[RE-wrenches] DC to AC derate

[boB at midnitesolar.com]

On 1/4/2012 3:01 PM, All Solar, Inc. wrote:
> Wrenches,
> Once again I am trying to size a grid tie w/battery system and I 
> struggle a little with the efficiencies of them.
> With PV Watts (v.1), is changing the DC to AC derate an accurate 
> method for getting the output?
> Thanks in advance!
> Jeremy


If you keep the batteries charged  to a voltage just above their resting 
voltage,
say, 52 volts for a 48V system, and the battery bank isn't too large, 
(~225 A-hours,
maybe a bit more), about 90%  PV to grid AC efficiency is in the ball park.

That's what we figured in the early days of GFX inverters at OB.  That's 
giving
5% for the electronics and 5% for keeping up the batteries.
Different and/or more accurate information may have come along since
that time.

boB








> All Solar Inc.
> Jeremy and Amy Rodriguez
> 1463 M St
> Penrose, CO 81240
> www.asolarelectric.com <http://www.asolarelectric.com>
> Phone 719-372-3808
> Fax 719-372-3804
> Email allsolar at scswifi.net <mailto:allsolar at scswifi.net>
> Email allsolar at live.com <mailto:allsolar at live.com>
>
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