allAfrica.com: Rwanda: Mininfra - Sun Shine - How Can We Use It At Night? (Page 1 of 2)

Solar Energy is one of the main sectors of renewable energy and has enjoyed extensive development in the world.

The sun is the very basis of the existence of life on our planet. It is the driving force behind other sources of energy such as: wind, biomass or hydro. On industrial level solar energy systems have been developed in recent decades for thermal and electric applications. Through solar collectors hot water can be generated or agricultural products can be dried. But sunlight can also be transformed into electrical energy through solar photocell systems.

Unfortunately, until now the solar technology is still very capital intensive, that way remaining prohibitively costly for massive use. That way therefore, solar systems still remain attractive to limited applications including; electrification of rural households through lighting, providing light to schools and health centers as well as running the computers. It might also be used for pumping water or for telecommunication purposes.

Since Rwanda, along with most other countries worldwide is currently eager to increase the share of renewable energy in general and electricity from renewable sources in particular towards the total national energy balance, solar energy becomes increasingly important to achieve our objectives.

While solar photovoltaics remain relatively expensive, the solar thermal systems that are mainly used for water heating are to some extent affordable.

What is a Solar Water Heater?

Each square meter of Rwanda receives sufficient solar energy each day to heat about 50 liters of water from the normal room temperature (20ºC) up to 60ºC!

This can be achieved with a Solar Water Heater (SWH), an appliance which is converting solar radiation into heat energy, by using solar collectors. These are available as flat plate collectors, evacuated tube collectors or concentrating collectors. They use both direct beam and diffuse solar radiation. The Solar Water Heater can be mounted on a roof, on a balcony or in a yard and its installation requires no special technology.

The Solar Water Heater is able to substitute other sources of energy currently used to heat water, like electric energy, gas or fuel, by solar radiation. Considering that solar energy is abundant, available and for free, Solar Water Heaters contribute substantially to saving energy as well as financial resources.

Solar water heaters are most widely used in households, hotels, hospitals or other public buildings. We know that 1 square meter of solar collectors can produce about 700 to 900 kilowatt-hours per year and thus avoid an equivalent of 3 tons of Carbon Dioxide otherwise emitted into the atmosphere through the use of other fuels for heating the water.

This is why it would be beneficial to the country to grant subsidies for the acquisition of solar water heaters or to oblige property developers and constructors to include solar water heaters in all new buildings.

Through incentives and obligations 180 million square meters of solar collectors have been installed world wide since 2007 that are producing 128 million kilowatt-thermal per year. A thriving solar industry has thus come into being in a lot of countries.

Solar Water Heating Potential in Rwanda

The Rwandan climate is very favorable for solar energy exploitation, even during the months of the rainy seasons there is daily and sufficient sunshine: 4 - 6 kWh per square meter and day can be produced which makes solar energy exploitation in Rwanda economically viable.

Going by our Economic Development and Poverty Reduction Strategy (EDPRS) target, it is expected that by 2012, electricity connections shall have moved from the current 92,000 to 350.000. Estimating that at least 20% of them use warm water in their showers or bathrooms, solar water heating could be installed in at least 70.000 households and some hotels, health centers, schools, hospitals, etc.

This is equivalent to a total sensor surface of 200.000 square meters which will potentially save 20.000 tons of oil equivalent per year or about 2000 Megawatt-hours per year. Taking into account the current price of oil, Rwanda could save fuel expenses equivalent to US$ 294 million (120$/barrel). On top of that, the country would profit from the employment created in a developing solar market.

Photovoltaic Solar Energy for electricity

As mentioned above solar energy can also be converted into electric energy and is a means of electrifying rural populations far from the national grid. This transformation is achieved through so called Photovoltaic Panels that can be installed on rooftops. The produced electricity is then transported to a battery where it is stored until usage. That means the energy that is generated by day can be used at any time of the day and thus for lighting purposes mostly at night.

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