[aprssig] Shack backup power

[Greg Dolkas]

Hi Bob,

On Sat, Jun 4, 2011 at 1:58 PM, Bob Bruninga <bruninga at usna.edu> wrote:

> >> ...With these small plug-in grid-tie inverters
> >> in the 250 Watt class, now it is possible to run our shack:
> >
> > Do you have a reference for these plug-in grid-tie
> > inverters?  I can not possibly see how these would
> > be legal but I want to see the manufacturer's
> > website if they exist.
>
> The Enphase or is it Emphase micro grid-tie inverters are designed for
> installation right on the back of each solar panel and put out 240 VAC to be
> paralleled with all other panels and then fed into the power panel.  They
> are UL approved, etc.  The other ones witn a standard 115 VAC plug output
> have no such approvals.
>

Ok, that brings up an interesting question.  If the inverter puts out 240v,
how does an appliance that runs 120v benefit?.  Is there also a neutral
connection?  If so, then how does it handle the balance between the two
legs?

Or, are we just pushing power into the grid to net offset what we pull out
of it?  If that's it, then I guess we're expecting the power meter to
somehow account for 240 going out and 120 coming in, because other than the
AC and clothes dryer, nothing really uses 240 around here.  It's not
offsetting an active load, so how in the world is it going to keep all that
straight?  I guess I've convinced myself that I have no idea how power
meters and 2-phase power systems really work.

Severely confused,

Greg  KO6TH
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