Solar Radiation Incident on the Surface

Related Resources: heat transfer

Solar Radiation Incident on the Surface

Heat Transfer Engineering
Thermodynamics
Engineering Physics

Hourly variation of solar radiation incident on various surfaces and the daily totals throughout the year at 40° latitude (from ASHRAE Handbook of Fundamentals, Ref. 1, Chap. 27, Table 15)

Solar radiation is radiant energy emitted by the sun, particularly electromagnetic energy. About half of the radiation is in the visible short-wave part of the electromagnetic spectrum. The other half is mostly in the near-infrared part, with some in the ultraviolet part of the spectrum

Solar Radiation Incident on the Surface,* W/m²
Solar Time
Date	Direction of Surface	5	6	7	8	9	10	11	12 noon	13	14	15	16	17	18	19	Daily Total
Jan.	N NE E SE S SW W NW Horizontal Direct	0 0 0 0 0 0 0 0 0 0	0 0 0 0 0 0 0 0 0 0	0 0 0 0 0 0 0 0 0 0	20 63 402 483 271 20 20 20 51 446	43 47 557 811 579 48 43 43 198 753	66 66 448 875 771 185 59 59 348 865	68 68 222 803 884 428 68 68 448 912	71 71 76 647 922 647 76 71 482 926	68 68 68 428 884 803 222 68 448 912	66 59 59 185 771 875 448 66 348 865	43 43 43 48 579 811 557 47 198 753	20 20 20 20 271 483 402 63 51 446	0 0 0 0 0 0 0 0 0 0	0 0 0 0 0 0 0 0 0 0	0 0 0 0 0 0 0 0 0 0	446 489 1863 4266 5897 4266 1863 489 2568 —
Apr.	N NE E SE S SW W NW Horizontal Direct	0 0 0 0 0 0 0 0 0 0	41 262 321 189 18 17 17 17 39 282	57 508 728 518 59 52 52 52 222 651	79 462 810 682 149 77 77 77 447 794	97 291 732 736 333 97 97 97 640 864	110 134 552 699 437 116 110 110 786 901	120 123 293 582 528 187 120 120 880 919	122 122 131 392 559 392 392 122 911 925	120 120 120 187 528 582 293 123 880 919	110 110 110 116 437 699 552 134 786 901	97 97 97 97 333 736 732 291 640 864	79 77 77 77 149 682 810 462 447 794	57 52 52 52 59 518 728 508 222 651	41 17 17 17 18 189 321 262 39 282	0 0 0 0 0 0 0 0 0 0	1117 2347 4006 4323 3536 4323 4006 2347 6938 —
July	N NE E SE S SW W NW Horizontal Direct	3 8 7 2 0 0 0 0 1 7	133 454 498 248 39 39 39 39 115 434	109 590 739 460 76 71 71 71 320 656	103 540 782 580 108 95 95 95 528 762	117 383 701 617 190 114 114 114 702 818	126 203 531 576 292 131 126 126 838 850	134 144 294 460 369 155 134 134 922 866	138 138 149 291 395 291 149 138 949 871	134 134 134 155 369 460 294 144 922 866	126 126 126 131 292 576 531 203 838 850	117 114 114 114 190 617 701 383 702 818	103 95 95 95 108 580 782 540 528 762	109 71 71 71 76 460 739 590 320 656	133 39 39 39 39 248 498 454 115 434	3 0 0 0 0 2 7 8 1 7	1621 3068 4313 3849 2552 3849 4313 3068 3902 —
Oct.	N NE E SE S SW W NW Horizontal Direct	0 0 0 0 0 0 0 0 0 0	0 0 0 0 0 0 0 0 0 0	7 74 163 152 44 7 7 7 14 152	40 178 626 680 321 40 40 40 156 643	62 84 652 853 547 66 62 62 351 811	77 80 505 864 711 137 87 87 509 884	87 87 256 770 813 364 87 87 608 917	90 90 97 599 847 599 97 90 640 927	87 87 87 364 813 770 256 87 608 917	77 87 87 137 711 864 505 80 509 884	62 62 62 66 547 853 652 84 351 811	40 40 40 40 321 680 626 178 156 643	7 7 7 7 44 152 163 74 14 152	0 0 0 0 0 0 0 0 0 0	0 0 0 0 0 0 0 0 0 0	453 869 2578 4543 5731 4543 2578 869 3917 —

*Multiply by 0.3171 to convert to Btu/h · ft². Values given are for the 21st of the month for average days with no clouds. The values can be up to 15 percent higher at high elevations under very clear skies and up to 30 percent lower at very humid locations with very dusty industrial atmospheres. Daily totals are obtained using Simpson’s rule for integration with 10-min time intervals. Solar reflectance of the ground is assumed to be 0.2, which is valid for old concrete, crushed rock, and bright green grass. For a specified location, use solar radiation data obtained for that location. The direction of a surface indicates the direction a vertical surface is facing. For example, W represents the solar radiation incident on a west-facing wall per unit area of the wall. Solar time may deviate from the local time. Solar noon at a location is the time when the sun is at the highest location (and thus when the shadows are shortest). Solar radiation data are symmetric about the solar noon: the value on a west wall before the solar noon is equal to the value on an east wall two hours after the solar noon.