<div dir="ltr">I am connecting a Kohler 12RES to my house, the roof has 3.1KW of PV connected to a SB3000.<div style>I thought we would have problems so we all knew to turn of the solar before turning on the generator. One day, we forgot, and it all worked. Since that I have left the solar on each time we ran the generator. As we are in a small island, power outages are common.</div>
<div style>The Kohler has a problem I cannot get to the bottom of and I'm going to pull a Generac from inventory and install it, so I will find out if that also works. My home and office is a test lab, I'll try anything there.</div>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Feb 11, 2013 at 8:44 AM, Drake <span dir="ltr"><<a href="mailto:drake.chamberlin@redwoodalliance.org" target="_blank">drake.chamberlin@redwoodalliance.org</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
Chris,<br><br>
It sounds like you are creating a generator supplied mini grid, if I
understand correctly, My reading is that your generator is creating
the AC voltage, and the inverter is synchronizing with it, allowing power
to be fed into the system from a PV source. <br><br>
This approach could represent a major innovation in solar industry.
I remember a decade or so ago when it was proposed, on this list, that
battery based inverters could be backfed to charge batteries, and someone
tried it. It worked. Today AC coupling is standard operating
procedure. <br><br>
Up to that time, it was only understood that to connect an AC source to
the output of a battery based inverter could damage it. Maybe the
next step is to AC couple to generator supplied sub panels and allow PV
usage during power outages. <br><br>
What inverter and generator are you using? How many Watts of PV are
connected?<br><br>
Thank you,<br><br>
Drake <br><div><div class="h5"><br>
<br><br>
At 02:04 PM 2/10/2013, you wrote:<br>
<blockquote type="cite">I have a generator and PV system
that just works together, despite all the dire predictions that it won't.
from my experience of PV and generators (I am also a generator tech), the
biggest issue is the AVR board and how it responds to back fed voltage,
and the generator controller's over voltage settings.<br>
I think that it would probably on only require a reprogrammed inverter to
make this work as follows.<br>
The AVR produces excitation voltage to vary the strength of the rotor
field and therefore the induced voltage in the stator. When the PV system
back feeds the generator, the excitation level is reduced to control the
voltage. When there is no load, the inverter keeps raising the voltage to
attempt to push the current to the grid and at some point the generator
trips out on overvoltage. <br><br>
If the inverter was programmed to reduce the production of power in
response to the rise in voltage, it would sync pretty nicely with the
generator. However, this would likely violate the IEEE parameters for a
grid tied inverter. SMA has off-grid mode, I suspect that is the best
solution.<br><br>
In a Sunny Island system, as I understand it, the Sunny Island caries the
frequency to communicate to the inverter to reduce the current output.
That avoid the problem of the inverter raising the voltage.<br><br>
<br><br>
<br>
On Sun, Feb 10, 2013 at 2:45 PM, Drake
<<a href="mailto:drake.chamberlin@redwoodalliance.org" target="_blank">
drake.chamberlin@redwoodalliance.org</a>> wrote:<br>
<dl>
<dd>Hi Kevin,<br><br>
</dd><dd>Thanks for the Eigg video. What a great place.<br><br>
</dd><dd>I didn't see evidence of any AC coupling of inverter produced AC to a
generator produced mini grid. I understand this is being done in a
homebrew manner by some.<br><br>
</dd><dd>The current wisdom on the issue is that the less the PV contribution
to the generator supplied grid is, the easier. It would seem that
if a grid tie inverter output could be regulated, using Sunny Island type
controls, it should be possible to have a small inverter generator create
a mini grid that could be fed by PV.<br><br>
</dd><dd>A system featuring this type of technology was linked in a posting on
this list some years ago, The link seems dead now. In that case a
large generator was feeding a number of houses, and PV was fed into the
system.<br><br>
</dd><dd>The reason for this interest is that battery backup systems are much
more expensive than generators. We need to find a way to utilize PV
arrays during outages without the expense of battery backup
systems.<font color="#888888"><br><br>
</font></dd><dd><font color="#888888">Drake</font></dd><br><br>
<br><br>
<dd>At 07:42 PM 2/8/2013, you wrote:<br>
<dl>
<dd>Hi Drake,<br><br>
</dd><dd>SMA has very good solutions for this. Does this out of the box
without a bunch of custom control systems. I have put a few systems in
like this, but the renewables not yet online (generator / battery now).
If you google Isle of Eig you will find some info on what they have done
there.<br>
</dd><dd><a href="http://islandsgoinggreen.org/about/eigg-electric/" target="_blank">
http://islandsgoinggreen.org/about/eigg-electric/</a><br><br>
</dd><dd>Kevin<br><br>
</dd><dd>-----Original Message-----<br>
</dd><dd>From:
<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">
re-wrenches-bounces@lists.re-wrenches.org</a><br>
</dd><dd>
[<a href="mailto:re-wrenches-bounces@lists.re-wrenches.org" target="_blank">
mailto:re-wrenches-bounces@lists.re-wrenches.org</a>]On Behalf Of
Drake<br>
</dd><dd>Sent: February 8, 2013 6:41 AM<br>
</dd><dd>To: RE-wrenches<br>
</dd><dd>Subject: [RE-wrenches] Generator Controlled Mini Grid<br><br>
<br>
</dd><dd>A potential customer is interested in a mini grid, set up by a<br>
</dd><dd>generator, to connect his array to.<br>
<br>
</dd><dd>Some years back, on this list, an article was linked about a<br>
</dd><dd>community with a central generator that had PV input to the
generator<br>
</dd><dd>supplied, local grid, using electronic controls.<br><br>
</dd><dd>Has any progress been made in this technology? Does anyone have
a<br>
</dd><dd>link to the electronic control equipment or any other relevant
information?<br><br>
</dd><dd>Thanks,<br><br>
</dd><dd>Drake<br><br>
</dd><dd>_______________________________________________<br>
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