RE: Re: Solar PV ?

[Marcus Warrington <marcus.warrington@xxxxxxxxxx>]

Lee


=D8  ... But why? The data from the inverter is more accurate.

I don't think he bought the sunnybeam or had a Bluetooth adapter but did
ha=
ve an energy clamp/meter. I agree with you that its not the best way to do
=
it and certainly won't be the way I do it.


=D8  The problem is the clamp on the 'normal' meter...

I didn't know that, so thanks for explaining.
So when my Solar array is up and running the OWL will actually be showing
t=
he absolute difference between generation and consumption i.e. I'll know
th=
e difference but not if its positive or negative.
That's another "hole" I shan't being falling into :)


=D8  ... I'll sort the shield out for you.

Thanks Lee, that's very generous  of you and much appreciated. I'll
obvious=
ly reimburse you for materials and time.


=D8  ...get the Arduino to 'fake' the input to the Owl transmitter

That's a really neat idea, a nice plug and play solution to
"upgrade" to so=
mething more accurate

Marcus

From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of V=
argster
Sent: 21 July 2011 12:59
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Re: Solar PV ?



>
> > Using an OWL to measure the consumption DOESN'T WORK when you
have sola=
r
> > PV. The OWL (or other meter) DOESN'TKNOW which way the current is
> flowing.
> >Eg.
> >Base load 1Kw solar PV 1Kw =3D Owl reading 0Kw
> >Base load 1Kw solar PV 2Kw =3D Owl reading 1Kw
> >Base load 1Kw solar PV 0Kw =3D Owl reading 1Kw
>
> Is that still the case when the OWL clamp is only on the AC cable from
th=
e
> Inverter to the consumer unit ?
> In other words, I think he had 2 OWL units one to monitor SolarArray
> production and one to monitor house usage.
>

If you put the clamp on the A/C cable from inverter to the consumer unit,
i=
t
will show the power being pumped from the panels just fine. But why? The
data from the inverter is more accurate.

The problem is the clamp on the 'normal' meter (where PV-less households
have them). Where there is solar generation, current could be flowing into
OR out of the house, and the unit can't tell which direction it's in...
If it's a blzing sunny day, and nothing in the house is on, it's a safe bet
you're exporting, if it's late in the evening and the kettles on, you're
probably importing, but it's not much use if your're trying to graph it and
make decision based onthe numbers...

> =D8 Which leads me to the "Open Energy Monitor" project,
using an Arduino
> with a
>
> Looks like an interesting project, but my soldering skills are pretty
> limited :( Is anyone selling ready assembled devices ?
>
>
No, they're not for sale (yet - though they are talking about it), but if
you give me a few weeks to build and test mine, I'll sort the sheild out
fo=
r
you.
I'm planning on keeping costs low and building it on a 1" square bit
of
strip board (rather than a full shield) that will plug into a standard
Arduino (lots cheap on Ebay).
The only two bits we'll have to standardise on are the CT clamps and the 9V
*AC* power supply.

The other thing that occured to me a couple of weeks ago, is to still use
m=
y
Owl meter, but get the Arduino to 'fake' the input to the Owl transmitter.
I've not looked into it yet, but in theory - the Arduino know the current
(and direction) on the whole house supply (which it sends every few sends
t=
o
the server).
The server knows the output from the PV inverter. It sends this to the
Arduino.
The Arduino subtracts on from the other and sets one of its PWM outputs to
the right frequency make the Owl transmitter think it's still connected to
it's sensor and send data to the display.
Many things may go wrong with this plan, but it's a neat idea!

Lee

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