Innovations in solar energy have the potential to bring electricity to much of the rural poor in developing countries.

The United Nations Development Programme estimates that 1.5 billion people -- including 89% of rural sub-Saharan Africa -- still lack electricity. African villages tend to rely on diesel generators and highly toxic kerosene lamps for light, even in rural clinics, despite the risk of respiratory diseases.

Solar power, however, is starting to make inroads in locations where extending the electric grid may not make economic sense. Various solar applications are becoming more affordable thanks to such technological innovations as photovoltaic panels that use thin films; light bulbs that captureenergy during the day to provide light at night; and solar mobile-phone chargers.

Speaking at a conference on solar lighting in Africa earlier this year in Nairobi, Kenya, Johannes Zutt, a World Bank country director based in east Africa, said that as recently as 2008 there were only a handful of quality solar products under $50. Today, he says, 'there is a wide variety of products between $25 and $50.'

Rural communities in developing countries could be a bounty for solar companies. For just sub-Saharan Africa, the World Bank estimates the off-grid electricity market at $17 billion a year.

Solar-powered projects have sprung up in some of the sunniest, poorest corners of the planet, financed by internationalfinancial institutions, nonprofits and microfinanciers. These range from water pumps in Bangladesh and Benin to makeshift hospitals in Haiti set up after the earthquake.

At 100 schools in East Africa, U.K. charity Solar Aid has installed booths where people pay to use solar power to charge their mobile telephones. The proceeds go to buy books for the schools. In northern Tanzania, locally based Zara Solar Ltd. has also installed more than 4,000 such systems with support from the United Nations Development Programme.

Asia, too, has seen rapid progress in some areas. The World Bank helped financeinstallation of 400,000 home solar systems in rural northwest China, for example.

Still, challenges remain before small-scale applications of solar technology can get further traction. Batteries for solar power, for example, can't hold charges for long. Their toxic components make disposal and recycling a challenge as well.

Benoit Faucon

• energy [´enədʒi] n.活力，精力；能力 (初中英语单词)
• despite [di´spait] prep.尽管 (初中英语单词)
• capture [´kæptʃə] vt.&n.捕获；俘获；夺取 (初中英语单词)
• conference [´kɔnfərəns] n.讨论(会)；会谈 (初中英语单词)
• director [di´rektə] n.指导者；....长；导演 (初中英语单词)
• variety [və´raiəti] n.变化；多样(性)；种类 (初中英语单词)
• planet [´plænit] n.行星 (初中英语单词)
• international [,intə´næʃənəl] a.国际的，世界的 (初中英语单词)
• financial [fi´nænʃəl] a.金融的，财政的 (初中英语单词)
• charge [tʃɑ:dʒ] v.收费；冲锋 n.费用 (初中英语单词)
• finance [´fainæns] n.财政；金融 vt.资助 (初中英语单词)
• challenge [´tʃælindʒ] n.&vt.向....挑战；怀疑 (初中英语单词)
• potential [pə´tenʃəl] n.&a.潜在的；可能的 (高中英语单词)
• electricity [i,lek´trisiti] n.电；电学；电流 (高中英语单词)
• billion [´biljən] num.万亿 (高中英语单词)
• handful [hændful] n.一把，少数，一小撮 (高中英语单词)
• bounty [´baunti] n.慷慨；恩惠；赠物 (高中英语单词)
• sprung [sprʌŋ] spring的过去分词 (高中英语单词)
• charity [´tʃæriti] n.施舍；慈悲；博爱 (高中英语单词)
• northwest [,nɔ:θ´west] n.&ad.西北(部) (高中英语单词)
• disposal [di´spəuzəl] n.处理；支配 (高中英语单词)
• kerosene [´kerəsi:n] n.煤油，火油 (英语四级单词)
• lighting [´laitiŋ] n.照明，发光 (英语四级单词)
• installation [,instə´leiʃən] n.就职；安装；装置 (英语六级单词)