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Power - Photovoltaic - School - 0.4 kW - Off-grid / Argentina
Case study assignment
A local public utility has undertaken an electrification program for rural schools in the province of Neuquén in the remote mountainous region of Patagonia, Argentina. The schools are generally far away from the electrical grid and the two main power supply options being considered are diesel gensets and stand-alone photovoltaic (PV) systems. You are an engineer at the utility in the provincial capital and you have been asked to evaluate the financial viability of using PV to supply electricity to a school in one particular village.
Site information
The school is located in the foothills of the Andes (39°S, 71°W), on the Aucapan reservation of the Mapuche people, one of the region's indigenous populations. The nearest major town is the provincial capital Neuquén, some 430 km to the northeast.
The school consists of classrooms and an apartment for a visiting teacher (who generally comes from an urban centre). The climate is harsh: hot and dry in the summer and cold, with high snowfalls, in the winter. Since the snow makes access particularly difficult, the school holidays take place in the winter (June through August) and the building is unoccupied at that time. When the school is open, its electric loads are estimated as follows (the lights and radio telephone use DC power while all other loads are AC): Based on your previous experience with similar projects, you decide to use imported polycrystalline PV modules from BP Solar rated at 50 Wp. Due to the occasional long periods of cloud cover in the mountains, you design the system for 6 days of autonomy.
Case study assignment
A local public utility has undertaken an electrification program for rural schools in the province of Neuquén in the remote mountainous region of Patagonia, Argentina. The schools are generally far away from the electrical grid and the two main power supply options being considered are diesel gensets and stand-alone photovoltaic (PV) systems. You are an engineer at the utility in the provincial capital and you have been asked to evaluate the financial viability of using PV to supply electricity to a school in one particular village.
Site information
The school is located in the foothills of the Andes (39°S, 71°W), on the Aucapan reservation of the Mapuche people, one of the region's indigenous populations. The nearest major town is the provincial capital Neuquén, some 430 km to the northeast.
The school consists of classrooms and an apartment for a visiting teacher (who generally comes from an urban centre). The climate is harsh: hot and dry in the summer and cold, with high snowfalls, in the winter. Since the snow makes access particularly difficult, the school holidays take place in the winter (June through August) and the building is unoccupied at that time. When the school is open, its electric loads are estimated as follows (the lights and radio telephone use DC power while all other loads are AC): Based on your previous experience with similar projects, you decide to use imported polycrystalline PV modules from BP Solar rated at 50 Wp. Due to the occasional long periods of cloud cover in the mountains, you design the system for 6 days of autonomy.
Financial information
For the project's 25-year analysis period, assume 5% fuel cost escalation rate, 2.5% inflation and 9% discount rate.
The PV modules are imported to Neuquén city at a cost of US$ 8,000 per kWp plus 10.5% value added tax (IVA). This IVA is a reduced rate for renewable energy equipment. The general IVA rate is 21%. The pre-2002 exchange rate is 1 ARS = US$ 1.
Local experience has shown that PV system batteries last about 3 years in these applications.
The smallest commonly available diesel genset (2.5-3 kW) and appropriate shelter are estimated to cost about ARS 3,200 (including 21% IVA). Even such a small genset however would be oversized for the school's small load and would likely run at a 10-20% load factor. Genset maintenance costs are high due to harsh operating conditions and inexperienced users. Based on the utility's study of genset operation in schools, maintenance costs are estimated to average ARS 500 per year (including periodic overhauls and travel expenses). Diesel fuel costs around ARS 0.5/L in the cities, but is estimated to be 50% more expensive in remote villages.
Prepare a RETScreen study, documenting any assumptions that you are required to make.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
Results
Ente Provincial de Energía del Neuquén (EPEN), the local public electricity utility in the province of Neuquén in northern Patagonia, Argentina, has been conducting a rural school electrification program since 1987. By 1997, photovoltaic (PV) systems had been installed in some 27 remote off-grid schools. School #306 in the village of Nahuel Mapi received its PV system in 1994. Monitoring of this and other PV systems was undertaken for four years following installation and showed that they operated effectively and reliably.
The main rationale for PV electrification was the need to improve teaching conditions and allow for new educational resources (e.g. lights, TVs, VCRs, computers) for rural students. Also, living conditions for teachers, who are often from the cities, had to be improved to combat the typically high staff turnover at such isolated posts. While gensets are used at some schools in the region, they have a track record of poor reliability due to factors such as inexperienced users, lack of maintenance, long wintertime shutdowns and dust storms. Maintenance has also proven to be an important issue for PV systems, but it is seen as less costly and more manageable than for gensets.
System description
The PV system's main components include eight polycrystalline PV modules totalling 408 W, 7 lead-acid batteries (each 12 V and 110 Ah) and one 250 W modified square-wave inverter. The PV array and controllers were imported while all other components and the installation labour were provided by EPEN. Electrical loads in the school consist of lights, TV, VCR, radio-cassette player and a radio telephone.
Lessons learned
Worldwide, it is estimated that about two billion people do not have access to electricity. Rural communities in most developing countries are often not connected to the electricity grid.
Education in rural communities is a critical priority for many countries. The provision of electricity to rural schools plays a key role in improving the physical environment for students (e.g. provision of lighting, water pumping), enabling access to modern teaching resources (e.g. computers, distance learning, telecommunications, TVs) and attracting and retaining qualified teaching professionals. PV systems have proven to be a successful means of achieving these electrification goals.
High priority PV applications in off-grid schools and medical clinics can also serve to introduce and demonstrate the value of PV to the broader rural population.
Photo
School - Photovoltaic - Remote, Neuquén, Argentina
References
For the project's 25-year analysis period, assume 5% fuel cost escalation rate, 2.5% inflation and 9% discount rate.
The PV modules are imported to Neuquén city at a cost of US$ 8,000 per kWp plus 10.5% value added tax (IVA). This IVA is a reduced rate for renewable energy equipment. The general IVA rate is 21%. The pre-2002 exchange rate is 1 ARS = US$ 1.
Local experience has shown that PV system batteries last about 3 years in these applications.
The smallest commonly available diesel genset (2.5-3 kW) and appropriate shelter are estimated to cost about ARS 3,200 (including 21% IVA). Even such a small genset however would be oversized for the school's small load and would likely run at a 10-20% load factor. Genset maintenance costs are high due to harsh operating conditions and inexperienced users. Based on the utility's study of genset operation in schools, maintenance costs are estimated to average ARS 500 per year (including periodic overhauls and travel expenses). Diesel fuel costs around ARS 0.5/L in the cities, but is estimated to be 50% more expensive in remote villages.
Prepare a RETScreen study, documenting any assumptions that you are required to make.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
- The coincident electrical load for the school is not expected to exceed 0.25-0.5 kW. Diesel gensets however are commonly only available starting at 2.5 or 3 kW. A genset therefore would be expected to run at 10-20% capacity, resulting in poor fuel consumption of around 1.5 L/kWh.
- The Argentinean peso (ARS) is taken to be on par with the US dollar for the purpose of this case study, since cost information is only available for the period prior to the currency devaluation of January 2002. Before devaluation, the Argentinean peso was pegged to the US dollar at a rate of 1:1.
- For either scenario (PV or genset), the same number of technicians will likely be brought in from the provincial capital to install the power supply and the inside wiring, light fixtures, etc., all on the same trip. Transportation costs are thus assumed to be equal for both scenarios. The only difference in labour is due to the longer time needed to install the PV system components. This incremental cost is conservatively estimated at ARS 800. A transportation and labour charge of ARS 250 is added to each tri-annual battery replacement.
- A 2.5 or 3 kW diesel genset, of acceptable quality, is estimated to cost about ARS 2,700 in Neuquén (including 21% IVA). It would require a secure, weather-protected shelter outside the building. The price of such a shelter (materials, labour and taxes) is estimated at ARS 500.
Results
Ente Provincial de Energía del Neuquén (EPEN), the local public electricity utility in the province of Neuquén in northern Patagonia, Argentina, has been conducting a rural school electrification program since 1987. By 1997, photovoltaic (PV) systems had been installed in some 27 remote off-grid schools. School #306 in the village of Nahuel Mapi received its PV system in 1994. Monitoring of this and other PV systems was undertaken for four years following installation and showed that they operated effectively and reliably.
The main rationale for PV electrification was the need to improve teaching conditions and allow for new educational resources (e.g. lights, TVs, VCRs, computers) for rural students. Also, living conditions for teachers, who are often from the cities, had to be improved to combat the typically high staff turnover at such isolated posts. While gensets are used at some schools in the region, they have a track record of poor reliability due to factors such as inexperienced users, lack of maintenance, long wintertime shutdowns and dust storms. Maintenance has also proven to be an important issue for PV systems, but it is seen as less costly and more manageable than for gensets.
System description
The PV system's main components include eight polycrystalline PV modules totalling 408 W, 7 lead-acid batteries (each 12 V and 110 Ah) and one 250 W modified square-wave inverter. The PV array and controllers were imported while all other components and the installation labour were provided by EPEN. Electrical loads in the school consist of lights, TV, VCR, radio-cassette player and a radio telephone.
Lessons learned
- PV systems can offer a more consistent, reliable, environmentally sound, quieter and, in the longer-term, more cost-effective alternative to gensets for rural school electrification. "Quality of service" concerns can be as important as economics.
- The relative cost-effectiveness, over the life cycle, of PV and genset systems is to a large part determined by their respective maintenance and repair requirements.
- Maintenance issues, particularly in regard to battery care, have to be addressed. At Nahuel Mapi, maintenance training, including a step-by-step Maintenance Manual, was provided to school staff and the utility organized regional technicians to do troubleshooting.
- Starting with the schools, PV technology has spread to residential applications and has now firmly established itself in the region.
Worldwide, it is estimated that about two billion people do not have access to electricity. Rural communities in most developing countries are often not connected to the electricity grid.
Education in rural communities is a critical priority for many countries. The provision of electricity to rural schools plays a key role in improving the physical environment for students (e.g. provision of lighting, water pumping), enabling access to modern teaching resources (e.g. computers, distance learning, telecommunications, TVs) and attracting and retaining qualified teaching professionals. PV systems have proven to be a successful means of achieving these electrification goals.
High priority PV applications in off-grid schools and medical clinics can also serve to introduce and demonstrate the value of PV to the broader rural population.
Photo
School - Photovoltaic - Remote, Neuquén, Argentina
References
- Alward, R., "Personal communication," CETC-Varennes, 2002.
- Jimenez, A.C., Lawand, T.A., Renewable Energy for Rural Schools, NREL, 2000.
- Lawand, T.A., "Personal communication," Solargetics, 2002.
- Lawand, T.A., Rapallini, A., Pedro, G., Photovoltaic Systems in Patagonia, SESCI, 1998.
- Pedro, G., "Personal communication," 2002.
- Ross, M. and Royer, J., Photovoltaics in Cold Climates, James & James, 1999.
