the glowstar project: developing the next generation of solar lantern

EWB-UK & EAP Education Conference 2012 ‘Changing Course: The Global Dimension to

Engineering Education’ 26th March 2012

Research Panel Paper Author: Samina Azreen Islam Institution: University of Manchester 8

The Glowstar Project: Developing the next generation of solar lantern Samina Azreen Islam

University of Manchester

Abstract In the early 2000s the Glowstar Lantern was developed to meet the need for low cost, robustly designed off-grid lighting solutions in Kenya. Despite meeting the criteria for a well manufactured product, the lantern failed to reach its target market due to its high cost. Researchers in previous years have worked on both the technical and business sides of the lantern, reducing the costs considerably, however the lantern still remains just outside the price range deemed the most affordable for Kenyan off grid communities. This project seeks to continue the technical development of the Lantern, taking the approach of looking into more innovative areas such as organic electronics as means to drive down the cost and widen the applications for the lantern.

Keywords: Solar, glowstar, lantern, Kenya, off-grid lighting

Introduction As of 2011, almost 3 Billion people [1] in the world- almost half of humanity- currently live without electricity, [2] the consequences of which are a life lived in poverty with little to no access to other basic rights such as medical care and education. [3]

In 1997 a World Bank report stated that 90% of Kenya’s population were off grid and owing to the geographical nature of the country identified a significant need for and gap in the market for solar technology solutions for off-grid applications [4].

In the early 2000s, Practical Action Consulting (PAC), the consulting arm of Practical Action known then as the Intermediate Technology Development Group (IDTG) responded to this need by creating The Glowstar Lantern (GSL) in partnership with Sollatek Ltd, a small manufacturing company specialising in solar products.

Figure 1: The Glowstar Lantern

The GSL was developed as a short term, “my first” technology solution to Kenya and Africa’s complex energy needs, enabling people to build capacity and economic growth for themselves through studying or working for longer hours in the evening, eventually putting them in a position where they could afford to join the grid or invest in more sophisticated technologies. It was also developed to be the major alternative to the current use of kerosene lanterns and candles, the former of which pose serious health risks due to inhalation of noxious fumes.

EWB-UK & EAP Education Conference 2012 ‘Changing Course: The Global Dimension to Engineering Education’

26th March 2012


Figure 2: The GSL allows for children to study in the evening

While solar lanterns are not wholly innovative, the GSL was considered a market leader product, with its overall unique selling point being it’s high quality, robust and reliable design and low cost, making it highly adaptable to the uncompromising, rural environmental conditions of Kenya, compared to other lanterns on the market at the time of which diverge from being low cost and badly made to well designed and far too expensive for the market.

However, the GSL did not meet the market demand as expected and feedback from test communities during field trials for the product stated that at the original price of $150 the GSL was too expensive, particularly as GSL market analysis conducted prior to the GSL’s conception postulated a projected price of $50 being the price most of the target market would be able to afford. To date, previous researchers have worked on the Glowstar Lantern both on the technical and economic side to substantially drive down the cost, which now currently stands at $55 for the GS5 model and $85 for the newer model. [5]

Project Specification The project brief stipulated by the project partners’ places emphasis on dropping the cost of the entire system by over 10% via re-engineering the solar lantern, (specifically the newest model GS7) to improve market uptake of the product and to improve the overall functionality and usability of the Lantern.

Aims of the Project Drive down the cost of the solar Lantern to meet and maintain market demand.

Broaden the applications and number of uses for the lantern.

Maintain the high quality design work and other unique attributes to the lantern that differentiate it from theother products on the market.

Objectives of the project Investigating the feasibility of using innovative organic and inorganic photovoltaic panels as an alternative to the

thin film panels currently used, as much of the cost of the lantern is due to the expense of the panel.

Perform a technology review of LED technologies and batteries and subsequently update the technology of thelantern.

Solar panel

According to the cost breakdown provided by previous researcher Chris White, the solar panel was found to be the most expensive aspect of the entire system. At a budget cost of £18.152 for a batch order of over 1000 including DC connectors, the solar panel contributes 51% of the entire budget cost of the GSL which stands at £35.577 [6].

The GS7 is charged by a thin film amorphous silicon (a-Si) solar module rated at 12V nominal and available at 10W, 20W and 30W dependant on the wattage of the lamp that is purchased. Although mainly mono-crystalline silicon is considered the base material used in the design of the most widely recognised solar cells from the perspective of the consumer market, it is expensive with its high cost hidden in its complex manufacturing process negated by an approximately 17% efficiency trade off.

Many other materials and technologies exist within the solar technology markets that are competitive to silicon based cells; combinations of other inorganic materials such as cadmium telluride (CdTe) and Copper Gallium Indium Selenide (CIGS) are amongst the most established within the market. The advent of organic electronics has given rise to the use of conductive organic polymers to develop photo-voltaic cells like the dye sensitised solar cell. However, the question of efficiency, chemical and environmental stability of such new technologies compared to cost needs to be investigated.


26th March 2012


Testing plan for PV panels: Halogen light has been found to have similar luminescence properties as sunlight. Expose solar panel, which has been connected to a resistance box (at fixed resistance), to light emissions from

Halogen lamps. Tilt panel to required longitude (01°17'S) and latitude (36°48'E) co-ordinates [7] to emulate the specific angle at

which sunlight hits the panel in Nairobi, Kenya and find the voltage output (Voc), calculating the short circuit current (Ioc) using the fixed resistance value.

Characterise each type of solar panel in terms of its I-V curve, subsequently identify the Maximum Power point of the panel as shown in figure 3:

Figure 3: I-V curve characteristic of a solar panel

Calculate the overall efficiency of the panel. Carry out comparative analysis on panels’ suitability for the lantern, without losing the lantern’s present level of

efficiency.

At present, discrepancies have been noted in the repeatability of this experimental method; this was discovered to be due to the non-uniform distribution of light emanating from the halogen lamps and the resistance and resistivity properties of the panel increasing due to the heat radiation from the halogen light.

Batteries

The original design of the GSL utilised lead-acid AA batteries mainly for their low cost and abundant availability. Previous research recommended the use of Nickel-Cadmium batteries due to their superior energy storage properties. While this is true, this project contests the suggestion of such batteries as cadmium is a highly toxic metal and its usage is highly restricted in Europe by the REACH regulation. [8]

The graph in figure 4 shows that the energy densities and battery storage capacity of Lead-Acid batteries compared to other established technologies is low. Nickel–Metal Hydride (NiMH) batteries are considered to be the most practical alternative, offering higher storage capacities; leading to longer battery life and exhibiting no memory effect, which has limited their usability in previous years. This would subsequently allow for the lantern to be charged less often, maintain a low cost and is a widely available technology.

Figure 4: The energy densities in Wh/kg of various types of battery technologies


26th March 2012


Light Technologies

Figure 5: Testing the luminescence and light distribution of the lamp in an anechoic chamber

The GS7 currently employs a Compact Fluorescent Lamp (CFL; essentially an energy saving light bulb). Phosopher or white LEDs are a key technology that has been considered so far as an alternative as initial “blackout” tests performed showed that they offer a higher intensity of luminosity, high levels of light distribution due to the availability of 15, 30 and 70 degree distributions and abundant presence in simple, widely used products such as torches and bike lights. Induction of White LEDS into the GS7 would also remove the additional circuitry present that is required to increase the voltage output for the CFL. The Lantern due to the low light distribution is commonly used as a table lamp, mainly by children to study. Previous researchers have attempted various LED configurations and insertion of reflective materials to increase the light distribution to a full 360 degree spread. This has so far been unsuccessful, although finding a solution would mean that the lantern could also be used outside for people who work in agriculture (a major industry in Kenya) to work for longer hours.

Further Work The lantern so far has been assessed and critiqued in terms of its individual components and it has yet to be understood what sort of results a cohesive re-design would yield. There is another researcher undertaking the Glowstar Project concurrently, who is assessing the lantern predominantly in terms of its product design, which also gives rise to how to final design could actually be realised.

This project presents the capacity of advanced technology research into the field of organic electronics to be applied in developing appropriate technology, eloquently demonstrating the trade off that exists between innovative research and product development. The implementation of such technologies in Kenya and other developing countries exhibits unique and distinct environmental and economic constraints which will be examined more in depth when concluding recommendations for the lantern.

Acknowledgements Professor Andrew Gibson, Dr. Arthur Haigh, Dr. Vladmir Markevich & John Kings

References [1] http://www.humanitycampaign.org/global-poverty-facts/

[2] http://www.undp.org/energy/

[3] http://practicalaction.org/energy

[4]http://rru.worldbank.org/Documents/PapersLinks/27.pdf [5]http://www.glowstar.net/index.asp [6]‘Developing the next generation of Glowstar Solar Lantern’ Chris White, University of Cambridge, 2010 [7]http://www.mapsofworld.com/lat_long/kenya-lat-long.html [8] http://www.reach-cadmium.eu/

Figures

Figure 1: http://adjei.co.uk/images/lantern_offa.jpg

Figure 2: http://practicalaction.org/images/solar-lantern-37005.jpg

Figure 3: http://solarcellcentral.com/images

Figure 4: http://metaefficient.zippykidcdn.com/wp-content/uploads/lifepo4-energy-weight-comparison-of-different-battery-types.gif

Figure 5: Photo taken by author during experimental work