New Web Interface for Solar Tracking is Right on Target

 
Published: 15 March 2004

New solar tracking interface helps eliminate judgment calls and create an objective assessment of tracker performance each day.

At ARM’s Tropical Western Pacific site, radiometer sensors mounted on solar trackers provide critical radiation balance measurements. If a tracker is off even a small amount, the data from the diffuse radiometers and the normal incidence pyrheliometer (NIP) are worthless, and therefore the overall combined data coming from the site’s other instruments is less valuable. As part of an investigation into performance problems with the trackers, local observers were asked to check and report on the trackers three times a day. Unfortunately, communication of the trackers’ ability to follow the sun was somewhat subjective due to the reporting method of faxing penciled-in diagrams.

To eliminate any judgment questions inherent in reading the diagrams, ARM software engineering developed a reporting tool that enabled the observers to enter tracker shading information directly into TWP’s routine ‘daily rounds’ report. Recently, the capability to view the tracker reports on the web (i.e., decode the shading report data and generate the corresponding web graphic) was added. This enhancement allows operators to easily note where the sunspot shadow outline from the rim of the NIP falls on the small target “bull’s eye” on the tracker body, and provides a good single point measure of the overall solar tracking accuracy. With this additional feature, TWP is providing a nice, clear graphic that the Daily Operations Coordinator can use to make a quick, objective assessment of tracker performance each day.