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The Role of Renewable Energy Technology in Holistic Community Development

Part of the book series: Springer Theses ((Springer Theses))

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Abstract

An interesting trend in the energy consumption pattern and growth for Nepal’s non-renewable and renewable biogas and micro-hydro energy resources over the years 1990–2002 (presented in TJ (1012 J)), can be seen in Table 3.1

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Notes

  1. 1.

    Averaged from Janet Ramage Energy A Guidebook, Oxford University Press, 1997; WEC 2005, 2004 Survey of Energy Resources, pages 247–252, 259, http://www.worldenergy.org/documents/ser2004.pdf (accessed July 26, 2012),. WEC 2007, 2007 Survey of Energy Resources pages 333–334, and http://www.worldenergy.org/documents/ser2007_final_online_version_1.pdf (accessed July 26, 2012).

  2. 2.

    Considering that ~95–98 % of all electricity is generated by hydro power plants > 1 MW in Nepal, with ~2–5 % of the nation’s electricity generated with diesel generators, an additional ~5,000 TJ Electricity generation can be added to the NEW Renewables’ Energy mix of 1,678 TJ, thus making up a total of around ~1.9 % of Nepal’s total energy consumption.

  3. 3.

    Life-cycle costs (LCC) include all costs of a project (cradle to grave), from its initial start, including planning, procurement of equipment, interest and inflation rates, transport, to infrastructure building, installation, operation, repair/maintenance, decommissioning and salvage value at the end of the project’s useful life time. The LLC calculation is an economic model, spanning over the entire project’s life time. LLC is expressed in economic terms/values, often as cost per unit of service/energy. The LLC analysis helps to choose the most, long-term cost competitive solution of ownership of a project.

  4. 4.

    During 1996–2000 the author lived in the remote mountain area of Jumla, where initially 23 micro-hydro power plants have been installed over the course of a decade. Out of these 23 power plants, only 3 were functional, providing the local communities with indoor lighting. All other micro-hydro power plants were not operational due to mostly simple technical and socio-economical problems.

  5. 5.

    Wikipedia provides a very good, detailed historical and technical discourse of the traditional incandescent light bulb at: http://en.wikipedia.org/wiki/Incandescent_light_bulb (accessed July 26, 2012).

  6. 6.

    The word “competitive” is used, because by providing merely the value of lm/W (lumens per watt), called Luminous Efficacy, indicating the ratio of luminous flux to power for a lighting technology, is not sufficient to provide enough information for the users to get a clear understanding or a “feeling” for the brightness of different lamps. It is important to include also the angle of radiation that light is emitted by a source. To know this important specific parameter for a light source means that one knows how much of the radiated light is usefully intercepted or applied. For example, an incandescent bulb, with a viewing angle of 360°, emits light all around, with a high percentage of it ending up to be in non-useful directions (e.g. upwards), while LEDs have often a much narrower viewing angle between 15 and 120°. Thus, an LED with a 30° viewing angle means that the light emitted from the LED forms the shape of a cone with a 15° angle around the centre axis of the cone. By changing the emitting angle of the same LED, e.g. from 30° to >30°, changes (decreases) the luminous intensity of the LED, called candela (cd) but not the luminous flux, called lumen (lm), and vice versa. Lumen and Candela measure different things and thus are not easily and direct comparable. Lumens, measuring the power of light perceived by the human eye, measure light output at the source. Lumens are defined as the luminous flux emitted into one steradian (sr) by an isotropic point source having a luminous intensity of 1 cd. Candela on the other hand measure the light emitted per unit of solid angle, a quantity that does not vary with the distance from the source of the light. Thus, a 1 cd (1 lm/sr) light source will produce 1 lm/m2 at the distance of 1 m from the light source. The candela (1 cd = 1,000 mcd (millicandelas)) is the luminous intensity, in a given direction of a source that emits light that has a wavelength of approx. 555 nm (yellowish-green and the most sensitive wavelength for the human eye) and that has a radiant intensity in that direction of 1/683 W per steradian. As the candela value is independent of distance, one can think of it as the emission from the lamp without being interested in what happens to the photons it has ejected. The candela is mostly used when dealing with focused light such as LEDs and flashlights. By taking into account both, the viewing angles and the lumen output, the comparison between a CREE white LED (CREE X-RE R2) with about 100 cd and a viewing angle of 90°, and an incandescent bulb, with about 105 cd and a viewing angle of 360°, as well as some other, more known and traditional light sources, looks like the following table, copied from http://www.ledrise.com/shop_content.php?coID=17 (accessed July 26, 2012).

    Light source

    lm

    lm/W

    Viewing angle

    Useful viewing anglea

    Useful lm

    CREE X-RE R2 White LED

    242

    92

    90

    100 %

    242

    100 W incandescent

    1200

    12

    360

    33 %

    396

    25 W Halogen

    260

    9

    360

    33 %

    85.8

    15 W T8 neon

    1350

    90

    360

    33 %

    445.5

    1. aWithout case or reflector
  7. 7.

    The AEPC (Alternative Energy Promotion Centre) web site is: http://www.aepc.gov.np/ (accessed July 26, 2012).

  8. 8.

    The AEPC (Alternative Energy Promotion Centre) solar PV system subsidy policy does not state for what the additional 50 and 2.5 % subsidies are, but the author interprets it as the 50 %, or maximum 4,000 NRs, due to the remoteness and the 2.5 % due to the increased transport cost to the remote village of the end-user.

  9. 9.

    The BP275F specification sheet is available at: http://www.oksolar.com/pdfiles/Solar%20Panels%20bp_75.pdf (accessed July 26, 2012).

  10. 10.

    Of these, 15 clusters have one 75 W PV module, and three clusters one 19 W PV modules, as these three small clusters have only 4–6 homes per cluster. Thus for 170 homes (in Sept. 2005), including an average annual 3 % population growth over 10 years, a total 1,182WR of PV modules have been installed, 7 W per household with each 3 WLED lights consuming each 1 W.

  11. 11.

    A pico-hydro power plant is considered as a power generation system with <5 kW power output.

  12. 12.

    See in Appendix 18 the Solar PV System Training Manual we developed for local village users.

  13. 13.

    The Australian Standard for “Interior Lighting” AS 1680.1-1990 is available for purchase at: http://www.saiglobal.com/PDFTemp/Previews/OSH/As/as1000/1600/16801.pdf (accessed July 26, 2012).

  14. 14.

    The Australian Standard for “Energy Management Programs—Guidelines for Financial Evaluation of a Project” AS 3595-1990 is available for purchase at: http://www.saiglobal.com/PDFTemp/Previews/OSH/As/as3000/3500/3595.pdf (accessed July 26, 2012).

  15. 15.

    As a rule of thumb, once a battery-bank is a few (≤3) months in use, no additional batteries should be added, even if they are new, from the same brand and with the same capacity (Ah).

  16. 16.

    SolRC version 1.3 (2001) is available in an Excel worksheet at: http://www.google.com.au/url?sa=t&source=web/ct=res/cd=1/ved=0CAgQFjAA&url=https%3A%2F%2Fclassshares.student.usp.ac.fj%2FPH301%2F2010-Dr.Raturi%2FLecture%2520Notes-First%2520part-Intro%2Csemicomductors%2CSolar%2CPV%2FSolar%2520radiation%2520calculator.xls&rct=j&q=SolRC+version+1.3+&ei=MsSrS5OLHIGMtAP90833Cw&usg=AFQjCNG9bk8FgHnq3s2liHIUYvYqCsD0IA(accessed March 30, 2010, on November 2, 2011 not available any more)

  17. 17.

    That means for every degree >25 °C (the standard temperature at which all PV modules are rated under laboratory conditions) these modules lose 0.4–0.5 % of their rated power output.

  18. 18.

    For example, it is important that the defined (developed and locally built or externally purchased) solar PV charge controller is able to handle the higher input voltages possible for a solar PV module, or a serially connected string of solar PV modules, when they are very cold, <5 °C, in particular if a higher system voltage, such as 24 V, 48 V or higher is chosen. This, because the voltage of silicon based solar PV modules, in general, increases proportionally compared to the indicated product specification by ~0.35 % per decrease in  °C < 25 °C. Thus, while the BP 275 Si mono-polycrystalline solar PV module, as used in most RIDS-Nepal solar PV village systems in Humla, is rated with a VOC of 21.4 V and a VMPP of 17.4 V at 25 °C, producing 77.5 W power output at 1,000 W/m2 (STC), it generates a VOC of 23.3 V and a VMPP of 19.2 V at 0 °C, producing 83.9 W power output, or even a VOC of 24.0 V and a VMPP of 20.0 V at −10 °C, producing 87.1 W power output, which is 12.4 % higher than at STC. Thus, for a 48 V solar PV system that means that instead of a system voltage of ~69.4 V at 25 °C with a power output of 310 W, the charge controller has to cope and handle a system voltage of ~80 V at −10 °C with a power output of 348.4 W. Further, at RIDS-Nepal’s HARS station (Fig. 3.59) we measure every year, particularly during the clear, blue sky months during the cold winter season, global solar radiation values of up to 1,200 W/m2, which is 20 % above the STC conditions for which each solar PV module has been rated. As the current generated is proportional to the intercepted global solar radiation, a significantly higher current is flowing through the solar PV system and through the charge controller, generating a whopping 104.9 W from a 75 W PV module! Taking these two parameters (lower temperature and higher global solar radiation) together, the 48 V solar PV system generates instead of 310 W, 419.6 W, or 35.4 % more power. Extreme as these conditions may be, they do occur in the high-altitude Himalayas and thus generate such a significant range of system voltages and power output increase. Thus the local context has to be understood in detail and has to be considered in the development and manufacturing, or purchasing of, equipment in the designing stage of the solar PV system.

  19. 19.

    The DoD defines the capacity (Ah) drawn in percentage from the battery’s full capacity. For remotely installed battery-banks it is advised to limit the DoD rates to 30 % of its full capacity, as the number of times and the level of DoD a battery is discharged, is related to its life-cycle expectancy. A battery-bank for a rural system should be designed to last between 5 and 10 years, as transport costs are very high, system down time should be kept low, and recycling opportunities are not yet available in Nepal. The DoD 30 % value is based on the author’s 16 years of practical experience with the locally available batteries for solar PV systems, so that they can perform their best for an expected reasonable life-time of 5–10 years.

  20. 20.

    In the realised cluster and central village solar PV system projects in Humla, Nepal, only armored underground cabling is used. The main reasons for that are the harsh climatic conditions with snow, storms, torrential rains, and floods. Additionally, the area suffers from dramatic deforestation due to heavy reliance on forest resources, and in any case the soft Himalayan pine tree poles, would last only for a few years due to rotting. These, plus the aim for high reliability and sustainability of the system justifies the substantially higher costs for underground cabling. The armored underground cables are initially defined so that they are able to carry twice to three times the initial current, dependent on the systems’ load demand, anticipated load growth over the next 10 years and the defined lighting services the users want and still can pay for.

  21. 21.

    In the case of the systems installed in Humla there is a well established project office and high-altitude research station in Simikot, Humla’s district centre, able to be reached from any place in Humla within maximum 2–4 days of walk.

  22. 22.

    One of the project’s main aims is to gain long-term experience with basic rural village electrification schemes, thus an initial baseline survey before the project starts, followed by the follow-up re-survey in the 2nd, 5th, 10th and 20th year after the project implementation is part of the design of each village system, which is itself part of the village’s long-term HCD program.

  23. 23.

    The periodical comprehensive family survey is carried out as part of the follow-up survey questionnaire (Appendix 14.2) which is carried out in the 2nd, 5th, 10th and 20th year of a “Family of 4” or “Family of 4 PLUS” HCD program.

  24. 24.

    The solar radiation “utilizability” is defined as the fraction of global solar radiation that is incident on a surface exceeding a specified threshold or critical level. It is a simple and elegant way of estimating the long-term effect of the global solar radiation on any solar process. Initially applied in the calculations of the performance of flat plate solar thermal collector it is now also used for thermal concentrators, passive and solar PV systems. For more detailed information and explanation see: Beckman W.A and S.A. Klein. 1986. “Solar Radiation Utilizability”, http://sel.me.wisc.edu/publications/journals/rosru84.pdf (accessed July 26, 2012).

  25. 25.

    Dhadhaphaya village, in the Humla district, is located at 29°59′ Northern Latitude, 81°57′ Eastern Longitude, and at 2,550 m above sea level. See the village in Google Earth via the link on the RIDS-Nepal web site: http://www.rids-nepal.org/images/stories/explore_nepal/google_earth/Dhadhaphaya.kmz (accessed July 26, 2012).

  26. 26.

    The “NASA90-m Horizon tool” is a digital terrain model (DTM) tool, tiled with a 90 × 90 m resolution, called NASA’s Space Shuttle Radar Topography Mission (SRTM). It uses satellite data of the surrounding area of a defined geographical location (latitude, longitude and altitude) and thus can identify the 360° surrounding mountain ranges of the defined geographical location (village). Because the model considers the altitudes of the 360° surrounding area (mountain ranges) it provides the defined geographical location’s (village’s) horizon angle of the incoming/intercepted solar radiation. This tool is not available to the public, but to the developer of the METEONORM software tool, who provided the author with the 360° surrounding horizon for Dhadhaphaya village.

  27. 27.

    Of these, 15 clusters have one 75 W PV module, and three clusters one 19 W PV module, as these three small clusters have only 4–6 homes per cluster. Thus for 170 homes (in Sept. 2005), including an average annual 3 % population growth over 10 years, a total 1,182 WR of PV modules have been installed, 7 W per household with each having 3 WLED lights consuming each 1 W.

  28. 28.

    Dalits, the “untouchables”, are the lowest caste in the hierarchy of the caste system. More relevant and detailed information is available at: http://en.wikipedia.org/wiki/Dalit (accessed July 26, 2012).

  29. 29.

    A charge/discharge controller is the piece of equipment in a solar PV system responsible for charging and discharging the battery-bank, as well as providing the demanded users’ load according to the solar PV module(s)/arrays’ power generation.

  30. 30.

    The author started a prototype battery recycling and testing program in 2009 with RIDS-Nepal.

  31. 31.

    Pinus wallichiana is a pine native to the Himalayas and Hindu Kush region from north-eastern Afghanistan onwards across through north Pakistan, India, Nepal and Bhutan. It grows in high-altitude mountain valleys (1,500–4,300 m.a.s.l.) and can grow to a height of 50 m. The wood is not very hard, but durable, if it is not put under the strenuous cycle of getting frequently wet/soaked and dried through rain and sunshine. It is highly resinous, the main reason why it is used to produce “jharro”, for the traditional indoor lighting (Figs. 3.3, 3.81, 3.101). It burns well and quickly, with an estimated average calorific value of ~14 MJ/kg, and has a strong resinous smoke, one of the main reasons for widespread respiratory diseases. It grows well in a more temperate climate with dry winters and wet summers. For more information see: http://en.wikipedia.org/wiki/Pinus_wallichiana (accessed July 26, 2012).

  32. 32.

    The BP375F solar PV specification sheet is available at: http://www.bp.com/liveassets/bp_internet/solar/bp_solar_usa/STAGING/local_assets/downloads_pdfs/pq/BP380_9-09.pdf (accessed July 26, 2012).

  33. 33.

    The technical specification sheet for the Kyocera KC16T poly-crystalline solar PV module can be consulted at: http://www.kyocerasolar.eu/index/products/download/English-cps-33141-files-62466-File.cpsdownload.tmp/KC16T_21T_32T_ENG_July_2009.pdf (accessed July 26, 2012).

  34. 34.

    Standard Test Conditions (STC) are the testing conditions to measure solar photovoltaic (PV) cells’ or modules’ nominal output power under defined laboratory conditions. These are: Global solar radiation of 1,000 W/m2, with a standard spectral distribution received on the solar PV module and the sun rays entering the earth’s atmosphere at an angle of ~48.2° (1/1.5 Invcosθ) to the horizon/horizontal PV module, corresponding to an Air Mass (AM) of 1.5. The PV cell/module junction temperature is held at constant 25 °C during the measurement. More details about the STC (Standard Test Conditions) can be found at: http://en.wikipedia.org/wiki/Solar_panel#Module_performance_and_lifetime (accessed July 26, 2012).

  35. 35.

    While a ~3–4 % drop in power conversion efficiency of serial and parallel connected solar PV modules may not sound significant, this has to be seen in context. A high quality, Si monocrystalline solar PV module, such as the BP275, has a rated intercepted global solar radiation conversion to DC electricity at STC of 12.04 %, indicated by the manufacturer. Thus, a 3–4 % drop due to non-STC conditions and mismatch of other solar PV modules installed in the same PV array means, that the whole solar PV array converts the intercepted global solar radiation at a rate of 8–9 % only, instead of 12 %. This 3–4 % drop has to be considered in respect to the solar PV module’s 12 % efficiency, thus a drop of 25–33 %, cannot be neglected in the initial design and development of a solar PV system.

  36. 36.

    When several solar PV modules are serial or parallel connected, so called “mismatch” losses have to be included in the system’s calculation. These losses are related to the fact that the PV modules in the array do not exactly possess all the same I/V characteristics (with slightly different short circuit current Isc, open circuit voltage Voc and maximum power point MPP values), because each PV module usually consists 36 individual solar PV cells (for a 12 V module), which do not have exactly the same characteristics. With various solar PV modules connected this fact is accentuated and thus increased losses occur which have to be accounted for in the design.

  37. 37.

    The author has two AC powered NSWP510BS diode WLED lamps, each with 12 diodes, under long term testing, one since 1st October 2006 and one since 13th July 2007. Thus, by the 30th June 2012 the first has ~50,000 and the second ~43,000 h. The visual illuminance drop measured by the author is ~50–55 % and ~40–45 % respectively. These, compares favourably with cheaper WLED diodes, with measured illuminance drops of ~75–85 % after 2,000 h, during tests conducted by Rudolfo Peon (University of Calgary, Canada) from 2004 onwards. The data and results are presented and documented in: 15x5 mm WLEDs Array Light Output Degradation vs Time (2006), Advanced Solid State Lighting Laboratory, Calgary University, Canada.

  38. 38.

    For more details and the technical specifications of the DT80 data logger from DataTaker see: http://www.datataker.com/DT80.php (accessed July 26, 2012). For reliability purpose, all DT80/DT605 data loggers are powered by their own, dedicated solar PV system.

  39. 39.

    The 2 parameters not listed are related to the DT80 data-logger: Internal DT80 temperature and the DT80 internal memory back-up battery voltage.

  40. 40.

    For more detailed information and technical specifications for the T-Type Thermocouple, see: http://en.wikipedia.org/wiki/Thermocouple#T (accessed July 26, 2012).

  41. 41.

    The RIDS-Nepal DataBank (http://www.rids-nepal.org/databank/) has been developed by the author and the RIDS-Nepal staff from 2008 onwards, in order to present each monitoring systems’ long-term performance in the local geographical, climatic and cultural context. This is important for various reasons: First, to come to a detailed understanding of how the installed solar PV systems perform under this harsh Himalayan climate over the course of the yearly seasons. Second, system downtimes, over- or under-production of electricity as well as how the various PV systems’ individual equipment perform under varying conditions, in order to continue to develop them. This information allows a direct evaluation and assessment of the system’s design and enables any shortcoming to be recognised in time, enabling the RIDS-Nepal staff to mitigate the shortcomings, or repair the failed equipment. It also provides information for future needed design improvements. Further, as the village based solar PV systems are all “first time” electrification systems for these village communities, it is vital to come to know how the communities learn to live with basic electric indoor lighting. Is their pattern of life changing with the availability of clean, electric light in their homes, and if so in what ways? Is the electricity demand and consumption over the course of the years growing as anticipated, with the systems able to provide the increased demand as predicted in the survey and design, or are adjustments/restrictions to the systems needed? All these issues are of great importance for the design, building and installations of more sustainable, remote rural electrification schemes. The DataBank offers the user the chance to investigate any of the various monitored systems. Within each systems’ own data bank the user can select from the different monitored parameters which ones he wants to be plotted, or extracted and downloaded into an Excel sheet for further calculations, assignments or reports etc. for a defined time period. With this tool, RIDS-Nepal offers a wider interest community of like minded community developers, solar PV system developers, scientists and students an important, and thus far missing instrument, to come to a more in-depth understanding of how defined power generation systems, such as solar PV and pico-hydro power systems, work under long-term field conditions.

  42. 42.

    Pamlatum village in Humla can be seen via Google Earth through the RIDS-Nepal based website link at: http://www.rids-nepal.org/images/stories/explore_nepal/google_earth/Pamlatum.kmz (accessed July 26, 2012).

  43. 43.

    SolData Pyranometer 80SPC, http://www.soldata.dk/PDF/pyrano%2080spc%20A4%20-%20UK.pdf (accessed July 26, 2012).

  44. 44.

    Kipp&Zonen CM 21, http://www.kippzonen.com/?product/1491/CMP+21.aspx (accessed July 26, 2012).

  45. 45.

    The Array Yield is defined as the ratio of the daily array energy generation to the peak installed capacity of the system, expressed in kWh/kWR per day.

  46. 46.

    The Reference Yield is the total daily solar insolation (kWh/m2) intercepted in the plane of the array (POA), divided by the array reference irradiance, which is the STC value of 1,000 W/m2. Thus, it represents the equivalent number of peak sun hours (PSH) a day (number of hours the sun shines per day at 1,000 W/m2). Therefore, the Reference Yield is equal to the number of peak sun hours. Hence the Reference Yield is calculated from: Reference Yield = Total plane of array insolation (kWh/m2)/1 kW/m2

  47. 47.

    The overall average Solar PV Array Efficiency = Power Generated by the PV Array/(Solar Irradiation × Total Area of the Array).

  48. 48.

    The calculated long-term efficiency of 9.47 % of the 4 serial- and parallel-connected BP275 solar PV modules (to make up the 300 W, 24VDC system) shows, in contrast to a single BP275 solar PV module at STC with a conversion efficiency of 12.04 %, a 2.57 % real efficiency drop, which is a 21.35 % relative drop in the solar PV modules’ power generation efficiency due to non-STC conditions and module mismatch losses measured under real field conditions. In addition, the high capacity status of the battery-bank throughout the year increases the potential energy generation losses, thus indicating a lower average solar PV power conversion efficiency, as well. That shows that the local meteorological conditions and the technical performance of the equipment need to be known for the proper design of the whole system. These values are important to know and include in the initial design of new village solar PV systems, in a comparable context, if one aims to install systems with a high availability, minimal LoL (Loss of Load) and high sustainability.

  49. 49.

    The Australian Standard AS 4509.2-2002 Stand-alone power systems—System design guidelines, Chapter 3.4.7.8 PV, wind or hybrid systems with no genset, page 35, recommends that stand-alone solar PV systems are designed with a typical autonomy of 5–10 days IF 100 % of energy is generated by solar energy. This, of course is dependent on the climatic conditions at the site. However, for the remote, high-altitude places in the Himalayas, an autonomy of 3 days has been chosen due to the fact that very low power consuming loads, only WLED lamps, are used, and the batteries have to be air lifted into the area (which makes them very expensive) and then carried by porters to the actual project site. Also, in the high-altitude areas of the Himalayas it is very rare that the sun is not shining for more than 2–3 days, due to the prevailing high-altitude climate. These factors, as well as considering the economic situation of these impoverished communities, justify a 3 day autonomy assumption for the battery-bank design.

  50. 50.

    The Final Yield is defined as the ratio of the daily load to the peak installed capacity of the system, expressed in kWh/day/kWR

  51. 51.

    Array capture losses incur mainly when the battery-bank is nearly full (90–95 % SOC) or full, as then the charge controller open circuits the PV array power flow to the battery-bank. Thus the available excess power cannot be utilised and thus is considered as loss. Other capture losses include PV module temperature incurred losses and shading losses.

  52. 52.

    The dataTaker DT605 was one of the main data logger models that dataTaker marketed until 2006, when the DT80 was introduced, replacing the DT605. Thus there is no web site anymore available for the DT605 model. However, a technical specification sheet for the DT605 can still be downloaded from ITS (Industrial Temperature Sensors), a distributor of dataTaker products. The web site can be visited at: http://www.itsirl.com/Product_Data_Sheets/DT500600_TS0056C1.pdf (accessed July 26, 2012)

  53. 53.

    Other external factors which influence the PV module cell temperatures include the soiling (dust, dirt, snow, ice) of the cell, the age of the cell and the serial cell connection wiring, which, based on the PV module’s history and exposure can have increased resistances. This can often be identified through a discoloring (turning more dark yellowish) of the cells serial string connections.

  54. 54.

    In the southern, flat parts of Nepal, with its tropical climate, the ambient temperature frequently reaches 40–45 °C during the 3 months of summer. It is realistic to say that the solar PV module temperature during a sunny day has about a 20–25 °C higher temperature compared to the ambient temperature, of 60–70 °C. With a power reduction temperature coefficient of 0.44 % per  °C (as per the manufacturer’s specification) above 25 °C (as defined in the STC), e.g. the BP 75 Wp monocrystalline solar PV module (as used by RIDS-Nepal for all its cluster and central tracking village systems) loses 15.4–19.8 %, or 11.55–14.9 W of its 75 WR power output at STC, due to the increased PV module/cell temperature. These are not insignificant values and thus have to be considered and included in the power/energy generation calculation of the solar PV system. On the contrary, in cold, high-altitude climate areas, such as Humla, where RIDS-Nepal is working (2,500–4,000 m.a.s.l.), during the 4–5 winter months at middays, high solar radiation values up to 1,150 W/m2, are intercepted by the solar PV module/cell, at PV module/cell temperature not higher than 10 °C. That means, that e.g. the BP 75 Wp monocrystalline solar PV module generates at these conditions 6.6 %, or 4.95 W more power due to the lower than STC module temperature condition, and 15 %, or 11.25 W, more power due to higher than STC intercepted global solar radiation condition. That amounts together to 16.2 W per PV module, or 21.6 %, more power output than its rated power output at STC, due to the local field conditions. Again, these conditions have to be known and need to be taken into consideration during the solar PV system design and calculation as the system cabling sizes and fuses have to be increased accordingly (at least 1.2 times the maximum current) in order to carry the increased currents without jeopardising the system’s security.

  55. 55.

    The “C” stands for the Capacity in Ah (ampere-hours) of a battery. The “20” indicates the amount of hours the battery has been discharged with a constant load (ampere) at an ambient temperature of 20 °C, so that the battery is considered flat or empty (according to the manufacturer’s specification, which is most commonly for flooded lead-acid batteries 1.75 V per cell) after 20 h. The total amount of Ah discharged specifies the battery’s capacity (Ah) under these defined circumstances.

  56. 56.

    The daily 15 % energy loss of the battery-bank can be explained as follows. The higher voltage during the battery-bank’s charging process (on a daily average ~13–13.5 V) compared to the lower discharge voltage (on a daily average ~12–12.5 V), the battery-bank’s internal losses due to the chemical reactions, the increased temperatures occurring during the battery-bank’s charging and discharging processes, and the losses occurring due to the resistances of the batteries’ terminals and wires connected to the battery-bank.

  57. 57.

    The Coulombic battery efficiency calculation takes only the Ah (ampere-hour) or capacity into and out of the battery-bank into consideration, avoiding the voltage difference losses of the battery-bank’s higher charging voltage and lower discharging voltage. Thus the Coloumbic battery efficiency value presents the battery-bank’s technical performance efficiency, which includes the battery-bank’s internal losses due to the chemical reactions, the increased temperatures occurring during the battery-bank’s charging and discharging processes, and the losses occurring due to the resistances of the batteries’ terminals and wires connected to the battery-bank.

  58. 58.

    The Albedo value, also called surface reflectivity, is the fraction (or ratio) of incident solar radiation reflected by the earth’s, or a body’s, surface to the amount incident upon it (commonly expressed as a percentage) back into space or an interrupted object/surface, such as a solar PV module. http://en.wikipedia.org/wiki/Albedo (accessed July 26, 2012), and http://nsidc.org/arcticmet/glossary/albedo.html (accessed July 26, 2012). A snow covered environment increases the ratio of reflected solar radiation (higher Albedo value) and thus solar PV modules, if they are free of snow, can, if their tilted angle is favorable, receive significant higher solar radiation values and thus generate more power.

  59. 59.

    The United Nations’ Human Development Reports, from the first in 1990 to the most recent, are all freely available for download at: http://hdr.undp.org/en/reports/(accessed July 26, 2012).

  60. 60.

    While the UN calculated the HDI for Nepal to be 0.428 and 0.458 in 2010 and 2011 respectively, the HDI value for the years 2003-2004 was 0.499-0.504 (NPC/UN 2005). That shows that either the UN had to review their values calculated in previous years, or Nepal’s actual HDI values have indeed decreased over the course of the last 5 years. The author is of the opinion that the previous HDI values were too optimistic, with the most recent HDI value for 2011 being more realistic.

  61. 61.

    The sinusoidal inverter Joker 802-S, as used in the RIDS-Nepal HASR office since 2004, from Studer in Switzerland is since 2009 new identified as AJ-1300-24, http://studer-inno.com/index.php?cat=sine_wave_inverters/id=430/pId=1197/tab=1#ul, and http://www.studer-innotec.com/upload/temp/Datasheet%20AJ%20series.pdf (both accessed July 26, 2012)

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  1. Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA

    Alexander Zahnd

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Zahnd, A. (2013). Power/Energy Generation and Lighting. In: The Role of Renewable Energy Technology in Holistic Community Development. Springer Theses. Springer, Cham. https://doi.org/10.1007/978-3-319-03989-3_3

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