SOLAR RECYCLE

SLL Young Lighter 2020, Aluwaine Manyonga outlines his award-winning paper on a sustainable solution to limited access to electricity in Africa

frica, the cradle of mankind, rich A in many natural resources and with an annual solar irradiance of 260W/sqm, still suffers limited access to electricity. According to the World Bank in 2018, only 47.7 per cent of the population has access, with rural areas being the most affected with a deficit of 68.5 per cent. This means 600m people have no access to electricity. School pupils are particularly affected since one in every three primary school students goes to a school without any type of electricity, according to the United Nations Department of Economic and Social Affairs (UN DESA) in 2014.

This limited accessibility has robbed students of one of the key benefits of electrification which is lighting, clearly essential to the education sector. To help rectify this situation, I would like to introduce the off-grid solar lighting system and Chigubhu Lantern concept. Combining off-grid solar lighting with the reuse of both electronic and plastic waste forms the basis of the solution. I believe this could be an answer to Africa’s limited access to electricity and ensure that every student has access to high-quality and reliable lighting.

As has become widely known, African school students are generally resorting to using fuel lamps and candles. Kerosene (paraffin) is the most popular fuel used and it has detrimental effects on health and the environment, and is costly for users. Kerosene lamps emit 270,000 tonnes of black carbon every year, contributing a major share to global warming. The health implications of these lamps include impaired lung function, asthma and cancer risks, and compromised visual health due to their low lumen output. Despite the low initial investment, these lamps have a higher maintenance cost which can account for 10 to 15 percent of E

'School pupils are particularly affected since one in every three primary school students goes to a school without any type of electricity'

household income. This expense leads parents to cut down students' study time. Light output from the kerosene lamps is also dull and flickers, which reduces the concentration and energy level of the student, hence the need for high-quality light sources.

THE BENEFITS OF LEDS

LED lighting has replaced a lot of kerosene lamps on the continent. As they have elsewhere in the world, LEDs have become a great competitor of conventional lighting technologies. The LED is a semiconductor based on the p-n junction of a diode that emits visible light of a certain colour when electricity passes through it. It has a long life, from 25,000 to 50,000 hours, and also a high luminous efficacy which ranges from 60-130 lm/W. It is therefore very useful in batterypowered systems, and continuously improving. Their efficiency reduces the operational cost compared to other light sources, and they produce higher luminous flux in smaller packages which is favourable in most lighting applications. There has also been a price drop in the LED industry, making it affordable to the rural population.

RECYCLED COMPONENTS

The concept uses off-the-shelf DC converters and chargers. LEDs are designed for lowvoltage DC which makes drivers a requirement for using them in AC systems. The drivers usually fail before the LED chip fails and this is due to poor capacitor construction, inefficient heatsink design and use of poor-quality components. Driver failure contributes to 60 per cent of LED luminaire failure.

Africa still lacks the infrastructure to manage electronic waste and this poses a challenge for ensuring proper collection and recycling. With the sharp rise in the production of batterypowered consumer electronics the continent is seeing more batteries finding their way to dumpsites before the end of their lifespan. These batteries can be reused to power LED chips from luminaires that have been disposed of, a proposition made more viable by the high efficacy of LED lighting.

OFF-GRID POWER

The high solar yields that are received in Africa generally makes off-grid solar lighting a highly practical solution for improving lighting in schools. Furthermore, the decrease in solar equipment prices also means there is increased potential for joint ventures between the government, NGOs and the general population to ensure that the schools get reliable lighting solutions. DC solar systems would be used to power LED chips directly, to increase efficiency and eliminate the use of sophisticated drivers which, as mentioned before, shorten the lifespan of the chip. DC solar systems in LED lighting have the following benefits compared to an AC solar system: • better for charging batteries • more efficient if most energy needs to be stored, meaning longer lighting hours • easy to set up and safe to work with for voltages below 48V • eliminates the use of inverters which reduces the overall system cost by 20 per cent

This system would be set up at schools and other central points so as to cater for students living far away from the school and ensure reliable access to lighting.

The off-grid solar lighting set up would consist of DC LED luminaires, solar panels, charge controllers, batteries, and charging ports (5V and 12V) for charging individual lanterns. The system would be sized to provide power for charging the batteries and the individual lanterns. The lumen method and Dialux Evo would be used to ensure 300 lux general lighting for classrooms is achieved.

Students and teachers would be taught the basics of setting up and maintaining the off-grid solar lighting system. Multiple USB charging ports would be provided for charging individual lanterns. The process would also involve establishing collection points and sorting areas for electronic waste, typically from LED sources, rechargeable torches, power banks and cellphone batteries. Students, teachers and the community would be trained on how to reuse the abovementioned e-waste to make lanterns.

Kerosene lamps have become a widely used light source at the expense of both health and the environment

SOLAR PHOTOVOLTAIC PANELS SOLAR CHARGER AND CONTROLLER CIRCUIT

BATTERY BANK

p Individual elements which make up the solar DC system

CHIGUBHU LANTERN CONCEPT

Chigubhu is a Shona word for any plastic container (water bottle). African countries are now leading in polyethylene terephthalate (PET) recycling and small-to-medium enterprises have created employment for many people who take part in plastic waste collection. Plastic water containers can be reused to produce custom-made housings for the lanterns, with the electronic waste combined and contained within. Transparent high-density polyethylene (HDPE) can be used to direct and diffuse the light to produce a high-quality source. To minimise the cost and maintenance of individual small solar panels for each light, the lanterns will be recharged at school or any of the central points within the off-grid solar lighting system. To date two lanterns, made using electronic waste, have been tried and tested. In summary, the Chigubhu Lantern comprises the following:

• LED chip • charging circuit (5V/12V) • rechargeable battery • control circuit • Chigubhu container

The concept can support various existing initiatives that are introducing solar-lighting kits across Africa. Extending the lifespan of the solar lantern will further minimise and help in controlling electronic waste disposal. To summarise, the concept will have a whole range of benefits.

LEDs offer high-quality light output which reduces compromise on visual health and, using higher CCT (cool white) sources, have proven to be effective when studying by increasing the alertness, attitude and energy level of the students. Classroom and studying time will be extended for the students, teachers would be able to work extra hours marking assignments and advancing their education, and adult evening classes can be offered. This will lead to improved pass rates and literacy.

Students and teachers will now use clean lighting sources and recycle e-waste, and there will be a reduction in the amount of CO2 emissions from fuel lamps. Extra income streams will be generated from repairing lanterns and collecting plastic waste. Students will have an opportunity to learn about the impacts of lighting on their overall performance. To conclude, limited accessibility to highquality lighting has negatively affected Africa’s education system. This concept can indeed be a game-changing solution.

DC LOADS (DC bulbs, DC fans, mobile chargers etc.)

p The Chigubhu lantern: plastic water

containers can be reused to produce custom-made housings for the lanterns

The author would like to thank Ruvarashe Manyonga for assistance with this feature