|Tracker: Dual Axis
Polycrystalline silicon array, dual axis trackers.
Dual axis tracking systems adjust the array’s tilt up and down, as well as moving from east and west through the day. This allows for the change in the sun’s height in the sky through the year.
Solar panels are best able to generate electricity from light hitting their surface directly. Adjusting their surface to follow the path of the sun increases their electricity production.
The cost of a dual axis tracking system should be weighed against the gain that it offers over a fixed array. The outputs from the Solar Centre's fixed pole-mount, single axis tracking and dual axis tracking arrays can quantify this advantage for an installation in central Australia.
These dual axis trackers respond to light sensors on the face of the array. The control system determines whether the available light is mostly direct or diffuse. In diffuse or cloudy conditions, the tracker will react with less sensitivity, to limit its readjustments through the day.
The touch screens at the Solar Centre's Interpretive Centre can be used to compare the input of this array with the fixed pole-mount and single axis arrays over the life of the system.
|Number Of Panels
|5 x 8
|5 x 8.02 m²
|Type Of Tracker
|Wattsun AZ-125 Tracker
|Inverter Size / Type
|5 kW, SMA SMC 5000A
|Sun, 30 Nov 2008
Notes on the Data
System Disconnection for Cabling Works
All arrays at the Solar Centre were disconnected from approximately 2.00pm to 3.00pm on Monday, 9 July 2018 in preparation for the cable between the main switchboard and distribution board being upgraded. Array sites #23-38 remained disconnected while the main feeder cable to these sites was replaced in subsequent days, but all systems were re-connected by early afternoon on Thursday, 12 July 2018.
Monitoring Interruption for UPS Battery Replacement
The disconnection and re-connection of the solar arrays and weather station equipment while a new site connection was being established prompted the already flattening UPS batteries which power the site’s energy meters to fail and require immediate replacement. Data recording was affected from approximately 2.30pm ACST, Monday 10 July to 4.00pm, Wednesday 12 July.
Affects weather data for DKASC, Alice Springs
Sites 5 and 6: Faulty Tracking Units
At both sites 5 and 6 the single and dual axis tracking units have for several years been experiencing intermittent outages and component failures. These tracking units are no longer directly supported by any suppliers in Australia and replacement parts (control boards, actuator arms, etc.) have become difficult to source and thus several of the trackers at both sites are have failed or only operate intermittently. Continuing efforts are being made to repair these units but please note that the PV output of these two sites is negatively impacted by these technical issues.
> Answer to Spotlight Question
Onsite at the DKA Solar Centre in Alice Springs are a series of quiz-like Spotlight Questions at each array. Visit the centre and scan the QR code at each sign to test your knowledge – and check your answer here!
Q: How does a tracker know where the sun is at any given time in a day?
A: Solar trackers use a range of methods to follow the sun throughout the day including pre-programmed timers, light sensors and heat sensors. Pre-programmed trackers rely on the fact that the sun’s position at any time of the day or year can be reliably predicted. These positions are programmed into the tracker, which then simply follows the positional algorithm. Trackers that use sensors, on the other hand, actively monitor the sun’s position using their sensing capabilities and then move themselves to a position giving maximum PV generation. Some trackers use a combination of these two approaches.