The interconnects are part of the circuit. Typical flexible cables used with batteries are THW rated (75C column), so in free air 2/0 interconnects would be good for 265 amps, before any temperature derates. Therefore, you'd be safe from a NEC point of view. However, if the inverter manufacturer has recommended 4/0 cables, then that recommendation would apply to all cables in the circuit. Battery based inverters are asked to surge many times their rated capacity -- a 24V 4kW inverter surging to 2x capacity (pretty normal circumstances) is going to draw over 360 amps (8,000 / 22), even if only for a short period of time. You don't want your interconnects to be the weak link in the system, causing shutdowns due to undervoltage unnecessarily.
I'd use 4/0. Phil Undercuffler Conergy On Fri, Feb 19, 2010 at 12:01 PM, Mick Abraham <[email protected]>wrote: > Example: 12 two volt battery cells in one 24 volt string. 4kW > inverter/charger has 250 amp DC breaker size and 4/0 cables...as the > inverter folks would want. > > So...do the "cell to cell" interconnect cables have to also be 4/0? In the > example above, 2/0 interconnects would suffice from the standpoint of basic > safety...and even from the voltage drop standpoint...right? > > Inverter company people may be best qualified to answer this, but any > replies will be appreciated. While I'm at it: do the inverter folks request > oversize cables because they want more capacitance on the DC input...or > what? > > Jolliness, > > Mick Abraham, Proprietor > www.abrahamsolar.com > > Voice: 970-731-4675 > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > >
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