Alliant Energy EPRI: Electric Power Research Institute
Madison Solar Demonstration Project
Madison Solar Demonstration Project

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About this website

This website was designed and developed by EPRI in collaboration with Alliant Energy, EPRI's Integration of Distributed Energy Resources and Solar programs, and EPRI's Power Delivery and Generation sectors.

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 Solar Radiation (Orientation Lab)
  3. Direct Normal (Pyrheliometer)

Direct Normal Irradiance (Pyrheliometer)

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)

Direct normal irradiance

Direct Normal Irradiance
Direct Normal Irradiance (W/m²)
Overview
Enlarge Image

Direct normal irradiance passes in a straight line from the sun to the observer. Imagine looking directly at the sun through a tube with a 5° field of view. The tube blocks all other sources of light, allowing measurement of the sun’s direct radiation. The exclusion of solar radiation outside the tube, such as light reflected by the sky and surrounding environment, is the main quality that differentiates direct normal from other solar radiation components.

Measurement Source

A pyrheliometer is employed to measure direct normal irradiance. Similar to the tube example above, a pyrheliometer has the appearance of a small telescope. The pyrheliometer must be mounted to a tracking system that keeps the sensor pointed at the sun, enabling measurement of direct sunlight at all times.

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):

  • Direct normal irradiance

Preset Date Ranges

Custom Date Range

to
Data are available from 4/1/2016 through 7/26/2020. 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.
DIRECT NORMAL 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):

  • Direct normal irradiance

Preset Date Ranges

Custom Date Range

to
Data are available from 4/1/2016 through 7/26/2020. 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.
DIRECT NORMAL 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):

  • Direct normal irradiance

Preset Date Ranges

Custom Date Range

to
Data are available from 4/1/2016 through 7/26/2020. 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.
DIRECT NORMAL IRRADIANCE
Cumulative Performance
Cumulative Performance

Chart (or charts) shows aggregated values for the date range 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.

Components Defined

These components appear in at least one chart (indicated in the legend):

    Measurements Plotted

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

      Image for Direct Normal Irradiance (Pyrheliometer)