# Struggling to figure out how to calculate actual power pulled from grid

Some quick help please, I’d appreciate someone correcting what I’ve gotten wrong, essentially it is a lack of understanding of the way logging logic works?

I’m wanting to accurately record the power being drawn from the grid factoring in solar generation (or not).
Current logging:

Current feeds:

TO clarify, this is setup as per the instructions, but sometimes “use” seems to be wrong as per this pic:

Hello @Mark_Sydney and welcome!

It looks like use in all example screenshots is negative, is use always negative? If it is only negative when your exporting solar then it means that you have a Type 2 setup as described here: Solar PV - Guide | OpenEnergyMonitor

Adding a little to Trystan’s reply, there are innumerable ways you can connect your monitor. But basically it comes down to where your PV “infeed” meets the rest of the wiring in your home.

If it is upstream (i.e. the grid side) of your distribution panel (“Consumer Unit” in English), then you have what we term a “Type 1” system. You’re able to measure the power that you’re using separately from anything else.

If the PV infeed goes straight into your distribution panel, or somewhere that’s fed from that, then you have a “Type 2” system.

What that means is for a Type 1 system, the Nett (grid) power = CT1 (use) + CT2 (PV); for a Type 2 system, Use = CT1 (Grid) + CT2 (PV)

You can change the sign of the power the c.t. reads by turning it round to point the other way on its wire.

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Hi @TrystanLea - thanks for welcome, replying, and seeking clarification!

I’ve captured another screenshot, this time with use positive, and no solar because it is night time now.

I’m in Brisbane Australia, where I have “net feed in”, so if I’m:

• generating 2kw, and using 3kw, then it should read 1kw of import from the grid
• generating 3.5kw and using 3kw, then it should read 500w of export from the grid

Hi @Robert.Wall thankyou also!
I’m 95% certain that it is connected my side of the distribution panel. Which I take it means I have a “type 2” system.

If I’m understanding you correctly, you’re saying that I if I have the clamp on the “grid” connector the wrong way, and that by turning it around it may fix the problem?

Thanks @Mark_Sydney you have the clamp the right way, its just that you have a type 2 system. I would delete the input processing and feeds that you have created and then restart following the Solar PV type 2 guide, hopefully that will then give you the result you are after

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Thanks for helping me out - I figured it was something “simple” I’d missed somewhere but couldn’t pinpoint it! I have re-created the inputs this morning and so far so good!

Cheers
Mark