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Solar lanterns

In developing countries the solar lantern is a cheap alternative to a Solar Home System (SHS) providing 4-5 hours of high quality lighting service. It provides higher quality light than the use of candles or kerosene lamps. They are also used to provide street lighting in rural areas. In this case Light Emitting Diode (LED) solar lanterns are usually used. In industrial countries solar lanterns are usually used outdoors to provide lighting in the garden or driveway or for other outdoors activities such as marine or camping applications. Solar LED lighting is also used for marine and aviation lights, road signs, road beacons, bus shelters, bus stops and many other applications. LEDs are durable and reliable surviving extremes of temperature and weather, vibration and Ultra Violet (UV).

Introduction top

In developing countries the solar lantern is a cheap alternative to a Solar Home System (SHS) providing 4-5 hours of high quality lighting service or 15 hours of listening to the radio. It provides higher quality light than the use of candles or kerosene lamps. They are also used to provide street lighting in rural areas. In this case Light Emitting Diode (LED) solar lanterns are usually used. The Glowstar lantern developed by Practical Action in the Kenyan context and now marketed by Sollatek is a good example of a robust version of a solar lantern, which can withstand harsh African conditions (see Practical Action). It uses a PV panel to charge up a 12-Volt lead-acid gel cell battery located in the base of the lamp which is designed to withstand many charge/ discharge cycles. Other manufacturers may have different battery specifications. The light source is a compact fluorescent tube which should last four years in normal operation. There are many lamps on the market but the main working principles are the same.

Solar Lanterns are commercially available through a range of companies, such as from MFG in California with a Ni metal hydride battery and up to 24 hours light delivery (MFG, 2007). In India, locally manufactured solar lanterns are considered to be a mature market and capital subsidies for the lanterns have now been withdrawn. They have a range of features and designs as can be seen in the following Figure.

illustration © climatetechwiki.org

Figure 1: Solar Lantern Types (Source: Practical Action)

In industrial countries solar lanterns are usually used outdoors to provide lighting in the garden or driveway or for other outdoors activities such as marine or camping applications. Solar LED lighting is also used for marine and aviation lights, road signs, road beacons, bus shelters, bus stops and many other applications. LEDs are durable and reliable surviving extremes of temperature and weather, vibration and UV.

The LED lamp uses a very small silicon ‘chip’ made of a special blend of crystals. When a small electrical current is passed through the chip it generates light. The LEDs used with the solar panels as used in the industrial applications above have the advantages of a range of colours. Depending on the blend of crystals, almost all the energy is converted to light. LEDs have a long lifetime of 27 years. They are shock proof and durable and provide a focussed beam of light.

The PV panels can be monocrystalline, polycrystalline, amorphous or thin film which affects the lifetime and price of the unit. The lantern materials vary, but usually contain a mixture of plastics and metal such as stainless steel. With LEDs solar lanterns can provide high intensity light for longer times, e.g., 6 hours. The ‘COSMOS’ LED solar lantern uses a rechargeable NiCad battery pack which provides over a year and a half of use (Sustainable Village, 2007).

Feasibility of technology and operational necessities top

There are scattered data on the feasibility of solar lanterns in several countries. For instance, Velayudhan (2003) looked at the Indian government dissemination programme for solar lanterns. Solar PV is suitable where the cost of grid extensions is high, insolation levels high, and the receptor communities geographically scattered. In India only 365,000 solar lanterns have been installed under the programme despite the favourable conditions for adoption. The programme allowed for a 50% subsidy by the government on the cost of the lantern with the remaining amount for the lantern and installation being met by the consumer and the state level government. Despite this, adoption was low. The acceptance of the technology is considered to be dependent on the relative advantage of the new technology over the alternatives and the process of communication flows through the community. The following lists the advantages and disadvantages of the solar lanterns from a survey of the adopters in India .

illustration © climatetechwiki.org

Figure 2: Solar Lanterns in India (Source: Velayudhan, 2003)

Velayudhan (2003) suggests that a focus on the relative advantages of the technology is important for dissemination and a subsidy is not enough. There needs to be consideration of the needs of different buyer groups and their ability and willingness to pay. Sources of information were limited to government and sources need to be much wider with proactive group meetings for dissemination.

See video

Video 1

Status of the technology and its future market potential top

Statistics on solar lanterns tend to be aggregated into the SHS figures so that it is difficult to get data on the status of solar lanterns individually. The work by the International Energy Agency (IEA) on PV power systems does not discriminate in terms of SHS and solar lanterns. The technical potential of the technology is obviously high both in developing and industrialised countries, since solar lanterns are now regarded as a mature technology. In industrialised and in some developing countries such as India and China the solar lantern is now a fully commercial technology using an indigenous supply chain with no subsidies. In other countries such as Kenya the lamp is supplied to the Kenyan market from a UK supplier which has factories worldwide including Egypt, Taiwan, Hong Kong, China, Mexico, Thailand and Indonesia.

In India, solar lanterns represent 4.5% of the Indian solar module consumption of 110 MWp (Srinivasan, 2007). Most work has been carried out in India investigating the rebound effect when providing solar lighting in the context of unsatisfied demand (Roy, 2000).

In India and China solar lanterns are locally made and commercially available. They are also exporting solar lanterns to industrialised countries and to other developing countries. There are also export flows from industrialised countries to developing countries, so that there is already a global market. However, there is still a long way to go to reach potential adoption levels. The study by Velayudhan (2003) on the programme for adoption in India illustrates how programmes which are not well designed can be improved to maximise the chances of success.

See video

Video 2

The case of Sri Lanka illustrates what is important for consumers. In Sri Lanka, the RERED project builds in consumer protection to ensure that the products being sold are of good quality and certified. The conditions also require that manufacturers provide efficient after- sales service and respond to complaints to enhance the social acceptability of the technology. This quality control, certification of products meeting their standards on quality, reliability, service and complaints procedures have been important in ensuring consumer confidence. Firms are also required to provide appropriate training in the use of the equipment for customers as well, so that they are protected from the problems which are beginning to show for CFLs where some sort of standardisation and quality control is needed.

There have been developments in almost all parts of the solar lantern. One of the main developments is the use of LEDs instead of CFLs with their longer lifetime and robustness advantages. Batteries have improved with time and charge controllers can prevent batteries from deep discharge and over charging. Controls can allow the light intensity to be varied to prolong lighting time and a good battery type such as NI –metal hydride can also provide long lighting times.

However, there seems to be no industry standard and no quality control along the lines of the RERED project in Sri Lanka. This would seem an area for improvement. There is still much to be done to reach the poorest but through markets for leisure and other uses and designs such as for the NEST lantern, the cost of these lanterns is decreasing making them more accessible to the poor.

How the technology could contribute to socio-economic development and environmental protection top

In developing countries the provision of good light in the evenings allows many activities not usually available; children can do their homework, radio provides a link to engage people with the political process, savings can be used for education or health care, social gatherings can take place in the evening, night classes and economic activities are also possible. Since 2003, the Glowstar has been available in Ghana, Kenya, Europe, USA and Asia. The lanterns also deliver cost savings over its lifetime compared to a kerosene lamp. On average a family may spend USD 4-5 a month on kerosene so that on that basis alone the payback time could be 20-25 months. These savings would be delivered for every year of operation as there would be no other running costs except for intermittent battery replacement. There are local supply chains for spare parts so that jobs are created with the adoption of the solar lantern.

As they supply an independent light source, lanterns can be accessed in areas where there is no prospect of any other electrical light source. They can be used therefore in clinics and hospitals and schools. Increased use of the solar lanterns can lead to an increased manufacturing and supply system with increased employment and income. Another benefit to developing economies is the reduction in kerosene imports.

The leisure and industrial uses of LED solar in industrialised countries allows increased reliability of safety lighting devices and savings in operating costs. The lamps also deliver social benefits by enabling leisure activities. Jobs are created in the manufacture and supply of the unit and spare parts.

Contribution of the technology to social development top

In developing countries the technology delivers a high quality lighting service to the poor who cannot afford a SHS. In Kenya for example, 96% of householders use kerosene for lighting. Dry-cell batteries for torches are also used. These sources have significant costs on a monthly basis so that a solar lantern provides not only kerosene savings but dry-cell cost savings. LED lamps solar lanterns can be used as street lights providing security to householders.

In industrialised countries solar LEDs in outdoors and industrial applications provide savings in terms of long-term reliability compared to ordinary lamps and low power requirements saving energy and replacement costs.

Contribution of the technology to economic development (including energy market support) top

Solar lanterns such as Glowstar are currently more expensive, at about USD 100 each in Kenya, than originally envisaged, although it is still much cheaper than a SHS. Nevertheless, poor people may need microcredit facilities to be able to afford it. The lantern is robust and reliable and can be maintained locally with spare parts available. The lamp lifetime is expected to be 10,000 hours while the unit itself is robust over a much longer time. With LEDs replacing CFLs the lamp life can be much longer at 100,000 hours.

In industrialised countries for leisure and industrial use they act as an energy efficiency measure reducing the demand for grid electricity. They offer a secure, reliable and affordable option.

Contribution of the technology to protection of the environment top

In developing countries the solar lantern delivers a lighting service which is 500 times that for a kerosene lamp. At the same time, it saves the emissions from kerosene in terms of CO2. For a monthly use of between 7-12 litre of kerosene, the average savings are 320 kg CO2/household/year (Begg, K., 2003). This is relatively small per household, but when multiplied up over many homes it can contribute to a significant reduction in CO2 emissions. For instance, the target sales for the Glowstar were 30,000, which would provide 9.6 ktonnes CO2 reductions per year. It also avoids the fires and consequent burns injuries associated with kerosene, and it reduces exposure to air pollution.

In industrialised countries, LED solar for industrial applications will replace grid electricity for less efficient lighting systems, as well as reduce resource use with the long lifetimes of the LEDs. The amount of savings has not been documented and will depend on the emission factor for the grid electricity being saved which is country dependent.

Financial requirements and costs top

The cost of a solar lantern varies with the design features, materials used, light source (CFL or LED) and country of origin and application. A short Internet survey indicates that CFL lanterns for providing home lighting in developing countries or remote locations cost about USD 85-120; for LED lanterns it is more difficult to find such cost figures, with the exception of MFG lanterns which cost USD 110 with a no-memory effect NI-metal Hydride battery and up to 24 hours light. In terms of performance, LED technology seems to be superceding the CFL versions.

Most facilitative programmes (for the uptake of solar lanterns) refer to PV systems and not to simple solar lanterns. However, there are some examples of explicitly solar lantern projects. The case of the solar lantern programme in India has already been described above in Section 25.2. Although it was directed at the very poor with no access to electricity, it was eventually taken up by agricultural and service people because the very poor could still not afford the equipment (Velayudhan, 2003). Practical Action has a programme of rural mass marketing of their specially designed Glowstar lantern which is affordable, accessible and appropriate. They hope to have 30,000 adopted in Kenya after an initial pilot programme.

The Bhopal solar lantern project in India is currently funded by a grant from Partners in Rural Development, which is part of CIREP (Canadian Indian Rural Energy Project). The project, run by Madhya Pradesh Gramin Vikas Mandal, has also received a soft loan from the US funding agency Winrock International, from their “Accelerating renewable energy commercialisation in India” fund. This loan is being used to support expansion of the solar lantern project in other cities. The project hires solar lanterns to market vendors and street hawkers who work at night in the street markets of Bhopal, a city in northern India. The idea is to provide them with a cleaner, cheaper, and safer form of lighting for their stalls instead of the kerosene and electrical lamps powered by diesel generators. This project hires out the lanterns at a cheap rate delivering the lanterns to the vendors each evening, and collecting them again at around 11.00 pm for recharging. The project is using 100 solar lanterns that were purchased using the CIREP grant. These have a 7-watt CFL lamp and are powered by a 12-volt battery. This project showed that it would be easy to cover all costs by charging less than the stall holders currently pay for lighting (MPGVM, 2003). A programme aimed at the very poor in Hyderabad is the NEST (Noble Energy Solar Technologies Ltd programme 2006). A solar lantern was designed to be affordable for the poor though even at USD 19 the poor still pay by instalments. The lamp pays for itself in 20 months through the savings in kerosene use. The distribution and payment collection network is local and reaches the very poor (NEST, 2006).

In Bangladesh there is a solar lantern programme aimed at the very poor with no access to electricity (LGED, 2007). This project is part of an overall sustainable rural energy programme funded under the UNDP supported Sustainable Environment Management Programme (SEMP). Government involvement is through the Ministry of Environment and Forest (MoEF) along with 21 ministries, divisions, departments and civil society bodies project. The solar lantern project is run under the Local Government Engineering Department (LGED) as a sub-implementing agency of Sustainable Rural Energy (SRE). 70% of people in Bangladesh are without electricity and have no prospect in the near future of any connection. Remote households of the Tangail district are being targeted by the project which offers low cost solar lanterns with four configurations and prices and duration of light.

References top

Local Government Energineering Department (LGED), 2007. Available at: http://www.lged.gov.bd/

MFG, 2007. LED Solar Lantern.

NEST, 2006. Available at: http://www.ashdenawards.org/winners/nest

Practical Action. Available at: http://www.practicalaction.org

Roy, J., 2000. The rebound effect: some empirical evidence from India, Energy Policy, 28, 6-7, pp. 433-438.

Srinivasan, S., 2007. The Indian Photovoltaic industry: a life cycle analysis, Renewable and sustainable energy reviews, 11, pp. 133-147.

Sustainable Village, 2007. Mighty Light LED Solar Lanterns. Available at: http://www.sustainablevillage.com/servlet/display/product/detail/41353

Velayudhan, S.K., 2003. Dissemination of solar photovoltaics: a study of the government programme to promote solar lanterns in India, Energy Policy, 31, pp. 1509-1518.