Panels and Hurricanes

adasadas Solar Expert Posts: 136 ✭✭✭✭✭
Aloha all. As many of you know we are in Hurricane season. Here in Hawaii we are preping for a "possible" this next week. What is the success rate of panels surviving? And what have you Successfully done in the past?

1: assuming your roof will stay on and your house structure is solid. Is it enough to be sure that the panels (if they are mounted within 1" of the roof will be alright? Or would you use some kind of web-security straps and lash them down to the purlins of the roof?

2: How about panels that are angled 1 1/2 feet on one end (long end). Will the panel withstand a cat 4 or 5 coming underneath the panel? Or would 125 mph snap the panel in two if the 3' width ends are fastened but center is not?

any suggestions would be helpful. thanks
Frank

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,196 admin
    Re: Panels and Hurricanes

    Adas,

    Are you mounting your panels to a properly engineered frame underneath--or is the aluminum framework of the panel the only structural support (with vertical legs attached to the aluminum frame of the panel)?

    My BP 4175 (175 watt panels PDF) are rated for:
    Static load front and back (e.g. wind) 50psf (2400 pascals)
    Front loading (e.g. snow) 113psf (5400 pascals)

    The panels are approximately 63x31 inches:

    63"*31" * 1/ 144 sq per foot * 50 psf = 678 lbs wind load per 175 watt BP panel

    So--if your framework will withstand the panel's mechanical design -- then you have done the best you could.

    According to this wind speed vs PSF (PDF):
    Roof starts loosing shingles
    Category 3
    Winds: 111 mph
    psf: 49.3

    Roof Sections fail, Palm trees start to loose crown
    Category 4
    Winds: 131 mph
    psf: 68.6

    :confused:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • adasadas Solar Expert Posts: 136 ✭✭✭✭✭
    Re: Panels and Hurricanes

    Aloha, the 24 panels are mounted on steel corrugated steel roof that is screwed into very strong purlins, welded to VERY strong steel trusses, welded to stationary posts. Posts are actually steel 4 40' containers (so each wall is 16' high by 80' long) so I see no problems with wind getting underneath the roof, BUT will be setting more screws into the corrugation to the purlins. The panels are mounted along the entire 5 foot edge by 16 gauge angle joining panel to the corrugated. This is the Warehouse system.

    The office is the one with the panels mounted at an angle to the sun off 1 1/2' from the solid steel roof and NO support in the center only along the 3' edges. (but the framework on the 3' ends is very strong 4" square tube steel welded to the roof.
    This is one I need to beef up I think
    Frank
  • BB.BB. Super Moderators, Administrators Posts: 30,196 admin
    Re: Panels and Hurricanes

    Frank,

    That is why structural engineers get paid the big bucks. ;)

    Anyway, Unirac (for example) has quite a bit of information (you, or your PE can use) to workout the structural requirements for building mount. Here is the PDF download.

    And here is their general Code Compliance FAQ page.

    It appears, that structurally, you should space your rails so that the panel overhangs the rails by 25% (basically, each rail supports 1/2 of the panel balanced over the center of each rail).

    By the way, how are your systems working out... I have been pointing people to your threads one your systems (large MSW inverters, industrial equipment, using old fork lift batteries, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • adasadas Solar Expert Posts: 136 ✭✭✭✭✭
    Re: Panels and Hurricanes

    Aloha Bill, well it has been 18 months on the Dead/revived forklift batteries. The 4x24v 875a/h or so ones have just needed monthly water and one time a good cleaning/hose down and grease/WD40 on the tops.

    The office system has 4 x 36v batteries that I had to jumper with homemade connectors from copper water pipe. These jumpers cross over dead cells so I can still add up to 24v. (easy to jumper as there are lead exposed connectors joining the cells. I need to check each cell again as I am down to 24.4 full charge, but still have 5x2volt cells to use. I check the cells not in use and keep them over 1.85v in case I need them. But both battery system seem to have the energizer bunny seal of approval on them! But I just picked up another 36v 875a/h forklift near new battery from a salvage yard for $100.00 just in case.

    I installed a jacuzzi and pool and now the system is running a 11amp pump all day and a 2 amp pump at nite. Plus I use quite a lot of power in the office and kitchen. Inverter is great and no appliances have died. But I am thinking about installing another pallet of 30 210amp blems for the office. Real Mcgiverized. BTW quite the system on the Unirac PDF u sent.


    frank
  • BB.BB. Super Moderators, Administrators Posts: 30,196 admin
    Re: Panels and Hurricanes

    Frank,

    Sounds like you got your system nailed!

    How about the inverter(s)... Out in the shop you are using big 'ol AIMS (sp?) MSW's and running fabrication & welders off of them?

    You were also having some grounding/ground loop/ground fault issue of some sort--If I recall correctly?

    Regarding the Unirac's--As from another thread, it is always nice to give a big thumbs up to people that support their products and customers. :D

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • adasadas Solar Expert Posts: 136 ✭✭✭✭✭
    Re: Panels and Hurricanes

    Aloha, Bill. I gave up on the Aims. I had issues with the place where I bot them and I did not like the units performance. On Craigslist I found some company selling some new-old-stock inverters. 3600 watts, MSW so I bot all 9 of them for $3000.00 total. They perform almost like a Sine wave in tests comparing with the AIMS. 90% effecient and about 80# in weight with a humongous transformer. I trip the 2 GFI's once in a while when there is a heavy rain, but having a GFI in the 110v outputs is maybe asking too much, especially with wiring, conduit going to several buildings, and underground etc. Office has not tripped off or has been shut off in almost a year though.

    I grounded every recipticle, light, etc. and just let it be and really have not messed with the system for 8 or more months. I bootleg 12 panel output from the warehouse at 100v running 200 feet underground on number 8 wire and put it into a spare FX60 for the office on weekends when the warehouse system is not used. I also bootleg off another 12 panels directly into charging 2 electric forklifts with 24v batteries. I think it is nicely done but there are McGivered panels with circuit breakers everywhere, not a typical home system that is for sure!!
    frank

    BTW Hawaiian Electric just raised rates another 15% . I figure I save $450.00 a month. I have a friend with an electronics store that has put together a grid tie system and produces almost 1 meg a month and reduced his electrical from $1300 a month to $50.00, the minimum. His payoff time is 3 years after tax credits. He has a Very very nicely done system. (he's German)
  • GreenerPowerGreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    Re: Panels and Hurricanes
    adas wrote: »
    Aloha all. As many of you know we are in Hurricane season. Here in Hawaii we are preping for a "possible" this next week. What is the success rate of panels surviving? And what have you Successfully done in the past?

    1: assuming your roof will stay on and your house structure is solid. Is it enough to be sure that the panels (if they are mounted within 1" of the roof will be alright? Or would you use some kind of web-security straps and lash them down to the purlins of the roof?

    2: How about panels that are angled 1 1/2 feet on one end (long end). Will the panel withstand a cat 4 or 5 coming underneath the panel? Or would 125 mph snap the panel in two if the 3' width ends are fastened but center is not?

    any suggestions would be helpful. thanks
    Frank
    Sound like you have them structurely secured to the roof. If possible, have plywood/plexiglass cut to fit the glass faces and premake steel/alunimum bar clamps across to screw on the sides of the panel to secure these plywoods. I am thinking to protect the glass from flying debris. It can withstand the wind force but a flying 2x4 at 75 mph or higher, I think not. I took all my 10 panels down, not wanting to take a chance, when potential cat-3 Ike came from the gulf.
    GP
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Panels and Hurricanes

    On a properly engineering installation, the panels have no different wind load that the supporting structure, if its a roof, the panels worst case have the same lift as subject to the roof. As for the panel frames, they are NOT structural. You have to mount to a ridge rack as per manufacture specs ... All my panels are secured to a grid of racking, not little individual little feet/supports

    By your description, there is no engineering and I would suspect your weakest link is the fact your using cargo containers as the structure, They maybe strong, but what is holding them into the ground? They have little mass as compared to the side wind loading and I would suspect, the panel would be damaged by the cargo container getting flipped like mobile homes do.

    Flying debris will take out concrete walls, Plywood ect with ease, covering the panels won't do anything as a hit to the plywood will likely shatter the glass underneath.

    If your going to have greater than CAT1 winds, I would simply strip the panels and store ... with two people, one can strip even very large installations in a few hours and with some planing put it back together in a similar time frame

    I have been thru 4 hurricane and a very close call on a minimal tornado at my home with over 80 panels on the roof ... highest winds were about 80-90mph guts ... nothing happened to the solar or the home, but the house is engineered for 125mph winds ( code for my inland location in Florida )... I doubt your cargo containers could handle 50 mph guts without movement unless there secured properly to 100 tons for concrete for a foundation like my home is.
  • BB.BB. Super Moderators, Administrators Posts: 30,196 admin
    Re: Panels and Hurricanes

    Trying to affix large sheets of plywood or Plexiglas makes probability of wind damage even higher (poorly secured cover sheets are ripped off and added to the mix of flying objects for your home and the neighbors too).

    Just looking around the area and removing loose items (patio furniture, stacks of wood, etc.) around the area would be something I would do...

    But, the reality is, I don't live in an area subject to hurricane force winds or tornadoes--so what do I know. :roll:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GreenerPowerGreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    Re: Panels and Hurricanes

    When Rita came a couple of years ago, I had mine covered with plywoods sandwitched with gym rubber mats, secure them down with steel straps. I hope the plywoods and the rubber mats would help cushioning and distribute the impact pressure. But for >CAT1 storm like Ike last year, I would take the panels down.
    GP
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