AC Coupled or Hybrid for future expansion

Looking for advice on best decision for GIV ENERGY solar storage battery :

I've a 4 kw Solar install and looking to add the battery storage Inverter + 8.2 KwH battery , the cheapest option is the Giv AC coupled inverter but I am considering the Hybrid to allow for future addition of panels :

I don't want to compromise my FIT for the current setup (panels > inverter >FIT meter) , but am I correct in assuming that because the additional panels would be DC direct to the separate hybrid inverter and then out to the batteries , that generation never feeds into the grid (purely additional DC for battery top-up and would be ok)

I'm running 2 EV's - so once I have a working system , looking to expand the battery capacity in stages to utilize the solar (potential 4 kw x 2) and Octopus overnight rate.
I'm interested to know if anyone else has completed this on a existing ( 8 years old and still going strong) solar install

I think much depends on where you want to site things.

Because our batteries were to go into our (separate from the house) garage we had to go AC coupled, since I was told that running DC cables underground is against regs.

If you do go AC coupled, you can, at a later stage, add a second inverter for the extra batteries (and thus increase your peak output levels - as things are, the maxiumum output is 3kW from a single battery inverter).

MrBananas This thread might tease out some of the issues for you, particularly regarding the window for overnight rate ie that it's not long enough to charge a large battery with a 3kW inverter.

We purchased our solar system after electricity suppliers started to go bust and gas/electricity prices rocketed so we haven't been able to change from the variable rate tariff for electricity that we landed on when our supplier went bust. However, we do have a large array and two 5kW hybrids each with its own 8.2kWh battery. If the sun shines, the batteries are fully charged by mid to late morning and the EV can be topped up in the afternoon (when it's on the drive) after the washing has been put on. The batteries are usually still more than 50% charged by the time the PV starts to charge again the next day. We can easily ride out one day of poor PV production but two or more in succession puts us back onto the grid. The weather here in north Wales was not brilliant yesterday and it took all day to charge both batteries up to 100%. That said, our import from the grid has reduced from over 100kWh/week to less than 10kWh/week, and that's in February and March, having bought the EV in February. We haven't actually tried to reduce our consumption, in fact it has gone up because of the EV, but we have changed where the energy comes from.

Thinking about your ideas, you may struggle if you have both EVs charging overnight and you want to charge more than one battery. Assuming that each EV charger is 7kW, that's about 30A each; 60A overnight import. Depending on the supply from your DNO, you might be limited to a 60, 80 or 100A main fuse. Even a 100A fuse would only give an additional 10kW to charge your batteries. Of course, if you only have one EV charging, then the issue becomes easier to solve, but still difficult to ensure you can match your demand to the DNO supply. Using your existing FIT-array to charge your batteries during the day would ease the situation and should be readily done by ensuring that the new equipment charges the battery in preference to exporting to the grid. Whether there's enough sunlight/PV capacity and time overnight to do all that you need might take a bit more thought.

I have a similar setup - solar panels->inverter->generation meter->house/grid with a very good FIT rate.
Also have an AC coupled Givenergy Inverter and 8.2kwh battery. The battery system is completely separate from from Solar so doesn't effect on FIT. However, since the GE system monitors grid and solar it complements the soalr very nicely, storing any excess from the solar for later use. Also the two inverters can output at the same time giving me times when inverters are both working to meet a short term heavy load without taking from the grid. You ay need to get DNO approval if both on same phase, but should be able to fast-track that application.
The hybrid inverters are favoured by installers because they don;t need to get permission from DNO but they don;t give you the benefit of two inverters. for heavy times of demand.

I went for the AC inverter to complement an existing PV system (same setup):

• The hybrid inverter cannot charge from export on the AC side
• Changing the existing PV system (replacing the inverter and meter) puts existing FIT payments at risk and signs away the 50% deemed export

Some competitor systems enable both AC and DC charging through a separate DC charge controller on top of the AC inverter - this may be feasible with GivEnergy but would void the battery warranty. If you ever want to add more panels, use a second inverter with export limiting to the overall 3.68kW.

kwmc I had to get dno approval with my hybrid system to get an export tarrif off octopus.
I don’t see what difference hybrid or ac makes tbh. If you are exporting to the grid you need dno approval. 3.6kw is usually just a box ticking exercise.