As the world continues to move toward an increase in renewable energy sources, one of the most important components of a successful solar energy system is understanding the solar angles of your property. The first step to understanding solar angles is to understand the difference between orientation and tilt. The orientation of solar panels is the direction they face relative to the sun, while the tilt is the angle of the panel in relation to the ground. Both orientation and tilt are important considerations when designing a solar energy system.
Orientation is important because the best way to maximize solar energy is to have the panels face the sun directly. This ensures that the panels are receiving the most direct sunlight and therefore producing the most energy.
Generally, a higher tilt angle will capture more sunlight, however, the optimal tilt angle can vary depending on the location and the time of year. If the solar panel is too flat, it will not capture enough sunlight and the system will be inefficient, while if the solar panel is too steep, it will not capture enough sunlight either.
More deep on solar angles?
The axis about which the earth rotates is tilted at an angle of 23.45 degrees to the plane of the earth’s orbital plane and the sun’s equator. The earth’s axis results in a day-by-day variation of the angle between the earth–sun line and the earth’s equatorial plane called the solar declination δ. This angle may be estimated by the following equation:
where N = year day, with January 1 + 1
The position of the sun can be defined in terms of its altitude β above the horizon and its azimuth ϕ measured in horizontal plane.
To determine the angle of incidence θ between a direct solar beam and the normal to the surface, the surface azimuth ψ and the surface-solar azimuth γ must be known. The surface-solar azimuth is designated by γ and is the angular difference between the solar azimuth ϕ and the surface azimuth ψ. For a surface facing the east of south, γ = ϕ − ψ in the morning, and γ = ϕ + ψ in the afternoon. For surfaces facing the west of south, γ = ϕ + ψ in the morning and γ = ϕ − ψ in the afternoon. For south-facing surfaces, ψ = 0 degree, so γ = ϕ for all conditions. The angles δ, β, and ϕ are always positive.
For a surface with tilt angle Σ (measured from the horizontal), the angle of incidence θ is given by
For vertical surfaces, Σ = 90 degrees, cosΣ = 0, and sinΣ = 1.0, so Eq. above becomes
For horizontal surfaces, Σ = 0 degree, sinΣ = 0, and cosΣ = 1.0, so Eq. leads to
Latitude φ is the angular location north or south of the equator, north positive; −90 degrees ≤ φ ≤ 90 degrees.
Zenith angle θz, the angle between the vertical and the line to the sun, is the angle of incidence of direct (beam) radiation on a horizontal surface (θz = θ).
Hour angle ω is the angular displacement of the sun east or west of the local meridian due to rotation of the earth on its axis at 15 degrees per hour; morning negative (−ωs) and afternoon positive (+ωs) (Fig.). The sun position at any hour τ can be expressed as follows:
If the angles δ, φ, and ω are known, then the sun position in the interest point can be easily determined for any hour and day using following expressions:
(
For any day of a year, solar declination δ can be determined in Eq. and for the hour τ, hour angle ω can be calculated in Eq. Latitude φ is also known and thus solar altitude β can be determined.
FREQUENTLY ASKED QUESTIONS
The tilt of solar panels affects their energy output by influencing the angle of incidence between the sun’s rays and the panel surface. A tilt angle that matches the latitude of the installation location is generally considered optimal, as it allows the panels to receive the most direct sunlight throughout the year. For example, a location at 30° latitude would have an optimal tilt angle of around 30°. However, the optimal tilt angle may vary depending on the specific installation and local climate conditions.
The surface azimuth (ψ) is the direction of the surface normal relative to true south, while the surface-solar azimuth (γ) is the direction of the sun relative to true south. To determine the angle of incidence (θ) between a direct solar beam and the normal to the surface, both the surface azimuth and surface-solar azimuth must be known. The angle of incidence can be calculated using the equation: θ = arcsin(sin(ψ) \* sin(γ) + cos(ψ) \* cos(γ) \* cos(β)), where β is the solar declination angle.
Seasonal changes affect the optimal orientation and tilt of solar panels due to the Earth’s tilt and orbit around the sun. During the summer months, the sun is higher in the sky, and a lower tilt angle may be beneficial. In contrast, during the winter months, the sun is lower in the sky, and a higher tilt angle may be beneficial. The optimal orientation and tilt may also vary depending on the specific location and climate, with locations near the equator requiring less seasonal adjustment than those at higher latitudes.
Incorrect orientation and tilt can significantly impact the performance of a solar energy system, leading to reduced energy production and efficiency. A deviation from the optimal orientation and tilt can result in a loss of up to 30% of the system’s potential energy output. This can lead to increased payback periods, reduced return on investment, and decreased overall system performance.
Software tools and simulations can be used to optimize solar panel orientation and tilt by analyzing various factors such as location, climate, and system design. These tools can simulate the performance of different orientation and tilt configurations, taking into account factors like shading, temperature, and irradiance. This allows designers and installers to identify the optimal orientation and tilt for a specific installation, maximizing energy production and system efficiency.
