Analyze Effect of Solar Tilt Angle on AC Energy Output

Effect of Solar Tilt Angle on AC Energy Output

In this post, the effect of solar tilt angle on energy output of solar panel.  Let us consider that residential 4 kW solar panel is installed in Surat, Gujarat, India. As Surat is in the northern hemisphere therefore the solar panel is installed south facing. The effect of solar panel tilt angle on the output AC energy is given here.

Tilt angle

• It is defined as the slope angle at which solar panels are mounted to the face of the sun. 
• The tilt angle of solar panel depends upon latitude of installation of site, time of year when energy generation is most critical, desired level of energy output.

• When the tilt angle of solar panel is set equal to latitude of the site, the solar panel generates maximum the annual energy output. 
• The recommended tilt angle of solar module structure to minimize wind pressure is < 15 degree for flat surface. 
• However, minimum tilt of 10 degree should be maintained for natural cleaning of solar panel.
• The PV array should face towards true south (in the northern hemisphere) as ideal orientation, however, for structural uniformity and to accommodate more solar array in limited RCC flat roof space, orientation could be aligned with roof orientation. 
• The solar PV modules/panels should be installed at the same tilt angle as that of orientation of the roof for inclined roof. 
• Solar PV module should be installed south facing in the northern hemisphere and north facing in the southern hemisphere. 
• As India is in the northern hemisphere, the solar panel modules will be always installed south facing. 
• The direction of north south can be determined by using magnetic compass.

Effect of solar tilt angle on AC energy output

Solar Panel Site: Surat, Gujarat, India

Latitude & Longitude: 21.20, 72.80

Azimuth angle: 180 degree

Elevation: 14 m

Solar Panel Position: Fixed Mounted

Month	AC Energy Output For Different Tilt Angle ( In Degree )
	100	200	210	300	400	500	600
Jan	533.4	581.8	585.8	614.7	632.2	634.3	621
Feb	544.7	579	581.7	598.9	604.3	595	571
Mar	651.9	667.5	668.2	667.3	651.3	619.2	570.6
Apr	648.9	640.5	638.8	617.1	578.6	525	456.2
May	643.8	617.1	613.6	576	520.7	451.8	370.2
Jun	466.9	444.4	441.6	412.3	371	321.2	264
Jul	356.9	343.1	341.4	322.6	295.8	263	224.8
Aug	381.2	371.9	370.6	355.1	331.1	300	262.2
Sep	438.4	439.2	438.8	430.5	412.4	384.8	347.9
Oct	539.8	562.7	564.3	572.4	568.7	551.6	521
Nov	494.4	532.8	535.9	557.5	568.8	566.3	550.2
Dec	489.8	538	542	571.8	591.2	596.2	586.7
Yearly	6190.1	6318.1	6322.6	6296.3	6125.9	5808.4	5345.9

 

Conclusion

From the above result, it is clearly visible that the solar panel generates highest units at tilt angle is equal to latitude of the site for fixed tilt angle.

• The solar panel tilt angle should be kept lower in the summer (April, May, June & July) in order to gain higher ac energy output. Similarly, the solar panel tilt angle should be kept higher than the tilt angle in the winter (November, December and January)in order to gain higher ac energy output.
• However, the tilt angle is kept < 15 degree if the site is located near the sea area considering protection of solar panel against higher wind speed or cyclone / typhoon.

Questions of Solar panel tilt angle

What should be ideal tilt angle for solar panel?

Latitude of the site

Why the solar panel tilt angle is kept higher than tilt angle in winter and lower in summer?

As the sun position is lower in the winter, tilt angle is kept higher to gain optimum output. Similarly, the sun position is higher in the summer, tilt angle is kept lower to gain optimum output.

How to calculate summer and winter tilt angle for solar panel

There are two methods to calculate summer and winter tilt angle for solar panel.

Method 1

Summer tilt angle = Latitude – 15 degree

Winter tilt angle = Latitude + 15 degree

Method 2

Summer tilt angle = 0.69 × Latitude + 3.7 degree

Winter tilt angle = Latitude + 10 degree

Average tilt angle = (Summer tilt angle + Winter tilt angle) / 2

Why the solar industries expert recommended solar panel tilt angle less than 15 degree?

The solar industries expert recommended solar panel tilt angle less than 15 degree for places where heavy wind blows frequently or cyclone or typhoon. The wind pressure may damage solar panel mounting structure as well as solar panel.

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