021 447X
  2. 2. Dissemination of solar water heaters in South AfricaKeh-Chin ChangEnergy Research Centre, National Cheng Kung UniversityWei-Min LinDepartment of Business of Administration, Tainan University of TechnologyGreg RossInstitute of International Management, National Cheng Kung UniversityKung-Ming ChungEnergy Research Centre, National Cheng Kung UniversityAbstract IntroductionGlobal concern over a looming energy crisis, water The level of greenhouse gas (GHG) emissions tak-scarcity and man-made climate change are driving a ing place today is staggering and unprecedented.huge demand for clean technologies, which focus Many scientists, geologists and academics believeon preserving the earth’s resources. In South Africa, that global warming and climate change havethe economy is very energy-intensive with coal indeed reached their tipping point. In particular, thebeing the main national energy supply. In view of level and momentum of polar ice sheet degradationthe growing depletion of fossil fuel, it is important has stunned scientists. Applications of renewablefor South Africa to adopt a more sustainable energy energy technologies represent an opportunity formix. This study examines the potential for wide- systemic change. They have the potential tospread dissemination of solar water heaters (SWHs) empower governments and individuals to con-in South Africa. Barriers and constraints to market tribute to mitigate climate change, while at the sameexpansion are analyzed to determine strategies for time facilitate employment and skill creation.overcoming these barriers. It is found that payback Among the applications, solar water heating is a rel-period of a SWH is shorter than the life-span of the atively simple technology which has been aroundsystem itself, indicating that SWHs are economical- for over fifty years but has demonstrated tremen-ly viable even with low production cost of electrici- dous potential in reducing the level of GHG emis-ty and thus represent a profitable investment propo- sions. Thus, SWHs are rapidly becoming an integralsition for end users, manufacturers and distributors. part of worldwide measures to combat the effects ofHowever, the subsidy programs offered by the gov- climate change. In 2008, the total capacity in oper-ernment of South Africa may not be sufficient to ation worldwide was 150 683 MWth, which corre-facilitate diffusion. This is attributed to the high ini- sponded to 215 262,126 m2 of solar collectortial capital cost of the system and low affordability of installed (Weiss et al., 2010).the majority of the South Africa population with low Since South Africa is located in the subtropicalincome. Alternative financing mechanisms are belt between latitude 22°S and 34°S, there is abun-required. dant sunshine throughout the year. It has one of the highest insolation rates in the world, between 4.5Keywords: solar water heater, South Africa, subsidy kWh/m2 and 6.5 kWh/m2, and receives about 2 500 hours of sunshine a year (over 300 days of sunshine per year in some provinces) (Munzhedzi et al., 2009). This high level of solar radiation enables solar water heating to be the least-cost method of meeting the national target for increased use of renewable energy technologies. However, it is known that SWHs are more expensive than con- ventional forms of hot water production by lique-2 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  3. 3. fied petroleum gas (LPG), natural gas or electricity. 2009, the accessibility was at a high of 91.7% in theSupport mechanisms such as subsidies have the Free State (the second smallest province in numbereffect of shortening the payback period, which of households) and a low of 69.8% in the Easternwould make the investment more attractive and Cape (the third largest province in number oftherefore increase the likelihood of adoption. households). Note that 13.5% of households also This study utilized complementary elements of had their electricity cut because of non-payment. Inboth desk and field research. Data was acquired addition, electricity consumption in South Africanthrough review of literature including journal households accounts for approximately 35% ofpapers, official publications and websites. In addi- peak demand with hot water production constitut-tion, a field survey was conducted using telephone ing 40% of that (Lumba et al., 2010). To alleviatecalls followed up by e-mail questionnaires to the burden on the national grid, Eskom launched aapproximately 20 SWH-related parties in South Demand Side Management Program in 2006. ThisAfrica, including manufacturers such as Suntank program, which is to facilitate a more sustainable(Pty) Ltd, Solar Heat Exchangers cc, Genersys energy mix, focuses on reducing electricity demandSouth Africa, Solar Harvest (Pty) Ltd, Kwikot (Pty) by 3 000 MW by 2012, and a further 5 000 MW byLtd amongst others, as well as governmental and 2025.non-governmental institutions such as theDepartment of Energy, the Central Energy Fund(CEF), the Sustainable Energy Society of South National policy of South Africa on SWHsAfrica (SESSA) and Eskom. The survey aims to The government’s White Paper on Renewablegain an in-depth understanding of barriers to wide- Energy Policy (2003) has supported the establish-spread dissemination of SWHs in South Africa. ment of renewable energy technologies, targetingPossible dissemination drivers are also proposed, the provision of 10 000 GWh of electricity (or 4% ofwhich would assist policy-makers in formulating projected electricity demand) from renewableeffective countermeasures and strategies. resources by 2013. SWHs could contribute up to 23% of this target. Note that currently less than 1%Energy situation in South Africa of electricity generated in the country originatesThe South African economy is very energy-inten- from renewable energy technologies (Visagie et al.,sive and is dominated by the mining and manufac- 2006). According to the latest report by theturing industries. The country uses a large amount International Energy Agency (IEA), Weiss et al.of energy for every unit of output, requiring 0.24 (2010) mentioned that the total collector areatons of oil equivalent to produce US$1 000 of GDP installed and operating in South Africa was 975 360at purchasing power parity. Energy efficiency is thus m2 by the end of 2008 and the total capacity of alla crucial part of energy planning. Further, the these systems combined was 682.8 MWth.national energy supply in South Africa has been It is considered that the delivery of SWHs coulddominated by coal, which contributes to about 70% potentially reduce the overall national energyof the primary energy supply and 92% of electricity demand and the load at critical peak times of theproduction (Winkler et al., 2006). Between 2002 day in South Africa. The SWH industry, however, isand 2006, South Africa alone raised its coal pro- faced with constraints in terms of standardization,duction by more than half the world’s increase in awareness, affordability and financing whichthe equivalent volume or primary energy from impede widespread dissemination. In particular, theother forms of new renewable energy since 1990 high upfront capital cost of a system is of great con-(Jefferson, 2008). However, the reliance on coal cerns. Thus, there is a significant body of knowl-has resulted in high levels of GHG emission (379 edge in both industry and academia to support themillion tons of carbon dioxide equivalent per year, modelling and development of SWHs in Southor 8.61 tons per capita) (Banks et al., 2006 ), mak- Africa. In 2003, SolaSure (the solar water heatinging South Africa one of the top 20 GHG emitters in division, SESSA) was established for the delivery ofthe world. Moreover, Winkler et al. (2006) predict- services in the SWH industry. Several task groupsed that future energy demand in South Africa will were initiated to address the following: (1) qualitydouble by the year 2050. This magnitude of expan- control and testing; (2) standards and testing facili-sion in energy demand is neither feasible nor sus- ties/procedures; (3) marketing and membership; (4)tainable. The state-owned power utility, Eskom, interaction with Eskom; (5) research and develop-would no longer have excess capacity it had and is ment; and (6) interaction with international bodiesstruggling to keep up with peak demand, not to (Visagie et al., 2006). The CEF also assistedmention the great impact of fossil fuel consumption SolaSure in executing these tasks. Some initiativeson the natural environment. were made to develop the skill base of the industry. While electricity generated from coal in South These included in-house training by individualAfrica is among the cheapest in the world, its acces- companies and Eskom, and national programssibility is still a problem for many of its citizens. In granted by the Energy Sector Education andJournal of Energy in Southern Africa • Vol 22 No 3 • August 2011 3
  4. 4. Training Authority (ESETA). lectors have always been 20%-30% those of Since SWHs have considerable potential to unglazed solar collectors, as shown in Figure 1.leverage electricity savings and reduce GHG emis- Presumably it was because unglazed solar collectorssions, some promotion programs were initiated by have been used mainly in luxury swimming poolsome local governments, such as the Kuyasa low- applications. In 2008, the area of solar collectorcost housing project, the Johannesburg Climate installed was about 100 000 m2 and 21 000 m2 forLegacy SWH project at Oude Molen, and the unglazed and glazed solar collectors, respectively.Driftsands SWH housing project (Visagie et al., However, a greater impact on sales of unglazed2006). Further, Eskom has granted rebates of up to solar collectors could be expected due to the recent30% (the maximum incentive amount at ZAR 5 economic recession. Furthermore, the size of glazed000) on accredited systems since 2008. Under the solar collector systems (domestic SWHs) is linked tocurrent initiative, each system is measured and allo- a hot water usage profile and the number of peoplecated an amount of rebate calculated according to living in a household. Since electric auxiliary heat-the energy footprint measured by the South African ing is usually not available in all areas, Holm (2005)Bureau of Standards (SABS). To receive rebates, indicated that a weighted national average wouldhomeowners must take delivery of systems by offi- require 4.69 m2 of solar collector installed percial Eskom suppliers. To become an official Eskom household. This corresponds to the major marketsupplier one must offer a five-year guarantee, have share of 200-litre SWHs (68%) in South Africa. Ina proven track record of viability, a certificate from 2009, the number of households was estimated tothe SABS and a membership with SESSA. It is be about 13 812 000 (SSA, 2010). For the poten-noted the application process still foresees to have tial SWH demand, this would create a demand ofthe customer pay the full cost of the system upfront about 64.8 million square metres (100% marketand claim the rebate thereafter. In 2010, Eskom penetration) or 19.4 million square metres (30%announced an increase in rebates for high-pressure market penetration). However, for the real potentialsolar thermal systems. The aim of this new program SWH market in South Africa, the disseminationis to encourage as many South Africans as possible barriers (such as affordability) should be furtherto move away from electric geysers (4.2 million in taken into account.the country), and replace them with SWHs (76 873operating units in 2009). Residential homeownersor tenants could be granted a cash rebate of up toZAR 12 500. This would make SWHs more afford-able to consumers, particularly for the rapid emer-gence of a non-white middle class.SWH marketA questionnaire survey was conducted by Eskom(2009). It intended to gather technical, financial andoperational information about the SWH industry inSouth Africa. Although there are over 100 suppliersin SESSA, only 39 suppliers gave some inputs tothe process, revealing that many of the suppliers Figure 1: Area of solar collector installed perwere not active. From the historical data of the annumSWH industry, significant growth took place during Source: IEAthe periods 1979-1983 and 2005-2008. The area ofsolar collector installed hit the 100 000 m2 mark in Dissemination barriers2008. However, the growth was accommodated by Dissemination of SWHs in South Africa is associat-the industry with very little additional capital equip- ed with a number of factors, which include corpo-ment apart from additional warehousing space for rate social responsibility (GHG emission and globalcompanies importing SWHs. climate change), consumer awareness (supporting In the South African market, both glazed and education and information programs), economicunglazed flat-plate solar collectors have been adopt- considerations (financial incentives, cost of electric-ed for most SWHs. Domestic manufacturers can ity, capital cost, income and expenditure), technicalmeet about 60% of the local demand in 2009. The support (training program, quality assurance andevacuated tube solar collectors, which are mainly standards), strategic marketing (brand image andimported from China and Germany, came on to the entire value chain) and regulations (housing proj-market in 2005 and only accounted for slightly over ect) (Visagie et al., 2006; Eskom, 2009). In particu-5% sales of glazed solar collectors. For the relation- lar, the economic feasibility of SWHs is consideredship between glazed and unglazed solar collectors, vital for market expansion. For income sources,a remarkable fact is that the sales of glazed solar col- most households in South Africa are dependent on4 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  5. 5. salaries (a low of 49.1% in Eastern Cape and a high performance tests for SWHs with specified condi-of 76.6% in Western Cape). However, grants also tions and apparatus. The SWH performance indi-constituted another major income source. The cator is given as the ratio of incoming solar energynational average was 43.7% in 2009 (a low of on solar collector area and useful heat absorbed by28.9% in Gauteng and a high of 57.7% in a SWH. SWH products bearing the SABSLimpopo). In some provinces (Eastern Cape, Approved Mark meet the required quality and min-Limpopo, Northern Cape and Free State), grants imum performance. Further, thermal performancewere the main source of income for many house- of a SWH should be associated with quality of solarholds (SSA, 2010). collectors. However, there are no South African Sidiras and Koukios (2004) pointed out that one standards for quality testing of solar collectors at thisof the major dissemination barriers for SWHs moment. This could be a serious obstacle in devel-among households is other investment priorities. If oping solar collector products for both local andthe capital cost is less than a specific fraction of fam- international markets. In addition, it is important toily income, the household might be willing to invest increase knowledge related to SWHs. Skill trainingin the purchase of a SWH. In South Africa, expen- workshops for local SWH manufacturers andditure on housing, transport and food dominated installers are required for quality products andhousehold consumption (close to 60% of the total), installation.especially for low-income households which allocat-ed a higher proportion of their expenditure to food, Financial analysisnon-alcoholic beverages, clothing and footwear As mentioned, the local market of SWHs in South(SSA, 2008). Thus, a high initial capital cost of a Africa has been mainly impeded by the financialSWH would be the biggest hurdle to market expan- barrier. The potential for widespread disseminationsion. Visagie and Prasad (2006) indicated that the of SWHs is essentially associated with economichousing plans made by the government of South profitability. Under this circumstance, some lesionsAfrica should include extra grant for SWH installa- can be learned from Taiwan market development.tion. Then SWHs could become affordable to the Indeed, the well orchestrated and concerted effortspoor and fitted in new housing as well as retrofitted (the long-term subsidy programs, 1986-1991,in old ones. The Clean Development Mechanism 2000-present) put forward by the government of(CDM) also provides a financing mechanism. This Taiwan have played a significant role in marketcould potentially make SWHs more accessible to expansion of SWHs during the last few decadesthe less well-off majority of the population (Chang et al., 2011). Furthermore, payback period Chang et al. (2009) indicated that the ownership is considered a critical element in the consumerand architectural type of buildings would limit the adoption decision process. In this study, a net ener-space available for SWH installation. Apartments gy analysis for SWHs by Sidiras and Koukiosand community housing are the major types of (2004) was adopted, in which the payback period ishousing in urban Taiwan. It would be difficult to calculated using the balance between the present-install a standalone SWH in those types of build- time cost of the system (initial plus yearly costsings. In South Africa, the full and partial ownership including operation, repair and maintenance), andof housing were 56.0% and 10.9% in 2009, respec- the benefits from conventional energy savings withtively; with 20.9% of the households being rented reference to the present time. For the initial capital(SSA, 2010). In terms of type of dwelling, most cost, the estimated unit price of a SWH (Eskom,houses were built with bricks (63.5%) or traditional 2009) is shown in Figure 2.materials (10.2%); and SWHs can thus be installedon the roof of houses. Furthermore, it is also knownthat there are many informal housing settlementswith a single water tap situated outside in SouthAfrica. This would be a significant barrier. To reinforce a product’s intrinsic features inSouth Africa, the SABS has issued the SABSApproved Mark. An independent certification isconducted by a third party. Thus, the mark is con-sidered a highly recognizable symbol of credibilityand a powerful marketing tool. For SWHs, estab-lishment of a standard is also one of the key factorscontributing to a positive acceptance of the con-sumers. South African standard (SANS 6211-2:2003) is in compliance with the existing local and Figure 2: Unit price of SWHsinternational standards, which includes one-day Source: Eskom (2009)outdoor and three one-day indoor basic thermalJournal of Energy in Southern Africa • Vol 22 No 3 • August 2011 5
  6. 6. As can be seen the average unit price increases with Thus, the Government of South Africa should leadtank size, particularly for the 300-litre system. This by example and have government buildings fittedis not consistent with the study by Chang et al. with SWHs, to encourage the general populace to(2009), in which the unit price of a SWH decreases adopt. The installation of SWHs should be madewith a larger area of solar collectors installed. Then mandatory in all housing being constructed by thein terms of cost breakdown, Holm (2005) indicated government.that the local manufacturers were reluctant to shareinformation. However, the average price of a glazedsolar collector system in South Africa was estimatedto be 3 736 ZAR/m2. Materials and labour account- Acknowledgementsed for 31.2% and 16% of the price, respectively. In Special thanks go to Mr. John Murray (former Vice-addition, the cost of distribution, installation and President of Newbridge Telecommunications Networks)maintenance of systems represented almost a third for his kind assistance in this study. Sincere thanks also goof the total installation cost. to Andrew Janisch, Sustainable Energy Society of South The benefit of using a SWH (output energy of Africa (SESSA), for providing essential data on SWHs insolar collectors) instead of traditional alternatives South Africa. This work was also supported by the(fuel price) can be realized in terms of the monetary Bureau of Energy, Ministry of Economic Affairs, Republicvalue of electricity saving. In South Africa, the aver- of China.age annual domestic electricity consumption for hotwater heating was about 3 400 kWh. With the solarinsolation and sunshine duration taken into Referencesaccount, there could be about 60% of hot water Banks, D. and Schaffler J. (2006), The potentialproduction (approximately 2 000 kWh) covered by contribution of renewable energy in SouthSWHs (Ross, 2010). However, due to low electrici- Africa, Sustainable Energy and Climate Changety cost, the yearly benefit is estimated to be only Project (SECCP).about ZAR 1 100. Furthermore, the discount rate Chang, K.C., Lin, W.M., Lee, T.S. and Chung, K.M. (2009), Local market of solar water heaters in(cost of system less discount by subsidy or tax Taiwan: Review and perspectives, Renewablerebate) and inflation rate could be also included in and Sustainable Energy Reviews, Vol. 13, 2605-the payback period calculation (Sidiras et al., 2612.2004). Ross (2010) pointed out that the payback Chang K.C., Lin W.M., Lee T.S. and Chung K.M.period of SWHs in South Africa is estimated be 4 (2011), Subsidy Programs on Diffusion of Solaryears while their lifetime could be up to 25 years, Water Heaters: Taiwan’s Experience. Energyindicating the feasibility of SWH expansion in Policy Vol. 39, Issue 2, 563-567.South Africa. However, the vast majority of South Eskom Distribution (2009). The South Africa solarAfricans with lower disposable incomes still cannot water heater industry.afford the high capital cost of SWHs without sub- Holm, D. (2005). Market survey of solar water heat-sidy. Thus, alternative financing methods need to ing in South Africa for the Energy Developmentbe implemented to make SWHs more accessible to Corporation (EDC) of the Central Energy Fundthe general public. For example, SWHs could be (CEF), SolaSure.offered on a lease basis where repayments are less Jefferson, M. (2008), Accelerating the transition tothan the electricity savings, so effectively the end sustainable energy systems, Energy Policy, Vol. 36, 416-425.user is getting a system for free or for a very small Lumba, P and Sebitosi, A.B. (2010). Evaluating the .monthly repayment sum. impact of consumer behaviour on the perform- Conclusions ance of domestic solar water heating systems in This study aims to gain insight into what factors South Africa, Journal of Energy in Southerninfluence the consumer adoption decision process, Africa, Vol. 21 No. 1; 25-34.which in turn, determines possible dissemination of Munzhedzi, R. and Sebitosi A.B. (2009). RedrawingSWHs in South Africa. As expected, economic con- the solar map of South Africa for photovoltaicsiderations are the key factors. Current subsidy pro- applications, Renewable Energy, Vol. 34, 165-grams are not sufficient to facilitate diffusion. 169.Alternative financing mechanisms such as third- Ross, G. (2010). Solar water heater diffusion inparty financing as well as low-interest loans and Taiwan and South Africa, Masters Thesis,access to credit for SWH purchases should be con- Institute of International Management, Nationalsidered. This would make SWHs more competitive Cheng Kung University.with traditional electric water heating systems. Sidiras, D.K and Kouhios, E.G. (2004). Solar sys- tems diffusion in local markets, Energy Policy,Indeed, the greatest benefit for South Africa is that Vol. 32, 2007-2018.SWHs can serve the greatest need. The challenge is Statistics South Africa (SSA, 2008), Income andhow to make SWHs available to the people who expenditure of households 2005/2006: analysisneed it the most, the population with low income.6 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  7. 7. of results, Report number 01-00-01.Statistics South Africa (SSA, 2010). General house- hold survey.Visagie, E. and Prasad, G. (2006), South Africa: Biodiesel and solar water heaters, Energy Research Centre. University of Cape Town, South Africa.Weiss, W., Bergmann, I. and Faninger, G. (2010). Solar heat worldwide: markets and contribution to the energy supply, 2010 editions, International Energy Agency.Winkler, H., Davidson, O., Kenny, A., Prasad, G., Nkomo, J., Sparks, D., Howells, M, and Alfstad, T. (2006), Energy policies for sustainable devel- opment in South Africa, Energy Research Centre. University of Cape Town, South Africa.Received 3 September 2010; revised 3 January 2011Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011 7
  8. 8. The challenges and potential options to meet the peakelectricity demand in MauritiusKhalil ElaheeFaculty of Engineering, University of Mauritius, Réduit, MauritiusAbstract OEP: Outline Energy PolicyThis paper reviews the current challenges facing MID: Maurice Ile Durable (Mauritius SustainableMauritius in terms of meeting peak electricity Island) projectdemand. As a fast-developing island-economy with SIPP: Small ondependent power producera very high population density, this is a crucial issue.The more so that it imports 80% of its energyrequirements in terms of fossil fuels, relies signifi-cantly on tourism and needs to protect its fragile 1. Introductionecosystems. The nature of the peak electricity As a fast-developing economy, Mauritius has todemand and its evolution is firstly analysed. meet increasing energy demand, particularly inReference is made to past scenarios for electricity terms of peak electricity as shown in Figure, the obstacles to their implementation and In 2009, the peak demand attained 389 MWtheir relevance in terms of sustainability. The fore- (Hansard, 2009a), representing an increase of 17 %casts underpinning the latter scenarios are found to over the last 5 years. The peak occurs during sum-be over-estimated. Demand-Side Management mer with the difference in the maximum demandsprojects are discussed and their potential to promote between summer and winter increasing from 25an alternative scenario based on revised forecasts MW in 2004 to 40 MW in 2008. This difference isare discussed. Hence a new Maurice Ile Durable due to the massive use of ventilation, air-condition-(Mauritius Sustainable Island, MID) scenario is pro- ing and refrigeration during the summer months,posed in view of stabilising the peak demand, particularly during the recent years that have beenreducing the rate of increase of total electricity marked with high average temperatures and thedemand and making the capacity margin positive. construction boom in the residential, tourism andThe newly-devised scenario is not only more sus- services sectors.tainable but also addresses several political and It has been demonstrated that the correlationsocio-economic issues to bring holistic win-win solu- coefficient between peak demand and atmospherictions. Institutional and regulatory reforms as well as temperature is above 0.9 (Badurally et al., 2009).a relevant Business Framework are also important This is illustrated for 2008 in Figure 2. It is to bein order to meet the challenges of MID. The new noted that both average humidity and number ofscenario relies only on existing technology with an hours of sunshine increase in summer and, hence,excellent track-record and provides the transition to tend to increase the peak demand.a more sustainable future. 1.1 SupplyKeywords: peak demand, electricity, Mauritius, Figure 3 illustrates how the peak demand is typical-demand-side management, sustainability ly met at the supply end. From the bottom of the chart upwards, electricity is generated from base- load coal or bagasse power plants owned by inde-Acronyms pendent power producers or IPPs (CTDS, Beau-CEB Central Electricity Board Champ, FUEL, CTSAV and CTBV). The otherCSO Central Statistics Office plants are owned by the Central Electricity BoardDSM Demand-side management (CEB), the sole distributor and supplier of gridDST: Daylight Saving Time power. It is to be noted that the CEB generatesGDP: Gross development product power from hydro (including Champagne), fuel oilIPP: Independent power producer (Fort George, St Louis and Fort Victoria) and8 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  9. 9. Figure 1: Peak electricity demand from 2004 to 2008 Source: CSO (2008a)Figure 2. Impact of GDP, temperature, humidity and number of hours of sunshine on peak Figure 3. Typical load supply curve of electricity from electricity demand for 2008 power plants (listed from bottom first) Source: Badurally et al. (2009) Source: Kassim (2010)kerosene (Nicolay). The latter, using a 76 MW gas even more expensive when compared to bagasse atturbine, is normally reserved for emergency pur- market prices. The latter is fully utilised but the effi-poses and is occasionally run for peaking only, ciency of its conversion can be improved by thegiven that its cost is at least four-fold higher. introduction of high pressure cogeneration plants. It is to be noted that the distribution losses Together with the use of other biomasses like caneamount to about 10% (CEB, 2008). The total tops and leaves, at least three times more electricityinstalled capacity is now 504 MW, including can be produced using currently available technol-allowance for maintenance, repairs and a 10% ogy (Autrey et al., 2006). This will ensure also aspinning reserve (Hansard, 2009b). Currently more stronger substitution of coal, used during the inter-than 60% of electricity is generated by the IPPs, the crop season, by renewable biomass. Figure 4 showsCEB being responsible mostly for the semi-base the energy mix for power generation for 2008. Theand peak load power supply areas. Much of the wind power indicated is negligible and refers to theCEB capacity is not fully exploited because of bind- island to contracts with IPPs to give priority to their base-load supply and because of the dependence on 1.2 Demand-side managementrainfall for hydropower. In 2009, the amount of power generated was It is to be noted that fuel oil and kerosene used almost the same as in 2008. Moreover, the peakby CEB are more costly compared to coal, and demand moved to the morning during the summerJournal of Energy in Southern Africa • Vol 22 No 3 • August 2011 9
  10. 10. Table 1: Power generation by source in 2008 understood that there is a growing awareness on Source: CSO (2008b) DSM resulting in an effective drop in power Source of energy GWh % demand, particularly in the evening. It is difficultPrimary energy 108.4 4.2 to estimate its exact impact but it is possible that Hydro (renewable energy) 108.0 4.2 it may reach as much as 15 MW occasionally, comparable to the drop noted immediately after Wind (renewable energy) 0.4 0.0 sharp rises in prices like in 2007.Secondary energy 2 448.8 95.8 iv) As a pilot project, Daylight Saving Time (DST) Gas turbine (kerosene) 6.6 0.3 was adopted from October 2008 to March 2009. Diesel & fuel oil 827.1 32.3 The project has now been dropped primarily Coal 1 128.7 44.1 because of public outcry related to social and Bagasse (renewable energy) 486.4 19.0 cultural disruption, but also because the expect-Total 2 557.2 100.0 ed energy savings were not achieved. The sum-Of which: renewable energy mer of 2009-2010 had ended without DST and(hydro, wind & bagasse) 594.8 23.3 there is no evidence to prove that the pilot proj- ect had a significant positive impact. Above all, since December 2008, but more regularly ever after, the maximum peak electricity demand hasmonths, instead of occurring in the evening as usu- been occurring in the morning during weekdaysally observed in the past. In fact, a plateau of about in summer. Nevertheless, it cannot be over-380 MW was recorded in the morning and early looked that DST did reduce the evening peak.afternoon during hot summer weekdays (Assirva- However, the actual amount may be much lessden, 2010). This confirms the trend noted recently than the 15 MW average that was been put for-with the massive use of ventilation, air-conditioning ward by the CEB (Elahee, 2008).and refrigeration in residential, touristic, commercialand office buildings. 2. Forecasts The stabilisation of the demand for electricity in In the light of the above, electricity demand fore-2009, together with a peak demand growth of only casts were revised slightly downwards in 20092%, were the direct results of Demand-Side (Hansard, 2009d). Figures 4, 5 and 6 depict the ini-Management (DSM) measures coupled with a slow- tial forecasted demands as from 2003 and the actu-ing of the economic growth to 2.5% in 2009. The al figures up to 2008. As noted, the demand forinfluence of GDP on peak electricity demand has 2009 is now known to be very close to that of 2008.already been evoked above. The obvious deduction from the graphs is that There were four DSM measures that interacted the forecasted CEB figures are well above actualto achieve the situation in 2009. values. The difference for 2010 stands at 50 MWi) Some 1 million Compact Fluorescent Lamps between the CEB forecast and the trend based on (CFLs) were distributed at subsidized costs to the the recent values recorded. In 2015, this gap general public from August 2008 to early 2009. increases to 100 MW. Even considering the latest As a result, the Government estimates that an forecasted values made public in 2009, the differ- average saving of 14 MW has been achieved ence is not less (Hansard, 2009d). The DSM impact during the evening peak (Hansard, 2009c). discussed amounting to a total average drop of Studies conducted at the University of Mauritius about 25 MW had not been considered in the CEB on Energy Management in the residential sector forecasts in 2003 and in 2007. indicates that the impact of CFLs was probably It can be argued that under the combined effect even more significant, of up to 25 MW (Baha- (1) of sustained DSM to bring a total reduction of door, 2009; Ramnarain, 2009). peak demand of 30 MW by 2012 and (2) of mod-ii) More than 25 000 solar water heaters were erate economic growth of between 2 and 5 % of installed in 2008 with the introduction of a direct GDP over the same period, the peak electricity subsidy of Rs 10 000 (approx. USD 300) per demand is likely to stabilise at about 400 MW. This unit. This has led to a reduced utilisation of elec- is close to the extrapolated trend shown in Figure 6. tric water heaters. It is reasonable to estimate an Similarly, Figure 5 depicts a more realistic trend average reduction of about 5 MW on the if DSM is pursued, along with moderate economic evening peak resulting from the latter measure. growth as is now predicted to happen over the nextIii) The Government introduced a national energy- few years by most specialists (EconomyWatch, saving campaign under the Maurice Ile Durable 2010). In any event, one of the key objectives of (MID) project focusing on all sectors. Sensitiz- DSM is to decouple GDP and energy requirement. ation on peak demand reduction was the focus This is made easier by the ongoing transforma- of a sustained campaign. Although the last tions in the economy of Mauritius as the services increase in electricity prices was in 2007, it is sector grows and diversifies at the expense of the10 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  11. 11. Figure 4: Forecast of peak electricity demand made in 2003 Source: CEB (2003) Figure 5. Forecast of total electricity demand and comparison with actual Source: CEB (2007a)energy-intense manufacturing and agricultural sec- ensure energy efficient practices related to appli-tors. ances and buildings respectively. DSM can be the key to meeting the energy iii) Solar-water heating, including in air-condition-demands, including morning peaks during week- ing and refrigeration, sustainable design ofdays in summer, provided the following specific ori- buildings and energy-efficiency improvement inentations are urgently adopted: industry and tourism should a full priority by thei) The Energy Management Office to facilitate private sector. DSM in all sectors, already announced by the iv) The onus should no more be on the CEB to pro- Government in the 2010 Budget, should be set vide 100% of electricity needed by industrial, up without delay (MoF, 2009). hotel and commercial promoters. The latterii) The Energy Efficiency Act under preparation and should be required to ensure optimal design and the Building Code should be promulgated to energy use on their facilities, including theJournal of Energy in Southern Africa • Vol 22 No 3 • August 2011 11
  12. 12. Figure 6. Forecast of peak electricity demand and comparison with actual Source: CEB (2007b) implementation of Energy Management pro- have had an estimated extra cost of 5%. The 15 grammes and recourse to renewable energy. MW coal/bagasse project scheduled for 2008 did New cities and similar projects should be sub- not happen. Thus far, no project has been complet- jected to strict environmental standards, includ- ed. The current intention of the CEB to promote the ing energy use. The proposed Land-Based construction of a 110 MW coal-fired plant and to Oceanic Industry (MLBOPL, 2009; MRC, 2010) invest in a 30 MW fuel oil-fired plant implies that is an example of such a new approach where the Base Scenario is very much the one on course, promoters are responsible for sustainable energy albeit with a delay of two, if not three years. input. The Compromise Scenario would have alsov) Pricing policy for energy, including Time-of-Use included the closing down of the 20 MW Beau Tariff for electricity and feed-in tariffs, as well Champ plant in 2009 and its replacement by an energy taxes should be integrated within a MID equivalent power plant in FUEL in 2009. This did Business Framework, together with incentive not happen. A 20 MW Waste-to-Energy project and packages for sustainable energy. a 25 MW wind farm, concomitant with the Compromise Scenario and expected to start oper-3. New MID scenario ating in 2009, are also behind schedule. In fact, theIn 2007, the Outline Energy Policy (OEP 2007c) , former has now been degraded to a 7 MW propos-was published focusing on changing the depend- al and is subject to much controversy just like theence of the country on oil to one on coal. The coal-only power plant.Compromise Scenario shown in Table 2 was the The concept of Maurice Ile Durable (Mauritiusone retained by the CEB. The All Sugar Cane Sustainable Island, MID) started to be formallyScenario was rejected on the basis that it would implemented in 2008. At the heart of the MID Table 2: Scenarios for power generation Source: OEP (2007d) Year Base Sugar cane CompromiseScenario Scenario Scenario 2008 30 MW diesel 42 MW coal/bagasse 15 MW coal/ bagasse 2009 42 MW coal/bagasse 50 MW coal 2010 50 MW coal 42 MW coal/bagasse 50 MW cCoal 2011 42 MW coal/bagasse 15 MW coal/bagasse 2012 50 MW coal12 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  13. 13. vision is the need to shift from fossil fuels, including top residues will be promoted. Biogas also cancoal, to renewables and to promote Demand Side be used. It favours the active and urgent imple-Management (DSM). The vision is that in 2028, as mentation of the wind power projects. Itmuch as 65% of the energy mix for electricity gen- assumes the coming into operation of a 30 MWeration in Mauritius should come from renewables fuel-oil power plant in 2010, as already pur-(MID Fund, 2008). This was confirmed by the chased by the CEB. In the long term, this facili-Prime Minister in December 2009 in Copenhagen ty should, however, switch to biofuels.with an appeal to help Mauritius achieve its objec- ii) Small plants: It also envisages the emergence oftive (IELS, 2009). Small Independent Power Producers (SIPPs) The delays imply that the capacity margin is at producing electricity either for the grid or foran extremely dangerous level of -70 MW currently local use (biogas, hydro, photovoltaic and windwith respect to the initial planning made in 2007 power units of less than 50 kW). A number of(OEP 2007e). Catastrophic black-outs would have , higher capacity renewable power projectshappened had it not been for the success of the should also start within that scenario (e.g. bio-DSM efforts explained earlier. Moreover, it has been gas, micro-cogeneration, trigeneration orreported that CEB is stretching the use of its hydropower projects of up to 2 MW). Stored orresources and this is not without undue risk. pumped hydropower will also be optimallyPossible accidents due to regular switching on-and- exploited to reduce peak of generators designed to operate constantly iii) DSM: The peak reduction due to DSM should becannot be excluded (Bibi, 2009). Similarly, equip- sustained under the MID Scenario and consoli-ment is being used beyond their normal lifetime. dated to reach a total of at least 30 MW by The Sugar-Cane Scenario offers best safe-guard 2012. This corresponds to an annual growth inin the medium-to-long term against negative capac- demand of 2 to 3 % as compared to the unsus-ity margins. The argument that it would have cost tainable 5 % average noted over the past5% more than the Compromise Scenario is not a decade.sound one to justify, alone, its rejection. Moreover,the re-engineering of the cane sector is a matter of Table 3: New MID Scenariostrategic importance for the country. 2010 30 MW fuel oil at Fort Victoria (confirmed, later Figure 7 illustrates the consequent evolution of switch to biofuel)the capacity margin in MW, including the benefit 2011 50 MW bagasse/coal cogeneration + 20 torelated to DSM, for a new MID Scenario that is 40 MW wind + SIPPsdescribed in Table 3. The initial planning with 2012 50 MW Bagasse/Coal Cogeneration + 50 MWrespect to the timely retirement of CEB old engines wind + SIPPsis retained in this scenario. The capacity margin isthe difference between the forecasted peak demandand the available capacity, allowing for mainte- Whilst being more sustainable, the new MID sce-nance, repairs and spinning reserve. The CEB initial nario also responds to immediate priorities relatedforecast for demand is used as benchmark in this to energy security, the re-engineering of the canecase. sector and ensuring availability of electricity. These The new MID scenario rests on three pillars: projects are technically ready to be implemented,i) Large plants: It replaces the controversial coal- some having lingered in the development stage for fired power plant by bagasse-coal plants that more than five years. The new scenario paves the operate in cogeneration with high efficiency in way towards reaching the key targets of the MID the context of the re-engineering of the cane project. The Compromise scenario, and even more industry. The use of other biomasses like cane- the Base Scenario, will drift the country away from Figure 7. Capacity margin (MW ) for New MID ScenarioJournal of Energy in Southern Africa • Vol 22 No 3 • August 2011 13
  14. 14. that vision with the reliance on coal peaking at 54% towards implementing DSM (including institutionalfor electricity generation by 2013 (MPU, 2007f; and regulatory measures) and introducing a coher-MREPU, 2009). It is to be recalled that the price of ent Business Framework to favour the new MIDcoal has known a rapid increase recently and that its Scenario for both centralized large plants andaccess costs, as well as other hidden costs, are more decentralized small power producers. The survivalthan 40% of the mine-to-user cost. Above-all in an of the cane industry as well as the opportunity ofera of global climate change, turning towards producing bioethanol from the latter industry areimported coal at the expense of indigenous closely related to the implementation of efficientresources is simply ridiculous. cogeneration plants where the use of bagasse, cane The main obstacle to the new MID Scenario, tops and leaves as well as biogas is promoted.however, is of a politico-administrative nature. A Sensitization, education and training should alsonew partnership must be defined between the pub- not be neglected both for the sake of DSM as for thelic and private sectors. The agreement reached by emergence of a green economy.the Prime Minister with sugar cane-producers in The need of back-up for renewable energy proj-December 2007 should serve as basis for innova- ects will be best handled through the integration oftive win-win agreements between the two parties. intermittent sources as well as the combination ofThe Cane Democratization Fund is an initiative in scattered decentralized units of diverse nature.the right direction opening up the ownership of Storage of energy and the recourse to forecasting ofbagasse-coal cogeneration plants to all stakeholders output from intermittent sources will be extremelyin a spirit of equity (MLP 2 010). , useful. Phased-out diesel or fuel-oil equipment as The controversial and over-delayed projects for well as disused hydropower facilities can still bea coal-only power plant and a Waste-to-Energy used to provide emergency response.plant are discarded under the New MID Scenario This paper discusses the transition to a sustain-and replaced by a more sustainable alternative. able energy future. After 2012, more ambitious projects like photovoltaic parks or geothermal4. Conclusion power can be considered in the context of a long-The maximum peak electricity demand will still term energy master plan.occur during week-days in summer, but in the To conclude, a holistic approach will have to bemorning rather than in the evening. Base and adopted putting politics and economy in the serviceCompromise scenarios for electricity supply have of society and its environment. This is the essencebeen proposed in the past based on overestimates of the MID project.of actual demand. DSM opens the way to a NewMID Scenario favouring energy efficiency and theuse of renewables. As a matter of fact, in spite of all the delays in Referencesthe installation of additional capacity, Mauritius has Autrey J. C, Kong W.C and Lau A.T., (2006). A Strategynot faced any catastrophic black-out yet. This is due for Enhanced Bioenergy Production from Biomass,to the grossly over-estimated forecasts, successful April 2006 jsp/projects/MauritiusDSM projects and lower economic growth. The %20Presentation.ppt (ac-cessed on 24th May 2010).energy-intensive sectors like manufacturing industry Assirvaden P (2010). Interview de P Assirvaden, ., . President du CEB, Mauritius Times, 22 Januaryand agriculture are also regressing as the expense of 2010.the services sector. Another factor that has helped Badurally Adam N., Elahee, M.K. and Dauhoo M.Z.,avoid blackouts, or even load- shedding, has been (2009). On the Influence of Weather and Socio-the overstretching of CEB facilities which is never Economic Factors on the Peak Electricity Demand indone without risk. Mauritius, Proceedings of the World Academy of There is the possibility of stabilizing maximum Science, Engineering and Technol-ogy, Volume 53,peak demand – in fact, achieving a high plateau Aug 2009, p406-417.spread over several hours in the morning – at Bahadoor Z., (2009). Energy Management: Impact ofaround 400 MW by 2012. This will also bring the Compact Fluorescent Lamps in Mauritius, B. Engcapacity margin to +17 MW by 2012. Thereafter, project report, Faculty of Engineering, University ofthere will be an optimal use of available installed Mauritius, April 2009.capacity, both during peak and off-peak periods, Bib C., (2009). CSG-Solidarity deposes to question pri-resulting in a growth of between 2 to 3% of elec- vatisation of power production and existing IPP agreements in Mauritius, demand annually. The corresponding peak news/viewinfo.php?recordid=15&recordid2 (Vieweddemand growth will be even less after 2012, partic- on 24th May 2010).ularly if the morning demand due to ventilation, air- Central Electricity Board, Mauritius (CEB, 2008). CEBconditioning and refrigeration is addressed proper- Annual Report, 2008, The capacity margin will also increase positively. Central Electricity Board, Mauritius (CEB, 2003). CEB Such outcomes will require urgent action Corporate Plan, 2003. http://ceb.intnet. mu/CEB/14 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  15. 15. CorporateInfo/cplan0304.pdf (Viewed on 24th May Energy Strategy 2009-2025, October 2009, p35. 2010). finalLTES.pdf (Ac-Central Statistics Office, Republic of Mauritius (CSO, cessed on 24th May 2010). 2008a; CSO, 2008b), Energy and Water Statistics Mauritius Research Council (MRC, 2010), Bringing out 2008, p13. Value from Deep Indian Ocean Water, www. gy.pdf (accessed on 24th May 2010). (Ac-EconomyWatch, (2010). Mauritius Economics Stat-istics cessed on 16th May 2010). and Indicators, economic- Ramnarain N., (2009). Impact of daylight saving time on statistics/country/Mauritius/year-2012 (Accessed on residential sector, B. Eng project report, Faculty of 24th May 2010). Engineering, University of Mauritius, April 2009.Elahee, M.K., (2009). Impact of DST in Mauritius, Proceedings of the World Academy of Science, Received 24 May 2010, revised 18 January 2011 Engineering and Technology, Volume 53, Aug 2009, p 431-433.Hansard, (2009a; Hansard, 2009b). Parliamentary Debates (Hansard, Mauritius), 30th May 2009, p3. (accessed on 24th May 2010).Hansard, (2009c). Parliamentary Debates (Hansard, Mauritius), 7th December 2009, p56. www.mauri- (accessed on 24th May 2010).Hansard, (2009d). Parliamentary Debates (Hansard, Mauritius), 30th May 2009, p3. www. mauri- (accessed on 24th May 2010).Institute of Environment and Legal Studies (IELS, 2009). Dependre à 60% des energies renouvelables d’ici 2025, dec20_copen- hagen.htm (Accessed on 24th May 2010).Kassim, S.H. Energy Storage towards meeting the peak electricity demand in Mauritius, B. Eng (Hons) Mechanical Engineering dissertation, Faculty of Engineering, University of Mauritius, March 2010, p14.Maurice Ile Durable Fund, (MID, 2008). Maurice Ile Durable Objectives, p1 file/ile.pdf (Accessed on 24th May 2010).Mauritius Land Based Oceanic Park Ltd. (MLBOPL, (2009). Expression of Interest for Equity Participation In An Eco-Park Based On Deep Sea Water Air- Conditioning At Flic En Flac. MLBOPL, Mauritius.Mauritius Labour Party (MLP 2010). Government , Manifesto, p22. Programme.pdf (Accessed on 24th May 2010).Ministry of Finance and Economic Development, Republic of Mauritius (MoF, 2009), Budget Speech Year 2010, November 2009. mu/portal/site/MOFSite/ (Accessed on 24th May 2010).Ministry of Public Utilities, Republic of Mauritius. (MPU, 2007a; MPU, 2007b; MPU, 2007d). Outline Energy Policy 2007-2025- Appendix I: Supply and Demand Forecasts up to 2013, p31. /mpu/file/Outline%20energy%20policy.pdf – (Accessed on 24th May 2010).Ministry of Public Utilities, Republic of Mauritius. (MPU, 2007d; MPU, 2007 e; MPU, 2007f). Outline Energy Policy 2007-2025- Appendix III: Systems Cost Analysis for the CEB Supply and Demand Forecasts up to 2013, p5.p20. file/Outline%20energy%20policy.pdf (Accessed on 24th May 2010).Ministry of Renewable Energy and Public Utilities (Republic of Mauritius). MREPU, 2009. , Long TermJournal of Energy in Southern Africa • Vol 22 No 3 • August 2011 15
  16. 16. Outdoor testing of amorphous and crystalline silicon solarpanels at ThohoyandouEric MalutaVaithianathaswami SankaranUniversity of Venda, South AfricaAbstract the community members generally resort to seekingThe use of solar panels is becoming one of the advice from us about the use and the installation ofoptions for some of the rural communities in solar panels to generate electricity. It has becomeLimpopo Province, South Africa, to get electrical necessary to assist the rural community regardingenergy for their radio and television sets as the the optimal use and the maintenance of the photo-national grid may not reach them in the near future. voltaic (PV) system that are usually available on theHence, dissemination of knowledge of how to use market. To provide a meaningful suggestion to thethe solar devices and their maintenance is crucial community, it is important to carry out field tests onfor these communities. This will be possible only if the suitability of the panels. Effecting a successfulthere is appropriate information available for the comparison between two different types of PVpotential end-users, installers and extension work- modules, would require the determination of theirers. With this in mind, an attempt has been made to outdoor performance at known irradiance and tem-evaluate the performance of an amorphous and a perature. For this purpose, we need to measure thecrystalline solar panel at our experimental site. open circuit voltage (Voc) and short circuit currentOutdoor tests were conducted to measure solar (Isc), which will in turn, lead to the measurement ofradiation, open-circuit voltage, short circuit current, the output power of the modules. We will alsocurrent-voltage (I-V) curve, fill-factor and conver- require the current-voltage (I-V) characteristics ofsion efficiency and hence to compare the perform- these modules to make a useful comparison of theirance of the two types of panels. It was found that efficiency.both types give a satisfactory performance for the The choice of a suitable PV module for a givenclimate of this region. location is generally guided by the actual energy output under outdoor conditions, the validity of theKeywords: Amorphous and crystalline silicon solar data supplied by the manufacturer and the implica-panels, solar radiation, peak power, I-V curve, con- tions on cost of installations. Though the power out-version efficiency, standard testing condition put and the efficiency rating of the panel given by the manufacture can be taken as the starting point, it is important to test these panels under outdoor conditions to access the validity of the data in a given location.1. Introduction 2. Experimental considerationsIn the north-eastern Limpopo, a large number of The present study was carried out at Solar Researchvillages are yet to be connected to the national elec- Site situated at the University of Venda, Thohoyan-tricity grid. People living in these villages opt for dou, Limpopo Province, South Africa, latitudesolar panels to get power for their television and 22.95°S and longitude 30.48°E. The site has aradio sets, which form a major source for accessing Delta-T Weather Station Mast, which was used toinformation from the regional communication sta- obtain the solar radiation and the temperature datations about the events taking place in the country during the performance of the study.and the world at large. The University of Venda is a In the present investigation an amorphous (a-Si)tertiary institution situated in the rural area of the far and a crystalline (c-Si) PV module are considerednorth of the Limpopo Province in South Africa and for evaluation and comparison. The module de-16 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  17. 17. Table 1: Specifications of the solar panelsSpecification Crystalline solar module Amorphous solar moduleManufacturer Astropower (AP-7105) Unisolar ( US-42-001416)Peak power (Pmax) 75W 45WMaximum power current (Imp) 4.4A 2.54AMaximum power voltage (Vmp) 17.0V 16.5VShort-circuit current (Isc) 4.8A 3.17AOpen-circuit voltage (Voc) 21.0V 23.8Vscriptions and the manufacturer data are given in (STC) (Treble, 1991).Table 1. Module or array open-circuit voltage and mod- The area of cross-section of each of the module ule cell temperature should be read concurrently,is 0.63m2, so that the radiation (energy) falling on since open-circuit voltage is a function of cell tem-the panels at any given time of the day is almost the perature. The module must be left in an open-circuitsame. The modules were purchased in South condition for a minimum of 15 minutes prior to theAfrica. taking of the open-circuit voltage reading to ensure In order to evaluate the performance of the two representative cell temperature reading (Markvart,panels under consideration, the solar radiation data 1994). Modules or arrays can contain cells, whichas well as the I-V curves are essential. Data Logger vary significantly in temperature throughout the(Delta-T 2000) was used to measure the radiation module due to hot spot heating, caused by crackedfalling on the experimental location and to measure cells, mismatched cell or cell shading. Short-circuitthe temperature (daily and ambient temperature), currents should be measured immediately after thewhile the DS tracer (DS Tracer 1996) was used to measurement of open-circuit voltage so that the testrecord an I-V curve by varying the electrical imped- conditions are nearly identical (Markvart, 1994).ance connected across the PV arrays terminals. Readings of the short-circuit current and irradianceVarying the impedance from zero to infinity causes must be made concurrently to minimize errors. Thethe array operating point to change from Isc to Voc. input signal (current-voltage to the DS Tracer) canWhen the module is connected, the DS-Tracer also be used to calibrate the DS Tracer for radiationaccomplishes the impedance change through its and temperature. The input signals provide neces-operating range and presents a set of current and sary details and after calibration they will be dis-voltage values that form the I-V curves. played along with the I-V curve (DS Tracer 1996). For designing and predicting the potential of any The calibration of the temperature can be carriedsolar appliances at a location, we need monthly out by recording the ambient temperature of theaverage daily solar radiation data on a horizontal panel using a thermometer and the details providedsurface. The operation and performance of PV could be utilized to get the temperature data on themodules mainly depend on system configuration curve. Apart from those methods, the temperatureand weather conditions. Furthermore, the module of the solar cell can be determined by the equilibri-temperature and solar irradiance determine the um between the sun’s radiation, the energy con-module’s operational curve and the coupling of the verted to electrical energy and the energy re-radiat-PV modules. In addition, the system components ed to cold space (Krishna et al., 2009)determine where a system will operate on the PVoperational curve (Hecktheuer et al. 2004). It is 3. Results and discussiondesirable to operate a system near the maximum It is a generally accepted fact that the performancepower producing point on the module’s operational of crystalline silicon solar cells varies from locationcurve either at all times (during the sunshine hours) to location (Lund et al., 2001). This variation isor during worst-case operation condition (Fitz- caused by the difference in irradiation at differentpatrick, 2004). locations, together with spectral response of the The outdoor conditions under which a PV mod- solar cell, temperature effects, etc. For solar cellsule is exposed are likely to be varying from the con- with a wide band gap (amorphous silicon solar cell)ditions stipulated by the manufacturer. Hence, the it was observed that no long-term light inducedmodule may not perform at the desired points on degradation exists in the recent modulesthe I-V curve in order to harness the maximum (Gottschalg et al., 2004). Lund et al., have studiedexpected output. Commercially available PV mod- the stability of the amorphous silicon modulesule rating and operating parameters are provided under outdoor conditions and reported that the effi-with respect to the standards of American Society ciency of the amorphous solar cell is stabilized afterfor Testing Materials (ASTM) at Standard Reporting the initial degradation. It was also deduced thatCondition (SRC) or Standard Testing Conditions under the actual working conditions the amorphousJournal of Energy in Southern Africa • Vol 22 No 3 • August 2011 17
  18. 18. solar cell could generate electrical power more Commercially available panels are rated with asteadily compared with the crystalline solar cell peak power, but it should be noted that generally(Lund et al. 2001). this peak power (observed maximum powers) will not be harnessed since the factory testing condition and the outdoor conditions are not similar. The observed maximum powers for the crystalline and amorphous modules for different months are given in Table 2. Though the sunshine duration is about 10 hours on a sunny day at the experimental site, readings are only presented from 10H00 to 15H00. From Table 2, it can be noted that the observed maximum power increases until it reaches a maxi- mum at mid-day and drops as it moves to the evening. It is observed that a maximum of 60W is obtained for crystalline against the rated value of 75W and 33W for amorphous against the rated Figure 1: Solar radiation at 12H00 for a period value of 45W (Maluta & Sankaran. 2007). The vari- of one year ation in the observed maximum power is more in crystalline module.3.1 Solar radiation characteristics and peak It may also be seen that the observed maximumpower power variation from the average value does notFor the evaluation and assessment of the perform- vary significantly in the case of amorphous. In thisance of a photovoltaic module at a given location, work, we have compared the variation by lookingit is necessary to get an overview of the solar radia- at the difference between the hourly observed max-tion characteristics. Measurements of solar radiation imum powers for each month. It can be observedat different times of the day during a period of one from the data that the variations of the crystallineyear were made. Figure 1 represents the radiation at and amorphous for the whole year are almost simi-12H00 for different months under study at the lar in magnitude. These results are consistent withexperimental site. It can be seen that an average earlier results observed for amorphous PVmaximum per month of 870 W/m2 was measured (Gottschlag et al., 2004).on a horizontal plane. Peak power is the maximum power, which is 3.2 I-V characteristicsgenerated by a solar panel in full sunshine. The other important electrical characteristics of a Table 2: Observed maximum power for crystalline and amorphous PV modules Observed maximum power for Observed maximum power for crystalline module (in W)1 amorphous module (in W)2 Time of the day(in –H00) Time of the day(in –H00) 10 11 12 13 14 15 10 11 12 13 14 15Jul 39 46 48 42 38 36 19 26 26 25 24 20Aug 46 47 52 48 47 45 21 27 29 27 24 23Sep 49 54 55 55 52 48 23 29 30 29 26 25Oct 50 55 57 54 51 50 25 29 31 28 27 26Nov 52 55 59 53 52 50 28 30 32 29 28 26Dec 52 58 60 56 53 50 28 31 33 29 28 25Jan 54 55 58 53 52 50 27 29 32 28 27 25Feb 48 50 55 51 45 43 27 28 30 28 26 24Mar 48 50 54 47 46 44 25 26 29 27 26 21Apr 44 49 53 51 50 46 24 26 28 27 26 25May 44 48 51 50 46 45 23 27 28 26 25 23Jun 43 46 49 44 42 41 20 28 27 25 25 23Notes:1. The maximum rated output power for crystalline (c-Si) module is 75W.2. The maximum rated output power for amorphous (a-Si) module is 45W (the data was taken from July 2003 until June 2004)18 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011
  19. 19. module are, short-circuit current (Isc), open-circuit voltage (Voc) and maximum power point (Pmax). A few sample curves obtained in the present study are given in Figure 2. Maximum power is generated at only one point on the I-V curve, at about the ‘knee’ of the curve, which represents the maximum effi- ciency of the solar device in converting sunlight into electricity. The maximum Voc obtained for amorphous Figure 2A1: for c-Si Figure 2A1: for a-Si solar panel is about 21.78V, whereas for the crys- module (Oct) module (Oct) talline solar panel the maximum Voc obtained is 19.83V both in the month of December, when we get the maximum radiation. The open-circuit volt- age increases with an increase in the incident radia- tion and time of the day. It can be noted from Table 3 that the values of Voc during mid-day for the entire period of study for both modules do not vary significantly. Though variations in the values of the open-cir- cuit voltage of an amorphous module and crys- talline module are very small, it is noted that the Voc Figure 2A1: for c-Si Figure 2A1: for a-Si is nearly the same for the amorphous module from module (Nov) module (Nov) September to June. The maximum value for Isc, obtained for amorphous solar panel is 2.736A, while the maximum value for Isc obtained for the crystalline panel is 4.566A. It is interesting to note that these maximum values are recorded in December 2003. A sample curve of the variation of Isc with the irradiation data collected for the month of May in the present study is given in Figure 5. It may be observed from this figure that as the irradiation increases the short circuit current also increases. Figure 2A1: for c-Si Figure 2A1: for a-Si This observation is concurrent with the observation module (Dec) module (Dec) that the current generated by the solar energy is proportional to the flux of photon with above-band-Figure 2: Sample I-V curves for c-Si (crystalline) gap energy. This is because the irradiance increases and a-Si (amorphous) modules for the months in the same proportion of the photon flux, which, in of October, November and December, 2003 turn, generates a proportionately higher current Table 3: Open-circuit voltage and short circuit voltage for both crystalline and amorphous solar cells at 12H00 Radiation (Wm-2) Crystalline Amorphous Voc (V) Isc (A) Voc (V) Isc (A)Jul 2003 460 19.00 3.552 20.50 2.136Aug 2003 500 19.30 4.268 21.78 2.220Sep 2003 513 19.37 4.180 21.25 2.443Oct 2003 500 19.42 4.468 21.59 2.642Nov 2003 810 19.78 4.542 21.50 2.549Dec 2003 870 19.83 4.566 21.10 2.736Jan 2004 801 19.58 4.540 21.08 2.478Feb 2004 792 19.32 4.455 21.70 2.378Mar 2004 500 19.75 4.345 21.57 2.565Apr 2004 510 19.54 4.435 21.56 2.363May 2004 533 19.20 4.260 21.50 2.400Jun 2004 490 19.30 3.752 21.70 2.236Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011 19
  20. 20. (Markvart, 1994). It must be noted that in this work, increases. It can be seen from equation (1), that asonly the solar radiation on a horizontal surface have the irradiation increases the parameters in thebeen considered. Other factors such as the differ- numerator also increase and we generally expect anence in the spectral responses to irradiance at vary- increase in the conversion efficiency. As stated bying incidence angle, and to irradiance of varying Dinçer et al., the effect of increase in the cell tem-spectral composition are not considered. perature also play a role on the conversion efficien- cy as Voc will decrease at high cell temperature (Dinçer et al., 20101). However, the increase in the open-circuit voltage and hence the peak power, is not remarkable while the irradiation increases. Hence, it is generally expected that the conversion efficiency decreases as the irradiation increases (Gottschalg et al., 2004; Markvart, 1994 & Stone, 1993). As evident from Figures 4 and 5, a similar trend Figure 3A: Variation of ISC versus irradiation is observed in our calculation. The average conver- for May 2004 for c-Si module sion efficiency of the crystalline module during our present study is 15.3 whereas the amorphous mod- ule conversion efficiency is 8. These values com- pare favourably with the generally expected values which are approximately 15-17 for crystalline mod- ules and approximately 5-7 for amorphous mod- ules (Valizadeh 2001; Graham & Ficher 1994). Figure 3B: Variation of ISC versus irradiation for May 2004 for a-Si module3.3 Conversion efficiencyThe conversion efficiency of a solar cell is the per-centage of the solar energy shining on a PV devicethat is converted into electrical energy. The efficien-cy of energy conversion is still low, thus requiringlarge areas for sufficient insulation and raising con-cern about unfavourable ratios of energies requiredfor cell production versus energy collected (Dinçer Figure 4: Conversion efficiency of theet al., 20101). Thus, not all energy from sunlight crystalline and amorphous module at differentreaching a PV cell is converted into electricity. This times of the day (July 2003–June 2004)may be due to the reflection and scattering of solarradiation in the afternoon and also the increase inthe cell temperature (Dinçer et al., 20101). Hence, 3.4 Transposing to standard testingthere is an increase in the amount of light reflected conditionaway from the cell surface. Therefore, minimizing Commercially available solar panels generally listthe amount of light reflected away from the cell’s the data for short-circuit current, open-circuit volt-surface can increase the module’s conversion effi- age at standard test condition (STC). When theseciency. modules are exposed to the outdoor conditions at The conversion efficiency can be computed an experimental site, it is generally not possible tousing the following relation (Markvart, 1994): get the same values for the module parameters. Obviously the irradiation and temperature of the (1) modules will not remain constant. Hence, an attempt was made to transpose the values of Voc and Isc obtained in the present investigation to theThe fill factor (FF), short-circuit current (Isc) and STC. For this purpose, the following two equationsopen-circuit voltage (Voc) increase as the irradiation (Hammond Backsus, 1994) were used.20 Journal of Energy in Southern Africa • Vol 22 No 3 • August 2011