Golf Ball Protection

Here in our area there are quite a few golf courses, and around them are homes that can afford solar. Does anyone have suggestions for how to protect an array from the errant golf balls?
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Comments

  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection

    Home owner's insurance, a lawyer to sue the golf club (when purchasing a home on a golf course, there may be an expectation of falling golf balls in the sales documents limiting claims)?

    Any "netting" would create shade and reduce the output of the solar arrays. Any plastic coatings would be costly and probably reduce output too.

    A "bird net" at the sides of the arrays may reduce some hits. You could also try bird netting just tossed over the array and see by how much the power is reduced. But then you may have HOA (home owners association) issues with placing netting a foot or so over the panels

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Posts: 7,874Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    Fingerprint the ball, and track down the golfer.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: Golf Ball Protection

    Around here it's the golf courses' responsibility to keep the balls in check, and they are liable for any damages resulting from errant drives. Even when their measures (such as road-side nets) fail.

    Mind you, none of this helps prevent your panels getting smashed in the first place. :cry:
  • Solar GuppySolar Guppy Posts: 1,959Solar Expert ✭✭✭
    Re: Golf Ball Protection

    I use to live on a golf course, its the Home Owners that have to hunt down the golfer, and the 100% of the time they just take off. My next door neighbor had a picture window taken out 3 times over the 6 years I owned that property. Cost wise, a solar panel is no more expensive than a window, so one could in theory have the insurance cover it, but then you risk rate hikes and renewal cancellations on the policy

    I have never heard of a golf course taking responsibility, its the golfer against the homes own here in Florida.

    As far as the statement "they can afford it", golf course homes aren't any more expensive to purchase than a similar home around here, they have a lot of down sides with the constant stream of strangers and damage that occurs, I much prefer my current home than when I lived on the golf course
  • icarusicarus Posts: 5,108Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    With Pv on the roof, at some oblique angle, the chance of a direct hit are pretty slim. I would guess that a glancing blow would be hard pressed to damage a PV panel. The impact power of a golf ball on such an angle would have to be less than a hail stone.

    Just a thought.

    Tony
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection

    I would not bet on angled solar panels being less likely to get shattered...

    Both windows on the sides of homes and skylights on roofs have been broken (in many states, both full wall windows and door, plus skylights, need to be tempered glass (at least).

    A solar panel glass cover is typically around 1/8" -- or the thickness of single weight window glass (that most people replace with heavier glass because it is so easy to break).

    It looks like the owner of the home takes the risk and the responsibility for tracking down the golfer that hits his/her windows/siding/solar panels/etc... In looking through the web--There was even a guy who complained that he has had 45 roof tiles broken by golf balls (and stucco is supposed to be damaged by balls too).

    The odds of hitting one 2 sq ft skylight (or solar panel) in a roof vs 200-800 sq ft of an entire roof covered with solar panels is going to change the odds dramatically (~100x more likely if roof is covered with solar array).

    I am surprised that nobody has turned it around to the golf course under the Attractive nuisance doctrine (and the fact that they charge $$$ to hit balls around the course). But--It looks like that only applies to "children" on the property where the danger/nuisance is. Does not appear to apply to outside the property?

    From looking around, a fair number of judges will even disallow claims against named golfers because the homeowner chose to live next the the golf course... And there is the old "golf course was here first" defense.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Posts: 5,108Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    Solar panels are built with tempered glass. Tempered glass is much harder to break than conventional glass. It will take a huge impact load on the face, (although it will take almost no impact load on the edges) which is why it is code requirement for doors and windows near doors, as well as areas in bathroom.

    So I basically stand by my assertion, that a golf ball striking a PV on the oblique angle would have to try real hard to break one, and ergo isn't very likely. Anybody wish to try a test on an already damaged panel. Barring that, used patio door glass panels can be had nearly free from most glass shops because when one pane get broken, they replace both as a unit to preserve the seal, and tempered glass is not recylable.

    Tony
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection

    Here is a neat youtube video on regular vs tempered glass (alternate video source)...

    Shows a big picture window, one in annealed glass, the other in tempered glass, showing that a thrown baseball will go right though annealed glass. Whereas tempered glass it just bounces off...

    They also did the same thing with a golf ball--Difference is that the golf ball that hit near the frame went right through the tempered glass while balls that hit the center did not.

    One other difference was the glass used for the test looked to be ~1/4"-5/16" thick or so. Whereas solar panel glass is 1/2 the thickness.

    The video claims that tempered glass is 4-6x stronger than annealed glass.

    One error in the video (or maybe over simplification) is they show the the stresses from tempered glass as running perpendicular to the surfaces of the glass...

    In real life, the surface of the glass is in compression while the center of the glass is in tension. Any stress cracks that try to develop in the surface of the glass are held closed by the tension in the core--until the surface stresses exceed the compression from the inner core.

    Basically glass and concrete (another example) are very strong in compression but weak in tension. With Glass, any defects in the surface when under tension cause the cracking to start and progress throughout the depth of the material.

    Glass is heated to near melting (pre-cut to the correct size as tempered glass cannot be cut to size), then the outer surface is quickly cooled (quenched) by air jets--this solidifies the surface. Now, the inner glass cools more slowly and starts contracting. This allows the inner glass to put compression in the outer surface.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Posts: 7,874Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    Well, if a golfball hits the edge of the panel, it's toast!
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • jcgee88jcgee88 Posts: 154Solar Expert ✭✭
    Re: Golf Ball Protection
    icarus wrote: »
    With Pv on the roof, at some oblique angle, the chance of a direct hit are pretty slim. I would guess that a glancing blow would be hard pressed to damage a PV panel. The impact power of a golf ball on such an angle would have to be less than a hail stone.

    Tony

    If you read PV panel brochures, manufacturers typically say
    their panels are tested against up to 1" hail. That's roughly the
    size of a golf ball, and hail's trajectory is more perpendicular
    to the panel.

    I agree with the other posters' comments that the offending
    golfer will run off. If golf balls are truly raining down on you,
    it might be worthwhile to set up a motion sensitive camera
    to catch the perp. Cheap at Sam's. ;-)

    John
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection

    The terminal velocity of a golf ball is around 76 miles per hour (34 meters/second).

    The typical hail stone spec. seems to be around 52 miles per hour.

    The addition energy from the extra speed:
    • 76^2 / 52^2 = 2.1x more energy (from velocity component)
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jcgee88jcgee88 Posts: 154Solar Expert ✭✭
    Re: Golf Ball Protection
    BB. wrote: »
    The typical hail stone spec. seems to be around 52 miles per hour.

    Hmmm, the arcane knowledge one can learn from this forum!

    What is the terminal velocity of an angry homeowner chasing
    a golfer, I wonder?

    John
  • mike95490mike95490 Posts: 7,874Solar Expert ✭✭✭✭
    Re: Golf Ball Protection
    jcgee88 wrote: »
    What is the terminal velocity of an angry homeowner chasing
    a golfer

    Is the golfer hindered by the mass of a golf club ?

    Although the odds of actually catching a specific golfer, while you are home are low, by camera while away, is even less. That ball can come from anywhere the camera is not aimed at.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • jcgee88jcgee88 Posts: 154Solar Expert ✭✭
    Re: Golf Ball Protection
    mike90045 wrote: »
    Although the odds of actually catching a specific golfer, while you are home are low, by camera while away, is even less. That ball can come from anywhere the camera is not aimed at.

    Mike,

    I respectfully disagree with your comment.

    The golfer will come looking for his ball, and
    will even trespass (btdt) to retrieve it. That's
    when the camera catches the guilty party!

    Golfers may not want to pay for the damage
    they cause, but they won't give up on a damm
    $2 ball without a fight.

    John
  • icarusicarus Posts: 5,108Solar Expert ✭✭✭✭
    Re: Golf Ball Protection
    BB. wrote: »
    The terminal velocity of a golf ball is around 76 miles per hour (34 meters/second).

    The typical hail stone spec. seems to be around 52 miles per hour.

    The addition energy from the extra speed:
    • 76^2 / 52^2 = 2.1x more energy (from velocity component)
    -Bill

    All right smart guy,,, calculate the impact load of a golf ball at terminal velocity striking a PV mounted on a 4/14 pitch roof, and then again on a 12/12 pitch roof.

    LOL Tony

    Not something my math skills could do!

    T
  • SlappySlappy Posts: 251Solar Expert ✭✭✭✭✭✭
    Re: Golf Ball Protection

    then here is a video of a solar panel with baseballs being lobbed at it. http://www.youtube.com/watch?v=SV3euyl8mlw
    jump to 3:47 in the time frame of the video?
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection

    Assuming the ball comes "straight down":
    • conservation of energy: 0.5 * mass * Velocity^2 * Cos (Tan^-1 rise/run) (i.e.; two pool balls hitting each other and bouncing apart)
    • conservation of mass: mass * Velocity * Cos (Tan^-1 rise/run) (i.e., clay impacting and sticking)
    -Bill "I think :confused:" B. :p;)
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Posts: 5,108Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    Don't be gettin' to techn on me. I wanna know the impact force on a 4/12 roof vs 12/12 roof with a golf ball struck at some reasonable angle from the ground. You should be smart enough to give me that simple answer!

    T
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection
    • conservation of energy: 0.5 * mass * Velocity^2 * Cos [(Tan^-1 rise/run)-Angle of Ball]
    • conservation of mass: mass * Velocity * Cos [(Tan^-1 rise/run)-Angle of Ball]
    Where angle of ball is 90 degrees if horizontal direction, 0 degrees if coming from sky. Assuming right angle trajectory to roof. Valid for Cos [0-180 degrees]... Negative angles imply the ball is coming from under the panel--not valid if panels are mounted on a roof.

    Weight of Golf Ball not to exceed 45.93 grams.

    Calculated terminal velocity of a golf ball is around 33.8 m/s

    Pick your numbers and run them through a spreadsheet.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Posts: 5,108Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    Did I ever tell you I flunked algebra in high school? My math prowess has shown up all over this forum! I believe I will let this one go, for fear that I will further embarrass myself.

    Tony
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection

    Even if you run the math and find out that you have ~24,000 joules of energy with a golf ball hitting the panel at a right angle--what does that number tell you?

    I don't know...

    From Slappy's video--you can see that a solar panel is still pretty fragile. Shattered by a baseball--not thrown that hard. (those evacuated tubes for solar thermal collectors are really fragile).

    The thinner solar panel tempered glass is just not as strong as the video of the tempered glass impact tests I linked to.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Posts: 5,108Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    Evacuated tubes are nearly as fragile as florescent tubes.

    Like I said Bill, I can't do the math, but I think you have made your point.

    T.
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection

    Tony,

    Hopefully my point was about fragile solar panels and not your math skills. ;)

    I am guessing at the formulas--And in any case, once we have a "number"--I am not sure what to do with it now that we have it. That was why I did not do the formula in a spread sheet and post a bunch of numbers.
    http://forum.solar-electric.com/newreply.php?do=newreply&noquote=1&p=62783
    Basically, the impact energy goes with the square of the velocity, and when you have a glancing blow--The sine or cosine of the angle (depending on how you measure the angle) just ends up as a factor between 0.0 and 1.0 (value of sine/cos function).

    Which is pretty obvious that a glancing blow is going to be less of an impact/chance of shattering.

    The tube based solar thermal collectors were scary how fragile they were (and not tempered/safety glass from how they broke). I also wonder how "Solyndra" tubular solar PV panels do with impact testing (and hail).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solarixsolarix Posts: 713Solar Expert ✭✭
    Re: Golf Ball Protection

    All right smart guys. Do not golf balls have a serious amount of spin on them which will add or subtract from the impact forces?
    How about the original question of what kind of netting and how much clearance and how taut does it need to be to catch golf balls?
  • icarusicarus Posts: 5,108Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    Bill,

    don't worry about offending me RE: my math skills, we all know how they stack up.

    My whole point was to posit that a glancing blow/oblique angle strike is way less likely to break a solar panel than a direct hit to a window fro example.

    My theory is also that the flatter the roof pitch, the better protected they ought to be.

    Tony
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: Golf Ball Protection

    I don't think they have a lot of spin normally--Would that not give you a hook or slice to your drive if golf ball were spinning?

    If somebody hooked or sliced into a window--I cannot believe the angular momentum would change the damage percentages very much.

    Angular energy = 0.5*I*w^2

    Ball = 46 grams and 4.27 centimeters diameter
    I sphere = 0.008387133999999998 g m^2

    Assume that we get ~24,000 joules from a golf ball at terminal velocity:
    • E = 0.5*I*w^2 (formula for angular energy)
    • w = [E/(0.5*I)]^0.5 (solve for angular velocity)
    • w = [24,000 joules / (0.5*0.008387 g m^2]*0.5 = 2,392 radians / second
    • 2,392 radians per second * 1/2pie = 381 revolutions per second
    • 381 rps * 60 sec/min = 22,900 RPM
    So--if my math was correct (a big IF), then for the ball to have equal angular energy as translational energy from terminal velocity, the ball would have to be spinning around 22,900 RPM.

    The ball spinning at that speed would probably be very close to self destructing.

    Plus, since the energy would have to come from impacting with the club (to impart both rotational and translational energy)--then significant energy would be "robbed" from hitting the club base and turning it into rotational energy--which would dramatically reduce the drive distance.

    Here is a Youtube video of different clubs hitting a ball... The wedges do give some back spin. But lower angled clubs do not.

    And somebody claiming to spin a golf ball at 70,000 RPM (may be true)--Notice how it "runs around the shop floor" for few seconds while bleeding off the angular energy.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dreesdrees Posts: 481Solar Expert ✭✭✭
    Re: Golf Ball Protection

    2-5 thousand RPM off the driver is fairly typical.

    Without spin, the ball would not fly half as far. I would not worry about the spin of the ball - it's primarily the speed and weight.

    Just about any old netting will catch the ball without problem if it will hold up to the elements. The difficulty comes with trying to make one that catches all the balls that may hit your array while keeping it from looking like an eyesore and blocking your view.
  • mike95490mike95490 Posts: 7,874Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    Maybe the netting wil solve the pesky bird problem too :)
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • icarusicarus Posts: 5,108Solar Expert ✭✭✭✭
    Re: Golf Ball Protection

    I don't have to worry about golf balls,,, just golf ball sized hail,, which I have seen! Infact I once saw (have a picture some where) of true baseball size hail! Does real damage too!
  • dwhdwh Posts: 1,341Solar Expert ✭✭✭
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