Author Topic: Home Rooftop Solar Power System Update - Shattered Panel!  (Read 41290 times)

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Offline warp_foo

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #100 on: December 07, 2015, 04:06:33 pm »
My bet is on a golf ball. I am waiting for another episode of Myth Busters, "can golf ball do that?" :)
I think Mythbusters got cancelled. :( Do they even play much golf in Australia?

There will be one final season in 2016. 8 or 10 episodes, I think.

m
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Offline NANDBlog

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #101 on: December 07, 2015, 06:38:09 pm »
I think it was the invading army of the G'Gugvuntts or the Vl'hurgs testing their super-weapon on your massive scale energy collector mega complex.

Quote
"After millennia of battle the surviving G'Gugvuntt and Vl'hurg realised what had actually happened, and joined forces to attack the Milky Way in retaliation. They crossed vast reaches of space in a journey lasting thousands of years before reaching their target where they attacked the first planet they encountered, Earth. Due to a terrible miscalculation of scale the entire battle fleet was swallowed by a small dog. The Hitchhiker's Guide to the Galaxy states that this sort of thing happens all the time."
 

Offline jnissen

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #102 on: December 07, 2015, 06:53:07 pm »
I wasn't expecting THAT amount of deformation!

Is that a regular golf ball?  I would have expected the case to crack deforming that much.

That is not a normal hit on the ball. Look again at Youtube and there are a lot of golf hit slow motion video's. Nothing comes close to the compression initially shown.

BTW - I will also vote for a cricket/baseball type of hit. As a kid I can recall playing croquet and hitting one of those wooden balls way up in the air. Could have killed someone if it came down on their head. Your neighbors have any of those?

Luckily I have not had any issue with my own solar panels being damaged from impacts. I was warned that if the panels are on a single story home you can still get errant rocks thrown up by lawn mowing. If you have anyone who mows the grass with a power mower they can hit rocks and launch a projectile at very high speed. Anyone with a lot of grass that needs to be trimmed nearby? Not familiar with suburban life in your area but if that is common it could also be a cause.
« Last Edit: December 07, 2015, 07:10:48 pm by jnissen »
 

Offline LaurenceW

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #103 on: December 07, 2015, 07:56:16 pm »
-1 for baseball-size hail.  We had a MEGA hail storm four years back - it smashed car windows, dented car panels and wrote cars off, smashed greenhouses, shredded trees and damaged tiles on dozens of house roofs (we lost 20+ tiles), but the PV panels were untouched! Indeed, I'd go so far as to say that the panels [protected the section of the roof that they cover!  And you kinda KNOW when a hailstorm like that hits. I think a one off (natural) hail stone is a non-starter.

However, the event did cause me to consider the need to replace a panel at some point - and here's the rub. My top-of-the-line Sanyo (now Panasonic) panels are already no longer manufactured! :-[ This may be common in this fast-moving market. So any replacement will stick out like a saw thumb (if your array is visible). Moral; if you need a replacement panel, get one while you still can!

And bypass diodes or not, I tend to find that when one panel goes into shade, it really kills the output of the whole string. It's VERY noticeable, beyond the loss of output of one panel alone. Pretty sure that once the rain gets in, you'll lose the output of that one panel.
If you don't measure, you don't get.
 

Offline keethrax

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #104 on: December 07, 2015, 09:42:10 pm »
I think the batterizer guys flew over and chucked a AA on him.
 

Offline DrGeoff

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #105 on: December 07, 2015, 09:53:08 pm »
I think the batterizer guys flew over and chucked a AA on him.

Of course!
Inter-Continental Batterizer Missiles!

Was it really supposed to do that?
 

Offline Muttley Snickers

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #106 on: December 07, 2015, 10:09:06 pm »
I think the batterizer guys flew over and chucked a AA on him.

Of course!
Inter-Continental Batterizer Missiles!

Couldn't have been them, they have a reputation for missing targets..... :phew:
 

Offline georges80

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #107 on: December 07, 2015, 11:41:40 pm »
Not the issue here...

There are arrays of panels in the bush in oz along the rail that runs to Kal and also is the line for the Indian Pacific. Lots of ore and other stuff travels on that line. There's a gravel access road between the solar array (that powers gear in the siding) but it's all round gravel.

Anyhow, we stop at the siding somethings since there's a rain water tank fed from the roof of the siding, tap to access the water so great to top up our own tanks. Looking at the solar array (which is tilted somewhat at the rail since the rail is to the north of the array) you can see quite a lot of rock shards (more like spear heads, NOT gravel) that have  impaled themselves in various panels of the array. There's a wire mesh 'shield' near the panel, so we assume that was installed after they found the damage on the panels. Presumably enough of the array continues to work that no need for replacement of the damaged panels has been necessary, yet...

We have assumed that those rocks are shot at very high speed when the train goes by, not sure if due to some of the rocks (falling out of the cars) ending up on the rail and then being spit out when a wheel tries to go over the rock. Pretty scary since I would not want to be standing (or in a vehicle) anywhere near that array (or similar distance) to the rail line.

The tempered glass doesn't shatter other than around where the rock penetrates. Some are partially visible on the rear side of the array. Some serious momentum at work...

cheers,
george.

 

Online Macbeth

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #108 on: December 07, 2015, 11:47:20 pm »
Bogans for neighbours and drongos for their kids. It's that simple.  ;)
 

Offline continuo

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Offline Smokey

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #110 on: December 08, 2015, 01:17:33 am »
I got it... I figured it out!! 
It was.... Dave Jones long lost brother....

Casey Jones!!

https://youtu.be/7_6KMGB_Pkw?t=2m7s
 

Offline Brumby

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #111 on: December 08, 2015, 01:24:29 am »
I wasn't expecting THAT amount of deformation!

Is that a regular golf ball?  I would have expected the case to crack deforming that much.

That is not a normal hit on the ball. Look again at Youtube and there are a lot of golf hit slow motion video's. Nothing comes close to the compression initially shown.


I did check out other videos of normal golf ball impacts and it is very clear that the impact in the link given is extreme.  I just found it difficult to believe that, in the case of such an extreme impact, the casing did not fail.

The other thing is, that the surface this ball (in the video) hit was completely unyielding (in any practical sense).  Dave's glass panel was far less so.  The deformation and failure of the glass would have reduced the peak deceleration by orders of magnitude over the video example - and the shape of the ball would not have changed much.  Certainly less than is visible in the other golf ball videos I saw.

While the point of the reference to ball deformation (that it would result in damage indicating a diameter larger than the projectile at rest) is clearly sound, I doubt the forces involved would have produced much of a variance.  Certainly nowhere near enough for a golf ball to leave a cricket ball sized imprint, IMHO.
« Last Edit: December 08, 2015, 04:46:19 am by Brumby »
 

Offline TooOldForThis

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #112 on: December 08, 2015, 02:50:37 am »
Can't this be 'fixed' by putting a sheet of polycarbonate over the broken glass and sealing the edges with aquarium cement?  The polycarbonate will absorb some of the energy, but it will keep the water out (assuming it's not already full of water).
 

Offline mtdoc

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #113 on: December 08, 2015, 03:44:06 am »
I got it... I figured it out!! 
It was.... Dave Jones long lost brother....

Casey Jones!!

https://youtu.be/7_6KMGB_Pkw?t=2m7s

Driving that train, high on....

 

Offline Tandy

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #114 on: December 08, 2015, 01:44:33 pm »
You are all wrong, it must have been Segan throwing his lego to see if it would fly  :P
For more info on Tandy try these links Tandy History EEVBlog Thread & Official Tandy Website
 

Offline Brumby

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #115 on: December 09, 2015, 02:29:38 am »
Wow ... Such a good arm on a little tacker...!!
 

Offline crispy_tofu

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #116 on: December 10, 2015, 08:46:29 am »
That's one big Lego...  :popcorn:
 

Online Kalvin

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #117 on: December 10, 2015, 02:48:46 pm »
Stray bullet perhaps? or someone with a slingshot and BB/marble?

No way a marble had enough energy to shatter that.
We don't have a gun culture in Australia, and so hardly anyone has one. So the odds of that are borderline zero.

Then, its a beer can. Foster's.

Or the kids were playing with something round and hard, and oops. Those things happen from time to time.
« Last Edit: December 10, 2015, 02:51:09 pm by Kalvin »
 

Offline Gunhaver

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #118 on: December 12, 2015, 07:33:33 pm »
Hi All. I'm curious if anyone else did some back of the envelope calculations? I read through this thread and didn't see any guesses to the properties of the impact object. I decided to work the problem with two different sets of assumptions.

Firstly i assumed the object was a bullet-type and based my assumptions on data for a 7.62 NATO bullet (11g, terminal velocity of 90 m/s both from wikipedia). I also assumed the glass has a shattering pressure limit of 70MPa (pulled from a random technical presentation of nominal tempered glass). I also assumed an impact duration of 1ms before the object bounced away at the end of the impact event. I also assumed the tip of the bullet hits first and deforms until the diameter of the impact surface is 7.62 mm. Using all of these values, and the formula for net force during an impact (Fnet = delta momentum / delta time), I calculated that the pressure imparted by the impact object was around 17.37 MPa. The lower bound i found for shatter pressure of tempered glass was 7 Mpa, so this number is in the right ballpark i think. This tells me that my assumptions are close. I also assumed a relatively low-velocity impact from essentially a vector normal to the surface of the glass after reading this summary of glass shattering forensics on the FBI's website: https://www.fbi.gov/about-us/lab/forensic-science-communications/fsc/jan2005/index.htm/standards/2005standards7.htm

I thought about this all so more, and i decided to also work the problem with the assumption that the impact event imparted a pressure 70MPa, and then figure the mass of the object based on that. This made more sense to me because we know at least a minimum amount of pressure was imparted, so it is a safer assumption. In this case, i assumed a spheroid object, which gives a drag coefficiant of 0.47 through air. I also assumed 70% relative humidity, 70 deg F (21 C), and an altitude of 19 feet (about 6m) EGM96 MSL. I also assumed the object's radius to be 0.5 inches this time around (about 1.27 cm). I also assumed an impact duration of 0.7 ms this time because wolfram alpha informed me that the average impact duration of a baseball hitting a bat is 0.7 ms. I could be way off here on the duration.

I should point out, that i read this thread after i assumed the radius, and there is a post in this thread that explains how the radius of the object is likely greater than the white crushed area on the glass. Even so, i think my numbers are still the right magnitude. Given all of the above assumptions, i now calculated the impact object's mass to be around 387.018 grams (or about 13 ounces, or 0.85 lbs). 13 ounces sounds right to me (it agrees somewhat with my first calculation), and i think it really points to a meteorite type object.

I could take this even further and calculate a probable radius for the final resting place of the object. It seems we could use the concentric ring pattern to extrapolate the impact angle, and then we can simply figure the angle relative to the earth. Then it would be a matter of figuring a range for momentum transfers to the glass (there would be an upper bound less than 100% transfer because the object was not embedded and is not sitting right next to the panel). At any rate, this would give us a range of trajectories that should draw a line on the ground. Treat this line as a diameter of a circle, and then you have a grid for Dave to search for a meteorite type object. I think it would be very cool if we predicted where the object would be, and then Dave actually found it.

Feel free to tear my calculations apart and make them better (or just point out what is wrong). It is all back of the envelope, so i'm not pretending any of it is accurate beyond magnitude level analysis. Does anyone else have any values? I'm very curious.

This was a very entertaining way to spend my morning when i'm feeling sick. Thank you for reading this far!
 

Online Macbeth

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #119 on: December 12, 2015, 08:44:08 pm »
Then, its a beer can. Foster's.
Nope. Beer cans are far to light when empty, and no self respecting bogan would chuck a full tinnie at the roof without consuming the fine malt liquor first. Far more likely the drongo chucked an empty stubbie of VB instead.  ;D
 

Offline EEVblog

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #120 on: December 12, 2015, 09:05:20 pm »
I have been contacted by LG Australia, and they said that not a single one of these panels has ever shattered in over 300,000 installed in this country. Not by hail or anything else.
 

Offline Lightages

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #121 on: December 12, 2015, 09:11:45 pm »
Aren't you lucky then!
 

Offline Ian.M

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #122 on: December 12, 2015, 09:39:20 pm »
Then, its a beer can. Foster's.
Nope. Beer cans are far to light when empty, and no self respecting bogan would chuck a full tinnie at the roof without consuming the fine malt liquor first. Far more likely the drongo chucked an empty stubbie of VB instead.  ;D

Blame the Murray Crays!

http://www.youtu.be/-6FSoKdPneo
« Last Edit: December 12, 2015, 09:47:10 pm by Ian.M »
 

Online Macbeth

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #123 on: December 12, 2015, 09:57:10 pm »

Blame the Murray Crays!

Those critters are just protecting you from the Drop Bears and the deadly Cassowaries


 

Offline DrGeoff

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Re: Home Rooftop Solar Power System Update - Shattered Panel!
« Reply #124 on: December 12, 2015, 10:49:22 pm »
I have been contacted by LG Australia, and they said that not a single one of these panels has ever shattered in over 300,000 installed in this country. Not by hail or anything else.

And none of their washing machines ever caused a fire either ...
Was it really supposed to do that?
 


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