What is a slew or slewing drive?
A slew (slewing) drive is a very sophisticated piece of machinery similar to a transaxle or differential in a rear wheel drive car. The big difference is the ability to turn at different speeds on two separate axis. And that is what makes it perfect for a a dual axis solar tracker. It can move east to west over 12 hours and return to start at a very controlled speed. Simultaneously the solar tracker can track the azimuth at an extremely low speed. All, when equipped with good electronic controls at extreme accuracy.
Great! Why don't we use these on our Suntracker do it yourself products? Our dual axis sun tracker solar trackers are designed for the DIY community to install inexpensively and without heavy equipment. And, our patented technology is equally accurate with much faster on demand response times.
WEIGHT is the issue. As the requirements for load and resistance (wind speed) go up, the mass of the slew drive goes up. By the time you get to 8 to 12 solar panels on a solar tracker you need an 8" slew drive at 800 plus pounds. Two or three guys on ladders are not going to install this 12 feet or more up on a tower.
Additionally, the slew drive can not respond quickly to the fast moving storms we have in the northern US. Our do it yourself Suntracker dual axis solar tracker units can be storm ready in minutes, and sometimes that is all you have.
UPDATE 1/1/2025 With our partners we have developed a slew drive light enough to be DIY installed on our trackers for 12 panels and up. New technology and new lightweight metals have made this possible. We are excited to make these new products available as of today!