Regs explained please? DC cables on PV systems

[Mike2007]

712.433.1
Overload protection may be omitted to the PV string and PV array cables when the continuous current-carrying capacity of the cable is equal to or greater than 1.25 times Isc STC at any location.

What does this mean in simple terms?

 

[Paul_C]

712.433.1
Overload protection may be omitted to the PV string and PV array cables when the continuous current-carrying capacity of the cable is equal to or greater than 1.25 times Isc STC at any location.

What does this mean in simple terms?

Isc is the short-circuit current of the PV array. STC means Standard Test Conditions, defined as 1000W/sq. m. which is supposed to represent normal sunlight on a clear day near the spring/autumn equinoxes with the panels oriented ideally.

So it's saying that so long as the cables are rated for at least 25% more current than the PV panels can deliver under standard test conditions when short-circuited, then overload protection is not required.

 

[ban-all-sheds]

STC means Standard Test Conditions, defined as 1000W/sq. m. which is supposed to represent normal sunlight on a clear day near the spring/autumn equinoxes with the panels oriented ideally.

Where?

The average for the UK is 10% of that.

 

[Paul_C]

The figure is a standardized measurement for peak solar power under ideal conditions, i.e. 1kW of solar power per sq. m. of receiving surface.

 

[ericmark]

The point is some solar arrays can sore in voltage if disconnected, so with some systems one would not want to use a fuse as if it went the voltage may sore so they are giving you an alternative which allows you not to fuse.