Solar Thermal Unit
The Solar Thermal Unit is one of the four research units established at the inception of the Centre in 1982. It carries out research and development in the use of direct solar radiation for applications such as solar drying, solar water heating, solar distillation and solar cooking.
Nigeria lies within a high sunshine belt, with solar radiation incident on the earth at a rate of about 2.0 × 10³ kWh per day; its intensity varies with location, season, day of the month and time of day. Solar radiation varies from about 3.5 kWh/m²/day in the coastal latitudes to about 7.0 kWh/m²/day in the far North.
Solar thermal technologies — particularly for water heating, drying and cooking — have been among the most promising areas of solar energy application, and already compete on equal terms with other sources of energy in many countries. Over the years the Centre has designed, developed and installed a number of these systems at prototype, pilot and large-scale level. The unit has fabricated and tested these systems to the level of commercialisation.
Solar Thermal Technologies
Circular Top Box Solar Cooker
The novel features of this box cooker are its circular top absorber and additional adjustable reflecting boosters, which can be directed to follow the sun through the day. It is suited to boiling — rice, potatoes, yams — and depending on solar intensity can boil 0.5 kg of rice, sufficient for about six adults, in around one hour. The circular top minimises the side shadow effects of conventional rectangular or square box cookers.
Hybrid Large-Scale Solar Dryer
A hybrid active and passive dryer for crops and jerky meat (“kilishi”). It uses Perspex as its glazing material and is fitted with air blowers powered by solar photovoltaic modules, so it can work by natural or forced convection depending on the product and its moisture content. The design can be expanded for large-scale agricultural and industrial drying, and has been patented.
Domestic Solar Dryers
Combined-mode solar dryers of both direct and indirect type, developed for domestic-scale drying applications.
Thermosyphon Water Heating Systems
Natural convection (thermosyphon) solar thermal water heating systems using flat-plate collectors and an elevated storage tank, requiring no pump to circulate water.
Evacuated Tube Water Heating Systems
Evacuated tube, forced-convection solar water heating systems developed for both domestic and industrial applications.
Distillers, Cookers and Community Systems
The unit’s field-installed systems include the spiral solar water heater, a 250-litre solar water heating system and solar dryer at Danjawa village, the kilishi solar dryer at Kuchi, community-based solar water heaters, parabolic and box-type solar cookers, and both standard and concrete solar distillers.