array disconnects and code compliance
Marco,
 
The allowance of an unfused disconnect for the Sunny Boy is specifically because, if there are no paralleled strings, the inverter has been certified by UL to pass only a small amount of current back to the array in the event of a fault (less than 10 amps). Since most modules are rated for more than 10 amps, there is no need for overcurrent protection. If you have more than two paralleled strings (very small modules--although I'm not sure why you would want to use that configuration), you may need fusing, to protect against the combination of current from the paralleled strings and the inverter.
 
Bill.
 
-----Original Message-----
From: Mangelsdorf, Marco [mailto:mmangelsdorf@hei.com]
Sent: Wednesday, January 09, 2002 12:56 PM
To: RE-wrenches@topica.com
Subject: array disconnects and code compliance [RE-wrenches]

Wrenches,

In order to be code-compliant, what is needed between the solar array, or combiner box, and the inverter in a battery-less system?  Does one need overcurrent protection in the form of a fuse or appropriately sized circuit breaker?  Or is an unfused disconnect acceptable?  The Sunny Boy folks specify an unfused Sq. D HU361RB to act as the array disconnect before going into the inverter. I've done this with no problem from the local AHJ but am now wondering whether an fused disconnect is Section 690 acceptable.  Any observations?

marco
proVision technologies
Hilo-town, Hawai'i 

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