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I'm looking to design a system that can control a solar panel through an electrical actuator for a range of motion of -45 to +45 degrees for maximum solar exposure. The panel will be mounted on a 10 feet pole and will be attached at the center of that pole. This means that either the mechanism will be at the pole's top or at least some kind of bearing to allow for the movement.

The caveat in this case (because the panel is attached high up) is that due to security reasons the system must be designed in such a way that the panel will be held stable (mustn't rotate and mustn't fall off) without relying on the actuator itself, in case of power failures.

I've started looking around for actuator mechanisms but haven't yet found anything that talks specifics about similar security requirements. I'm looking for pointers / ideas as I'm not yet experienced in such cases.

PS: For anyone who would be interested in numbers the panel weighs about 150 kg and will possibly receive a horizontal wind force of 300N. Also a torque of 100Nm will need to be applied in order to change its facing direction.

PentaKon
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    A linear actuator using a lead screw would be intrinsically self-locking. You could attach the panel to the actuator using some sort of linkage to convert the linear motion into rotation. The fact that you don't need high-speed motion in this application is your friend! – alephzero Jun 29 '18 at 08:55
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    @alephzero, your answer should be an answer, as one cannot upvote a comment. Another advantage to using a linear actuator is the large range of travel available in the various mechanisms on the market, the wide range of weight/power capacity and the ease of implementation for this application. – fred_dot_u Jun 29 '18 at 14:07
  • I am not sure but some of the numbers do not add up. If you have a 150 kg panel, then the area of the solar panels should be between 5 and 10 $m^2$. However, if that's the case, then the wind drag seems quite low. It seems like you are using max wind speed 10$m/s$, on an area of 5$m^2$. If you get a wind gust with double the speed then the forces will be 4 times greater. Also the 100[Nm] torque suggests a much larger system. – NMech Aug 17 '20 at 18:30
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    A worm drive motor has the locking action you're looking for. – Drew Dec 15 '20 at 22:19

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There are lots of home-brew projects completed and written up in this magazine.

One used a water bucket with a controlled fill to follow the sun and a controlled tap to empty the bucket with a return spring.

Another used a small 3v motor with two small pv panels and a « lens » made from a jar filled with water...

https://www.homepower.com

Solar Mike
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I have seen some massive PV tower actuators torn to bits from a windstorm. This is your biggest challenge and is a non-starter without simulation and design experience.

Tony Stewart EE since 1975
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