Hi. Can you re-send the link go the digital meter you referred to in this post? It returning HTTP 404 Not Found. Thanks.
adiculiniute: Hello dwienie! Man, If I could, I would retract my previous post... since it is not 100% a thing you can trust. Indeed the voltage is higher when you produce power, but this is not a reliable indication of injection in grid.
So, I gave up on this, and I switched to plan B. I bought a digital meter: http://www.adeleq.gr/product/24794?lang=en This one, has a reverse indicator (LED). So, I put a LDR in front of this reverse indicator LED, and when it is ON, the arduino knows that injection is happening :) You can search any meter who has the reverse indicator. This model, is not very responsive, compared to my main grid meter (the one who belongs to my electricity company) It needs a couple of seconds to detect the reverse condition... but I can get over this...
Best regards! Adrian