My other half was strimming outside (I know, but he prefers it to the scythe...) and it seems as though a small stone has flown up and hit the glass on front of one of the solar panels.  It's a grid feed system, so I want to repair it as soon as possible.  There is a tiny chip in the glass, and it is now in the process of crackling, like a smashed windscreen on a car. 

Can I fix this?  How much of a problem will it be?  What when it rains? Is it a diy job or do I have to get the pros in, bearing in mind it's a grid feed system?

We had a whole array of solar panels blow off a roof (bad planning -- they weren't tied down "yet") and most of them had cracks, and some were smashed. Amazingly enough, many of them continued to work for a while. Not great, I think, but they did give some power. We don't really get any rain most years though.

I've heard about automobile windshield repair kits bring sold at auto stores. They supposedly fill in a pock mark and/or stop a crack from traveling. I've never used it so I don't know how effective it is.

I have used the windshield repair kit on a windshield. I think it would be worth a try on your panel but it would be good to do it soon. Dirt or moisture in the crack makes it harder. If the crack has spread to far you may have to fill it in more than one place so try to get a kit that has more than one adhesive gasket. Good luck and let us know what happens.
   Just a thought, I would try to do it myself but if you're not comfortable trying it most areas have people who repair windshields and one of them might be able to do it for you but if you follow the directions in the kit it isn't hard and you might find a video on Youtube that will show it being done just be sure its for the same kit you have. I think there are 2 types.

I would agree with trying the auto glass repair kit.  The kit should include a suction cup with a syringe and an epoxy mix.  You apply the suction cup and use the syringe to apply a vacuum to the glass this pulls out any dust or glass debris.  Next you inject the epoxy.  Worth a try.  To much diy for you remove the panel and bring it to an auto glass place probably a small local one not a big chain. The small guy will be more willing to experiment. Failing that you contact your installer to have a matching panel installed.  Question for you :do you have one central inverter or micro inverters on  each panel?
Best regards, David Baillie

Lots of good suggestions, hopefully Burra can find something like that in her part of Portugal.

Hi, i have to say, DON'T DO ANY WORK ON A GRID-TIE SYSTEM WITHOUT FIRST DISCONNECTING FROM THE GRID!!! Phew, now I can relax. Please cut the main power, disconnect the entire solar array from the solar controller, then remove the busted solar panel and play around with it. Even professionals can get zapped bad when working with grid-tie systems, so safety first.

I would recommend you remove all the glass and apply a silicon epoxy layer to protect the face, then remount it after it's dry. Glass is beautiful but it's heavy and fragile. Good luck!

I agree with Bobby Bobberson.  Treat it like a separate item and remove the danger to your entire system by turning it off and disconnecting it.  You need to know how much damage you have.

Just because the glass is broken, does not mean the silicon substrate is.  Remove solar panel from the system and see what the output voltage is in full sun compared to the rated output voltage of the solar panel.  You can rap on your panel's frame a bit to see if the voltage is intermittent and the cell is cracked.
Since you are merely charging batteries, and not running off a prescribed voltage from the panel, you will likely still be fine just by-passing the particular cell, or cells that are damaged with a short jumper wire. 
Think of it like your 12V car battery only needs a few volts over it's rated full capacity voltage (13.2V) to be applied by the voltage regulator (14.0-14.5V).  Since each individual cell in the solar panel is added together (connected in series) to get the entire voltage of 24V, or whatever your panel is using, by-passing one cell will hardly matter.  Total rated output voltage, divided by your number of round/square cells that you see, will tell you how much you'll be affected.  Online tutorials on how to fix a damaged cell are available on YouTube, as well.

Broken windshield kits will sometimes tell you the limitations on the length of crack they will actually be good for.  Personally, I don't have any luck with longer cracks.  Clear 100% silicon will patch/waterproof the damaged glass, while decreasing the sun's rays a bit.

Well you have a couple options.

You could remove the glass, and replace it. Though finding glass to fit the frame and all that can be difficult, not to mention the issues of taking apart the panel frame.

Easier method is to use a polyurethane to fill in the cracks. There are many youtube videos explaining how to do this. Though you might have to accept that you will likely get slightly less performance out of the panel after such a repair.

Just figured I would include a link to the product used in the first 2 videos.

http://www.mlsolar.com/encapsulation/

I had suggested polyurethane, since that is easy to find and low cost. Especially figured it was a good option since the OP is not in the US, so figured easy to find options is the best solution. However, the product above is specifically designed for solar panels. It might be worth the $35 cost if you really depend on your solar. Just figured I would add the link in case you or someone in the future wished to find that product.

Well we've replaced the broken panel, and now have the shattered one available for some kind of project. 





We have a friend arriving in a few days who has a lot more experience with all kinds of alternative energy stuff, and my son will be home the following week, so we're going to check out the possibility of changing the glass vs coating with silicone, then maybe set it up as part of a bike shed to charge the electric bikes, which have 36 volt batteries and seem to be a good match!



I'll be sure to keep this thread updated with all the progress, and loads of photos!