The sunny blue skies of Africa attract not only tourists, but those with an eye for innovative and energy-saving technology. dena, or the German Energy Agency, is working in Africa and one of its successful programmes is the Solar Roofs programme.

Solar roofs worldwide serve as flagship projects for German renewable energy expertise in the field of photovoltaics, solar cooling and solar thermal energy. All of the plants designed and implemented under this programme demonstrate the flexibility of German renewable energy technology and know-how, working with given local circumstances while meeting discerning user-specific requirements.

Enlarge image The photovoltaic plant at Solar Valley, just outside of Addis Ababa (© dena/SunTransfer GmbH) The goal is to create an understanding of the possibilities and various applications of solar technology, to train local experts and to build up local sales and marketing partnerships. The solar roof projects also help to build up acceptance of renewable energy sources in the countries where they take place.

All of the solar roof projects developed by dena are designed as public private partnerships (PPP) and co-financed by the German Ministry of Economics and Technology. Since 2004, 30 projects have been realised, i.e. in South Africa, Australia, China, Russia, Costa Rica, India, Indonesia, Turkey, Palestine and Taiwan.

Five of the projects are in Africa, specifically in Ethiopia, Namibia, Senegal, South Africa and Tanzania. They are based both in cities and rural areas, providing vital cost savings and power generation to institutions and communities.

In November 2010, just west of the Ethiopian Capital Addis Ababa, the Solar Valley was inaugurated (two solar systems with generating capacity of 9,43 kWp, including the premises of the International Solar Energy School); in Windhoek, the capital of Namibia, 200 square meters of panels were installed in a joint venture between dena and SUNSET Energietechnik, creating the largest photvoltaic system in the country (producing 14.28 kWp at peak capcity) and in rural Senegal, SOLAR23 installed three solar systems (total 8.4 kWp) which now electrify the entire village.

Beyond meer statistics, the impact of specific projects are impressive. At the German International School of Johannesburg, Schüco International KG implemented a solar energy system on the roof for generating hot water and electricity. Thanks to its new installation, the school has improved its energy and environmental balance, reduced its energy costs, increased the well-being of teachers and pupils alike, and ensured the operation of important power consumers, such as the telephone lines, computer system and emergency lighting during power cuts.

The system consists of three components: a solar thermal installation for the kitchen, three thermosiphon systems to generate hot water for the school showers and a photovoltaic installation (3.5 kWp) serving as a battery-assisted stand-alone system with parallel grid connection in the event of power cuts. In total, the Schüco solar energy system saves 22300 kWh and prevents the potential generation of 18000 kg CO2 per year.

Enlarge image Solar panels atop a building at the convent in Mbinga (© dena/Energiebau Solarstromsysteme GmbH) Similarly, a solar hybrid system is in place in Mbinga, rural Tanzania, producing electrical power for the Association of the Vincentian Sisters, completely from renewable energy (sunlight and the oil of the Jatropha plant, which can be cultivated on-site). As a decentralised small power station, the system provides power in an exemplary,  environmentally friendly manner and does not need a long-distance line thanks to the proximity of the energy consumer.

The system has been designed in such a way that a 24-hour energy supply with a total demand up to 40 kWh is guaranteed, just through the solar system. If more power is required, the power generator will be started, which can run on either diesel oil or Jatropha oil and produces not only electric current but also hot water. The combination of a solar power system with a pure plant oil generator is regarded in Mbinga as a forward-looking and sustainable technology.

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