# Dual axis solar tracker motor Selection



## Tesseract (Sep 27, 2008)

ajit.nayak87 said:


> Dear all ,
> 
> I am trying to build dual axis solar tracker . I need help to select proper guide motor relevant motor driver.


You're on the wrong forum, but besides that, the general consensus is the minor improvement in power output from a dual-axis tracker will not offset the high cost and decrease in reliability compared to a simple fixed mount for the panels.


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## tomofreno (Mar 3, 2009)

A two axis system increases panel output by about 30% compared to a fixed system (see nrel's PVWATTS). The main effect is in azimuth tracking, with altitude adding significantly less output gain. Most people don't use tracking because the financial incentives are biased against it. The rebate system set up by my state government and administered by the utility company is based on nominal wattage of the installed panels according to CEC ratings. Because of that, it was more cost effective to add more subsidized panels to get that extra 30% than to add unsubsidized tracking in 2008 when I installed pv. Even more so today since panels are so cheap.

You could use about any DC motor with sufficient torque for your system weight/friction with gearing for a 1440:1 speed reduction (24hrs*60mins) for each 1 rpm motor speed (panels need to rotate in azimuth once per 1440 minutes). A filtered photocell can provide feedback to track the sun and to trigger a reset to position the panels back toward the east after sundown. It of course doesn't need to be nearly as accurate as telescope tracking so a very simple speed control system for occasional corrections would work fine. You might check to see if someone has implemented this using Arduino. Could also check the astrophotography forums (several on yahoo groups) for diy tracking systems - there is quite a bit of free shareware for webcam based systems.


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