Abstract
The transition to renewable energies is an unavoidable step to guarantee a peaceful and sustainable future for humankind. Although solar radiation is one of the main sources of renewable energy, there are broad regions of the planet where it has not been characterized appropriately to provide the necessary information for regional and local planning and design of the different solar powered systems. The Caribbean, and Cuba in particular, lacked until very recently at least one long-term series of surface solar radiation measurements. Here we present the first long-term records of solar radiation for this region. Solar radiation measurements manually conducted and recorded on paper were rescued, reprocessed and quality controlled to develop the solar radiation climatology at the Actinometrical Station of Camagüey, in Cuba (21.422°N; 77.850°W; 122 m a.s.l.) for the period 1981–2016. The diurnal cycle based on the average hourly values of the global, direct and diffuse horizontal variables for the entire period have been determined and analyzed showing the dependence on solar zenith angle (SZA) and clouds. The annual cycle of global solar component given by the mean monthly daily values presents two maxima, one in April and another one in July with values of 5.06 and 4.91 kWh m−2, respectively (18.23 and 17.67 MJ m−2 per day for insolation), and the minimum in December (3.15 kWh m−2 or 11.33 MJ m−2). The maxima are governed by the direct solar components and are modulated by cloudiness. Both, diurnal and annual cycles of the diffuse solar component show a smoothed bell shaped behavior. In general solar radiation at this station presents a strong influence of clouds, with little seasonal variation but with higher values during the rainy season. Daily global radiation annual averages showed its maximum value in the year 1983, with 17.45 MJ m−2 explained by very low cloudiness this year, and the minimum value was reported in 2009 with a value of 12.43 MJ m−2 that could not explained by the cloud coverage or the aerosols optical depths registered that year. The effects of the 1982 El Chichón and 1991 Mount Pinatubo volcanic eruptions on the solar radiation variables at Camagüey are also shown and discussed. The results achieved in this study shown the characteristics of solar radiation in this area and their potential for solar power applications.
Highlights
Taking as base the hourly irradiance values, we have evaluated the monthly mean for the whole period of measurements, 1981–2016, according to Guide of Climatological Practices (GCP) recommendations
The great cloudiness (Figure 7) across this area can be inferred since the highest values are far from maxima hourly values observed in other locations [27] where even the solar zenith angle (SZA) does not reach lower values than Camagüey
Monthly and annual values of irradiance and solar insolation have been determined in order to characterize the diurnal and annual cycles and the year-to-year variability
Summary
The solar radiation reaching the Earth’s surface is a topic of interest at global, regional and local levels, due to the role it plays on the energy balance of the earth-atmosphere system [1]. It is the main source of energy with dominant influence on the weather, climate, and in the mechanisms and effects associated with climate change [2]. The use of solar energy-derived production has been increasing all over the world in the last decades [4] as assessed by recent reports [5] which show a growing number of solar radiation applications in the energy sector. A recent assessment of the solar energy potential at global scale, using solar radiation satellite measurements and numerical model simulations outputs, determined
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