Amazon has made an attempt to go green, by adding solar cell cover across their roofs; to reduce their energy use. They have had about half a dozen rooftop fires across the USA, and have been forced to shut down their solar projects for safety!
Article on Amazon rooftop fires:
https://www.cnbc.com/2022/09/01/amazon-took-solar-rooftops-offline-last-year-after-fires-explosions.html
These fires are apparently design related, from what I've been able to find out. They apparently have been trying the solar system in directly before the main breaker on incoming power! With no inline breaker or disconnecting contactor...
I understand that line surge was the cause of these fires, even though the inverter should have been designed to absorb this kind of problem!
Image from article:
From an engineering standpoint, I see several problems with this installation plan.
- The only way to turn this solar system off, is to turn off the Sun, with this direct tie-in...Bad idea. Chernobyl was designed so it couldn't be turned off too!
- The DC power of all these panels, feeding a common inverter must be astronomical, it should be broken into smaller segments. This combination design, is usually done to reduce costs. Connections at this kind of power levels, must be done carefully, and must be sealed to all moisture for safety!
- Tied to the incoming line, it becomes inevitable that line surges will burn out the output side of this single inverter. It looks like no upstream spike protectors were installed.
- Tying in to the incoming power lines puts electrical workers at risk, by back-powering lines. In the event of a power failure, this back-feed can electrocute workers trying to repair the failure!
- Solar designs can be done by poorly trained workers, as there is little or no standards for this type of install! Most systems don't even require a licensed electrician to install them. I'm in favor of diy work, but not on a system of this magnitude!
- I suspect that Amazon (like most large corporations) will bleed the vary last dollar out of capital projects. Breakers and contactors are expensive, which would explain the lack of this gear.
Here is a video from a source I trust on this:
There is a lot of good information in this video. I totally agree with them on the ability to disconnect a solar system! IMHO, this is a minimum design requirement; and well worth the small added expense.
I'm sure none of us want a panel or inverter fire! The best way to avoid this specific failure, is to never toe to the grid to begin with. Connecting properly would be a close second, this looks like it was wired by a greenie!
A simple spark gap surge suppressor that hams used for almost a century, made with two points bolts adjusted close together (one on each side of the line); would likely have saved massive cash and embarrassment to Amazon. Guess that's what you get when you take the lowest bid, and beat them down lower!