Dataset of solar energy potential assessment for Adama city (Ethiopia)

Abstract

This paper focuses on estimation of available solar radiation from sunshine hour duration. Sunshine hour duration data from 2013 to 2017 G.C recording from Adama metrology agency, average daily global radiation in horizontal and tilt surface for global, diffuse and beam radiation are calculated also hourly global radiation and diffuse radiation data are calculated in tilt surface reach. Finally global and diffuse radiation data for January 5, 2017 and July 5, 2017 are calculated.

Specification table

Subject area	Thermal energy and renewable energy
Specific Subject area	Estimation of solar radiation
Type of data	Table
How data was acquired	Recording the survey result
Data format	Raw
Experimental factors	Sunshine hour durations data between the years 2013–2017 GC has been taken.
Experimental feature	Data available from Adama metrology agency measuring sunshine hours every 3 hours
Data source location	Adama, Ethiopia (altitude 1648 m above sea level, 8.558 oN, 39.28 oE
Data accessibility	Data is included in this article
Related research article	A.D. John, and W.A. Beckman, Solar engineering of thermal process: solar energy laboratory, university of Wisconsin-Madison, fourth edition, 2013.

Value of the data •The data is useful to the researcher on site selection based on solar radiation potential in horizontal surface •The data is useful to the researcher to know maximum harvesting solar radiation potential data in tilt surface for Adama city •These data can also be useful to the researcher on solar radiation potential data separately beam, diffuse and global in both horizontal and tilt surface.

1. Data

Sunshine hours is a climatological indicator, measuring duration of sunshine in given period(usually, a day or a year) for a given location on earth, typically expressed as an averaged value over several years. It is a general indicator of cloudiness of a location, and thus differs from insolation, which measures the total energy delivered by sunlight over a given period [6]. Table 1 shows Sunshine hour duration for five years and Table 2 and Fig. 1 shows five years average Sunshine hour duration from nearby metrology agency. The monthly average daily global radiation, diffuse radiation and beam radiation in horizontal surface are tabulated in Table 3, Table 4 and Table 5 respectively and compared in Fig. 2. The sunset hour angle 1 and 2 are listed in Table 6, Table 7 and the minimum values are given in Table 8. In Table 9 & Fig. 3, the maximum possible solar energy harvesting potential of total solar radiation reach on tilt surface is given. The hourly global radation and diffuse radiation reach on tilt surface are shown in Fig. 4, Fig. 5. The global radiation and diffuse radiation for the particular day 5th of January and 5th of July 2017 are given in Fig. 6, Fig. 7. Adama Station - Latitude (ϕ) = 8 33′ 23.8″ N = 8.558°, Longitude = 39 17′ 2.5″ E = 39.28°, Altitude = 1648 m above sea level, Dominating climate of the city is hot/arid climate type [1].

Table 1.

Sunshine hourly duration.

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
2013	8.9	10.05	8.4	8.12	8.35	7.89	5.3	6.8	7.7	8.3	8.78	10.10
2014	9.46	8.7	8.6	9.0	8.6	8.6	6.4	6.9	6.6	8.7	9.1	8.85
2015	9.7	10.1	9.5	8.7	8.8	7.5	9.3	8.0	8.3	9.0	9.07	8.8
2016	7.7	8.5	9.3	6.7	7.6	7.8	6.4	6.7	7.2	9.8	10.05	9.7
2017	7.9	8.9	9.2	9.5	7.8	8	6.6	5.9	6.8	8.7	9.9	9.3

Table 2.

Five years average sunshine hour duration.

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Average (2013–2017)	8.73	9.25	9.0	8.4	8.23	7.96	6.8	6.86	7.32	8.9	9.38	9.35

Fig. 1.

Sunshine hour duration Vs months of the year.

Table 3.

Monthly Average daily global radiation (MJ/$m^2/day$) in horizontal surface.

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Average (2013–2017)	21.7	23.6	24.7	24.6	23.9	23.2	21.8	22.5	23.1	23.6	22.4	21.5

Table 4.

Monthly Average daily diffuse radiation (MJ/$m^2/day$) on horizontal surface.

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Average (2013–2017)	6.9	6.8	7.9	9.1	9.3	9.5	10.6	10.7	10.1	7.5	6.1	5.8

Table 5.

Monthly Average daily beam radiation (MJ/$m^2/\text{day}$) on horizontal surface.

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Average (2013–2017)	14.9	16.8	16.8	15.5	14.6	13.6	11.2	11.8	13.1	16.2	16.3	15.7

Fig. 2.

Daily solar radiation Vs months of the year.

Table 6.

Sunset hour angle 1.

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sunset hour angle	86.7	88.0	89.63	91.43	92.93	93.67	93.3	92.0	90.3	88.5	87.0	86.3

Table 7.

Sunset hour angle 2.

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sunset hour angle	96.1	93.6	90.7	87.4	84.6	83.23	83.8	86.21	89.4	92.7	95.4	96.74

Table 8.

Minimum value from Table 6 and Table 7(degree).

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Minimum value	86.7	88.0	89.6	87.4	84.6	83.2	83.8	86.2	89.6	88.5	87.0	86.3

Table 9.

Total solar radiation (MJ/m²/day) reach on tilt surface.

Months	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Global radiation on tilt surface	36.8	37.9	33.7	29.4	27.5	25.3	25.2	27.7	29.6	31.1	31.0	33.1

Fig. 3.

Daily solar radiation Vs Months of the year

Fig. 4.

Hourly global radation (MJ/m²) reach on tilt surface Vs hours of day.

Fig. 5.

Hourly diffused radation (MJ/m²) reach on tilt surface Vs hours of day.

Fig. 6.

Radation (MJ/m²) for January 5, 2017 on tilt surface Vs hours of day.

Fig. 7.

Radation (MJ/m²) for July 5, 2017 on tilt surface Vs hours of day.

2. Experimental design, material, and methods

Estimation of available solar radiation on horizontal and tilt surface from five (5) years average sunshine hour duration seen in Table 1 by using Modified angstrom-type regression equation for surface with surface azimuth angle y = $0^o$ and Collector tilt ($\text{β})$ the yearly optimum slope angle of solar collector as βopt = $\varphi$+ 15$°$ at a location with latitude. The ground reflectance is 0.2 for all months except December and March (p = 0.4) and January and February (p = 0.7) using the isotropic diffuse assumption. Fig. 1 shows Sunshine hour duration for Adama city in five years (2013–2017) averages.

2.1. Modified angstrom-type regression equation [7]

$$H_0=24\ast 3600\ast \frac{I_{sc}}{\pi }(1+0.033\cos \left(\frac{{360}^{\ast }n}{365}\right))\ast (\cos \varphi \cos \delta \sin \omega s+\pi \ast (\sin \varphi \ast \sin \delta ))$$ (1)

$H_O$ = Monthly average radiation at extra-terrestrial region for the same location

Solar constant $I_{sc}$ = 1367 $\frac{W}{m^2}$

$$\text{Declination}\text{angle}\left(\delta \right)=23.45\ast \sin \left(\frac{360}{365}\ast \left(284+n\right)\right)$$ (2)

$$\text{Sunset}\text{hour}\text{angle}\left(\omega s\right)={\cos }^{-1}(-\tan \varphi \tan \delta )$$ (3)

$$\text{a}=-0.110+0.235\cos \varphi +0.323\ast \left(\frac{n_s}{N_s}\right)$$ (4)

$$\text{b}=1.449-0.533\cos \varphi -0.694\ast \left(\frac{n_s}{N_s}\right)$$ (5)

a and b are empirical constant [8].

$$\text{Ns}=2/15\left(\omega s\right)$$ (6)

$$\frac{H_d}{H}=0.931-0.814\ast \frac{n_s}{N_s}$$ (7)

From above equations, monthly Average daily global radiations on horizontal surface are listed on Table 3.

From above equation and Table 3, monthly Average daily diffuse radiations on horizontal surface are listed on Table 4.

Beam radiation $\left(H_b\right)$ radiation directly come to the object without scattered obtained by subtract diffuse radiation from global radiation as follows. Monthly Average daily beam radiation on horizontal surface are listed on Table 5. Fig. 2 shows beam, diffuse and global solar radiation on horizontal surface.

2.2. Conversion factors [5]

Beam radiation factor ($R_b$) the ratio of the average daily beam on the tilted surface to that on a horizontal surface for the month is$R_b$, which is equal to$\frac{H_b^{\text{'}}}{H_b}$.

For surface that are sloped toward the equator in the northern hemisphere that is for surface with surface azimuth angle y = $0^o$[4].

$$R_b=\frac{\cos (\varphi –\beta )\cos \delta \sin \omega ’s+(\pi /180)\omega ’s\sin (\varphi –\beta )\sin \delta }{\cos \varphi \cos \delta \sin \omega s+\left(\frac{\pi }{180}\right)\omega s\sin \varphi \sin \delta }$$ (8)

where $\text{ω’s}$ is the sunset hour angle for the tilted surface for the mean day of the month.

$$\omega \text{'}s=\min \left[{\cos }^{-1}(-\tan \varphi \tan \delta )\text{or}{\cos }^{-1}(-\tan \left(\varphi -\beta \right)\tan \delta )\right]$$ (9)

Sunset hour angle 1 and Sunset hour angle 1 are listed in Table 6, Table 7 respectively. The minimum value from Table 6, Table 7 are listed in Table 8.

Collector tilt ($\text{β})$ the yearly optimum slope angle of solar collector as βopt = $\varphi$+ (10–15)$°$ at a location with latitude [2].

$$\beta =\varphi +15°=8.558+15\cong 24$$ (10)

$$\omega \text{'}s=\cos ˆ-1(-\tan \varphi \tan \delta )$$ (11)

$$\text{Or}\omega {\text{'}}_{\text{s}}=\text{cosˆ}-1\text{(}-\text{tan}\text{(}\varphi -\beta \text{)}\text{tan}\delta \text{)}$$

Diffuse radiation factor ($R_d$).

$$R_d=\frac{1+\cos \beta }{2}$$ (12)

Reflected radiation factor (Rr).

$$Rr=\frac{1-\cos \beta }{2}$$ (13)

The ground reflectance is 0.2 for all months except December and March (p = 0.4) and January and February (p = 0.7) using the isotropic diffuse assumption [3]. Global solar radiation reach on tilt surface are listed in Table 9. Fig. 3 shows global solar radiation on tilt surface in meter quarter Vs months of the year.

Prediction of hourly global radiation: the hourly global radation can be calculated from the knowledge of the daily global radiation. Monthly Averages of daily global radiation are shown in Fig. 4.

$$\frac{I}{H}=\frac{\pi }{24}(a+b\cos \omega )\frac{\cos \omega -\cos {\omega }_s}{\sin {\omega }_s-\frac{\pi }{180}{\omega }_s\cos {\omega }_s}$$ (14)

where

$$\text{a}=\text{0.409}+0.5016\text{sin}\left({\omega }_{\text{s}}-60\right)$$ (15)

$$\text{b}=0.6609-0.4767\text{sin}\left({\omega }_{\text{s}}-60\right)$$ (16)

$$\omega =15(t-12)$$ (17)

Prediction of hourly diffused radiation: the hourly diffuse radation also can be calculated from the knowledge of the daily radation. Monthly Averages of daily diffuse radiation are shown in Fig. 5

$$\frac{I_d}{H_d}=\frac{\pi }{24}\frac{\cos \omega -\cos {\omega }_s}{\sin {\omega }_s-\frac{\pi }{180}{\omega }_s\cos {\omega }_s}$$ (18)

Solar intensity in particular days From Sunshine hour duration (9.3) in the day of January 5, 2017 Fig. 6 is generated to show daily radiation amount pattern within specific day. Total global radiation amount on horizontal surface 21.6 MJ/m² and tilt surface 37.9 MJ/m²

From Sunshine hour duration (6.1) in the day of July 5, 2017 Fig. 7 is generated to show daily radiation amount pattern within specific day. Total global radiation amount on horizontal surface 20.614 MJ/m² and tilt surface 23.471 MJ/m²

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