What happened here?
 

Came home from a trip and found this.
It's a glass panel (not slider) in my enclosed lanai. That's not rain drops. It's a shattered pattern, but glass isn't broken. Any thoughts on the cause?
I couldn't find any evidence that something hit it. Could a close lightning struck have caused it? Manufacturing defect? This panel was replaced under warranty a year or so back due to a broken seal, so I wonder.

I am going to guess a lawn mower hit a stone which then hit your glass panel. The spider web of broken glass suggests (IMHO) a hit on the right side of the panel about halfway up. Tempered glass is designed to shatter just like this. I am guessing id you look very carefully on the outside you will find a small (vary small) ding in the glass and this is what caused the pane to shatter.

I had a lawn guy that did that to me 3 times, with a weed whacker.

This (Nickel Sulfide Inclusion)might explain it, if you find no point of impact. I think I can see the “butterfly” effect that they refer to.


How Does Nickel Sulfide Inclusion Cause Spontaneous Glass Breakage?

Shattered
 

That was my first thought, but no stones anywhere near. The grass hadn't been cut in over a week. We were gone just three days. I understand there was a storm during that period (6/14-17) which is why I thought perhaps lightning was a factor. My neighbors said the wind wasn't particularly strong. I vote for defective product.

This makes sense: High heat day, then a cooling rain.

nickel sulfide
 

This makes sense: High heat day, then a cooling rain.

Had the same thing happen some time back, up in Minnesota. Woke up one morning to find the glass in one of our sliding patio doors in the exact same shape. It has been quite cold the night before (-30 or so). Guy who fixed it said that it was most likely caused by defective installation coupled with sudden temp. change. Apparently glass needs a little room to move.

I once had a glass panel break due to a pressure change between the outside and the inside. It sounded like an explosion. I think the atmospheric pressure dropped suddenly on the outside and created a higher pressure on the inside than on the outside.

In my previous home, one of the glass shower doors literally exploded. Thank God no one was taking a shower. The manufacturer’s rep came out and said, we’ll get you a new one – no charge. When I asked what happened, he said this is tempered glass - sometimes they explode. What???

Interesting. Thanks for sharing this link.

Happened to me in my car. Boiling hot day out and I hopped in the car and cranked on the air while driving. Within just a few minutes the back window totally shattered like that. It was loud, thought someone was shooting at me. Extreme temperature change.

I had similar thing happen. I caused it. I was weedwacking nearby patio area. Came inside to get a drink of water. Heard weird noise and pile of glass on floor. That is tempered glass and it breaks in small pieces by design. I presume whoever does your yard work hit a stone and it broke the glass.

This can happen with tempered glass for no apparent reason. In my courtyard villa in the "middle" of the night a glass slider panel burst and glass in very small pieces flew every where. Luckily my tenant was asleep and not sitting near this side door. The company that replaced the glass from Orlando said this can happen and does without anything hitting it. Just the way tempered glass is. I wouldn't look for a reason, as there may not be one.

Tempered glass just explodes, any light defect it it will make it happen. My friend was showing when hers do, I could post a photo of the grisly scene but won't. I had a brand new car, went in the garage in the morning and the windshield looked like your door. Google exploding shower doors.