## 5 Conclusions  
Ten minute and hourly data of global horizontal (\(G\)), direct normal (\(B_{n}\)), reflected (\(R\)) and diffuse (\(D\)) irradiances were obtained from the actinometric station of Athalassa, an inland location in Cyprus at the height of 160 m, covering the period June 2020 to May 2021. Initially, the assessment of the measured radiation components was performed, followed by the modeling of the diffuse fraction and the estimation of diffuse and direct normal irradiance based on the BRL model. Finally, the estimation of solar energy on incline surfaces was carried out. A detailed quality control procedure was implemented on the radiation components which are based on the suggested limits proposed by the BSRN network. The tests include physically possible limits (PPL), extremely rare limits (ERL), and configurable climatological limits (CCL). The comparison tests concentrated on the ratios of \(k_{b}\), \(k_{bt}\), \(k_{d}\), and \(k_{t}\) and their relationships. The ratios are generally lower than 1. Finally, step and persistency tests were applied on the hourly data set. Only a few observations were considered as invalid and were excluded from the analysis. The daily values were also tested against the extraterrestrial irradiation and the estimated highest daily sums on clear days as well as by comparing the daily global radiation with the daily sunshine duration. From this investigation the following results can be highlighted:  
Monthly mean hourly values of shortwave irradiances are shown by means of isoline diagrams. These values are considered representative of the solar radiation behavior along a typical year and can be useful for exploiting solar energy applications. July was found to be the month with maximum values of direct horizontal and global radiation. The hourly average global irradiance fluctuates between 450 W/m\({}^{2}\) in January and 950 W/m\({}^{2}\) in July at local noon. The respective ranges of direct horizontal irradiances are 230 W/m\({}^{2}\) and 800 W/m\({}^{2}\), while the diffuse irradiances fluctuate between 120 W/m\({}^{2}\) and 240 W/m\({}^{2}\). The BRL model was used to obtain hourly diffuse radiation and from that the estimation of the direct normal solar radiation. Considering the error analysis, the results showed that the BRL model can estimate satisfactory both the diffuse solar irradiance as well as the direct normal irradiance. The model was developed based on a one-year dataset. The estimated parameters were close to those obtained by [PERSON] et al. at Adelaide of Australia, i.e., a location with similar climatic conditions with Cyprus. The annual average daily global radiation intensity is around 19 MJ/m\({}^{2}\), whereas the horizontal beam and diffuse radiation is 12.9 MJ/m\({}^{2}\) and 4.7 MJ/m\({}^{2}\), respectively. Consequently, the fraction of the beam component of the global radiation is relatively high, i.e., the annual average daily fraction is \(\geq\)0.600 at this site. The monthly mean daily values for the global radiation ranged between 8.7 and 28.3 MJ/m\({}^{2}\), for the direct horizontal radiation they ranged between 4.6 and 22.0 MJ/m\({}^{2}\) and for the diffuse radiation they fluctuated between 3.2 and 7.1 MJ/m\({}^{2}\). Daily clearness index (\(K_{T}\)) is an objective measure of the influence of cloud cover on solar radiation flux. As indicated earlier, the sky conditions could be classified in four intervals of clearness index based on the relation between hourly irradiances of global, direct, and diffuse radiation and the clearness index:  
Class I: Cloudy: \(K_{T}\leq 0.35\) or \(\sigma\leq 0.3\);  
Class II: Partially cloudy with predominance of diffuse component: \(0.35<K_{T}\leq 0.55\) or \(0.3<\sigma\leq 0.6\);  
Class III: Partially cloudy with predominance of direct component: \(0.55<K_{T}\leq 0.65\) or \(0.6<\sigma\leq 0.85\);  
Class IV: Clear sky: \(K_{T}>0.65\) or \(\sigma>0.85\). The annual average of \(K_{T}\) is 0.620 with a standard deviation of 0.121.