Yash
The solar panels are given the right solar tilt to receive maximum sunlight.
I mean, they are aligned at the proper angle with respect to the horizontal surface of the earth.
In this post, we’ll try to find the best placement of the solar panels so that you get smooth electricity from your solar panels.
You’re not going to get one answer (angle) for this.
Because the relative position of the earth with respect to the sun is changing every moment.
so does our best placement angle.
But
it is not practical to change the position of the solar panels every time.
We’ll try to find the optimum static angle on which solar panels are aligned, absorbing most of the solar energy.
The tilt of the solar panels depends on:
- Hemisphere
- Declination angle
- Latitude of the location
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Solar tilt depends on the Hemisphere
If you live in the northern hemisphere then face your solar panels towards the true south, or true north if your location is the southern hemisphere.
True north is not the same as magnetic north.
True north or south are the points from where the earth’s axis of rotation is passing.
Whereas,
Magnetic north or south are the points where your magnetic compass needle points.
If you’re living in the equator then your panels should be placed directly overhead facing the sun.
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Understanding the term latitude
By what angle you should align the solar panels depends on the location (latitude) on earth.
Your location on earth can be exactly determined by the coordinate system:
Latitudes and Longitudes.
Latitude is a metric that describes your position (in degrees and minutes) north or south of the equator.
The greatest possible values of latitude are 90° North or 90° South of the equator.
Whereas,
Longitude is a measurement of your location east or west of the prime meridian.
(*We’ll restrict our discussion to latitude only as it is used to determine the tilt of the solar panels).
For example,
The position point ‘A’ with latitude 20° North means, it is subtending an angle of 20° at the center of the Earth.
If you live 20° north (latitude) then you should face your panels towards the south making an angle of 20° with the earth’s surface.
Or
A person living in 30° south should face the solar panels towards the north, making an angle of 30° with the horizontal surface.
Simple!
isn’t it?
The above calculation would be right if the earth’s axis of rotation is not tilted.
The earth’s axis of rotation is tilted
Its axis of rotation is not upright, it is tilted 23.5 degrees.
The gravitational pull of the Moon gives stability to this tilt.
This tilt is responsible for seasons on Earth.
The earth’s axis of rotation always points in one direction when it circles around the sun.
While circling around the sun, each hemisphere receives varying amounts of sunlight.
For some time, the Northern hemisphere leans towards the sun.
It is the time when we see long day hours, temperature increases and we have summers.
When Earth moves to the other side of the sun, the Northern hemisphere leans away from the sun.
The days become short, temperature drops and the winter season arrives.
The places near the equator see less variation in the sunlight but when we move towards poles, this variation becomes more pronounced.
The declination angle
The angle that the sun rays make with the equatorial plane of the Earth is called the declination angle.
This angle varies from -23.5° to +23.5° while circling around the sun.
It is:
- 23.5° in Summer Solstice and -23.5° in Winter Solstice
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The complete scenario is shown below:
The declination angle can be calculated using the following formula:
where N is the day of the year ( 1 to 365 or 366 in case of a leap year).
We take Jan 01 as the first day of the year.
For example,
The declination angle on the 150th day would be 21.8°
Similarly,
you can find the declination angle on any day of the year.
We should combine both latitude and declination to know the right tilt of the solar panels.
Finding the right solar tilt
In summer solstice, the northern hemisphere is leaning towards the sun and its equatorial plane is making 23.5 degrees with the sun rays.
At this time, the latitude of 23.5° N is just aligned with the sun’s rays.
It means the sun rays are falling straight on this location.
Therefore, you should place your solar panels directly overhead (making 0° with the surface of the earth) and facing south to capture the maximum sunlight.
The right formula for calculating the tilt is:
Tilt angle = Latitude – Declination angle (i)
The value of Latitude of any place is constant but the declination angle is changing every moment with the movement of the earth.
Similarly, the tilt angle keeps on changing.
The solar panel tilt angle on 150th day on location 23.5° N is:
Tilt angle = 23.5° N – 21.8°(as calculated above under heading declination angle)
Tilt angle = 1.7° from the horizontal surface and should be facing south direction
Similarly,
you can find the tilt angle of any day for location 23.5 degrees North, using the following formula by putting the value of declination in equation (i):
If I find the tilt angles from 23.5°N from day 1 to day 365 then the chart will look something like shown below:
But I can not change the solar panel tilt every day as it is not feasible.
Therefore, I should find the optimum tilt angle that can work most of the time.
Fixed solar tilt in a year
If you are going for fixed-tilt for your solar panels around the year then it is generally found by reducing the latitude by 15% or multiplying the latitude by 0.85.
For example,
a place with a latitude of 30° will have solar panels inclined at:
= 0.85 x 30°
= 25.5° with the surface of the earth.
The fixed angle is convenient but the disadvantage is that you are going to capture around 75% of sunlight than what you get when you keep changing the position.
(*These calculations are acceptable up to 50° latitudes)
If solar panels are not given right solar tilt
The simple answer is the efficiency will reduce.
Your solar panels will produce less current.
For example,
The optimum angle for a place is 45° (with the surface of the earth)
But it is placed horizontally to the surface.
The situation is depicted below:
The solar panel is placed at 45° with the horizontal surface would receive maximum sunlight, say ‘x’.
But
when placed horizontally, the component of light that is perpendicular to the panel is xsin 45° or 0.71x (sin 45° = 0.707)
The output will be reduced by almost 30% in this case.
It shows the importance of the right tilt of the solar panels.
Conclusion
It is most convenient to mount your solar panels at a fixed tilt and just leave them.
But, the sun is high in summers and lowers in winters, one can adjust the tilt twice a year to capture most of the sunlight.
This way, you can have more current from your panels than you were getting from the panels at a fixed tilt.
Let me share with you the tilt angles when you are adjusting them twice a year.
If you go adjust your solar panels 4-times in a year then the increase in the efficiency would be less when compared with the increase in the cost.
In the last, we can say that the right tilt helps us in increasing the output of the panels and improves the financial feasibility of the solar power system.
