Sizing solar home systems for optimal development impact

Energy Policy 42 (2012) 699–709

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Sizing solar home systems for optimal development impact M. Bond, R.J. Fuller, Lu Aye n Renewable Energy and Energy Efficiency Group, Department of Infrastructure Engineering, The University of Melbourne, Victoria 3010, Australia

a r t i c l e i n f o

abstract

Article history: Received 9 August 2011 Accepted 24 December 2011 Available online 12 January 2012

The paper compares the development impact of three different sized solar home systems (SHS) (10, 40 and 80 Wp) installed in rural East Timor. It describes research aimed to determine whether the higher cost of the larger systems was justified by additional household benefits. To assess the development impact of these different sizes of SHS the research used a combination of participatory and quantitative tools. Participatory exercises were conducted with seventy-seven small groups of SHS users in twentyfour rural communities and supplemented with a household survey of 195 SHS users. The combined results of these evaluation processes enabled the three sizes of SHS to be compared for two types of benefits—those associated with carrying out important household tasks and attributes of SHS which were advantageous compared to the use of non-electric lighting sources. The research findings showed that the small, 10 Wp SHS provided much of the development impact of the larger systems. It suggests three significant implications for the design of SHS programs in contexts such as East Timor: provide more small systems rather than fewer large ones; provide lighting in the kitchen wherever possible; and carefully match SHS operating costs to the incomes of rural users. Crown Copyright & 2012 Published by Elsevier Ltd. All rights reserved.

Keywords: SHS Development impact East Timor

1. Introduction Solar home systems (SHS)—a standard package combining PV module(s), battery and lamp(s)—are commonly used for off-grid lighting in developing countries. A policy maker seeking to determine the optimal size of SHS to promote for widespread use in rural communities faces a difficult decision. On what basis should the size of the SHS be selected? In cases of single system purchases such decisions may be safely left to the households concerned. Van der Vleuten et al. (2007) note that successful commercial markets for SHS operate in countries such as Kenya, Morocco, Sri Lanka, China and Zimbabwe, amongst others. The market approach provides householders with the opportunity to select a SHS best suited to their needs and budget. Nieuwenhout et al. (2001), however, estimate that one third of systems are likely to be provided through non-commercial channels. In those instances, where a government or donor agency promotes particular hardware, bureaucrats not householders decide on what size system to promote or subsidise. Nieuwenhout et al. (2001) found that typical SHS system sizes range from 10 to 110 Wp, with the most common sizing being in the range 45–54 Wp. Morante and Zilles (2008), in their study of SHS in Brazil and Peru, note a similar predominance of systems in this size range. They argue, however, that some users require much larger SHS than the average and that SHS programs should be designed to accommodate these households.

n

Corresponding author. Tel.: þ61 3 8344 6879; fax: þ 61 3 8344 6868. E-mail address: [email protected] (L. Aye).

Where governments or donors have a say in determining SHS sizing, a question arises as to what size is optimal. For a given budget, should many small systems or fewer large systems be provided? What will produce the best development outcome? As the authors noted in a previous paper discussing policy for the introduction of SHS in East Timor, the literature is silent on this matter (Bond et al., 2007). If there is no or a weak correlation between SHS size and development impact then small SHS may provide much of the benefit of larger systems. If that is the case, then there is a strong incentive to promote smaller systems rather than larger ones. Conversely, if size and impact do correlate then greater consideration needs to be given to larger systems. To investigate the size/development impact relationship, the research described here assessed three sizes of SHS installed in East Timor. Development impact was defined as ‘good change’ with Timorese SHS users articulating both the types of change they valued and their relative importance. Each of the systems evaluated provided electricity for lighting purposes only, limiting the ‘development impact’ to those changes associated with the use of electric lighting. It should be noted that the relevant initial findings were reported in Bond et al. (2010).

2. Small, medium and large SHS The research evaluated the development impact of three sizes of SHS, namely 10 Wp (‘small’), 40 Wp (‘medium’) and 80 Wp (‘large’) systems. The 10 Wp systems had been installed by a

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non-government organisation, the Communidade Edmund Rice (CER). CER operates a broad range of community development activities in the Railaco sub-district of Ermera, several hours drive west of East Timor’s capital, Dili. CER’s solar PV lighting program commenced in 2004 and has installed almost 1000 systems across five sucos or village clusters (Tynan 2006, personal communication.), 26 August). CER’s program operated on a principle of universal access and aimed to provide a subsidised service to as many households as possible with the limited budget available. Consequently, the solar lighting systems CER provided were a low-cost design using a small PV module to operate a single light. The first 600 systems were SHS consisting of a 10 Wp panel, a 5 W compact fluorescent lamp (CFL), and a 12 V 9 Ah battery on which a charge controller was directly mounted. The 5 W CFL was mounted in a luminaire fitted with a reflector to improve lighting efficiency. Households were required to make a one-off payment of $10 before their system was installed. No ongoing user fees were charged. An estimate of the design performance for the CER systems is set out in Table 1 based on a minimum solar insolation of 4.6 kWh/m2/day (NASA 2006) and an average of five hours of lighting use per night (equal to the average daily demand identified during the research). It may be noted that the system output and daily demand and are almost equal. The NASA insolation data suggests that the CER systems are likely to experience some instances of low-voltage shut down during the three cloudiest months each year—February, April and December. The ‘medium’ sized SHS evaluated for the research were installed as part of the United Nations Development Programme’s (UNDP) ‘Participatory Rural Energy Development Programme’. As the title implies, this project considered energy broadly, rather than just electricity, and in addition to SHS trialled biogas, microhydro and fuel-efficient stoves. SHS were installed in 68 households in six communities spread over three districts on the north side of East Timor—Dili, Liquica and Manatuto (da Silva, 2006, pers. comm., 29 August). The six communities represented a mix of coastal and mountainous areas, locations that were remote from and close to urban centres and four different Timorese language groupings. In each of the six project communities UNDP staff selected ten households by lottery to receive a SHS (a further eight systems were installed in Burlete, one of the six communities). In these households UNDP installed a 40 Wp system with three lamps—12 W CFL, 3 W CFL and 1 W LED. Systems were installed over a three month period between January and March 2007. The systems had no DC power socket or AC inverter, but UNDP Table 1 SHS physical parameters and theoretical design performance. System performance

Physical parameters Module rated power Number of lamps Nominal system voltage Battery capacity Peak power demand

Small (CER)

Medium (UNDP)

Large (RDTL)

Unit

10 1 12 9 5

40 3 12 117 16

80 4a 12 100 40

Wp V Ah W

118 48 3

220 165 14

Wh Wh %

Theoretical design performance Daily system output 29 Daily energy demand 25 Battery daily depth of 23 discharge Days of autonomy 1.7

12

2.9

days

a A few of the RDTL SHS were supplied with six lamps. In that configuration the daily demand rises to 215 Wh, the daily DOD to 18% and days of autonomy falls correspondingly to 2.2.

purposefully selected a system with more than one light with the expectation that this would enable income generating activities to be carried out in the evening. Whilst households were expected to make an upfront contribution of $15, none of the recipients reported having done so and very few were paying the intended $2 monthly maintenance fee. Design operating performance (Table 1) was estimated for the average daily demand determined through the household survey carried out for the research. The system output and the battery capacity are large in comparison to the daily demand (Table 1). This results in very low levels of battery discharge for UNDP systems and suggests that the UNDP batteries could be expected to achieve a seven to ten year operating life (Solar Energy International, 2007; Trojan Battery Company, 2008). The ‘large’ SHS evaluated in this research were installed by the Government of East Timor (RDTL) in Cairui, Manatuto district. Cairui is rural and remote, as was the case with the CER and UNDP locations, but the arrangement of communities was unusual. Five of the seven communities that have traditionally viewed themselves as part of Cairui are co-located in a single ‘Cairui’ village of about 500 households. In 2007 the Government installed 240, 80 Wp systems throughout Cairui and in nearby Samalai in response to community demands for increased access to services (Ximenes, 2007, pers. comm., 18 October). The RDTL systems consisted of a pole-mounted 80 Wp PV module, four 10 W tubular fluorescent lamps, a sealed lead-acid battery of unknown capacity (estimated to be 100 Ah based on its physical dimensions) and a 10 A controller. A few of the systems (approximately 40 SHS) were provided with six 10 W lamps. Recipient households were selected by community leaders and some chose to share their SHS with a neighbour (each household being fitted with two luminaires). Whilst the systems were provided by the Government free of charge, the community leaders decided that each household should pay a monthly fee—$1 for systems with four lamps or $2 per month for six lamps. According to a Timorese renewable energy adviser consulted by the Government on design of the systems, the RDTL SHS were designed to provide three days autonomy and a two-year battery life (Almeida, 2007, pers. comm. 18 October). Assuming that the battery capacity is approximately 100 Ah, battery average DOD for the four lamp systems sits comfortably within the recommended 10–20% of battery capacity (Solar Energy International, 2007). Based on the NASA (2006) minimum insolation data there are no months of the year when the system could be expected to shutdown automatically because of low voltage. For the six lamp systems, however, the output during periods of minimum insolation is very close to the system daily demand and those households could expect to experience several months each year when their systems shutdown occasionally due to low battery voltage. When data collection for this research was conducted, ten months after installation, faults had been reported with batteries or controllers in about ten per cent of systems.

3. Research methodology The literature details a wide array of evaluation methodologies for rural electrification projects, including those using SHS technology. Initial consultations with user households (as described below) highlighted that purely financial approaches, for example that used by Meier (2003), would be unable to deal with the many non-financial, social benefits that users valued. Complex economic approaches, such as used by ESMAP (2002) in the Philippines, monetise social benefits (such as entertainment opportunities and education outcomes) but are expensive to conduct and require large sample sizes. Less detailed survey techniques have also been used to

M. Bond et al. / Energy Policy 42 (2012) 699–709

capture social benefits such as health, education, leisure, and convenience (Mehta (2004), Chaurey (2000) and Gustavsson and Ellegard (2004)) but are narrow in scope and exclude end users from the analysis process. Recent practice has seen a move towards combining surveys with qualitative enquiry, such as that recommended in the ESMAP (2003) Monitoring and Evaluation in Rural Electrification Projects: A Demand-Oriented Approach. The ESMAP approach was adapted as the basis for comparing the development impact of the three sizes of SHS in East Timor. Adaptation of the tools commenced with a set of Initial Community Consultations held with five rural communities in East Timor (four with experience of SHS electrification and one without). These consultations used participatory rural appraisal techniques to investigate community perceptions regarding electrification generally and SHS in particular. The aim was to learn from rural Timorese households how they use electricity (or would use electricity if it was available) and, with respect to SHS, to understand what they value in their systems and why. The results enabled testing of the researchers’ initial assumptions about potential benefits of electrification, drawn from studies elsewhere, and identification of benefits that are highly valued by East Timorese communities. Results from the initial consultations revealed two aspects of SHS that the households across the five communities thought were important. First, a range of activities were identified for which SHS lighting was found to be particularly useful. These benefits—termed here ‘lighting-derived benefits’—were classified into four categories:

 Studying, reading.  Domestic tasks (such as looking after children, preparing food, cleaning).

 Productive tasks (making objects for sale, trade or use at home 

such as baskets, cloth, furniture production, and processing of agricultural products). Social interaction (meetings and gatherings either within families or involving the wider community).

The second type of benefits were attributes of SHS that users found intrinsically beneficial in comparison to other forms of

701

lighting and are termed here ‘intrinsic benefits’. Four types of intrinsic benefits were identified:

 Light (quality and level of illumination).  Financial (cost savings in comparison to non-electric light).  Health (perceived health improvements due to elimination of smoke and fumes).

 Convenience (ease of turning on and use in all weather conditions). Having identified these two categories of benefits it was possible to develop a participatory evaluation (PE) process that enabled SHS users to assess the changes brought about by their SHS. The PE consisted of six exercises that assessed each of the lighting-derived benefits and compared the relative importance of the lighting-derived and intrinsic benefits. Two additional exercises investigated household willingness-to-pay for additional lighting services. Whereas the Initial Community Consultations used open-ended questions to explore values and benefits broadly, the PE exercises were developed around a set of fixed questions to facilitate comparison of the results across the many groups involved in the research. The PE tool was applied in six communities for each project type. In each community, a sample of approximately ten women and ten men were selected from SHS-user households. These participants were facilitated to work through the eight PE exercises in small groups of women or men. Materials used in the PE exercises were entirely pictorial which enabled full participation by community members irrespective of their level of literacy. Where scoring was required, groups of participants created their own representation of change or weighting using corn kernels or coffee beans (as illustrated in Fig. 1). Facilitation was provided by experienced Timorese community facilitators working in Tetun, the national language of East Timor. The participatory nature of the PE exercises enabled the participants to discuss and clarify both their understanding of the exercises and their own experiences in the local dialect for each community. To supplement findings from the PE, a Socio-economic Household Survey (SES) was developed. This was based upon the ESMAP

Fig. 1. Domestic tasks, ease—scoring template for women’s group, Bohemata village, CER project.

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DOA model (ESMAP, 2003) and covered household demographics, usage of and expenditure on non-electric energy sources, and user experience with SHS. The survey also included a section exploring user perceptions of the performance and value of their system. Across the eighteen communities where the PE exercises were held, four hundred participants were involved (181 female and 219 male), working in 77 small groups (31 groups of female and 46 of male). Across all locations the PE process lasted an average of 3 h, requiring almost 60 h of participatory investigation for the three projects. SHS users generally participated very enthusiastically in the PE exercises. Application of the PE process in the first community was considered a trial for the facilitators and the results from the six groups involved were discarded from the research set. Of the other 71 groups, four were observed to engage very poorly and either copied analysis from other groups or were unable to explain their scoring or ranking. Results from these four groups were also discarded. For the UNDP project, in which the fewest systems had been installed, every user household was invited to participate in the PE exercises. For CER and RDTL communities, selection of participants for the PE was determined by community leaders, usually the Chefe Aldeia (village leader). This precluded the use of random sampling but was an essential element of respect for local cultural practices. For the CER project many households had received more than one SHS and many had experienced some form of fault or failure with their system. In response, the CER communities were selected so as to maximise representation from households with a single SHS in working order. For the SES, 65 of the 78 UNDP user households were surveyed. In CER and RDTL communities, random sampling of households was undertaken from lists of user households provided by community leaders. Eighty-two surveys were completed for CER households and 58 for RDTL households. Ten of the RDTL households surveyed had six-lamp systems, a proportion which matched the occurrence of six-lamp SHS amongst the 240 RDTL systems.

4. Results 4.1. Lighting-derived benefits 4.1.1. Study During the Participatory Evaluations groups of users were asked to consider whether their SHS had made any difference to the ease of studying and/or reading in their household. Participants were able to indicate their response within a five-category scale ranging from ‘more difficult’ to ‘much easier’. None of the groups from any project judged their SHS to have made study/ reading more difficult or to have made no difference. Most of the responses fell into the ‘easier’ or ‘much easier’ categories (Table 2). To strengthen statistical testing by eliminating the low frequency responses, the ‘little easier’ and ‘easier’ responses were consolidated into a single category. Testing of the results for these categories showed no statistically significant difference between the three project samples (Chi-square test, P value 0.47). ‘‘A p-value is the probability that the value of the test statistic is at least as extreme, relative to the null hypothesis, as the value that was observed, when the hypothesis is true’’ (Ryan, 2007). Similarly with the duration of reading and study, most user households reported an increase (Table 3). Between CER and RDTL groups—those with the smallest and largest SHS—there was no statistically significant difference in the reported increase in duration (P value 0.21). UNDP households, with the ‘medium’ sized systems, were more likely to report that study/reading had

Table 2 Improved ease of study with a SHS, frequencies by project.

Little easier Easier Much easier Total

CER

RDTL

UNDP

5 10 8 23

1 13 9 23

3 7 11 21

Table 3 Change in study duration due to SHS frequencies by project.

Much more Little more/more Total

CER

RDTL

UNDP

4 18 22

8 15 23

12 9 21

increased ‘much more’ with installation of their SHS. Discussions with households in one UNDP community (Ermera) revealed that several of the houses with a UNDP SHS had become ‘hubs’ for evening study. These users reported that not only did their children study more because of the SHS but that their neighbours’ children were also studying more. Data regarding reading and study were also collected within the socio-economic household survey and provided a means to cross-check and further analyse the PE results. Analysis of response patterns for the small and large SHS showed no significant difference in the proportion of adults or children who habitually read/study or who read/studied on the evening prior to the survey. There was also no difference in the mean duration for regular study across the three sample or for study on the evening prior to the survey. The SES included questions regarding the continued use of traditional lighting sources (candles and home-made kerosene lamps) for study/reading. Use of these lighting sources was found to have been completely eliminated in households with the ‘large’ RDTL systems. A small number of CER (‘small’) and UNDP (‘medium’) households (five and seven, respectively) continued to use these sources even though their SHS were functioning. Had study/reading benefits been strongly related to system size one might have expected that the UNDP and RDTL results would be similar. Both systems provide multiple lights and the largest UNDP CFL (12 W) provides better task lighting than the 10 W RDTL lamps. Despite these similarities, UNDP systems (at the time of the evaluation) had not eliminated the use of candles and kerosene for reading. The explanation of this unexpected outcome may lie in the fact that most UNDP households still require the use of traditional lighting sources in the kitchen since none of the three UNDP lamps was installed in the kitchen. This was a conscious decision made by the UNDP project technical staff who were concerned that lamps installed in the kitchen would deteriorate quickly in the smoky environment. It is possible that while there is ongoing use of candles and kerosene lamps for general lighting in a household, people will continue to use these light sources to supplement electric task lighting. Elimination of candles and kerosene lamps for study/reading suggests that the RDTL systems had a greater impact on ease of this task than the medium and small systems. Given the results of the PE however, where all systems were reported to have made study/reading easier, the difference in impact may be characterised as ‘slight’. Overall, both the PE and SES results suggest only a weak correlation between system size and impact on study/ reading.

M. Bond et al. / Energy Policy 42 (2012) 699–709

4.1.2. Domestic tasks Important domestic tasks identified during the Initial Community Consultations included looking after children, preparing food for eating and storage, cooking meals, washing clothes and dishes, and cleaning the house. Most of these activities can be conducted with low levels of illumination and hence area lighting rather than task lighting is the main requirement for these domestic tasks. During the PE most groups for the medium and large systems reported that carrying out domestic tasks was ‘easier’ or ‘much easier’ as a result of their SHS. The response for users of the small systems was more complex than for the other two project samples. The modal response was ‘little easier’ but almost as many groups rated domestic tasks as being ‘much easier’ as did those with a rating of ‘little easier’ (Table 4). The reason behind the bi-modal response for CER households was that during the PE they noted that their SHS had made carrying out some of the domestic tasks much easier and other tasks no easier at all. The absence of lighting in the kitchen for most CER households means that the small SHS do not provide any assistance with some important domestic tasks, principally cooking. It should be noted, however, that not all food preparation is undertaken in the kitchen. Food is also prepared in the main house building as well as the dedicated kitchen (Fig. 2 shows a typical rural Timorese dwelling with the kitchen built separately from the main house). The rating approach used in the PE allowed groups to reflect this complexity by allocating their scoring tokens across a number of results (from ‘no change’ to ‘great change’). As with CER systems, the UNDP systems also provided no light in the kitchen, since none of the three lamps was installed in there. This was a conscious decision made by technical staff for the UNDP project who were concerned that lamps installed in the

Table 4 Improve ease of domestic tasks with a SHS, frequencies by project.

Same Little easier Easier Much easier Total

703

kitchen would deteriorate quickly in the smoky environment. Absence of lighting in the kitchen, however, was not reflected in the UNDP PE results. Comparing the small and large systems only, the PE clearly indicates that larger RDTL systems made completion of domestic work easier than the single lamp CER systems. The SES included a perception question about the usefulness of SHS for domestic tasks. On a four-point scale from ‘not useful’ to ‘very useful’, respondents from all projects overwhelming opted for ‘useful’. This response accounted for 83% of CER responses and 97% of RDTL responses suggesting that the gap between the usefulness of small and large systems for domestic tasks is moderate rather than substantial. 4.1.3. Productive tasks There was relatively little difference in the results of the PE exercises for users of the large and small systems. Most RDTL groups rated the change as ‘easier’. CER ratings were approximately evenly spread between ‘little easier’, ‘easier’ and ‘much easier’ (Table 5). When results for both projects were consolidated into two categories—‘little easier/easier’ and ‘much easier’—there was no statistically significant difference between the RDTL and CER results (P value 0.15). As with domestic tasks, the CER results displayed perceptive use of the PE exercise on the part of the participants. Approximately half of the groups used the range on the scoring template to distinguish between those tasks requiring task lighting and those suited to area lighting. Activities requiring task lighting such as sewing or cloth weaving were rated to be a ‘little easier’ with use of the SHS and those using area lighting such as basket weaving and broom making were rated as being ‘much easier’. Clearly, the single 5 W CFL of the CER systems is very useful when area lighting is required but less useful for productive activities requiring task lighting. The UNDP and RDTL systems, with their Table 5 Improved ease of productive tasks with a SHS, frequencies by project.

CER

RDTL

UNDP

1 10 4 8 23

0 2 15 6 23

0 3 5 13 21

Little easier Easier Much easier Total

CER

RDTL

UNDP

7 9 7 23

2 18 3 23

1 10 10 21

Fig. 2. Typical house in Kolhuinamu with kitchen (left) built separately to the main house.

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M. Bond et al. / Energy Policy 42 (2012) 699–709

more powerful lamps, meet the needs for both these types of activities. The PE exercises enquired directly into changes in duration of productive tasks as a result of SHS use. There was no statistically significant difference between results for the small and large systems (P value 0.78) and the modal response for each sample indicated that ‘more’ productive activities were carried out. Time spent on productive tasks was not assessed directly in the SES but respondents were asked about their waking hours. Longer waking hours could create opportunities for more productive work (and also for the other types of activities). The mean waking hours for adults was 15.9 h and for children 14.7. There was no significant difference in the means for adult males or for children (P value 0.23 and 0.28, respectively). For women, however, respondents from households with the largest systems had slightly shorter waking hours than those from households with small or medium systems (P value 0.01). This suggests that there is no correlation between larger systems and longer waking hours, which in turn might have been allocated to increased duration of productive tasks. The research did not attempt to quantify monetary benefits of productive tasks or attribute changes in income to SHS use. The SES did, however, ask respondents about the use, or potential use, of their SHS for home businesses. The results showed no significant difference across the three samples in the proportion of households who operated home businesses (P value 0.28). Respondents from all projects overwhelmingly perceived their SHS as being ‘useful’ for running an existing home business or potentially running a business in the future. Ninety per cent of existing businesses involved activities requiring area lighting such as running a small shop (50% of all businesses), agricultural processing (20% of businesses) and household-level bakeries (10% of businesses). For these activities the area lighting of small and large systems provides similar benefit.

4.1.4. Social interaction During the PE exercises, groups from all three projects were strongly positive about the contribution their SHS made to improving the ease of social interaction. The modal response for CER and UNDP groups was ‘much easier’ and there was no statistically significant difference between the response patterns for these projects (Table 6). RDTL groups were less emphatic in their response, being more likely to characterise the impact as having made social interaction ‘easier’ rather than ‘much easier’. This response for RDTL groups is unlikely to be associated with the number or quality of SHS lamps. All RDTL households had at least one lamp located in a space used for communal purposes (generally a living room or veranda) and during discussion none of the participants suggested that their systems provided too much light. On this basis, the difference is likely to be explained by the more restrained approach RDTL groups took to scoring improvements than their CER and UNDP counterparts. With respect to duration of social interaction, the modal response for increased duration amongst CER and RDTL groups was ‘more’ and there was no statistically significant difference between the results (P value 0.22). UNDP groups scored their Table 6 Improved ease of social interaction with a SHS, frequencies by project.

Little easier Easier Much easier Total

CER

RDTL

UNDP

2 10 11 23

0 20 3 23

0 7 14 21

systems as having provided the greatest increase in duration with most groups reporting social interaction taking place ‘much more’ than before their SHS was installed. It is plausible that since relatively few households in UNDP communities had access to electric lighting—only 10 households were selected to receive a SHS in each community—those households with SHS became a focus for social interaction. Results from the SES support this position, with female UNDP respondents reporting greater frequency of visits than women from CER and RDTL households. The strong rating for CER systems for this activity type is not unexpected. Several households with small, CER systems were visited and in each location the single CFL lamp was always placed in a location that would illuminate communal spaces. Given that area lighting is required for social interaction, even a single-lamp system is likely to make a substantial difference to the convenience of conducting activities such as socialising with family, neighbours and friends, eating together or holding meetings with community leaders. 4.1.5. Relative importance of activity types The PE exercises provided SHS users with an opportunity to rank and weight the importance of the lighting-derived benefits associated with the four activity types. This was important when seeking to understand overall value of the different lighting systems. Changes in the ease or duration of activities where the lighting-derived benefits were seen as important should be valued more than the same degree of change for activity types where benefits were considered to be less important. Across all three projects, improving conditions for study/reading and domestic tasks through SHS use were considered to be the most important benefits for SHS. Assisting with productive tasks and social interaction were rated much lower. CER groups ranked assistance with study the highest priority. RDTL and UNDP groups most commonly ranked domestic tasks first but only slightly more frequently than ranking study first. Ranking of benefit types was carried out by consensus within each group. Weighting of the benefit types, however, was determined by individuals in each group ‘voting’ for their preferences and hence tested the ranking consensus. This was done by each person dividing a set number of corn/coffee kernels across the four benefit types. For CER groups, domestic tasks were weighted highest, followed by study, and for UNDP and RDTL study was weighted first closely followed by domestic tasks (Fig. 3). Overall it was clear that assistance with study/reading and domestic tasks were of similar importance for all three project types and much more important than productive tasks or social interaction. The results described above regarding the impact of SHS use on various activity types, combined with the ranking/weighting results, are summarised in Table 7. 4.2. Intrinsic benefits The light output from a SHS was found to be closely linked to the SHS size. Given that the three SHS included in the research were designed only to provide light, this relationship is not unexpected. Whilst participants in the research noted the quality and output of light as a benefit of their SHS—quite naturally—the valuing of that light output was assessed by the uses to which it was put (as described above). Results for the three other benefits intrinsic to the use of SHS—finance, convenience and health—are presented below. 4.2.1. Finance Financial benefits reported by households during the evaluation relied upon the savings made from avoiding expenditure on

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Fig. 3. Lighting-derived benefits, weighting of activity types by project. Table 7 Summary of impact versus size for lighting-derived benefits. Activity type

Importance to users

Variation of benefits between SHS of different sizes

Domestic tasks

High

Study/reading

High

Productive tasks

Lowa

Social interaction

Low

Moderate RDTL (large) systems provide greater ease for domestic tasks undertaken in the kitchen. No difference between CER households with small systems and UNDP households with medium-sized systems Slight Non-electric lighting sources in RDTL households have been eliminated; a small number of CER and UNDP households still undertake study/reading using candles or kerosene Slight CER (small) systems are of limited benefit to the conduct of some activities requiring task lighting None

a Domestic tasks and study/reading were allocated weightings approximately twice that of productive tasks and social interaction. Consequently, their importance is ‘low’ in relation to domestic tasks and study/reading.

non-electric lighting sources, namely candles and kerosene used in home-made, simple wick lamps. All but three households in the RDTL sample were found to have eliminated the use of candles or kerosene. About half the CER households continued some use of these lighting sources. For UNDP households, approximately half had ceased to use candles but 80% of households continued to use kerosene for lighting on a daily basis. Results from the SES enabled comparison of pre-and post-SHS expenditure on non-electric lighting sources. RDTL households were found to have reduced expenditure by $4.80 per month and CER and UNDP households by $3.60. Because fees paid by users for each project are small or non-existent, on average the avoided expenditure on candles and kerosene produces a net financial benefit for households in each sample. If systems are to provide long-term service, however, users would be required to meet the recurrent costs of operating their systems. As a minimum this would require replacement of lamps and batteries as they failed. An estimate of the replacement costs for each type of system is set out in Table 8, averaged on a monthly basis and calculated for the design parameters presented in Table 1. It may be noted that the operating fees for the RDTL and UNDP systems would be larger than the avoided expenditure on non-electric lighting sources. Under these conditions both systems would have a negative financial impact on users. The average operating costs for the RDTL systems would be more than twice the typical savings on non-electric lighting sources. The single-lamp CER systems would continue to provide a small net financial benefit. If the systems were to be provided on a commercially sustainable basis then the users might also be required to meet the capital costs of their systems. An estimate of the capital costs is also set out in Table 8, based on the retail prices for system components, a discount rate of 10% p.a. and a twenty year system life. Combining estimated capital costs with recurrent costs to provide an indication of net economic benefits suggests that CER

Table 8 Financial and economic impacts of different sized systems. Item

CER

UNDP

RDTL (4 lamps)

Upfront costs paid by users ($) 10 0 0 Ongoing fees paid by users ($/mth) 0 0 1 Estimated system capital cost ($) 273 778 1450 Savings on candles and kerosene ($/mth) 3.60 3.60 4.80 Battery & lamp replacement costs ($/mth) 0.88 5.78 11.60 Estimated capital costs ($/mth) 2.60 7.50 14.00 Net savings ($/mth) 0.12  9.68  20.80

systems would have a neutral economic impact. Economic costs of the RDTL and UNDP systems would far outweigh the benefits represented by avoided costs. The possibility remains that RDTL and UNDP users would find the increased amenity of their systems (i.e., the benefits beyond the avoided costs) worth the additional expense associated with owning and/or operating them. This matter was explored within the SES with a set of questions on willingness-to-pay for SHS services. Respondents to the survey were asked to state how much they would be willing to pay to retain the services of their current SHS. Users across all three projects nominated a mean value of approximately $1 per month more than the current user fee to retain access to their systems. This suggests that households with medium or large SHS would be highly unwilling to pay monthly operation fees that would meet recurrent or capital costs.

4.2.2. Convenience and health Comparing the convenience associated with different sized systems presented a challenge. Rather than attempting to define a concise, easily explained metric, the research equated convenience to the elimination of non-electric lighting sources. The

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argument behind this position is that if there is added convenience involved in moving from non-electric to electric lighting sources, then continued use of candles and kerosene represents less convenience than eliminating their use altogether. It was noted that convenience in this context was not related to the ease with which various household tasks could be undertaken since this advantage had already been assessed through the evaluation of lighting-derived benefits. As noted above, most households with small systems (approximately 80%) had completely eliminated the use of candles or kerosene for lighting. All but three households with large systems had eliminated use of non-electric lighting sources. Whilst it is not possible to quantify this difference in convenience between the small and large systems, the results indicate that the difference might best be characterised as moderate or slight. A significant number of UNDP households were found to have continued with the use of kerosene lamps. Nonetheless, it would be difficult to justify a position which suggested that the threelamp UNDP systems had a lesser impact on convenience than CER systems. Rather, ongoing use of kerosene lamps in UNDP households—despite access to three lamps—points to the importance of lamp location and indicates that if there is no lamp in the kitchen many households will continue to use non-electric lighting sources. Assessment of the likely health impacts used similar logic to that applied for convenience—reduced exposure to smoke-producing candles and kerosene lamps would result in improved health. For health benefits, however, the research assumed that deleterious health effects are more likely to be related to the use of traditional lighting sources for task lighting rather than area lighting since close proximity to non-electric lighting exposes users to higher concentrations of harmful emissions. The homemade, unregulated simple wick lamps used in rural Timorese homes (Fig. 4) are particularly problematic from an air quality perspective, producing a continuous plume of black smoke when they operate. The data on use of candles and kerosene for reading and study provided an indication of the number of households in each sample where members remained exposed to fumes from candles and kerosene lamps. No RDTL households used non-electric lighting for reading or study. For the CER and UNDP samples (in those houses where the SHS was working) approximately six out of seven households had eliminated these lighting sources for reading or study. If the RDTL result is seen as maximising the health benefits from the introduction of SHS then the smaller CER and UNDP systems achieved this result for 85% of users. Since rural households are exposed to particulate loading from kitchen cooking fires—the health impacts of which are well documented (Ezzati and Kammen, 2001; Mestl et al., 2007; Zhang and Smith, 2003)—simply eliminating the emissions from candles and kerosene lamps will not remove harmful particulate emissions from the home. Particularly for women and girls, who spend long periods of time exposed to cooking fires, avoiding kerosene and candle emissions may have a relatively small impact on respiratory health. A similar argument can be made for adult males who smoke cigarettes, which is common in East Timor. On this basis, the health benefits from using SHS are likely to be moderate at best and the benefits offered by the RDTL systems only slightly greater than that of the CER and UNDP systems. 4.3. Relative importance of intrinsic benefits When the rankings and weightings of the intrinsic benefits were examined through the PE exercise it was clear that the SHS users in East Timor value their systems for the light provided. As noted above, the three systems were designed only to provide

Fig. 4. Typical home-made kerosene lamp used in rural Timorese homes.

lighting and, as expected, light output varies with system size. Of the other three intrinsic benefits, finance was clearly the most important to users for all projects (Fig. 5). Some CER groups even rated financial benefits of greater importance than the quality of lighting provided. The ranking and weighting of health and convenience varied between projects. Health and convenience were given similar weightings in each project. For the combination of all three project samples, health was weighted slightly higher than convenience. The weighting of health and convenience were about two thirds of that applied to finance. A summary of the importance of the intrinsic benefit types and the extent to which they varied between the three projects is set out in Table 9.

5. Policy and programming implications 5.1. Optimising use of development funds by promoting small systems The research clearly found that small systems, such as the single lamp CER systems, deliver much of the impact afforded by larger systems. Low power, single lamp systems were highly valued when used for each of the four important household activity types. With the exception of assisting with domestic tasks that occur in the kitchen (where the single lamp CER systems provide no benefits), users of the small systems reported much the same benefits as those of large systems. If users are required to meet recurrent operational costs then financial benefits to households will be much greater for small systems than for large ones. Differences in convenience and health benefits are likely to be slight. These findings provide useful guidance regarding the most efficient use of resources within the rural electrification sector. Where governments in developing countries aim to provide a basic level of service to as many rural households as possible then providing small systems should be considered. For a given investment this will allow governments to reach the greatest number of households. Importantly, the benefit per household

M. Bond et al. / Energy Policy 42 (2012) 699–709

UNDP

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0.00

0.00 es nc

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C

Li

en

ea

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es H

nc

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na Fi

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0.10

en

0.10

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0.10

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0.20

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0.20

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0.20

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0.30

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0.30

t

0.30

t

0.40

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0.40

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0.40

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RDTL

Fi

CER

707

Fig. 5. Intrinsic benefits, weighting of benefit types by project.

Table 9 Summary of impact versus size for intrinsic benefits. Intrinsic benefit type

Importance to users

Variation of benefits between SHS of different sizes

Finance

High

Convenience

Moderate

Health

Moderate

High Because users currently pay low or no operating fees, all systems evaluated provide a similar financial benefit. Larger systems, however, would produce a substantial disbenefit if households were required to pay an appropriate level of fees to meet recurrent costs and provide sustained operation of their systems. The financial disbenefit would be proportional to system size and for RDTL systems high in relation to avoided expenditure on non-electric lighting Slight Larger RDTL systems have almost entirely eliminated use of non-electric lighting sources, maximising convenience benefits. CER and UNDP systems produce similar levels of convenience, eliminating non-electric sources in approximately 80% of households Slight Larger RDTL systems have eliminated any harm associated with reading and studying in proximity to candles or kerosene lamps. CER and UNDP systems have eliminated this harm in 85% of households

will be much the same as if larger systems had been provided. Not only is this appropriate from a capital subsidy perspective but it is likely to provide much greater scope for users (or governments or donor agencies) to afford the operational costs that must be met to ensure sustainability. 5.2. Provide lighting in kitchen areas Inclusion of the UNDP systems—with three lamps—in the research provided important insights into why development impact of SHS did not vary directly with system size. The small CER systems and the large RDTL systems provided a direct comparison of benefits delivered by small and large systems. If there was a strong relationship between size and development impact then it might have been expected that the benefits offered by the medium-sized UNDP systems would lie somewhere between the extremes presented by the CER and RDTL systems. This, however, was not the case. The UNDP systems were very popular with users and reported to be very effective for most household activities. In contrast to the RDTL households however, where use of non-electric lighting sources had been all but eliminated, UNDP households continued to use candles and kerosene lamps for lighting. The continued use of kerosene was quite marked and even more common in UNDP households than in the single-lamp CER homes. Half of UNDP households reported ongoing expenditure on kerosene and one in seven households continued to use candles or kerosene lamps for study/reading. For those households where the SHS was functioning and where post-SHS kerosene expenditure was reported, the average monthly expenditure was found to be equal in the CER and the UNDP samples. Since UNDP systems were equipped with three lamps, all of which were installed in the main house building, it is likely that most of the kerosene use occurred outside the main

house. This strongly suggests that kerosene use in UNDP households is largely related to continued use of simple wick lamps in kitchen areas, away from the main household. The similarity between average kerosene expenditure in CER and UNDP households fits with a scenario in which those CER households that continue to use kerosene are also using it for lighting in the kitchen. This finding highlights the critical importance of lamp location if the benefits of multi-lamp SHS are to be maximised. Simply providing larger SHS will not necessarily result in significantly greater benefits. Even though UNDP systems were thoughtfully designed and provided with a good range of lamps (12 W CFL, 3 W CFL and 1 W LED) they did not eliminate the use of kerosene or candles, as the four-lamp RDTL systems did. Neither did the UNDP systems provide any assistance with those domestic tasks undertaken in the kitchen. Domestic tasks, along with study/ reading, were viewed by rural Timorese households as the most important activity type with which SHS could assist. If development benefits are to be maximised where multi-lamp SHS are provided, then at least one lamp should provide lighting in the kitchen. Given the low levels of lighting currently provided by kerosene lamps, this lamp could be a low wattage device. Whilst the additional demand on the SHS would be modest, the increase in benefits from this arrangement would be substantial. Good SHS programs should be designed with an understanding of how women and men benefit differently from SHS use. Providing a lamp in the kitchen is a very effective means by which to maximise benefits for women and girls. 5.3. Match system recurrent costs to user ability to pay The third program design implication from this research concerns the operating costs of SHS and ensuring that they are affordable for users. The research clearly demonstrates that whilst

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there is a very strong linkage between the size of a SHS and its likely operating cost, there is only a weak relationship between system size and financial savings from avoided expenditure on non-electric lighting. Average reduction in kerosene and candle expenditure for the small CER systems was two thirds that of the RDTL systems. Operating costs for the large systems, however, are an order of magnitude greater than for the small ones. For the medium-sized UNDP systems, operating costs are likely to be more than five times that of the CER systems, even though there was no difference between the average kerosene and candle expenditure savings for these two system sizes. For the rural households in East Timor, financial benefits were found to be a very important outcome. Their experience of using SHS, and hence the perception that they brought to the evaluation, was that SHS use reduced household expenditure. If the users had been required to meet operational costs then—rather than offering financial benefits—users of UNDP and RDTL households would have increased their expenditure on household lighting. For UNDP households with medium-sized systems the average net increase in expenditure to switch to a SHS would be modest in relation to average pre-SHS expenditure on lighting. For RDTL households, however, the additional expenditure would be more than twice the pre-SHS expenditure. Based on the willingness-to-pay questions in the socioeconomic survey it appears that very few of the households would choose to operate a large SHS, if they were required to meet the full operating costs. If one is to assume that pre-SHS expenditure on lighting sources provides a guide to household ability to pay for operating costs then many households would find it difficult to sustain operation of even the medium-sized systems. These findings are particularly significant for programs that aim to operate with a pro-poor focus. In settings where rural incomes are large in comparison to SHS operating costs the much higher cost of sustaining larger SHS may be relatively unimportant to user households. In countries where rural incomes are very low this is a critical consideration for the design of SHS programs. If the East Timorese government (or a donor program) were to undertake a program involving large SHS and decided to subsidise capital cost but not operating costs then all but the most affluent of households would find it a financial burden to maintain their systems. If systems are going to meet rural users’ expectation of financial benefits then it is important that they are sized so that households can meet the recurrent costs (or that recurrent costs are subsidised accordingly). For programs intended to provide electricity services broadly within rural communities then operating costs must be kept low in relation to average rural incomes, pointing to an emphasis on small systems. As well as small SHS, the findings are also favourable with respect to very small, pico PV systems (systems sized from 1 to 10 Wp). Reiche et al. (2010) suggest the market for these systems may be as great as 300 million households in low-income countries, most of whom could not afford a 50 Wp SHS even when when heavily subsidised. From a financial perspective, this research certainly supports the promotion of pico PV systems. As noted above, systems with at least two lamps (or two portable PV systems) such that lighting can be provided in the kitchen area offer important benefits for women. Products approved under the joint IFC-World Bank funded Lighting Africa program highlight how pico PV can now provide low cost, multi-lamp lighting systems that can also provide mobile phone charging capabilities (Lighting Africa, 2011). Pico PV systems represent an evolution of the small SHS technology evaluated in East Timor and strengthen the case for promoting small SHS to maximise development impact. If a government (or donor) wishes to provide broad access to SHS in

rural communities then small systems are likely to provide most of the benefits of larger systems at a cost that more households will be able to afford. Such an approach is entirely compatible with allowing the commercial sector to meet the demand of more affluent households for larger systems.

6. Conclusions The research findings provide a strong indication that in the East Timorese context increasing the size of SHS will not result in proportionate increases in development impact. Many of the factors present in the East Timorese communities involved in the research are common to rural areas in other developing countries and hence the research implications are applicable to many other low-income countries. Particularly in regions where households rely upon subsistence agriculture and have access to small levels of cash income, striking an appropriate balance between operating costs and the ability of users to meet them is of great importance. The authors’ observation of rural houses in other parts of Asia and in Africa suggest that constructing houses without a ceiling is also common in many countries. Hence the opportunity to provide multi-room lighting from a single lampwhich was an important element in the effective use of the small systems presented here-may also operate in a number of other countries. Whilst no important country-specific factors became apparent during the research similar investigation in other countries is required to confirm whether the findings can be extrapolated to other contexts. In addition to cultural factors, levels of wealth in other geographical settings should also be considered. Testing the size-impact relationship in other countries where rural communities have access to higher levels of cash income than they do in East Timor and consequently may have higher expectations for service levels-would establish to what extent the results are sensitive to household wealth. In closing, it must be emphasised that this paper neither argues for nor offers support to the idea that people in developing countries, particularly those in the least affluent countries, deserve or need only small SHS. Such communities have every right to high levels of service and the means to achieve high standards of living. Rather, the research underpinning this paper makes clear that where electrification services are extended via a SHS program smaller systems have the potential to provide much of the development impact of larger systems and from a financial perspective may provide significantly greater benefits overall. References Almeida, A., 2007. Adviser, UNDP Participatory Rural Energy Development Programme, personal communication 18 October 2007. Bond, M., Fuller, R.J., Lu Aye, 2007. A policy proposal for the introduction of solar home systems in East Timor. Energy Policy 35, 6535–6545. Bond, M., Aye, Lu, Fuller, R.J., 2010. Solar lanterns or solar home lighting systems—community preferences in East Timor. Renewable Energy 35, 1076–1082. Chaurey, A., 2000. Ramakrishna Mission Initiative impact study: final report. NREL/SR-520-28601, National Renewable Energy Laboratory, Golden. ESMAP, 2002. Rural electrification and development in the Philippines: measuring the social and economic benefits. ESM255, Energy Sector Management Assistance Programme (ESMAP), Washington D.C. ESMAP, 2003. Monitoring and evaluation in rural electrification projects: a demand-oriented approach. ESMAP Technical Paper 037, Energy Sector Management Assistance Programme (ESMAP), Washington D.C. Ezzati, M., Kammen, D.M., 2001. Indoor air pollution from biomass combustion and acute respiratory infections in Kenya: an exposure-response study. The Lancet 358 (9282), 619–624. Gustavsson, M., Ellegard, A., 2004. The impact of solar home systems on rural livelihoods. Experiences from the Nyimba Energy Service Company in Zambia. Renewable Energy 29, 1059–1072.

M. Bond et al. / Energy Policy 42 (2012) 699–709

Lighting Africa, An innovation of IFC and the World Bank. Products that meet Lighting Africa Recommended Performance Targets. Accessed at /http:// www.lightingafrica.org/product-performance-targets.html?layout=itemS; November 2011. Mehta, K., 2004. The social, economic and environmental impacts of solar home systems in Karnataka, India. MSc in Environmental Change And Management thesis, University of Oxford. Meier, P., 2003. Economic Analysis of Solar Home Systems: A Case Study for the Philippines. Asia Alternative Energy Program (ASTAE), Washington. Mestl, H.E.S., Aunan, K., Seip, H.M., 2007. Health benefits from reducing indoor air pollution from household solid fuel use in China—three abatement scenarios. Environment International 33 (6), 831–840. Morante, F., Zilles, R., 2008. Electric consumption in SHSs in rural communities of Brazil and Peru and recommendations for sizing. Progress in Photovoltaics: Research and Applications 16 (2), 171–179. NASA, 2006. Surface meteorology and solar energy (release 5.1), renewable energy resource website with satellite-derived meteorology and solar energy parameters. /http://eosweb.larc.nasa.gov/sse/S. Nieuwenhout, F.D.J., Dijk, A.v., Lasschuit, P.E., Roekel, G.v., Dijk, V.A.P.v., Hirsch, D., Arriaza, H., Hankins, M., Sharma, B.D., Wade, H., 2001. Experience with solar home systems in developing countries: a review. Progress in Photovoltaics: Research and Applications 9, 455–474.

709

¨ ¨ Reiche, K., Gruner, R., Attigah, B., Hellpap, C., Bruderle, A., 2010. What Difference can a PicoPV System Make? Early Findings on Small Photovoltaic Systems—An Emerging Low-Cost Energy Technology for Developing Countries. Deutsche ¨ Technische Zusammenarbeit GmbH (GTZ), Eschborn. Gesellschaft fur Ryan, T.P., 2007. Modern Engineering Statistics. Wiley-Interscience, Hoboken, NJ. Silva, V. da., 2006. National Project Manager, UNDP Participatory Rural Energy Development Programme. Dili, East Timor, personal communication, 29 August 2006. Solar Energy International, 2007. Photovoltaics: Design and Installation Manual. Revised edition, 2007 edn New Society Publishers, Gabriola Island, BC. Trojan Battery Company, 2008. Theoretical battery life for Trojan TMX270. 9 Oct 2008, email communication from Ronald Paredes of Trojan Battery Company. Tynan, B., 2006. Coordinator, Communidade Edmund Rice. Railaco, East Timor, personal communication, 26 August 2006. van der Vleuten, F., Stam, N., van der Plas, R., 2007. Putting solar home system programmes into perspective: what lessons are relevant? Energy Policy 35, 1439–1451. Ximenes, R., 2007. Chefe Suco, Cairui, East Timor, personal communication, 18 October 2007. Zhang, J., Smith, K.R., 2003. Indoor air pollution: a global health concern. British Medical Bulletin 68 (1), 209–225.