kumasi

What is Ghana’s solar power potential ? The country is blessed is with decent solar  irradiation year round.Ghana is in fact  notorious for its scorching sunlight.

Before I begin, permit me to ask this, if Oil and Gas for Thermal Power Plants and the other fossils are that “Cheap” as some want us to believe, why then are electricity rates still going up?Every hour, the sun radiates more energy onto our earth than the entire human population uses in one whole year. The technology required to harness the power of the sun is available now. Solar power alone could provide all of the energy Ghanaians consume and there is no shortage of solar energy like there has been with the Akosombo Dam in recent days. The truth is, we do not need advanced math skills to follow and perform the solar arithmetic to prove that Ghana’s energy independence could be achieved with solar energy.

Every square meter (1m²) of the earth’s surface, when exposed to direct sunlight, receives about 1000 watts (1 kilowatt) of energy from the sun’s light. In reality, this power per hour for every square meter (1m²) might be more or less, depending on the angle of sunlight, which changes with the time of day, and the geographical location. On average, the sub Saharan region of Africa receives about (3 – 4 kilowatt per hour) of solar energy.

Nonetheless, studies have revealed promising potential for this resource in Ghana. According to the SWERA Ghana Project report, Wa, the capital of the Upper West region, has the highest level of solar irradiation (5.524 KWh/m²-day) across the country. May is the month with the highest solar irradiation (5.897 KWh/m²-day), with August recording the lowest measurement (4.937kWh/m²-day) in Wa. Akim Oda on the contrary is the location that records the lowest radiation (4.567kWh/m²-day) measurements across the country. The highest measurement in Akim Oda was recorded in the month of April (5.176kWh/m²-day) and the lowest in August (3.802kWh/m²-day).

 

Table 1: Summary of Solar irradiation in kWh/m²-day – SWERA Report

Synoptic Station	Ground (kWh/m2-day)	Satellite (kWh/m2-day)	% Error
Kumasi	4.633	5.155	-11.3
Accra	5.060	5.180	-2.3
Navrongo	5.505	5.765	-4.7
Abetifi	5.150	5.192	-0.8
Akuse	4.814	5.58	-15.9
Wa	5.520	5.729	-3.7
Akim Oda	4.567	5.177	-13.3
Wenchi	5.020	5.093	-1.5
Ho	5.122	5.223	-2.0
Kete Krachi	5.280	5.345	-1.3
Takoradi	5.011	5.200	-3.8
Yendi	5.370	5.632	-4.8
Bole	5.323	5.570	-4.6

 

This estimate tells that sunlight will provide useful solar energy for about 4 to 6 hours per day because during the early hours and late hours of the day the angle of the sun’s light is too low.Therefore, let us assume for every square meter (1m²) exposed to continuous direct sunlight [in an optimal geographical location] for an average of 4.5 hours a day, we will have received 4.5 hours x 1000 watts = 4500 watthours (4.5kwh/m²) of solar energy during the course of a day (Ghana’s solar power potential). It would be great if 100% of the sunshine became electricity, but solar energy and electricity are not the same. Technology accomplishes the conversion of solar energy to electricity.

Conversion of one form of energy to another always causes a loss of energy. In other words, the new form of energy will be less than the original. Efficiency is the word used to describe the difference in power resulting from the conversion of one form of energy to another. The efficiency of commercially available solar panels (PV) is now between 15% – 40.7%. This means that when a solar panel converts the sun’s light to electricity, only about 15 to 40.7 percent of the energy in the sunlight becomes electricity. The same thing is true of gasoline in your car and other thermal engines. Your car’s engine can only convert about 25 percent of the energy in gasoline to mechanical energy that turns the wheels.

With an average efficiency of 15 to 40.7 percent, every square meter (1m²) of solar photovoltaic cells (PV) would produce (4.5 kilowatthours of solar energy multiplied by 15% =) between 0.68 kilowatthours of electric energy per day.

Solar panels (PV) covering an area of 100m²(1 Plot of Land) would produce 100 x .68 = 68 kilowatthours of electricity per day. It is worth noting that 68kwh per day is a lot of electricity for a single family home.

 

Let’s juxtapose this arithmetic nationwide to the unused land surface:

– Size of Unreserved forest land in Ghana = 5 x 10³km² è 5 x 10⁹m².

– Assuming a Conversion Efficiency (Solar Panels) of 15%.

– Average Solar Irradiation 4.5kilowatthours (kwh) è 4500wh/day

– Annual average solar radiation = 4.5 x 365 è 1642.5kwh/m².y

– Assuming a Performance ratio, coefficient for losses of 0.75

So, 0.15 x 1642.5kwh/m².y x 5 x 10⁹m² x 0.75  è 923.9Gwh/y

Like in Germany where Solar energy powered 50% of its midday electricity needs on May 26, 2012, this amount of energy can be used for same in Ghana.It is interesting to note that this amount of energy has been calculated from an area of 5,000km² which is only 2% of the total surface area of Ghana.In 2004, Ghanaians consumed 5,158 gigawatthours (GWh) of electricity. NEDCO alone contributed 340GWh out of this figure. This contribution from NEDCO is only one third of my estimate of the calculated solar potential. It is estimated that about half of this amount is consumed by domestic (or residential) consumers for household uses such as lighting, ironing, refrigeration, air conditioning, television, radio and the like.

In conclusion, let me say that the improved technology surrounding solar power is very significant. It has brought clean energy within practical use. Given the significant environmental benefits, there is a very strong case for government intervention to accelerate the switch to solar power. Considering Ghana’s solar power potential,  the reluctance to switch to solar power is delaying our national progress in living standards.

Source: Maxmillian Kwarteng | Gramax Energy Group – GEG | [email protected]