It is very evident that the current climate in most parts of Ghana is does not permit installed solar panels to generate optimum electricity due to excessive dust and other molecular particles seen in the sky. Currently in many parts of the country, one does not need to use any kind of special lenses to notice that our air quality has reduced drastically since January 2024 and continues to decline.
The live air-quality index as indicated in Figure 1: Air Quality Index map showing Air Quality across West Africa (Live map accessed on 05/02/2024 at 16:00). showed that Ghana among many countries within the Sub Saharan region currently has unhealthy air quality across most parts of the country with the major cities such as Accra and Kumasi labelled “Very unhealthy” as shown on the map. Refer to the Air Quality Atlas on this link: “https://www.iqair.com/air-quality-map?lat=5.603717&lng=-0.186964&zoomLevel=10”
Could this be harmattan? Harmattan is a dust-laden north-east wind that blows from the Sahara towards the Gulf of Guinea in the period of November to March. This period is usually characterized by dry, windy, and dusty atmosphere with elevated temperatures. Formerly, many people experience dry lips, cracked lips, bleeding nose, and cracked soles of the foot. However, dry lips, bleeding nose, and cracked lips are not common phenomenon of this year’s edition of harmattan.
Under the conditions, it is recommended that solar PV cleaning contractors undertake frequent washing of solar arrays to optimize electricity generation. Figure 2 below shows an image of a characteristic dusty environment where the solar array shown in Figure 3 is located. Name of location and capacity of system are intentionally left out since that is not the focus of the article.
Figure 2: A shot from a video from a solar array site in Ghana.
A survey conducted by the author during operations and maintenance activities within this year reveals that most arrays are covered in dust most part of this year. Arrays get soiled within 14 days after cleaning. Very huge grid-connected solar systems are observed to be underproducing during this period. Below are some images of some of the arrays observed by the author.
Figure 3: Soiled solar array cleaned to optimize generation.
Arrays covered in such soiling can lose 60% to 80% of its generation capacity which will result in daily loss of revenue as long as the soil exists on the array.
Below are other images of solar arrays in Ghana experiencing frequent soiling under the current dusty conditions.
Figure 5: Dirty array as a result of dusty atmosphere in Ghana.
Just as it may not be very practical to clean large arrays on daily basis, it will be recommended that PV monitoring departments of large array operators set a minimum threshold which must trigger washing during this period. Models should be developed to compare how much money is lost to soiling and how much money it will cost to clean the array. If the latter is less than the former, then cleaning must be done as often as possible to ensure optimal gain by the operators.
It must be noted also that hotspots can also develop in the cells of the module are abandoned in soiled state for a long time.
A good deal for cleaning contractors is to charge a commission of revenue from additional production after cleaning. This may as well pay for the cleaning; thus a win-win situation.