I’ve got an old owl monitor and looked into some other suppliers and few have bi directional CTs requiring one facing in another direction to measure the feed in.
I have two questions.
Does this unity have bidirectional. I have the solar water divert but the read out unit is with the meggaflow in a hard to access cupboard. At some point the divert sensor disengaged and I lost a few months of free hot water. One way of detecting this is a complete absence of export of generated electricity. Our house runs at 500-900 watts so when there is nothing special happening and we are generating 2k, if I’m exporting 1k, I know there’s a problem with the water heating divert at least until the water is too hot for the thermostat.
I have noticed that our owl seems to be blind to the working of the Solar divert so I wonder if that operates on a pulse that the owl is simply out of time with.
The owl measures the amps in both directions so if we are generating excess it shows up on the owl as if nothing was being diverted to the hot water cylinder, but if you look in the cupboard, the expected excess is going to the hot water.
I want to invest in something that is proven to not suffer the same bugs,
I’m not sure what you mean by “bidirectional”. Yes of course the current transformer itself is bi-directional, because transformers only work on alternating current. It is what happens to the signal afterwards that might be the problem.
I think you should look at Robin Emley’s (@calypso_rae) website: http://www.mk2pvrouter.co.uk/
A complete list of his designs is published here Robin's Mk2 Code variants and associated tools. | Archived Forum and details of how it all works are on his website and here in the ‘Learn’ section. There is enough information here if you want to build your own diverter based on an emonTx, or Robin might be able to supply a kit of parts.
I suppose where I’m going with this is how does this unit diferenciate between exported energy and imported energy. My owl does not. If my house is using 500watts and I’m generating 1500 watts it reads 1000, as if I was using 1000 BUT in the cupboard you can see that the main meter is not flashing and alternated between RED and the current total which does not change,
Meanwhile my SolarBoost in the cupboard reads boost 1000watts but does not show up on the owl at all. Thus I suspect that the boost has a brief pause where it decides how many watts to send to the immersion heater and that the owl read in that same instant.
Regardless of that. This system seems to suggest that you can read import and export with just one clamp. That would solve my problem.
I was also interested to see if anyone else with a solar boost are finding it’s actions are invisible with this system.
I don’t know how either SolarBoost or Owl work in detail, but the ability to measure the direction of power flow depends on being able to measure the relationship between the current waveform and the voltage waveform. There’s an explanation here in ‘Learn’: An Introduction to AC Power — OpenEnergyMonitor 0.0.1 documentation
The emonTx, the emonPi and Robin’s designs all work in the same way and all are able to differentiate between imported and exported power when used with an a.c. adapter. It is the a.c. adapter that both measures the voltage accurately and provides the reference that gives the ability to determine the direction of power flow.
Do you want to only display your energy use, or do you want to replace the SolarBoost (as well)?
If you want to replace the SolarBoost, or you think you are likely to want to do that in the foreseeable future, I would advise you to look at Mk2PVRouter.
If you only want to display (via a web browser or smartphone app) and record your energy use, then the emonPi is likely to be what you require. The emonPi has two inputs for current and one for voltage. With one c.t. and the a.c. adapter, it will show nett power and energy on your grid connection. Therefore it will “fill in” when your meter displays “RED”. In other words, the emonPi’s records would give an answer to this problem:
If you add a second c.t., (subject to where you can put the c.t. on the house wiring) you can measure either your house consumption, PV generation or the power/energy diverted to heating water.
If you want to measure more than the two currents, then you need to add an emonTx, which will give you an additional 4 measurement points.
I thought that was the case (but didn’t look it up - thanks Bill) and if so, it confirms Kazek’s observation and it will be unable to differentiate between import and export.