Posted on 02/20/2014 4:14:53 PM PST by matt04
In my area, if a major structure fire occurs FD normally has the primary and secondary power shut down for the entire street to avoid any accidental contact.
I’m amazed Mass gets enough sunshine to make this worthwhile.
Well, in the homes of luddites there will still be an inverter.
Solar power is generally inadequate for cooking and heating.
With the advent of adequate LED lighting it makes far more sense to design for 12 VDC grid lighting solutions that can use easily replaceable vehicular batteries for storage. With such a system the article premise is moot.
The largest one, has generated a whopping 6kW this week. That particular installation has approx. 2,500 panels and cost almost 600K.
The Chief doesn’t seem concerned about it, but I wonder how many fires he has personally fought lately?
In this regulation-laden place I’m surprised there isn’t an electrical code requirement (US electrical codes were and are promulgated by a national fire prevention agency, and modified locally as authorities deem fit) that firefighters be granted ready access to shutoff switches, similar to the way they can control elevators with a special key.
This is one of the reasons I put my 4.5KW solar panels on the ground. It also gives me a nice shelter for the outside power tools.
Do you mean, a whopping 6 kilowatt hours?
Solar HEAT often can do well for cooking and heating.
Luddites....: )
Yes, kilowatt hours.
Sounds like the switches kill the power at the ground, but they are still lift wiht live wires from the roof to the switch.
I’m not an electrician, but aren’t those solar panels on a circuit breaker? If not, why not?
“Sounds like the switches kill the power at the ground, but they are still lift wiht live wires from the roof to the switch.”
Not true on all systems now, micro inverters installed on the roof & under the panels need to sense grid power before sending power back down.
Cut a disconnect and the micro-inverters shut down, there’s no hazard.
From the article and some additional research, the issue seems to stem from the fact that they have live wires running from the roof, thru the building, to a disconnect, which should interrupt the DC power to the inverter. However, they have no cue what a homeowner may have done inside.
without solar panels, they simply call the POCO to have them kill power to the structure, or if necessary the street.
were older systems designed differently?
“were older systems designed differently?”
Yes, the new systems send 240 volts AC up to the micro-inverters to synchronize, the panels then create DC current which is converted to AC on the roof and then sent back down to the house panel. Cut power at the panel or utility meter and all that is left is individual panels that are still “live” during daylight hours but there’s no circuit per se.
The old method (though still used, and still legal to install) was to string groups of dc panels together and send them down to a centralized inverter via metal conduit. Shutting off the inverter stops current flow but there’s still dc voltage present (400 VDC or more being fairly common) derived from the string of panels. It would be possible to get shocked with the system off in this type of install.
The new 2014 NEC requires rapid shutdown of both types, the micro-inverters pretty much do so by design already, the older centralized inverters will require relays, rooftop disconnects or dc to dc maximizer to comply on new installs.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.