Solar panel as a wind resistance cheater.





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  1. #1
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    Default Solar panel as a wind resistance cheater.

    Going over Ou Kaapse Weg just now I noticed a 110 Land Rover nicely kitted out for off the beaten track application.

    At the front of its roof carrier it has a full width solar panel fitted at say 45 degrees presumably to act as a wind deflecter to decrease the resistance from the canvass roof top tent and other paraphernalia.

    The first thought crossing my mind was what if a flying stone hits it, and then I recalled something about drag eliminating the benefits of wind cheating devices.

    I can recall in the early eighties a popular addition to caravans were deflectors bolted vertically to the rear corners of a caravan, apparently reducing the drag effect.

    Seeing that the Landy is in any event shaped after a brick and a half, would such a deflecting device serve a justified purpose given the risk of damage?

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  2. #2
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    Default Re: Solar panel as a wind resistance cheater.

    I believe that the constant vibration caused by the wind on the panel will destroy the cells in no time.

  3. #3
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by River Rat View Post
    I believe that the constant vibration caused by the wind on the panel will destroy the cells in no time.
    I doubt that it is even possible.

    I mean the cells are covered by glass and they are designed to be used outdoors.
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by Die SwartKat View Post
    I doubt that it is even possible.

    I mean the cells are covered by glass and they are designed to be used outdoors.
    This an extract from this article: https://www.vivintsolar.com/learning...ar-panels-last

    Wind - Wind is usually a non-issue, however, thatís not always the case. If a wind is strong enough, it can cause the entire solar panel to vibrate. If your panels experience enough vibrating, the bonding that is holding different parts of the solar energy system together can come apart. Think of it as if someone is shaking another piece of equipment in a way that itís not supposed to. With enough shaking the whole thing will come apart. The wind does the same thing

  5. #5
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    Default Re: Solar panel as a wind resistance cheater.

    This more likely to happen as a result of vibration from the vehicle itself and we have not heard any such reports thus far that I know of.

    That would have to be serious gale storm winds for this to happen in my opinion.

    Solar panels are actually very robust.
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  6. #6
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by Die SwartKat View Post
    This more likely to happen as a result of vibration from the vehicle itself and we have not heard any such reports thus far that I know of.

    That would have to be serious gale storm winds for this to happen in my opinion.

    Solar panels are actually very robust.
    100-120km/h is quite a bit of wind especially if you have it for 5 - 6 hours day after day. There was also a report on this forum about vehicle vibration too but I think the constant battering from the wind would have a greater effect.

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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by River Rat View Post
    I believe that the constant vibration caused by the wind on the panel will destroy the cells in no time.
    This applies to the semi flexible ones.

    Poen, that solar panel must have extended for about 500mm above the roof rack at an angle of 45 degrees, increasing the frontal area. Don't think there will be any savings aerodynamically. There is definitely a danger of damage from stones, but probably not down Ou Kaapse Weg and elsewhere in town.

    I found that the tyre on the bonnet actually helps with aerodynamics - no figures to prove it. It transforms a Defender from a brick with sharp corners to a brick with rounded corners


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  9. #8
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    Default Re: Solar panel as a wind resistance cheater.

    That panel is to prevent the landy from lifting due to speed, same as F1 cars
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  11. #9
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    Default Re: Solar panel as a wind resistance cheater.

    It works. Mine is mounted at about 30 degrees. I have driven over 1000 kilos on corrugated sand roads and it's still good. Regarding stones it is very unlikely that a stone will ever be lifted that high.

  12. #10
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    Default Re: Solar panel as a wind resistance cheater.

    The panel is made of of various mechanical elements but more importantly up to 120 Solar Cells which are interconnected with electrical connections.

    Vibration is actually quite a benign force on the panel. However buffeting causes severe stress because of the large physical excursions.

    This is quite a well documented failure mechanism for panels that are mounted on the roof/roofrack of vehicles. It is even recommended to seal the edges between the panel and the roof surface to reduce the buffeting effect.

    Even solid wind cheaters designed for the purpose are very prone to mechanical failure.

    -------------------------------
    I'm not going to go searching Google for evidence right now, but the above is my opinion based on what I have read at some point in time.

    -------------------------------
    OK 2 minutes of Google tells me to mount the panels on a rigid substrate like a wooden board before mounting on the car. Makes sense, if there is a pressure difference between the top and underside of the panel their will be huge forces applied.
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  14. #11
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by mikeml View Post
    This applies to the semi flexible ones. Poen, that solar panel must have extended for about 500mm above the roof rack at an angle of 45 degrees, increasing the frontal area. Don't think there will be any savings aerodynamically. There is definitely a danger of damage from stones, but probably not down Ou Kaapse Weg and elsewhere in town.I found that the tyre on the bonnet actually helps with aerodynamics - no figures to prove it. It transforms a Defender from a brick with sharp corners to a brick with rounded corners
    There was a test done on the spare wheel on the bonnet and it made quite a difference in the aerodynamics. I will see if I can find the article. That is why I am thinking of making a bin on my bonnet plate to help. Can always put some recovery gear or something in there.
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    Default Re: Solar panel as a wind resistance cheater.

    Wheel on Bonnet = Aerodynamic improvement Here is proof, for those who want to read it all I have attached the full South African University research paper, ....for the rest of us here is the main findings: "Placing a tyre (spare wheel) on the bonnet of a Land Rover Defender decreases the vehicles aerodynamic drag by roughly 8%. The best position for a short roof rack is at the most rear position on a vehicle. The addition of an unloaded roof rack can increase fuel consumption with roughly 21% for the Land Rover Defender and 26% for the Toyota Hilux Bakkie (Ed: ute)." Attached Files Attached Files File Type: pdf Final Report version 3b.pdf (5.16 MB, 193 views)
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  17. #13
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by Disco Smiley View Post
    Wheel on Bonnet = Aerodynamic improvement Here is proof, for those who want to read it all I have attached the full South African University research paper, ....for the rest of us here is the main findings: "Placing a tyre (spare wheel) on the bonnet of a Land Rover Defender decreases the vehicles aerodynamic drag by roughly 8%. The best position for a short roof rack is at the most rear position on a vehicle. The addition of an unloaded roof rack can increase fuel consumption with roughly 21% for the Land Rover Defender and 26% for the Toyota Hilux Bakkie (Ed: ute)." Attached Files Attached Files File Type: pdf Final Report version 3b.pdf (5.16 MB, 193 views)
    Now go and invent a transparent solar panel and mount that at an angle between bonnet and roof rack


  18. #14
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by mikeml View Post
    Now go and invent a transparent solar panel and mount that at an angle between bonnet and roof rack
    No thanks. I am happy as is. Will only change my bonnet plate slightly as I will use the "bin"..
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by River Rat View Post
    100-120km/h .
    You are giving the Landy too much credit. ;-)

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  21. #16
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by mikeml View Post
    Now go and invent a transparent solar panel and mount that at an angle between bonnet and roof rack
    Transparent PV Panels have been available for some time.
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  23. #17
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by Fluffy View Post
    Transparent PV Panels have been available for some time.
    Interresting, aparently there are also solar panels that can produce little power at night, according to my electrician. Anyone know of this?

    Back to the OP, In my experience owning many differnet vehicles and each modded the same but different, anything you slap onto a vehicle will affect the aerodynamics. Even on a defender that starts off with zero aerodynamics. We have had 3 seriously modded defenders. On the Ranger I can see a much bigger effect after fitting extras. So,ething as simple as a angled solar panel will have no effect on cheating wind resistance in my opinion.

    While we are on the subject of cheating wind. Remember the old cheesevans had a piece of wind reflector at the back? Curving around the canopyat the rear. This was designed to keep dust from entering the rear. Does this work? And how badly will this affect your fuel economy? I am considering something like it for the kgalagadi.

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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by River Rat View Post
    100-120km/h is quite a bit of wind especially if you have it for 5 - 6 hours day after day. There was also a report on this forum about vehicle vibration too but I think the constant battering from the wind would have a greater effect.
    And what about those on mobile homes, campervans and especially yachts all over the world. Would they fit them if thats the case??

  25. #19
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by mikeml View Post
    This applies to the semi flexible ones.

    Poen, that solar panel must have extended for about 500mm above the roof rack at an angle of 45 degrees, increasing the frontal area. Don't think there will be any savings aerodynamically. There is definitely a danger of damage from stones, but probably not down Ou Kaapse Weg and elsewhere in town.

    I found that the tyre on the bonnet actually helps with aerodynamics - no figures to prove it. It transforms a Defender from a brick with sharp corners to a brick with rounded corners
    There was a test done sometime back by one of the magazines and it benefitted the Defender but no other bakkie.

  26. #20
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    Default Re: Solar panel as a wind resistance cheater.

    Quote Originally Posted by dgwmundy View Post
    And what about those on mobile homes, campervans and especially yachts all over the world. Would they fit them if thats the case??
    Aren't these mounted flat on top of the roof and not constantly catching the wind as described in this example?

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