What makes a grid tie inverter TURN ON?

 many panels.  bright sun.  grid tie.  No power.

Understood.  Accepted.

What, on the inverter's grid side, happens to make the inverter turn ON
and let power flow from the grid and from the panels into my happen
little house?

  Chuck Yerkes wrote:

Grid tied inverters don't control what power flows into your house.
Your house is still plugged into the grid the same way it always was
and when the grid power is restored your house would have power. The
inverter simply looks at the power coming from the grid and makes
sure it's stable before it starts pumping power back into it. In a
way, the inverter is pumping power into the entire grid and it just
happens that your house is also connected to the grid nearby.

Anthony

 Anthony Matonak wrote:

Okay, so how does the inverter define "stable"?  Is there something more
than just a token sine wave at a couple milli-amps?

Where I'm trying to go with this is that for a grid tie system, in an
outage during solar generation time - what is needed to 'trick' the
inverter into allowing the solar power to flow (with grid cutoff via the
kill switch of course).

Now, granted, a big ol cloud can drop your solar output to a couple amps
and that would harm things plugged in. But if I have something on the AC
side of the inverter that can temporarily pick up the holes, then I
should be set.

What that SOMETHING is is what I'm trying to figure out. If I'm down to
5 amps (lights off cause it's daytime, but perhaps just fridge and
minimal stuff) then a 1000watt generator would do it.  Or a *small*
battery system powered by just a couple panels an the alternate small
inverter.

I'm just straining because to me I should be able to take a 500-1000
watt battery backed system and use that to kick on a 4-5kw system.

How minimal a system is needed for this?  If 2 panels can charge up
batteries that are used ONLY for backup, then you can have many
batteries, they will charge eventually.  Once charged, any "extra" can
be used to the grid on house side of the kill switch.

Lose power?  Hit the kill switch, get the second inverter to go into
generate mode and 4kw of roof solar flows.  In darkness you have 1kw.
In bright sun, you have 4kw + 1kw.


What's wrong with this picture?

 Chuck Yerkes wrote:

Yes. I believe they typically measure a few different things and one
of them is how much the input from the inverter affects the power on
the grid. Since the grid generators are huge compared to a home sized
inverter their output, and hence the grid waveform, isn't going to be
affected much by the inverter.


Since inverters are designed specifically to not do this then I'd say
you would probably have to work hard to fool it. You would do better
to simply get an inverter + battery combination that does what you
want in the first place. That is, you want an inverter/charger/battery
that will maintain a battery bank and provide your house with power
automatically when the grid fails. Such things exist but they are
a little more expensive than straight grid tied inverters.

Anthony

 On Thu, 20 May 2004 05:52:14 GMT, Chuck Yerkes


The units check a number of parameters, including frequency and voltage.



Why not just use an inverter that is designed to do what you want?


-- ron  (off the grid in Downeast Maine)