Setting up a emonpi - odd PV readings

I've only just got around to trying to set up my Kickstarter unit. I've had to factory reset the system as in a fit of newbieness I deleted the main feed (oops). The unit is now running ok and updating the readings every 5s. 

What I can't understand is the PV feed only reading 5 - 10W feed despite the inverter showing 2kw or so. I've tried swapping the current sensors around and both display a sensible reading when on the supply side, but only a negative value. So for some odd reason the PV feed isn't being read.

I assume I've missed something important - but have no idea what.

Any idea as to what I've missed?

Installation is an Emonpi with the latest firmware and software as I've updated the card post 17th June. 2 current sensors bought from the shop, as well as a thermometer and an AC sensor psu. I've not yet sussed out how to link the unit and the energy management, but that'll happen once I reread the instructions for the 6th time.....

 

 

Robert Wall's picture

Re: Setting up a emonpi - odd PV readings

Is your PV current transformer on a single, ac, cable and in the right place to measure the PV infeed?

If you transfer it to the main incomer, does it read the same as the other CT?
(To change the sign of the reading, just flip the CT on its cable.)

bearded_walker's picture

Re: Setting up a emonpi - odd PV readings

I think it's in the right place: the main cable from the PV meter to the house contact breaker box. If I transfer over, i.e. move the clip on to the supply main then it reads that ok. (and the one on the supply main displays the same odd reading if I transfer it to the PV).

 

Robert Wall's picture

Re: Setting up a emonpi - odd PV readings

Is that "main cable from the PV meter to the house contact breaker box" a single-core or a two-core cable, i.e. which one of these: http://openenergymonitor.org/emon/Current_Transformer_Installation

bearded_walker's picture

Re: Setting up a emonpi - odd PV readings

Thanks Robert, I've ASSUMED it's a single core cable, but I don't know. I'll check.

Tony

Robert Wall's picture

Re: Setting up a emonpi - odd PV readings

If there are two running in parallel, it is. If there aren't, it isn't, and that's your problem.

Peter Galbavy's picture

Re: Setting up a emonpi - odd PV readings

Also, worth testing your clamp as one of mine has a cracked ferrite thing and a 1/2" chunk was missing. I was sent a replacement overnight and all was well - great service.

If no visible damage still test the clamp on a known working cable such as the main grid line - eliminate which part of the system is causing the fault.

Robert Wall's picture

Re: Setting up a emonpi - odd PV readings

"test the clamp on a known working cable"
It's not a clamp, it's a Current Transformer, and if you read the initial post, he's already done that.

Peter Galbavy's picture

Re: Setting up a emonpi - odd PV readings

My bad. My original reading missed the but between swapped and negative. Apologies for the wasted post.

bearded_walker's picture

Re: Setting up a emonpi - odd PV readings

The solar panels supplier has confirmed that the cable is a twin & earth, and has told me what to look for in the fuse box. I'll turn the power off, and take a look. If it's straightforward then I'll move the PV CT there. If it isn't I'll get a sparks in to sort something out. 

I'll feed back once more is known, thanks all for you're help.

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