Solar power for the poor: facts and figures

By admin On August 16, 2010 · In Energy

Solar power could help alleviate rural poverty.David J. Grimshaw and Sian Lewis shine a light on its progress, potential and pitfalls.

Increasing access to energy is critical to ensuring socioeconomic development in the world’s poorest countries.

An estimated 1.5 billion people in developing countries have no access to electricity, with more than 80 per cent of these living in sub-Saharan Africa or South Asia. [1]

The problem is most acute in remote areas: 89 per cent of people in rural sub-Saharan Africa live without electricity, which is more than twice the proportion (46 per cent) in urban areas. [1]

For these people, even access to a small amount of electricity could lead to life-saving improvements in agricultural productivity, health, education, communications and access to clean water.

Options for expanding access to electricity in developing countries tend to focus on increasing centralised energy from fossil fuels such as oil, gas and coal, by expanding grid electricity. But this approach has little benefit for the rural poor. Grid extension in these areas is either impractical or too expensive.

Neither does this strategy help tackle climate change. Power already accounts for 26 per cent of global greenhouse gas emissions and while most of this comes from the developed world, by 2030 developing countries are predicted to use 70 per cent more total annual energy than developed nations.[2]

There is therefore a clear need for pro-poor, low-carbon ways to improve access to electricity in the developing world — solar power could be one such solution.

Place in the sun

The Earth receives more solar energy in one hour than the world population consumes in an entire year.

Almost all developing countries have enormous solar power potential — most of Africa, for example, has around 325 days of strong sunlight a year, delivering, on average, more than 6 kWh energy per square metre a day (see Figure 1).

The Desertec Foundation, a joint German and Jordanian company, estimates that covering just one per cent of global deserts in solar panels could power the whole world. [3]

And yet the countries that receive the most solar energy are often also the ones least able to benefit from it, due to a lack of knowledge and capacity to harness solar power and convert it into electricity.

The technology

There are two ways of using power from the sun: collecting its heat (solar-thermal) or converting its light into electricity (photovoltaics).

Solar-thermal devices use ‘collectors’ — ranging from flat plates put on roofs to parabolic dishes, power towers or solar pyramids used in solar power plants — to absorb sunlight and produce heat.

Solar-thermal devices can be most simply used for heating or cooling but are also suitable for drying crops, pasteurising water or cooking (see Table 1).

Through concentrating solar power (CSP) systems, that use a combination of lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam, they can also be used to provide electricity. The concentrated sunlight heats water to produce steam to drive a turbine, connected to a generator.

Solar photovoltaic (PV) systems use solar cells, linked together in ‘modules’ (solar panels), to convert light into electricity. They range from a few small cells that can run a calculator to huge solar power stations with thousands of solar panels.

More than 90 per cent of PV systems are based on silicon materials. PV systems that are connected to the electricity grid include a device called an inverter to turn the direct current (DC) power generated by solar panels to the alternating current (AC) power used on the grid.

Off-grid PV systems may also include an inverter but also require batteries to store surplus energy, and an electronic charge controller to prevent the batteries from overcharging.

At present, solar-thermal systems are about 30 per cent efficient at turning heat into electricity — compared with approximately 15 per cent efficiency for PV systems. But, in the long run, the development of newer materials for PV systems, such as polymers and nanoparticles, should increase their efficiency.

Rising interest

Neither solar-thermal nor PV are new technologies, but they are not widely used to generate electricity because, compared with carbon-based energy supplies, they remain relatively expensive.

The International Energy Agency calculates that, in 2007, solar PV and solar-thermal contributed less than 0.2 per cent of gross global electricity production. [4]

Yet with rising fossil fuel costs, growing concern about supplies — some analysts suggest we could run out of oil as early as 2025 — and increased awareness of fossil fuels’ role in climate change, market conditions will increasingly favour solar power. Government subsidies may also help encourage the growth in solar power.