Regarding the first: in spite of the thick glass floor we partner with PV installs, a ordinary panel includes a lot of flammable material. Why? Well, the very great solar panels on the market nowadays are about 22% efficient and most are in the 15-17% range. That means a lot of floor region is needed and it has to be supported somehow, but no longer be so huge as to require heavy set up methods.
Example: Assuming you spring for these first-rate panels (because, in accordance to L’Oreal, you’re really worth it) and expose them to direct daylight at 1050 W/m^2, plus a quantity of different simplifying assumptions…you get a scenario the place every rectangular meter of photo voltaic panel meeting is rated for around 230W of DC strength output. That’s for an hour or so at midday, southern exposure, with angels singing overhead. There are extra conversion losses before that DC energy becomes AC electricity in the grid.
To construct that output to a usable level, we’ll want at least various of these large devices, constructed the usage of the best combination of low cost, light weight, average rigidity, high moisture resistance, and suitable electrical insulation. Say some thing like that and a smart product dressmaker without delay thinks “plastic.” Modern PV solar panels are regularly constructed on a plastic substrate, laminated to a glass top and framed with aluminum.
The catch: any petrochemical plastic contains a lot of stored electricity in search of an ignition source. If it finds one, it will burn merrily and unfold melty flaming bits around the neighborhood. Less of a Lifetime plot and greater of an ISIS plot, in other words. So either the plastic must be made flame retardant, with added environmental costs, or the panel must be particular and examined to engage with fashionable roofing substances in a way that resists excessive fireplace spread.
Which receives us to our 2d question: Ignition sources. These guys be aware of a aspect or two about the subject, and I advise analyzing the complete thing. But if you want the Cliff’s Notes, the reasons divide roughly as follows:
Wiring fault on the electricity cables or conductors (poor set up practice, moisture incursion, animals, etc.). Bad wiring can overheat or commence arcing.
Faulty floor connections (poor installation practice, poor maintenance). Bad or missing grounds can permit an overvoltage to happen in the panel array, causing a breakdown of electrical insulation in the array or surrounding conductors.
Arcing fault in the panel (poor installation practice, panel deterioration). Damage to the panel or speedy deterioration of a poorly designed panel can lead to emerging electrical faults in the panel assemblies.
Of course, an inverter fault or different machine downstream can also begin a fire, but the above are the essential motives why the actual panel assemblies may light up on the roof.