[clug] Exercise and pay the bills!

Steven Ring smr at southsky.com.au
Sun Feb 8 23:51:58 GMT 2009


The inverters have an "anti-islanding" circuit which compares the
voltage/phase of the mains current with its own inverter (solar or
bicycle powered). If mains voltage disappears or if phase drifts away
from that of the inverter, the invert is shutdown or otherwise
disconnected from the grid.

There is some concern that multiple inverters in the one area might
fool each other into thinking that mains are still present. Some
design measures are taken to avoid that risk (such as a tendency for
the inverter to drift lower than the standard frequency). But I'm
getting out of my depth.

ACTEWAGL seem to take a conservative approach. During a recent
scheduled outage for tree trimming in my backyard they visited each
home with a photovoltaic system and isolated it from the grid.


On Mon, Feb 9, 2009 at 10:28 AM, Robert Edwards <bob at cs.anu.edu.au> wrote:
> Hi Paul,
> If you get an appropriate alternator (ie. 48V), you can get more-or-less
> constant voltage across the range of RPMs by adjusting the stator
> voltage. I believe that this is how wind-farm generators work (could be
> wrong) and is how most car alternators regulate their output voltage to
> give more or less constant 13.8VDC (not 12VDC!).
> A (smallish) car alternator (ie. 13.8V) and a 12V-48V inverter might be
> the best bet to get 48V into your power feed-in.
> Hope this helps.
> Bob Edwards.
> btw. does anyone know how the electricity authorities "switch off"
> a segment of their 240V power line (eg. for tree-clearing or other
> maintenance) when there are all these solar-powered power feed-ins
> popping up everywhere and effectively juicing up the line? I have
> always wanted to know how they turn it all off.
> Paul Wayper wrote:
>> Hash: SHA1
>> I'm assuming a reply to the list is what you wanted here, Brad:
>> Brad Hards wrote:
>> | On Sunday 08 February 2009 07:45:56 am Paul Wayper wrote:
>> |> Most exercise machines sold these days just use either friction,
>> magnetic
>> |> coupling or resistive loads as the 'sink' for work done.  Since Kate
>> and I
>> |> are in the process of getting a solar panel system put in, and the
>> inverter
>> |> can take 48VDC and put it onto the grid as 240VAC, I was thinking of
>> |> getting a 48VDC generator and hooking it up to some exercise system and
>> |> generating actual usable power while I work out.
>> | I think this is the part you are going to have trouble with. You need to
>> sort
>> | out the interaction with the storage system and the grid-connect part.
>> (A
>> | path from 240V line power to the bike isn't such a good idea...)
>> The plan is to stick the 48VDC at variable amperage into the input side of
>> the
>> inverter - which is already designed to cope with a bunch of solar panels
>> are
>> already providing fixed voltage at variable amperage throughout the day.
>> HTH,
>> Paul
>> Version: GnuPG v1.4.9 (GNU/Linux)
>> Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org
>> /qcAn39Jik91i9bDu3DMr8xTwLsimwNh
>> =yyyj
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