Solar Resource Assessment

Renewable Energy CourseEEM-405

Institute of Business ManagementKarachi

Syed Akhtar Ali-Visiting ProfessorCEO-PROPLAN

proplanassociates@gmail.com

• Average insolation (kWh/m2/day)• Amount of electromagnetic energy (solar

radiation) incident on the surface of the earth. Also referred to as total or global solar radiation.

• Midday insolation (kWh/m2/day)• Average insolation available within 1.5 hours

of Local Solar Noon.

• Clear sky insolation (kWh/m2/day)• Average insolation during clear sky days (cloud

amount < 10%).• Clear sky days (days)• Number of clear sky days (cloud amount <

10%).

PARAMETERS FOR SIZING AND POINTING OF SOLAR PANELS AND FOR SOLAR THERMAL APPLICATIONS:

• Insolation on horizontal surface (kWh/m2/day)• Amount of electromagnetic energy (solar radiation) incident on

the surface of the earth. Also referred to as total or global solar radiation. The average and percent difference minimum and maximum are given.

• Diffuse radiation on horizontal surface (kWh/m2/day)• Amount of electromagnetic energy (solar radiation) incident on

the surface of the earth under all-sky conditions with direct radiation from the Sun's beam blocked by a shadow band or tracking disk at the Earth's surface.

• Direct normal radiation (kWh/m2/day)• Amount of electromagnetic energy (solar radiation) at the

Earth's surface on a flat surface perpendicular to the Sun's beam with surrounding sky radiation blocked.

• Insolation at 3-hourly intervals (kW/m2)• Amount of electromagnetic energy (solar

radiation) incident on the surface of the earth.• Insolation clearness index (dimensionless)• Fraction of insolation at the top of the atmosphere

which reaches the surface of the earth.• Insolation normalized clearness

index (dimensionless)• Zenith angle-independent expression of the

insolation clearness index

• Clear sky insolation (kWh/m2/day)• Average insolation during clear sky days (cloud amount

< 10%).• Clear sky insolation clearness index (dimensionless)• Fraction of insolation at the top of the atmosphere

which reaches the surface of the earth during clear sky days (cloud amount < 10%).

• Clear sky insolation normalized clearness index (dimensionless)

• Zenith angle-independent expression of the clear sky insolation clearness index.

•

SOLAR GEOMETRY:

• Solar Noon (GMT time)• The time when the sun is due south in the

northern hemisphere or due north in the southern hemisphere.

• Daylight Hours (hours)• Time between sunrise and sunset.

• Daylight average of hourly cosine solar zenith angles (dimensionless)

• The average cosine of the angle between the sun and directly overhead during daylight hours.

• Cosine solar zenith angle at mid-time between sunrise and solar noon (dimensionless)

• Approximate monthy average ratio of horizontal surface solar beam radiation to direct normal radiation.

• Declination (degrees)• The angular distance of the sun north (positive) or south

(negative) of the equator.• Sunset Hour Angle (degrees)• The angle that the earth has rotated between the time of

solar noon and sunset.• Maximum solar angle relative to the horizon (degrees)• The maximum vertical angle of the sun above the horizon.• Hourly solar angles relative to the horizon (degrees)• Hourly solar azimuth angles (degrees)• The arc of the horizon measured clockwise from true north,

to the point where a vertical circle through the sun intersects the horizon

PARAMETERS FOR TILTED SOLAR PANELS:

• Radiation on equator-pointed tilted surfaces (kWh/m2/day)

• Radiation on tilted surfaces is calculated from the monthly average insolation on a horizontal surface. Tilt angles are 0, latitude - 15, latitude, latitude + 15, 90, and the optimum angle. The optimum angle provides the monthly averaged maximum radiation.

• Minimum radiation for equator-pointed tilted surfaces (kWh/m2/day)

• Radiation on tilted surfaces is calculated from the monthly minimum insolation on a horizontal surface. Tilt angles are 0, latitude - 15, latitude, latitude + 15, 90, and the optimum angle. The optimum angle provides the monthly averaged maximum radiation.

• Maximum radiation for equator-pointed tilted surfaces (kWh/m2/day)

• Radiation on tilted surfaces is calculated from the monthly maximum insolation on a horizontal surface. Tilt angles are 0, latitude - 15, latitude, latitude + 15, 90, and the optimum angle. The optimum angle provides the monthly averaged maximum radiation.

Cloud Information:

• Daylight cloud amount (percent)• Percent of cloud amount during daylight within

a region.• Cloud amount at 3-hourly intervals (percent)• Percent of cloud amount within a region.• Frequency of cloud amount at 3-hourly

intervals (percent)• Percent of time the cloud amount is less than

10%, between 10 - 70%, and greater than 70% within a region.

Meteorology (Temperature):• Air Temperature (° C)• Daily Temperature Range (° C)• Difference between the average daily maximum and

average daily minimum.• Cooling Degree Days above 18° C (degree days)• The monthly accumulation of degrees when the

daily mean temperature is above 18° C.• Heating Degree Days below 18° C (degree days)• The monthly accumulation of degrees when the

daily mean temperature

Earth Skin Temperature (° C)• Daily Mean Earth Temperature minimum,

maximum and amplitude (° C)• Minimum: 22-year average of the minimum daily

mean earth temperature for each month.• Maximum: 22-year average of the maximum daily

mean earth temperature for each month.• Amplitude: One half of the difference between the

average daily earth temperature minimum and maximum.

Supporting Information

• Top-of-atmosphere insolation (kWh/m2/day)• Amount of electromagnetic energy (solar radiation)

incident at the top of the atmosphere.

• Surface Albedo (dimensionless)• Fraction of insolation reflected by the surface of the

earth

Name Population Latitude/Longitude

1 Karachi   , Sindh11,624,219

24.906 / 67.082

2 Lahore, Punjab 6,310,888 31.55 / 74.344

3 Faisalabad   , Punjab 2,506,595

31.417 / 73.083

4 Rawalpindi   , Punjab 1,743,101

33.601 / 73.068

5 Multan   , Punjab 1,437,230

30.196 / 71.475

6 Haidarabad   , Sindh 1,386,330

25.392 / 68.374

7 Gujranwala   , Punjab 1,384,471

32.162 / 74.188

8 Peshāwar   , North-West Frontier Province 1,218,773

34.008 / 71.578

9 Quetta   , Balochistān 733,675

30.199 / 67.01

10 Muzaffarabad   , Azad Kashmir