Import/export meter

Maybe not quite what the Workshop is generally used for on here...but Compostman has just built and is testing out an electricity Import /Export meter, for the PV's.

He used an Arduino Uno microcontroller, a current transformer and a plug in the wall power supply, plus a bit of Cm designed and built circuitry. He used a lot of helpful info from

HERE

It is running on the laptop at the moment, but eventually will have its own, small display plus an SD card to store the data on for downloads at regular periods.


It displays the Voltage ( if it is -ve, we are EXPORTING hurrah) Current, Power factor and a few other bits of info.

Mesmerising to watch it go up and down, as we use various bits of kit or as the clouds go in front of the Sun.

Will allow us to monitor our electriciy usage so as to alter even more our usage patterns to match up to when we are generating our own electricity. We want to try to use as much as we can when we are generating, so we are not exporting during the day, and then importing during the night!

I am so impressed with Compostman, he continually surprises me with his skills!

Screen showing us importing electricity ( boo, hiss!) in the first column.




Columns (L-R) are

PV power generated, apparent power (Vrms x I), power factor, V rms, I rms.

Screen showing us exporting electricity ( hurrah!)

Oh and I have just had it pointed out to me that I said it recorded Voltage, in my first post. Of course I meant Power.

The 5 columns are actually:
Nett real power coming into the house from the grid, so negative numbers mean export
Apparent power (product of rms voltage and current)
Power factor (ratio of the two above and deviates from 1 for reactive loads like motors or fluorescent lamps)
Mains voltage (rms)
Mains current (rms)

Compostman wrote:The 5 columns are actually:
Nett real power coming into the house from the grid, so negative numbers mean export
Apparent power (product of rms voltage and current)
Power factor (ratio of the two above and deviates from 1 for reactive loads like motors or fluorescent lamps)
Mains voltage (rms)
Mains current (rms)

I knew there was a good reason why I didn't want you on here!

I sit, corrected ( a bit like the figures!)

Welcome CM! Breadboard electronics, love it!


Looks like CW is going to have to behave now!

mark barker wrote:Welcome CM! Breadboard electronics, love it!


Looks like CW is going to have to behave now!

Ha,ha, you wish.

Mmm.. breadboard and IC tinkering, lovely.

So, the kit is producing about 1.3 kVA at any time, abouts? Or that's the net plus? I take it to read net plus. What's the kit total output, y'know perfectly sunny, full moon, plucking the right goose feathers, etc. And what do you average? Or is this still addressing the questions of "What is says on the tin" vs what it does on MY roof? Can't wait to see how it goes.

mr_sfstk8d wrote:Mmm.. breadboard and IC tinkering, lovely.

So, the kit is producing about 1.3 kVA at any time, abouts? Or that's the net plus? I take it to read net plus. What's the kit total output, y'know perfectly sunny, full moon, plucking the right goose feathers, etc. And what do you average? Or is this still addressing the questions of "What is says on the tin" vs what it does on MY roof? Can't wait to see how it goes.

In that last photo of the screen shop, we were exporting about 1.3 because we had the washing machine running and various fridges, freezers etc.

It was actually producing about 2.4. ( I fully expect CM to log in and correct me, but he isn't here so I will give you a rough figure.... )

April and May have been particularly good months for sunshine, here!

Average figures...well they reside on CM's computer ..we have a daily log from since it first went on the roof last year.

If you are interested see http://forum.homemadelife.com/t706p10-pv-s-going-up-at-compost-mansions