How are solar production estimates generated?

Solar energy is an increasingly popular and essential resource in the transition towards clean, sustainable power. As the demand for solar power systems grows, understanding how solar production estimates are created becomes crucial for both homeowners and businesses. In this article, we will dive deep into the various factors that contribute to these estimates, such as shade, azimuth, tilt, geography, system size, and type of equipment.

Shade: An Important component in Solar Production

A key factor affecting solar production estimates is the amount of shade that falls on a solar array. Shade can significantly reduce the output of a solar panel system, making it crucial to accurately account for it when estimating production. There are three primary sources of shade:

  1. Nearby trees, buildings, and other obstructions: These can cast shadows on the solar panels at different times of the day and year, depending on their size and distance.
  2. Topographical shading: Hills, mountains, or other natural features can cause shading, particularly during sunrise and sunset hours.
  3. Self-shading: This occurs when solar panels are installed too close together or improperly oriented, causing some panels to cast shadows on others.

To account for shading, your DelphiSun Customer Experience Professional will use tools like solar pathfinders, 3D modeling software, or drone-based imaging to create a shading analysis report. This report helps determine the percentage of sunlight that will reach the solar panels throughout the year and is factored into the overall production estimate. 

Azimuth: The Direction Your Solar Panels Face

The azimuth, or orientation, of solar panels significantly impacts their energy production. In the Northern Hemisphere, solar panels should ideally face true south for maximum exposure to sunlight. The further the panels deviate from true south, the less energy they will produce. For example, solar panels facing southeast or southwest will produce less energy than those facing due south.

We use GPS devices to determine the precise azimuth of a solar array. This information is then combined with other factors like tilt and shading to estimate the total solar production.

Tilt: The Angle at Which Solar Panels Are Installed

Tilt refers to the angle at which solar panels are installed relative to the ground or roof surface. The optimal tilt angle depends on the latitude of the installation site, as it affects the amount of sunlight that strikes the solar panels throughout the year.

At higher latitudes, a steeper tilt angle is necessary to capture the maximum amount of sunlight. Conversely, at lower latitudes, a shallower tilt angle is more effective. At DelphiSun we use tools like tilt meters or smartphone apps to measure the angle of the solar panels accurately. We also consider factors like roof slope, structural integrity, and potential shading when determining the optimal tilt angle for a solar array.

Geography: The Impact of Location on Solar Production

The geographic location of a solar installation plays a crucial role in determining its energy production. Solar insolation, which measures the amount of sunlight received per unit area, varies based on factors such as latitude, climate, and regional weather patterns.

In general, solar production is higher in regions with more abundant sunlight, such as the southwestern United States. Conversely, areas with less sunlight, like the Pacific Northwest, will typically have lower solar production. We use use data from sources like the National Renewable Energy Laboratory (NREL) or the National Oceanic and Atmospheric Administration (NOAA) to determine the solar insolation for a given location.

System Size: How Big Is Your Solar Array?

The size of a solar array directly influences its energy production. Larger systems with more solar panels can generate more electricity, while smaller systems will produce less. System size is typically measured in kilowatts (kW), which represents the maximum power output of the solar array under ideal conditions. To determine the appropriate system size for a given location, we take into account factors such as the your energy consumption, available roof space, and budget.

When estimating solar production, the system size is combined with other factors like shade, azimuth, tilt, and geography. For example, a 5 kW system in a sunny location with minimal shading and optimal tilt and azimuth may produce significantly more energy than a 5 kW system in a cloudy location with heavy shading.

Type of Equipment: Choosing the Right Solar Panels and Inverters

The type of equipment used in a solar installation also impacts the overall energy production. There are three primary factors to consider when choosing solar equipment:

  1. Solar panel efficiency: This refers to the percentage of sunlight that is converted into electricity by a solar panel. Higher efficiency panels can generate more energy in a smaller space, making them ideal for installations with limited roof space or high energy demands.
  2. Inverter efficiency: Inverters convert the direct current (DC) electricity generated by solar panels into alternating current (AC), which is used by household appliances and the power grid. The efficiency of an inverter determines the percentage of DC power that is converted into usable AC power. A higher efficiency inverter will result in less energy loss and higher overall solar production.
  3. Degradation rate: Solar panels and inverters degrade over time, leading to a decrease in energy production. The degradation rate is typically expressed as a percentage of lost power per year. When estimating solar production, we will factor in the degradation rate to account for the system’s decreasing performance over its lifetime.

Accurately estimating solar production is a complex process that takes into account various factors such as shade, azimuth, tilt, geography, system size, and type of equipment. By understanding these factors and using the appropriate tools and data sources, we can provide reliable estimates for our customers considering solar power. This, in turn, helps you make an informed decision when choosing a solar power system that meets your specific needs and expectations.

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