5 ms·

I wonder how much efficiency would be lost by using a thicker glass -- or even bulletproof material -- on the panels. I imagine this has been considered but th

by mikece 3y ago

I wonder how much efficiency would be lost by using a thicker glass -- or even bulletproof material -- on the panels. I imagine this has been considered but there are technical and financial reasons not to.

bombcar 3y ago
It’s cheaper to just replace the panels if it happens (and probably get a capacity upgrade) Even clear glass heats up so it takes some of the energy the panel wants.
starwatch 3y ago
I reckon you could suspend a net above each solar panel. Just make the gaps a bit smaller than the diameter of a hailstone that would cause damage. That'd be quite a bit cheaper.
- MisterTea 3y ago
  Nets have their own issues as they can ensnare birds and trap debris blown around by the wind.
  - dredmorbius 3y ago
    Nets which could be deployed (manually or automatically) during periods of high-risk for hail might be an alternative. Minimises the risks you highlight, maximises protection of the solar panels themselves. In this case, the netting need not even be particularly transparent. You're looking for loss-minimisation, rather than maximising electrical production at all times. So a fairly thick or heavy webbing might work. Keep in mind that as the damage inflicted increases with the kinetic energy, that is, with the square of velocity, even a net or webbing which permitted contact of hail with panels but at significantly reduced speed should serve to avoid most damage.
- sparrish 3y ago
  I think you'd need a kevlar net to catch baseball sized hail going 150mph and that won't be cheap.
anonym29 3y ago
There is no such thing as material that is "bulletproof", only varying levels of bullet resistance can be certified to specific and highly complex applications of materials or combinations of materials. You know how car safety is complex and isn't solely attributable to any one system or component, like a seatbelt, or airbags, but rather the combined effects of the whole system of components, in that specific application? Bullet resistance is similar. My idea for this is basically an enormous, rail-guided heavy, metal garage door that can be raised remotely to cover the entire installation from above. You could even power it with a small power reserve battery that got recharged from the panels, have it automatically get raised when the barometric pressure went too low or after a weather alert for hail came in, etc. Trying to engineer resistance into the panels for the top 0.1% most extreme hail load is going to increase the cost for everyone, including those who never even get pea-sized hail. Seems wasteful to me.
uzerfcwn 3y ago
I imagine having automation to turn the panels vertical during a hail would have saved a good portion of them. I assume these already have motors for turning, so it should be relatively cheap.
- titzer 3y ago
  And that system would pay for itself at the first event.
  - rjmunro 3y ago
    But most places will suffer 0 events on this scale in their lifetime, so it's not clear it would pay for itself on average.
    - titzer 3y ago
      Sure, then don't do it, and instead pay into a risk pool, aka insurance.
another2another 3y ago
Would it not be sufficient to angle the panels to 90 degrees so that they're sitting vertical instead of angled to the sun. That would at least minimize the surface are exposed to the falling hail (unless it's really falling at an angle). I'm guessing the top edges of the panels are (or could be made) strong enough to handle a direct hit. * * * * * | | | | | \ \ \ \ ---------- instead of. -----------
- peteradio 3y ago
  That would exactly negate the efficiency of the panel. You want the normal of the panel to be pointing at the sun which is generally towards the clouds emitting hail. Or are you suggesting an automated panel movement when hail is approaching?
  - another2another 3y ago
    >Or are you suggesting an automated panel movement when hail is approaching? Yes, big Red Button to re-orient all panels when hail is approaching. Some of these farms are massive so I think it would save enough of them to make it a cost-effective feature. Not sure how much human monitoring goes on though, or if an automated system would be better in case it happens e.g. late at night. (sorry about the formatting +embarrassed smiley+ )
    - mbreese 3y ago
      I think the question is all about cost. How much would it cost to add such a system? And how much is hail damage insurance on those panels? How much does your insurance decrease if you had such a system? So long as the system costs more than the insurance savings, it won't be common. However, if your insurer starts demanding it, then it will be installed everywhere quickly.
- aidenn0 3y ago
  That would mean mounting the panels a lot higher, and not all panels are mounted on motors due to cost already. The real question is how many panels will be damaged by hail in a 10 year period and back-calculate what it's worth to protect them.
anigbrowl 3y ago
Why not just put a wire mesh cage above them? You only care about hailstones larger than a certain size, so the mesh is going to be pretty open and won't have much impact on collection. Galvanized steel is cheap and will do fine, no recycling issues either.
usrusr 3y ago
I'd put my money on something lighter that has enough elasticity to take the punches without shattering

by mikece 3y ago

bombcar 3y ago

It’s cheaper to just replace the panels if it happens (and probably get a capacity upgrade) Even clear glass heats up so it takes some of the energy the panel wants.

starwatch 3y ago

I reckon you could suspend a net above each solar panel. Just make the gaps a bit smaller than the diameter of a hailstone that would cause damage. That'd be quite a bit cheaper.

MisterTea 3y ago
Nets have their own issues as they can ensnare birds and trap debris blown around by the wind.
- dredmorbius 3y ago
  Nets which could be deployed (manually or automatically) during periods of high-risk for hail might be an alternative. Minimises the risks you highlight, maximises protection of the solar panels themselves. In this case, the netting need not even be particularly transparent. You're looking for loss-minimisation, rather than maximising electrical production at all times. So a fairly thick or heavy webbing might work. Keep in mind that as the damage inflicted increases with the kinetic energy, that is, with the square of velocity, even a net or webbing which permitted contact of hail with panels but at significantly reduced speed should serve to avoid most damage.
sparrish 3y ago
I think you'd need a kevlar net to catch baseball sized hail going 150mph and that won't be cheap.

anonym29 3y ago

There is no such thing as material that is "bulletproof", only varying levels of bullet resistance can be certified to specific and highly complex applications of materials or combinations of materials. You know how car safety is complex and isn't solely attributable to any one system or component, like a seatbelt, or airbags, but rather the combined effects of the whole system of components, in that specific application? Bullet resistance is similar. My idea for this is basically an enormous, rail-guided heavy, metal garage door that can be raised remotely to cover the entire installation from above. You could even power it with a small power reserve battery that got recharged from the panels, have it automatically get raised when the barometric pressure went too low or after a weather alert for hail came in, etc. Trying to engineer resistance into the panels for the top 0.1% most extreme hail load is going to increase the cost for everyone, including those who never even get pea-sized hail. Seems wasteful to me.

uzerfcwn 3y ago

I imagine having automation to turn the panels vertical during a hail would have saved a good portion of them. I assume these already have motors for turning, so it should be relatively cheap.

titzer 3y ago
And that system would pay for itself at the first event.
- rjmunro 3y ago
  But most places will suffer 0 events on this scale in their lifetime, so it's not clear it would pay for itself on average.
  - titzer 3y ago
    Sure, then don't do it, and instead pay into a risk pool, aka insurance.

another2another 3y ago

Would it not be sufficient to angle the panels to 90 degrees so that they're sitting vertical instead of angled to the sun. That would at least minimize the surface are exposed to the falling hail (unless it's really falling at an angle). I'm guessing the top edges of the panels are (or could be made) strong enough to handle a direct hit. * * * * * | | | | | \ \ \ \ ---------- instead of. -----------

peteradio 3y ago
That would exactly negate the efficiency of the panel. You want the normal of the panel to be pointing at the sun which is generally towards the clouds emitting hail. Or are you suggesting an automated panel movement when hail is approaching?
- another2another 3y ago
  >Or are you suggesting an automated panel movement when hail is approaching? Yes, big Red Button to re-orient all panels when hail is approaching. Some of these farms are massive so I think it would save enough of them to make it a cost-effective feature. Not sure how much human monitoring goes on though, or if an automated system would be better in case it happens e.g. late at night. (sorry about the formatting +embarrassed smiley+ )
  - mbreese 3y ago
    I think the question is all about cost. How much would it cost to add such a system? And how much is hail damage insurance on those panels? How much does your insurance decrease if you had such a system? So long as the system costs more than the insurance savings, it won't be common. However, if your insurer starts demanding it, then it will be installed everywhere quickly.
aidenn0 3y ago
That would mean mounting the panels a lot higher, and not all panels are mounted on motors due to cost already. The real question is how many panels will be damaged by hail in a 10 year period and back-calculate what it's worth to protect them.

anigbrowl 3y ago

Why not just put a wire mesh cage above them? You only care about hailstones larger than a certain size, so the mesh is going to be pretty open and won't have much impact on collection. Galvanized steel is cheap and will do fine, no recycling issues either.

usrusr 3y ago

I'd put my money on something lighter that has enough elasticity to take the punches without shattering