Can someone provide some guidance if I should go with Burst Mode or Phase Control power diverter. I read Learn | OpenEnergyMonitor but it did not provide the guidance on which option is better for a particular application. I will be dumping 200w of power at the most.
thanks for the help.
The choice might come down to how your energy supplier’s meter works. At 200 W, which is nothing really, you should not experience any major side effects from either flicker (burst mode) or harmonic interference (phase control), but if your meter uses a very small energy packet size to make its measurements, then you might find that burst mode is the only one that’s viable.
Unfortunately, data on the meter’s packet size is hard to come by, and you might only find out when you implement your burst-mode system.
Thanks for the reply Robert. My meter is also locked up in the cabinet outside, so I do not have a means to find out what type of meter it is. Burst mode it is then, I guess I need to order MOC3041 for the burst mode operation.
I already have Arduino Mega with 10 CT’s monitoring various circuits in my house and uploading data online. I am, guessing since diverter need much quicker loop cycles than my current setup, I will need to use another Arduino for the diverter. Hopefully I can use Voltage input from my existing setup.
I think you are probably right. The max speed of the ADC that you have in the Mega is about 9.6 k samples per second - you cannot use the standard ‘discrete sample’ method with a diverter, so you would need to extend Robin’s or MartinR’s sketch to read all 11 channels and do the processing as well as control the diverter. At best, you would end up with a very slow (and inaccurate) sample rate for each channel - I think 14 samples per cycle.
Provided that you connect the two GNDs of the two Arduinos together, you should be able to share the voltage signal.
I presume this is the same house that you were asking about how the PV inverter shared its output?
I figured that it will be too slow, 10 CT inputs, LCD control, upload data to two different websites and download data from one website 
I got a lot going on there …
This is for the same house.
That is good that I should be able to utilize the same voltage signal. Would I be able to utilize CT data/readings as well (if I hook up right after the diodes)? Or will I need to move 2 CTs to the second Arduino for the diverter to work correctly, and then send the readings to the first Arduino in order to upload to the web.
You could share the CTs - the second Arduino would need to have its burden resistors removed of course, and you only need a single c.t. on the leg that has the PV infeed for the diverter to work. The second c.t. is purely for information, so that could stay on the other Arduino. If you do that, you don’t need to send any data from the diverter - it will just sit there doing it’s thing and the 10-channel Arduino will do all the monitoring and reporting.
Note: When I say you can share inputs, I assume both Arduinos will run at the same voltage for the ADC reference - probably 3.3 V or 5 V. If not, you can’t share (because the mid-point bias for the two inputs will be at a significantly different voltage - a few millivolts won’t matter, the difference between 1.65 V and 2.5 V will).
Yes, both Arduino’s will run from 5V. Hopefully from the same old Brackberry usb charger that produces very clean voltage.
By “need a single c.t. on the leg that has the PV infeed”, do you mean CT by the Supply meter in the diagram? So diverter will try to make a current of 0 when PV is producing power, right?
My solar panel will be hooked up into the circuit that currently feeds living room. I currently have a CT that monitors this circuit. For the reporting purposes, how can I monitor on how much power PV produces? My thinking was, that if the feed value turns from positive to negative, then PV is producing and I can send only negative values showing how much power my solar is producing… Is my thinking correct?
I do.
That is exactly the principle on which it works - or a tiny bit more precisely - the average energy flow over the cycle time of the bursts, and that cycle time depends on the current in each direction and how far apart you set the detection thresholds, which therefore defines how long it takes to reach one threshold for the other. You might like to read the ‘meters’ article, if you haven’t found it already.
That idea will only work (i.e. tell the truth) when you are not consuming in the living room. If the c.t. is on the supply side of the “p.c.c.” (point of common connection), then it will record the nett energy flow at that point, which will be (Dining Room consumption - PV Input). So to record only the PV input, the c.t. needs to be on the PV infeed before it connects with anything else.
Robert,
When you say that I can share CT’s just need to remove burden resistor, I see the diagram being as below. Is that correct?
I don’t know whether you have the correct pins on the photographs of the Arduinos, but assuming you have, then yes, you are wiring it correctly.
(I had briefly forgotten that you might not be using the emonTx Shield, which has the burden resistor on the pcb, which would have meant you had two in parallel.)
Got it. Yeah pins I will figure out later. The main thing was wiring of the CT.
thanks again for your help!
