The inverters' input capacitors may be charged and so that must also be
isolated near the inverter.
A grid operated contactor will not work for a battery-back up system.
Also, 600V DC can weld contacts closed and if this happens and there is
no feedback to show that
the contacts definitely opened, this can ruin a firefighter's day.
Otherwise, a system of contactors from AC grid could work in a grid-tie
only system.
The new UL rapid shutdown specifications are supposed to be released
very soon now.
Maybe within the month ?
boB Gudgel
K7IQ
MidNite Solar
On 2/2/2015 1:23 PM, Mark Frye wrote:
In order to clear up the conversation...
I you put a relay in a box within 10 feet of the array on the roof,
you can use an relay with a DC rated Normally Open contact to open and
connect/isolate the array DC voltage.
You can drive the coil of that relay with either AC or DC, but either
way, if you lose voltage to drive the coil, the contact opens and
isolates.
My point is, for simple grid-tied system, there is no need for a
"stop" switch anywhere in the system. It doesn't matter whether the
contactor coil is driven by the premise AC or by a DC power supply
connected to the premise AC, when the the main is opened or the meter
pulled, the array Dc will become isolate.
Therefore, there is no need for the "stop" switch and yet as I
understand it, such a switch is now required by the Code. The switch
is not needed but is required.
Mark Frye
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