From candles to PV electricity: a four‐year experience at Iguape–Cananéia,Brazil

A PV rural electrification experience, based on the solar home system (SHS), is being carried out at a coastal region in the state of São Paulo (Brazil). Particular attention has been paid to aspects, relating to the integration of PV technology into the pre‐existing social system. Regarding technical aspects, some special features have been designed: a ‘battery shelter’ made by the users; combined use of ‘high power’ fluorescent light with ‘low power’ incandescent light, etc. Regarding organizational aspects the technical training should be outlined. We initially decided to train one user in each community more intensively. This user was chosen from among those who appeared to be more skillful in relation to our requirements. This apparently common‐sense oriented procedure was shown to be less than appropriate, because it interfered with social relationships that we knew very little about. We observed that later on the community decided who would be responsible for the maintenance; this time widely accepted by all the users. The technical and organizational aspects together conform to a particular rural electrification scheme that can be useful for general SHS projects. Copyright © 2000 John Wiley & Sons, Ltd.     

A case study for micro‐grid PV: lessons learned from a rural electrification project in India

Micro‐grids in developing countries present a significant application opportunity for photovoltaics (PV) as an energy‐enabling technology. The authors project 10 GW for this application in the next decade. The growth of this sector will be enhanced by shared learning of the best practices. The authors are part of a team that successfully installed 1/3 MW in micro‐grids and presented the lessons learned and a useful methodology for determining key metrics. The PV is part of the rural electrification in India and is representative of current global PV micro‐grids. This project provides basic lighting and electricity for 57 villages in Visakhapatnam in India. The project was carried out with a goal of optimizing power against cost. Various metrics are presented: costs, time, operations and maintenance, and performance. Also discussed are implementation strategies for cost containment, stakeholder considerations, and post‐install support and user payment collection. Learning points are presented on project execution, engagement of local people, and challenges addressed. The aspect of demand capacity level (hours of availability) is examined in more detail, with modeling being performed to identify an optimal approach to increasing the level given the cost constraints. The combination of real data and modeling is a useful approach for PV and micro‐grid optimization. This case study quantitatively supports the value of the use of PV for rural electrification. Beyond this example in India, where the federal government is planning an increase to more than 2000 sites, there is a significant opportunity for PV in the global micro‐grid electrification context. Copyright © 2013 John Wiley & Sons, Ltd.     

Distributed power generation versus grid extension: an assessment of solar photovoltaics for rural electrification in Northern Ghana

The competitiveness of distributed solar photovoltaic (PV) power generation for rural electrification in northern Ghana is assessed and compared with the conventional option of extending the national grid and increasing the capacity for centralised power generation. A model is constructed to calculate the life‐cycle cost (LCC) of the two options and to test the sensitivity of different parameters. All calculations are based on information from the GEF/UNDP pilot region in the East Mamprusi District. In addition to the economic aspect, issues of quality and environmental effects are discussed. The LCC of distributed PV is lower than that of a grid extension for an electricity demand corresponding to solar home systems of 140 W_p or smaller. Thus, distributed PV is cost competitive for purposes of lighting, entertainment, information and basic public facilities, such as schools and hospitals. The LCC for the option of grid extension with central power generation is dominated by the cost of low‐voltage micro‐grids within the communities. Important factors are the density of households and the penetration (fraction of households electrified), as they affect the line length per connected household. The relatively low cost of regional medium‐voltage grids makes the geographical location of each community less important than expected. Battery replacement every fifth year makes up the major part of the LCC of solar home systems and is also responsible for the large energy input in the production of the systems. This could limit both future cost reductions of distributed PV and its potential to mitigate greenhouse gas emissions. Copyright © 2002 John Wiley & Sons, Ltd.     

Experience with PV‐diesel hybrid village power systems in Southern Morocco

In October 2002, under the auspices of Spanish Cooperation, a pilot electrification project put into operation two centralised PV‐diesel hybrid systems in two different Moroccan villages. These systems currently provide a full‐time energy service and supply electricity to more than a hundred of families, six community buildings, street lighting and one running water system. The appearance of the electricity service is very similar to an urban one: one phase AC supply (230 V/50 Hz) distributed up to each dwelling using a low‐voltage mini‐grid, which has been designed to be fully compatible with a future arrival of the utility grid. The management of this electricity service is based on a ‘fee‐for‐service’ scheme agreed between a local NGO, partner of the project, and electricity associations created in each village, which are in charge of, among other tasks, recording the daily energy production of systems and the monthly energy consumption of each house. This register of data allows a systematic evaluation of both the system performance and the energy consumption of users. Now, after 4 years of operation, this paper presents the experience of this pilot electrification project and draws lessons that can be useful for designing, managing and sizing this type of small village PV‐hybrid system. Copyright © 2007 John Wiley & Sons, Ltd.     

Experimental analysis of battery charge regulation in photovoltaic systems

The influence of charge regulation on batteries for stand‐alone photovoltaic systems is analysed in relation to two factors: battery lifetime and the daily energy service supplied. The regulation thresholds adjusted in the charge controller (for disconnection and reconnection), in overcharge and deep discharge conditions, determine the whole system operation. Laboratory testing procedures are proposed and applied to different components of the photovoltaic rural electrification market. Finally, technical recommendations for charge regulation of lead–acid batteries are presented. Copyright © 2003 John Wiley & Sons, Ltd.     

Dependability analysis of stand‐alone photovoltaic systems

Long‐term performance of PV stand‐alone systems is analysed in this work in terms of dependability. On one side, the quality of a PV system, the energy service supplied to the users, depends on the initial design and sizing and on the component ageing that progressively decreases the availability of supply on demand (energy reliability). On the other side, technical failures lead to system stoppage until repairing is performed (technical reliability), which is crucial in real rural electrification applications. All those factors are analysed together with the basis of an extended field, laboratory and bibliographic review work. Copyright © 2006 John Wiley & Sons, Ltd.     

Photovoltaic residential electrification: a case study on solar battery charging stations in Brazil

Solar battery charging stations (SBCSs) were initially conceived to bring the price per household of electrification within the capacity to pay of the rural poor, and to foster the establishment of community businesses supplying the modest electricity demands of end users far from the grid in an entrepreneur‐based electrification model. The great foreseen advantages of SBCS were security of payment for the electricity service and operation under much higher system final yields and capacity factors. However, an analysis of the annual costs of SBCSs indicates that they are in reality more expensive alternative than solar home systems (SHSs) owing to the shorter lifetime of batteries. Moreover, battery transport for recharging and lower energy capacity, among other drawbacks, make users opt for the added convenience of a SHS. A financial analysis of a general case study is presented, with SBCS and SHS designed to offer equal electricity services. The local field experience is that after one and a half years SBCSs were replaced by SHSs. Copyright © 2001 John Wiley & Sons, Ltd.     

Rural photovoltaic electrification programme on the Bolivian high plateau

From 1988 to 1993, the Institute of Solar Energy at the Universidad Politécnica de Madrid carried out a programme on the Bolivian high plateau that attained photovoltaic (PV) electrification of 1500 rural households by means of individual Solar Home Systems (SHS). This programme focused on three aspects: domestic electrification, transfer technology and user participation. In the case of domestic electrification, the SHS design presents some special features related to reliability and security, including the use of car batteries with lower than usual electrolyte density. The transfer technology process has been focused o n the fabrication of lamps and charge regulators specifically designed for this programme. At present, good-quality and competitive local products are available in Bolivia. User participation has been structured around a specific organization named ADES ( Asociación de Electrificación Solar). Each user has contributed an initial fee of US$ 80 plus a monthly maintenance fee of US$ 1. The results of the programme show the maturity of PV technology for rural electrification projects in developing countries. In our particular case it is also the cheapest way to achieve rural electrification on the Bolivian high plateau.     

Test procedures for maximum power point tracking charge controllers characterization

Photovoltaic stand‐alone systems (PVSAS) are the most widespread technology for rural electrification of off‐grid areas, for communication systems, and for satellite applications. Such applications require high reliability to guarantee an adequate electrical supply. In these systems, charge controllers and inverters are used to fit the PV output power to the load. The power adaptation stage is essential to the proper performance of the PVSAS and to the optimization of the energy management of the system. However, there are no international standards yet approved that cover the quality requirements of this stage. This paper deals with the performance of those charge controllers that use maximum power point tracking algorithms. The aim of this work is to define the specific parameters that describe the real performance of these controllers, paying attention to their static and dynamic efficiency and establishing the acceptable minimum thresholds required for each one. A set of measurements of three commercial controllers was developed. Their behavior in real varying conditions was monitored along 1 year of operation. Results are presented here after being checked with repetitive indoor measurements using a PV array simulator. Main results of the operation in a PVSAS are included in the paper for selected representative days along the year. To perform the daily analysis, we have classified each day according to its weather conditions. The purpose is to analyze the relation between the performance of the controller and the weather variations. Within the conclusions of this work, some guidelines for the definition of test procedures for maximum power point tracking charge controllers are included. Copyright © 2011 John Wiley & Sons, Ltd.     

Photovoltaic Rural Electrification

The history of photovoltaic rural electrification (PVRE) from the early systems installed at the end of the 1960s is reviewed and presented in three different contexts: developed countries, international aid and developing countries. The progression from community applications (school televisions, village drinking water pumps, health centres, etc.) to individual applications (domestic electrification) is outlined. Differences between the concepts of ‘basic’, ‘perceived’ and ‘standard’ electricity needs are discussed. Relative advantages of the different products comprising current PVRE are analysed in the light of potential user perceptions. Proposed large-scale PVRE programmes based on solar home systems are analysed, paying special attention to two aspects that have become controversial issues in the PV community: the capabilities and role of the users; and the need for systematic quality control procedures. Finally, some economic figures related to investment and maintenance costs are proposed. © 1997 John Wiley & Sons, Ltd.     

基于家用电器耗电量的广东省城乡居民用电需求分析

居民生活用电一直是电力市场中最具潜力的增长点,而对城乡居民生活用电需求的分析也一直是各界人士倍受关注的热点问题之一。本文基于leap模型从家用电器耗电量的角度分析广东省城乡居民未来5年的用电需求。结果发现,2016-2020年城镇空调、电冰箱的使用引起的用电量年均增长率分别为8.21%和8.33%;而农村空调、电冰箱的使用引起的用电量年均增长率分别为11.41%和7.31%。城乡居民用电潜在需求较大。     

Low‐cost data communication network for rural telecom network management

The backbone networking infrastructure of rural telecom networks is often costly and is of limited bandwidth. The availability of connectivity such as DSL or leased lines is scarce. In order to keep operational costs low, these rural telecom networks are often kept unmanned and are managed from a centralized network management station (NMS). This often requires a low‐cost, efficient and reliable data communication network (DCN) between the rural telecom equipment and the central NMS. The conventional DCN used for telecom management consists either of leased lines or Internet connectivity. These are often costly and not freely available in rural areas. We have developed a new DCN model, based on dial‐up, which is easily available. Using mathematical models and measurements we show that this DCN meets the QoS requirements of a telecom network at an affordable cost. We have implemented this DCN in corDECT networks. This is in use in India and Tunisia, and is under implementation in other similar countries. Copyright © 2007 John Wiley & Sons, Ltd.     

Analysis of information and communication needs in rural primary health care in developing countries.

This article presents three studies dealing with information and communication needs in rural primary health care from Peru and Nicaragua. Results show that primary health-care systems in rural areas of developing countries are very inefficient. Among the main reasons we found factors related to communication infrastructure, information sharing, and continuous training of health professionals. We conclude that telemedicine systems can improve this situation, but the lack of infrastructures, low income levels, and other conditions, impose strong limits to the introduction of new technologies. The main conclusion is that differences in needs and conditions between developing countries and industrialized ones force to use different solutions and approaches. This article presents some proposals on technology requirements and how to deal with the use of telemedicine in rural areas of developing countries. These proposals can be useful to all kind of actors (national public administrations, multilateral institutions, industry, academy, civil society, etc.) in order to promote really relevant and sustainable proposals in telemedicine for rural regions of developing countries.     

基于引入取舍规则的Lyapunov指数法的电力负荷预测

基于Lyapunov指数法，在引入取舍规则基础上建立了电力负荷预测模型，并利用此模型对某农电局的电力负荷进行预测，取得了满意的结果。     

Electric consumption in SHSs in rural communities of Brazil and Peru and recommendations for sizing

The lack of data records of electric power consumption of small photovoltaic home systems, independently of the method used for sizing them, drives to consider the demand as a constant. However, the existing data reveal the variability of the consumption due to the influences of some social, cultural and psychosocial aspects of the human groups. This paper presents records of consumption data obtained from several solar home systems (SHSs) in Brazil and Peru, and it discusses about the Gamma distribution function that can express to a great extent the behaviour of the demand. By this analysis it was verified that ‘a lot of people consume little and few people consume a lot’. In that sense, a few recommendations for sizing procedures that can be useful in the implantation of extensive programmes of rural electrification by SHSs are presented. Copyright © 2007 John Wiley & Sons, Ltd.     

Crystalline silicon photovoltaic modules: characterization in the field of rural electrification

The need to characterise photovoltaic modules in the general field of ensuring technical quality in photovoltaic rural electrification (PVRE) has often been pointed out. The ongoing national PVRE initiatives announced world‐wide, together with the fact that PV modules with an actual power smaller than the nominal value can still be found on the market, make it advisable to apply systematic control to supplied power procedures. This paper argues that it is possible to carry out such control in the case of crystalline silicon PV modules, by means of experiments performed outdoors under a wide range of operation conditions, and using reduced and conventional equipment. A simple characterisation procedure specifically aimed at PVRE programmes is described and validated with an extensive experimental campaign. Copyright © 2002 John Wiley & Sons, Ltd.     

Rolling Friction Enhanced Free‐Standing Triboelectric Nanogenerators and their Applications in Self‐Powered Electrochemical Recovery Systems

Heavy metals contained in wastewater are one of the most serious pollutions in natural resources. A self‐powered electrochemical recovery system for collecting Cu ions in wastewater by incorporating a rolling friction enhanced freestanding triboelectric nanogenerator (RF‐TENG) is developed here. The RF‐TENG utilizes integrated cylindrical surfaces using the conjunction of rolling electrification and freestanding electrostatic induction, which shows outstanding output performance and ultrarobust stability. By using the kinetic energy of flowing water, a collection efficiency of up to 80% for Cu²⁺ ions in wastewater has been achieved. Self‐powered electrochemical systems are one of the most promising applications of TENGs for independent and sustainable driving of electrochemical reactions without the need for any additional power supply. This research is a substantial advancement towards the practical applications of triboelectric nanogenerators and self‐powered electrochemical systems.     

Organic Tribotronic Transistor for Contact‐Electrification‐Gated Light‐Emitting Diode

Tribotronics is a new field about the devices fabricated using the electrostatic potential created by contact electrification as a “gate” voltage to tune/control charge carrier transport in semiconductors. In this paper, an organic tribotronic transistor is proposed by coupling an organic thin film transistor (OTFT) and a triboelectric nanogenerator (TENG) in vertical contact‐separation mode. Instead of using the traditional gate voltage for controlling, the charge carrier transportation in the OTFT can be modulated by the contact‐induced electrostatic potential of the TENG. By further coupling with an organic light‐emitting diode, a contact‐electrification‐gated light‐emitting diode (CG‐LED) is fabricated, in which the operating current and light‐emission intensity can be tuned/controlled by an external force–induced contact electrification. Two different modes of the CG‐LED have been demonstrated and the brightness can be decreased and increased by the applied physical contact, respectively. Different from the conventional organic light‐emitting transistor controlled by an electrical signal, the CG‐LED has realized the direct interaction between the external environment/stimuli and the electroluminescence device. By introducing optoelectronics into tribotronics, the CG‐LED has open up a new field of tribophototronics with many potential applications in interactive display, mechanical imaging, micro‐opto‐electro‐mechanical systems, and flexible/touch optoelectronics.