Grid Interface Meters [GIFs]

I wish to use within my property as much as may be possible of the otherwise exported surplus energy produced by my 3kWp PV system.

I note from other content within the OEM site that the designs to achieve this rely upon either the use of physical integration of imported/exported power periods in the old-fashioned electro-mechanical GIFs or the simulation of this effect within the new 'electronic' meters.

I note that you have discovered that the energy bucket size over which integration of imported/exported power is designed to occur in the new 'electronic' GIFs was initially 3600J but that examples are now occurring where it is lower (1250J).  This sort of change will undermine (absolutely destroy) the basis of the design of your power-diverter offerings.

I can see that the Power Supply Companies will wish the bucket size to be (ideally) infinitely small so that they will maintain access to this source of energy that they are on-selling at a huge 350% mark-up in price.


Are the new 'electronic' GIFs formally required to exhibit this characteristic or, is it just a non-required design feature that we must expect will be progressively removed from future GIFs?  After all, it will be very simple to just ignore (or set to zero) all instantaneous power samples that show a negative 'imported' value.

With thanks,



Robert Wall's picture

Re: Grid Interface Meters [GIFs]

I don't see how it will be possible to totally ignore every sample that shows power being exported, given that in the UK at least domestic consumers only pay for real power and there is no charge for vars. Clearly if every export sample was ignored, there would be an implied charge for imaginary power because of course imaginary current is taken from and returned to the supply over the mains cycle. I believe the energy packet is the result of a more-or-less exact emulation of the mechanical meter movement and that a likely reason for that was to ensure customer acceptance. I can easily envisage the size of the packet being reduced over time simply so that, as you suggest, canny users can't use the supply network as an energy reservoir.

There are solutions to this problem, but as always these carry a cost implication with more complicated electronics.

I suspect the answer to your question lies in the IEC standards for energy meters, and unfortunately I don't have access to a copy.

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