Help with monitoring grid usage

Spies

Since having solar comissioned, my CT clamp on my meter is reporting strange values which don't appear to add up, when solar is generating it looks like the CT clamp is reading whats being added back into the grid, the values are positive regardless of the direction the power is flowing.

I have data which gives me the power the solar is producing at 5 minute resolution, but I cant think of a way of using those two numbers together in order to work out what power the house is using at that time?

QrizB

Many of the basic CT meters (including both of mine, a Scottish Gas branded humm minim and a Souther Electric branded Current Cost Envi) can't distinguish the direction of current flow. Mine also get confused by the inverter (I think it does something odd to the waveform at low outputs) so have a noise floor of ~400W whenever the sun shines.

I did obtain a https://loop.homes/loop-shop/ monitor (the hardware option) which still can't distinguish the direction of flow but doesn't have the noise floor.

I got by by having two, one monitoring generation and the other monitoring the grid, then looking out of the window and deciding for myself which way the grid current was flowing. If I was still undecided, putting the kettle on would give the answer.

My Sofar battery-storage inverter *can* tell the direction of current using its CTs, so clearly it's possible but I don't know of a standalone produce that will do it. Sorry.

EricMears

If you've got a 'smart' meter,  you might consider a 'Glowmarkt' product : the GlowStick for SMETS1 meters or Glow  IHD/CAD  for SMETS2 meters.
See https://shop.glowmarkt.com/products
 

Spies

EricMears said:

If you've got a 'smart' meter,  you might consider a 'Glowmarkt' product : the GlowStick for SMETS1 meters or Glow  IHD/CAD  for SMETS2 meters.
See https://shop.glowmarkt.com/products
 

I do have a SMETS2 meter which detects export, I wonder if that IHD would give me that data that I can use inside home assistant. 

Meatballs

Spies said:

EricMears said:

If you've got a 'smart' meter,  you might consider a 'Glowmarkt' product : the GlowStick for SMETS1 meters or Glow  IHD/CAD  for SMETS2 meters.
See https://shop.glowmarkt.com/products
 

I do have a SMETS2 meter which detects export, I wonder if that IHD would give me that data that I can use inside home assistant. 

Yes there is an integration for glow and you can ask them to setup MQTT for you. I'm waiting for cad units to come in stock but might just grab a glowstick.

They don't say they support export though, and only a few comments on it on the forums...

Spies

I suppose if I can measure house usage and I have what my solar is generating I can use a bit of simple maths to work out export. 

Meatballs

Suggests it goes negative to denote export:

https://forum.glowmarkt.com/index.php?p=/discussion/106/export-meter-reading


but that's a reasonable fallback option!