[RE-wrenches] Trace SW4024 feeding back to grid

[Zeke Yewdall]

Did the utility say that it was feeding back in 1A continuous, or had fed
back in 1A at some point?

With better metering, especially the new smartmeters, utilities are finding
a lot of PV systems that are connected without authorization, by seeing
tiny amounts of backfed power that used to be invisible.  I had one SolArk
system get caught.  For the systems that operate in parallel with the
utility doing zero sell it needs to have a certain offset for the minimum
amount drawn from the utility, such that it doesn't inadvertently sell a
little bit during readjustment during load changes.  In the case of the
SolArk system, it was set to 0 watts from the utility, and when the load
changed, it would sell a little bit for a few seconds.  This is enough for
the utilities to see with the new meters, and lets them know that there is
solar that they haven't been told about. I changed it to a 120 watt minimum
draw from the utility, and it no longer overshoots zero during load changes
now, but also draws power from the utility all of the time.  We do have to
get this system permitted and an interconnection agreement in place soon
though, because now they know about it, and they are going to pull the
customers service if he does not do that, or get rid of the solar
completely.  This is something that everyone should know, that operating in
parallel with the grid without having an interconnection agreement is a
risk.

The only way to safely do solar without getting an interconnection
agreement (and I think the only legal way) is to never have the solar
operating in parallel with the grid, but have a transfer switch such that
the solar is never connected to the utility.  For many of the newer
systems, connecting the grid to the generator input port instead of the
grid port can accomplish this (though it varies from system to system --
some systems can operate in parallel with the generator too).  But almost
all of the new systems (all in ones, some operating modes of the Radian and
XW) operate in parallel with the utility rather than switching back and
forth, so when the grid is connected to the grid input of the inverter, it
can potentially backfeed the grid, even if for only a second or less.

The HBX/LBX modes of the SW and the Outback switch back and forth, rather
than operating in parallel, and so should not have this issue.  I think...
I am not 100% certain even with these modes, although I've never seen them
have an inadvertent sell issue, due to the inverter being off anytime it's
connected to the grid.    The transfer switch in this case would be inside
of the inverter.

Zeke
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