SkyMan

Solar panel wind danger?

9 posts in this topic

Solar panels are fairly light but seem fairly strong.  On a roof, no problem with wind but on a tracker I wonder about wind damage.  If a panel was supported by steel braces across the back at say 25% and 75% of the height of the panel and standing up at 90 degrees awaiting the rising sun and a strong wind came from the east, would that be a problem for the panel or more the problem for whatever it's mounted on?  The reason I'm asking is partly due to the strength of the actuators used to move the panels.  There are fairly cheap actuators (~$30) with 300+ lift force and then some with as high as 7000lb force for like $250.  The tracking system should be balance so the panels can be moved around with one finger without the actuators attached so the only reason I can see for high strength is if it is fighting wind.  The other reason is because some tracking controllers have a wind speed input so you can park the panels at a safe angle in high winds but I wonder if that's due more to having weak actuators than the panels themselves?

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If you look at this financially, it is cheaper to add a few extra panels, than it would be to build a pole mount with actuators, a tracker and brackets to support your solar array. 

If you are going to go the solar tracking route, buy the stronger actuators. They will last longer and handle heavier loads. The tracker itself, you can buy with an optional anemometer that will "park" the tracker, to help protect it from heavy winds. 

My :twocents:

 

1 hour ago, SkyMan said:

The tracking system should be balance so the panels can be moved around with one finger without the actuators attached so the only reason I can see for high strength is if it is fighting wind.

I would agree with this statement. The actuator has to be able to hold the load, which would become a huge sail in heavy winds. 

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I think I'm going to go with the cheap actuators just get to work out any bugs.  Then if they fail I can go with the strong ones.  I normally go for better quality for less problems later but the cost difference is so high on these...

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30 minutes ago, SkyMan said:

I think I'm going to go with the cheap actuators just get to work out any bugs.  Then if they fail I can go with the strong ones.  I normally go for better quality for less problems later but the cost difference is so high on these...

Well, it's your money and your decision, of course. But, the trend nowadays is, for example, building two permanent mount arrays, or three - if you have the money. One facing say, Southwest, the other facing Southeast. If you have the extra money, put one facing directly South. 

I found a place, even here, where I can buy panels for well under $1.00 USD per watt. 

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panels are cheap now...  ( in Aus anyway ),  when my brother done his solar system 15 years ago,  he said he paid over $1,000 for each panel (150W),  now you get a 250W panel for less than $250

buy extra panels, and don't bother about a tracker..  and as do Paul suggest  ( virtual tracker )

Edited by noddle
fix my spelling..
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10 hours ago, Paul said:

Well, it's your money and your decision, of course. But, the trend nowadays is, for example, building two permanent mount arrays, or three - if you have the money. One facing say, Southwest, the other facing Southeast. If you have the extra money, put one facing directly South. 

I found a place, even here, where I can buy panels for well under $1.00 USD per watt. 

Remember that in cebu the sun is to the north about 3 months a year

cebu is on  about 10th north latitude

and Tropic of Cancer is located at 23 ° 27 'north latitude

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Actually the sun is transiting on the north emisphere approximately from april 20 to august 20 here.

By the way those monts are also the one with the longest daylight and usually april and first half of may with strongest average solar radiation (net of clouds).

I would install a solar panel with a slight inclination of about 5-8° southwards  that's to say practically horizontally

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18 hours ago, Woolf said:

Remember that in cebu the sun is to the north about 3 months a year

cebu is on  about 10th north latitude

and Tropic of Cancer is located at 23 ° 27 'north latitude

Understand completely. I was just using that as an example, as I stated, due to the angle of the majority of solar arrays in the Northern Hemisphere.

17 hours ago, Lory said:

I would install a solar panel with a slight inclination of about 5-8° southwards  that's to say practically horizontally

What about for the rest of the year? 

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On 2/20/2017 at 7:13 PM, Woolf said:

Remember that in cebu the sun is to the north about 3 months a year

cebu is on  about 10th north latitude

and Tropic of Cancer is located at 23 ° 27 'north latitude

Right, which is why a typical US or European tracker setup won't work right here.  Well, above the tropics, the E-W tracking is done by rotating the unit clockwise (maybe ~150 deg) and the inclination is set by tipping the panels back (0 - < 90 deg).  Here that works through the winter until the Equinox when that system would get confused.  The E-W actuator would want to follow the sun to the north but already be at the limit of it's travel so the N-S tracker would follow the sun by tipping back until noon but then it would be at the far end of it's travel.

 

So my solution is to track E-W on a horizontal axis aligned with Polaris and declined 13.1 deg to the north from level. The E-W actuator would rotate the unit over the top, east to west.  The inclination would be the zero position for the N-S tracker and correspond to solar tracking on 21 June.  As the sun tracks south into the winter the N-S actuator would tip the panels up to horizontal and then up to 33.9 degrees for a total angle change of ~47 deg.  I think if the angle of the (semi) horizontal axis is perfect, the N-S actuator would do nothing all day except for a sunrise correction under normal circumstances.

It may be cheaper and easier to just cover the roof with panels but this is cooler and I think a fun project.  And I get a functional sundial in my yard. :)  I also found a cool thing that the lot line on the north side of my (where the tracker is going) lot is almost exactly lined up with the setting sun on 21 June.  

My current single panel is working just by laying on top of my dog kennel roof which pitched a bit south.  I'll have to move it to the north side in a few months when the eaves of my house start blocking it.  It's grid tied on a microinverter and will probably do the same with 3 more panels on the tracker.  I plan to build the tracker to handle eventually 6 panels but perhaps going off grid with 2 additional panels.

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