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Hi Jeff, <br><br>
Use Outback off grid inverters for the backup, and break the AC from the
grid tie inverters. An advantage of this is that you can use a
standard generator and transfer switch to charge batteries through the
off grid inverters. The grid tie inverters take care of the anti
islanding, etc. <br><br>
Drake <br><br>
<br>
At 10:11 AM 4/16/2010, you wrote:<br>
<blockquote type=cite class=cite cite="">Hope I have not posted this
before, but it keeps coming up. We do many systems that
include a battery connected inverter and generator to provide backup
power for upscale homes. Although we have no problem with roof
mounted arrays, many of these homes may be large, but usually are either
shaded or their roofs are broken up with all kinds of dormers and
chimneys, with no large areas facing south. <br><br>
In addition, many of these homes have large landscaped yards and gardens
up against the home, so we end up having to install a ground-mounted
solar array as much as 200 or more feet away. Since we want to
charge the battery from the solar array during an outage, but do not want
to run huge cable sizes due to the long wire runs typical for low voltage
DC arrays, we mount a SunnyBoy on the back of the array, then run 240 VAC
back to the battery/inverter/generator system in the basement or garage
using an AC coupled design with relay cut-out to dis-connect on high
battery voltage during off-grid operation. (still not sure why
inverter manufacturers can't control over-charging from back-feed AC when
not grid connected).<br><br>
Anyway, where to wire in the utility dis-connect that needs to be near
the meter base. The most logical is in the 240 AC output from the
solar array inverter before it enters the emergency loads panel.
However, there is still the matter of the battery inverter which could
easily backfeed the grid if programming is changed by others. This
would then require the dis-connect between the AC output of the battery
inverter and the house panel, but this would kill the emergency loads
panel if the utility actually decided to lock out. Not likely, but
still possible. Just concerned that code officials will see the
inverter in the house, a solar array in the yard, and want a dis-connect
that kills everything to grid.<br><br>
Have any other states already addressed this issue?<br><br>
Jeff Yago<br><br>
<br>
<br>
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<x-sigsep><p></x-sigsep>
<font color="#0000FF">Drake Chamberlin<br>
Athens Electric<br>
OH License 44810<br>
CO License 3773<br>
NABCEP </font><font size=1 color="#0000FF">TM
</font><font color="#0000FF">Certified PV Installer <br>
Office - 740-448-7328<br>
Mobile - 740-856-9648 </font></body>
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