Newbi AC Coupled Question

I currently have a 3.99 kWp Solar PV system installed in 2011.

I am thinking of adding an AC coupled 3kW inverter and two 9.2kWh batteries.

I understand this combination will be able to store energy from the grid (at off peak times) and prevent me from exporting “excess” solar energy during the day (assuming battery capacity is available).

The AC coupled 3kW inverter seems to come with a single current meter (EM115). In order to store the “excess” solar energy the Inverter would seem to have to know the power being exported to the grid rather than the power being generated by the solar inverter.

Why then do the GivEnergy diagrams show the current meter installed between the solar inverter and the generation meter rather than by the grid meter?

What am I missing?

The AC3 has 2 x CTs.
EM115 Grid Export/Import via EM115 Meter
Passive CT on the Solar Power Live wire from the Solar Inverter (Usually in the Consumer Unit)
or
The Solar can also be via another EM115 with MODBUS ID02 set, if the Solar power is over 5m from the GivEnergy Inverter.

So Yes the AC3 needs to know 2 pieces of information, Solar production and Grid power (+ve or -ve)

Thank You

As my solar power is >15m from my proposed inverter site I need to learn more about the “second” CT/EM115 requirement. Is this documented anywhere?

Am I correct in thinking this “second” CT/EM115 is only required for display/information purposes? I assume the AC Coupled inverter can actually work without it?

ZenSlo As @TheDragon (GivEnergy) said, two EM115s are specified in the installation. However, if there was only one which measured the energy flow in and out of the premises, I would have thought that a single EM115 would be sufficient for the AC3 to divert grid export to charge its battery and to reduce grid import by discharging from its battery. Someone out there will be able to answer whether the EM115 measuring the PV output is for control or display purposes.

The (new) AC3 has a maximum of 3.6kW output, which means it would take about 5 hours to fully charge your batteries. If you have an off-peak tariff with a 5 hour or larger window, you will be fine to charge both batteries up from the one AC3.6. Should you stretch to a second AC3.6, you would be able to support a greater house load (kettle/oven etc) from each battery. However, there are issues with AC3s getting confused, so perhaps your proposed solution is a good compromise between power available and time to charge.

ZenSlo AC3 needs a solar daya input in order to use excess solar.
Its not enough just to look for excess.
Another installer thought just excess monitoring was fine.
It wouldnt charge from solar without Solar data input

The 2nd CT will be part of your installer survey and design.
If you search Google you will find some old installer manuals.
Which give you an idea

@Tim 3.6kw on an AC3? Maybe mixed up with a Gen2 Hybrid.
AC3 is 3kw in and out.

TheDragon (GivEnergy) 3.6kw on an AC3? Maybe mixed up with a Gen2 Hybrid.
AC3 is 3kw in and out.

Quite right; confusion with HY3.6!

@ZenSlo You'll need over 6 hours to fully charge your Batt9.5s, but you'll still be able to charge 15kWh in a 5 hour off-peak window and as long as that's enough to last you until the next window, you'll be good to go.

Thanks everyone.