EPRI: Electric Power Research Institute
Southeastern Solar Research Center
Southeastern Solar Research Center

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Contact EPRI

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About this website

This website was designed and developed by EPRI in collaboration with Southern Company, other member utility companies, and EPRI's Renewable Generation program.

Help: information about this page...

Component View

After reading the overview, try interacting with the comparison chart(s) to learn more about the data's characteristics and trends.

Panels

This page contains several panels: Performance Snapshot, Overview, etc. Tap or click the "?" button in the upper right corner of a panel to see more information about its content.

  1. Site Overview
  2. Total Sky Irradiance (Solar Radiation)
  3. Diffuse Horizontal (Solar Radiation)

Diffuse Horizontal Irradiance (Shaded Pyranometer)

Performance Snapshot
Performance Snapshot

This panel may show a sampled measurement (e.g., power) and/or a cumulative measurement (e.g., energy generated).

When the sampled measurement is available, a gauge and trend chart will appear.

When the cumulative measurement is available, its value will be shown over the date range indicated.

Sampled Value (Gauge and Chart)

Diffuse horizontal irradiance

Diffuse Horizontal Irradiance
Diffuse Horizontal Irradiance (W/m²)
Overview
Enlarge Image

Diffuse horizontal irradiance is essentially the inverse of direct normal irradiance, consisting of the solar radiation reaching a horizontal plane with the exception of direct sunlight. Diffuse horizontal irradiance includes light that is reflected from clouds, the atmosphere, and other objects above its horizontal plane of measurement. Imagine holding a tennis ball up to the sun so that the ball casts a shadow in your field of view. Diffuse horizontal irradiance would be the measure of solar radiation outside of that shaded area.

Measurement Source

Diffuse horizontal irradiance can be measured with a pyranometer sensor and a shading disk. The pyranometer is mounted to a horizontal base, while the shading disk is mounted to a tracking system that moves as the sun travels across the sky. The purpose of the shading is to keep the pyranometer shaded throughout the day by blocking direct sunlight, enabling the sensor to measure indirect solar radiation.

Time Series Profile
Time Series Profile

Chart (or charts) shows trends for a specific component. Each data point represents an aggregated value for the time interval indicated (e.g., 15-minute average).

Chart Navigation

Tap or click on the chart titles (if more than one shown) to switch the view between charts. The title of the displayed chart is highlighted in orange.

Zoom and Pan

To zoom in on and get a closer view of a plot area in a chart:

  • On a touchscreen: Use two fingers to spread apart (expand) the plot area, then use one finger to slide the plot area left and right.
  • Using a mouse: Click and drag to select a section of the plot area, then hold down the Shift key while dragging left and right.
  • Tap or click on the "Reset zoom" button to return the chart to its original size.

Toggle Legend Items

Tap or click on a legend item (if more than one shown) to hide or show its data in the plot area.

Measurements Plotted

Chart (or charts) includes one or more of the following measurements (indicated in the legend or title):

  • Diffuse horizontal irradiance

Preset Date Ranges

Custom Date Range

to
Data are available beginning 5/1/2014. Clear the end date to view the most recent data available.
Tip: click "?" (next to the Edit button) to learn how to interact with the chart.

Download Chart Data

Save chart data as a comma-separated values (CSV) file:
Note: timestamps (first column in the CSV file) are adjusted to your computer's time zone and represent the beginning of each interval.
Warning: downloading data is intended for desktop and laptop computers. This feature may not work for smartphones or tablets.
DIFFUSE HORIZONTAL IRRADIANCE
Daily Performance
Daily Performance

Chart (or charts) shows trends for a specific component. Each data point represents an aggregated value for the date indicated.

Chart Navigation

Tap or click on the chart titles (if more than one shown) to switch the view between charts. The title of the displayed chart is highlighted in orange.

Zoom and Pan

To zoom in on and get a closer view of a plot area in a chart:

  • On a touchscreen: Use two fingers to spread apart (expand) the plot area, then use one finger to slide the plot area left and right.
  • Using a mouse: Click and drag to select a section of the plot area, then hold down the Shift key while dragging left and right.
  • Tap or click on the "Reset zoom" button to return the chart to its original size.

Toggle Legend Items

Tap or click on a legend item (if more than one shown) to hide or show its data in the plot area.

Measurements Plotted

Chart (or charts) includes one or more of the following measurements (indicated in the legend or title):

  • Diffuse horizontal irradiance

Preset Date Ranges

Custom Date Range

to
Data are available beginning 5/1/2014. Clear the end date to view the most recent data available.
Tip: click "?" (next to the Edit button) to learn how to interact with the chart.

Download Chart Data

Save chart data as a comma-separated values (CSV) file:
Note: dates (first column in the CSV file) are based on the site's geographic location, which may be different from your computer's time zone.
Warning: downloading data is intended for desktop and laptop computers. This feature may not work for smartphones or tablets.
DIFFUSE HORIZONTAL IRRADIANCE
Monthly Performance
Monthly Performance

Chart (or charts) shows trends for a specific component. Each data point represents an aggregated value for the month indicated.

Chart Navigation

Tap or click on the chart titles (if more than one shown) to switch the view between charts. The title of the displayed chart is highlighted in orange.

Zoom and Pan

To zoom in on and get a closer view of a plot area in a chart:

  • On a touchscreen: Use two fingers to spread apart (expand) the plot area, then use one finger to slide the plot area left and right.
  • Using a mouse: Click and drag to select a section of the plot area, then hold down the Shift key while dragging left and right.
  • Tap or click on the "Reset zoom" button to return the chart to its original size.

Toggle Legend Items

Tap or click on a legend item (if more than one shown) to hide or show its data in the plot area.

Measurements Plotted

Chart (or charts) includes one or more of the following measurements (indicated in the legend or title):

  • Diffuse horizontal irradiance

Preset Date Ranges

Custom Date Range

to
Data are available beginning 5/1/2014. Clear the end date to view the most recent data available.
Tip: click "?" (next to the Edit button) to learn how to interact with the chart.

Download Chart Data

Save chart data as a comma-separated values (CSV) file:
Note: dates (first column in the CSV file) are based on the site's geographic location, which may be different from your computer's time zone.
Warning: downloading data is intended for desktop and laptop computers. This feature may not work for smartphones or tablets.
DIFFUSE HORIZONTAL IRRADIANCE
Image for Diffuse Horizontal Irradiance (Shaded Pyranometer)