IAEEL newsletter 2/96

PV Lighting

Efficient lighting can help photovoltaic cells go Big Time. Despite their high kilowatt-hour prices, photovoltaic solar cells are often the cheapest way to get a few watts of power for lighting in Third World villages. But if the efficiency of the lighting systems is neglected, most people in developing countries will be unable to afford PV lighting.

The first few watts of power make an enormous difference for a Third World villager. With no grid connection, it is pitch dark at 6 pm, unless light is provided by an open fire, a kerosene lamp, or a car battery which has to be transported from the nearest diesel generator or grid connection.

Figure: Stamp. Solar street lighting in India

With a very modest power supply, pupils and students can do their homework or attend night classes. A doctor can examine or operate on a patient. Handicraft can continue. Water pumps, fans, TV sets (often communal), and other applications can also operate on PV systems, but lighting is the most important end use. The tens or hundreds of watts needed for lighting can be cost-effectively provided by a photovoltaic array. PV lighting can be 100-times more efficient than kerosene lighting. If burning hours are short, lighting from a PV kit is not necessarily much cheaper on a life-cycle cost basis than that provided by a kerosene lamp, but the lighting quality is greatly improved with increased light levels.

MILLIONS LACK ELECTRICITY
The costs of connecting hundreds of millions of villagers to the electric grids within the foreseeable future are prohibitive. Moreover, in most Third World countries the overburdened electricity supply systems are in a sorry state of repair, and there is little money available to maintain or fix them. Electric utilities in developing countries face a multitude of problems, including blackouts, "brownouts", large numbers of unpaid bills, and electricity thefts -the latter through dangerous non-professional connections.

Most of these problems could theoretically be solved by a steep price hike for electricity, which could pay for better maintenance, new power stations, and more efficient administration, while also providing incentives for using electricity more efficiently. However, this is unlikely to happen in the near future since most governments consider large increases in electricity tariffs to be very dangerous politically.

The use of photovoltaics is a realistic, small-scale alternative in many nations. According to professor Bob Hill at the University of Northumbria in Newcastle, England, 20 000 individual PV systems have made it into the market in Kenya. In countries such as Brazil and South Africa, the governments see PVs as a cost-effective strategy for achieving rural electrification. In South Africa alone, 2 million homes are targeted for PV electrification. According to the European Commission, domestic PV systems will account for most of the PV applications through 2010, which means that domestic PV systems will be a major force in furthering the development of photovoltaics and achieving economy of scale.

INTERNATIONAL FUNDING
The Global Environment Facility and the International Finance Corporation (the private sector affiliate of the World Bank Group) regard the large-scale promotion of Third World PV electrification "as one of the best long-term prospects for a low carbon energy future". Their joint "PV Market Transformation Initiative", also known as the "Green Carrot", has a budget of almost US$60 million. One of the strategies behind the program is to use PV-lighting systems to help stimulate the overall market for photovoltaics. Eventually, large-scale solar cell production will be cheap enough to compete with traditional sources, even for utility-scale power production.

The purpose of the program is to accelerate manufacturer improvements and market growth by 3 to 5 years. The $60 million awards (soft credits, with added private-sector and governmental "leverage" of about three-times this sum) will be awarded to 3 to 6 national projects for market development and manufacturing, with the aim of overcoming market barriers. The program addresses issues such as:

Financing: Even if PV solutions are cost-effective on a life-cycle cost basis, the prospective customer may not have the money in his or her hand. Projects will encourage innovative financing mechanisms and help persuade banks not to be over-conservative when deciding whether or not to lend money for purchasing household PV systems.
Manufacturing capacity: If there is a guaranteed market for the first years' output, manufacturers will be willing to invest in more new capacity.
Level the playing field: subsidies to grids and diesel generators distort the market for renewables and efficiency. Support to PV systems helps them to compete.
Consumer awareness: Many prospective customers don't know anything about PVs, and utilities are conservative with regard to all small-scale, decentralized technologies.
Transaction costs: Low customer density renders sales, installation, service, and payment collection expensive and difficult.

It is obvious that efficient use of energy is important in all PV applications. For instance, a PV module will support more fluorescent lamps than incandescent lamps.

Indeed, it is clear that initiatives such as those of the GEF/IFC should push not only for expanding the market for PV systems but also for increasing efficiency. While good efficiency and long lifetimes for luminaires, ballasts, lamps, and other electronic gear are important in general, they are especially vital in the case of PV lighting since the extra efficiency pays off so well there.

Figure: Indonesia: Break-even thresholds for PV- and Grid-Based Electricity Supply

COMPONENT QUALITY CRUCIAL
System life optimization is not quite as self-evident. The solar cells themselves are always reliable. But lamps, ballasts, batteries, and battery-charge controllers vary greatly in quality. A cheap system will have a much more limited life. "Technical people will usually recommend better systems, though those are more expensive", says Bob Hill.

The ballasts have often proven to be one of the weakest parts in a PV lighting system, and where low-quality products have been chosen, systems have failed early as a rule. To ensure, for example, that frequent switching does not limit the life of the lamp, a warm-start ballast should be chosen. Developing a good electronic ballast design for dealing with a low-voltage supply is a key task. Of course, such technical details should not worry the end-user or supplier. "They should have a box with two wires and know that it works", says Bob Hill. (See also Hard Facts on PV Hardware and The Future Belongs to PVs.

In the early nineties, the World Bank estimated that only about 44% of the 3.3 billion people who lived in the World's rural areas had access to grid-based electricity. Electrification has just barely kept pace with population growth, so this share has been fairly constant since 1970. For non-electrified areas, the combination of PV and efficient lighting is often the best option to get access to electric lighting.

Fredrik Lundberg

See also: Selected Sources on PV Lighting.

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