I have recently increased the number of PV panels and now I regularly have excess energy to dump.
I have a 3kW immersion element spare in the tank so that is the load I am going to use. I want to use a pulse method controller which uses an adjustable pulse length with zero crossing triacs.
I will try to use a pulse distribution system so the load pulses are as regular as possible rather than a simple on-off waveform.
Does the Smart Meter still record the total consumption accurately with this type of load?
My alternative method is phase angle switching which creates a lot more RFI.
As far as I’m aware, yes they do. However, the real question is what do they do with the numbers once the energy has been faithfully measured, and therein lies the problem. Some apparently behave very much like a mechanical meter where there’s a fairly wide band where energy can be exchanged with the supply with no nett energy flow over a long period and so the short bursts of import between bursts of export aren’t charged. Other specimens can and do have a much narrower band over which this is allowed to happen so it becomes impractical to “defeat” the charging mechanism when you’re using a burst-fire controller to balance your load against the excess PV.
This is worth looking here Technical Information - Association of Meter Operators and read “Reverse Running Meters Guidance”
How applicable this is now, I don’t know. And bear in mind, it’s only “guidance”.
Despite the many problems with phase angle control or fast PWM and the need for extensive filtering, these would appear to be the only methods able to offer any certainty against being charged for import that’s balanced by export over a period that’s longer than (possibly) one half-cycle of mains.
I have obtained a 3kW missing pulse type of controller. I propose to conduct an experiment with a 3kW load (immersion heater). I have OB115-Mod Single phase 1 module energy meters on both my main supply and the feed from the two PV systems as well as a Smart Meter. I also have data from the PV inverters.
The plan is to pick a cloudless day so the PV energy is fairly constant over a short time period. I will then increase the load in 10% increments and check all power readings and Smart Meter at each load setting over a five or ten minute period. If the Smart Meter is measuring the energy correctly (or not) then it should be clear to see.