[RE-wrenches] Ten K Solar

[William Miller]

Chris:

The issue is not so much the voltage as the amperage.  Utility power has 
amperage capabilities that far exceed the rating of the usual over current 
protection devices.  In a fault, the current is temporarily very high, 
opens the OCPD and the problem is resolved.

With PV, the power is current limited and we want to draw 100% of the 
amperage available, so OCPD must be sized smaller than the available 
ampacity of the string, otherwise the OCPD would trip every sunny day.

This is the crux of this very serious problem, and the reason PV wiring 
should aspire to the highest standards.  There is no breaker that will 
protect your wiring.

(OCPD is required and is useful in preventing parallel strings from 
back-feeding each other in a fault condition.)

William Miller

At 11:08 AM 10/22/2012, you wrote:
>Maybe we should reduce our household voltage to 70V also, it would be save 
>and you could fuse it...