Bringing a 30Amp AGA cooker into the mix

I'm after some advice. My setup is 5kWp panels, dual 3.6 Gen 2 hybrid inverters each with a 9.5kW battery, (EV charger and Hyundai Kona 64kW car - ON ORDER but still waiting..) and a 30Amp AGA range cooker.
Historically I've used an Economy 7 tariff which is fine for the AGA which needs 7 hours overnight to fully charge. But now I have several choices, could stay with Economy 7 and charge the car and AGA overnight at the 15.62p/hour rate. Or I could go with Intelligent Octopus which gives me 6 hours at 7.5p. But IO's 6 hours isn't long enough to fully charge the AGA so I'd end up pulling 1 hour which is 5.5Kw, either from the batteries or the grid. But if I go with IO I have a question on what happens if Octopus decide to go with a charge outside of the 6 hour window. How do I stop the batteries draining to the car rather than taking cheap rate from grid.
Can anyone suggest how to set this up or am I being overly optimistic thats its possible?

BarryForde Welcome to the forum. Unfortunately, Mystic Meg hasn't been seen for a little while, so the prospect of definitive advice regarding tariff won't have the inside track to best deal. We are all different and have different requirements and concepts of acceptability.

You're used to off-peak charge and maybe your best bet is to stick with what you know. Your PV is good but the main resource is the 9.5kW battery attached to each 3.6kW hybrid.

From the sounds of it, you need to pull 5.5kW for AGA, 7.2 kW for EV (when it's delivered) and potential for 7.2kw for Givenergy hybrids; totalling about 20kW - that's about 80A. As long as your DNO fuse and system is good for that, then getting the best tariff is a simple maths job. 7 hours at 15.62p vs 6 hours at 7.5p (vs maybe 5 hours at 4.5p EDF EV tariff).

If your batteries have sufficient capacity, after charging the AGA for an hour, to last you the rest of the day until the next off-peak, IO would work. Even better would be the 5 hour tariff as it's a quarter of your E7.

WRT to battery drain to car, just set the timed charge window on Givenergy inverters to be the same as the EV charger timed windows and they shouldn't interfere with each other.

Tim Hi Tim, The problem is bit more subtle than it first seems. The obvious tariff to take is the Intelligent Octopus one which gives 6 hours of cheap rate 7.5p/kWh. This would give the lowest overall cost for running the house/AGA and EV. But there is a problem.
The AGA does not work in the time domain but is event driven, it goes active if the cheap rate terminal on the meter goes active or if the core temperature drops below 375C. So ok for the standard IO 6 hours it pulls power and we can set the batteries to charge only between 0030 and 0630. The AGA will sense the cheap rate and charge, the battery's will also stay in charge mode.
But Intelligent Octopus is designed to give them flexibility to match EV charge times to grid conditions. So they may well decide to charge the EV outside of the 0030-0630 slot, perhaps going for several non contiguous slots! That means we cannot know what time slots to push the battery's into charge only mode. So if Octopus decide on a windy evening to start charging my car at 2200 the cheap rate terminal will go live and the AGA will begin pulling 5.5kW to charge itself. The battery's are not set to only charge at that time and will prioritise discharge rather than grid consumption and bobs your uncle I have a pair of flat battery's.
So what I need is the facility for the Inverters to detect the cheap rate signal on terminal 5 (or in some other way) and automatically change the battery status to "Charge only". The EV will carry on charging, the AGA too, which is fine, and ditto the batteries as we will be on cheapo 7.5p rate.

Can anyone suggest how to implement an automatic detection of power on terminal 5 and automatically put the batteries into charge only mode? Or come up with some other method of detecting cheap rate periods other than using time of day?

BarryForde What you require is some home automation. An event-driven system set up to sense the switching on terminal 5 could trigger the inverters to change mode, and losing the terminal 5 supply could trigger an inverter "return to" mode.

I know Octopus do have integration with Givenergy inverters and someone on here will be able to tell you whether what you are alluding to can be controlled by allowing Octopus to take over control of your inverters. through your API key to their cloud servers. It's up to you whether relinquishing this control is something that you are happy to do or not but it would be the simplest solution.

If not, then you'd have to look at some simple home integration. This could be achieved using any of the well-known voice activated home controls, or Home Assistant, or Node-RED, probably even IFTTT. It all depends on how motivated you are to own the solution. Controlling the Givenergy inverters is readily achieved via Givtcp (local and doesn't rely on internet access) and/or Givenergy API, which does need internet access to be available. All of the DIY solutions would require something to run the home automation on; old PC/laptop/Mac, eBay refurbished Wyse terminal (£20-£40) or just leave your home computer at home and switched on all the time. The only other thing you would need is something to sense the voltage on terminal 5. This could be a shelly, sonoff basic; anything that will switch on and send an MQTT message to your DIY home automation system. It's all perfectly feasible but does require some application.

Tim That sounds very encouraging. I think the best thing for me to do is wait till my install completes and I've migrated to Intelligent Octopus and then dig into the options for sensing cheap rate (Terminal 5 live) via some extra hardware and software to set the batteries to charge only. Sounds feasible, maybe when I get there someone on here will own up to having done some pioneering work I can plagiarise. Thanks again for your help.
Jinko panels are due with installers tomorrow, batteries and inverters are here. Only possible hiccup now is LoRa units which are out of stock at midsummer but hopefully the installer already has them. I need two links, one for each inverter.

BarryForde maybe when I get there someone on here will own up to having done some pioneering work I can plagiarise

There are literally hundreds, dozens, at least several who have done this (including myself). However, there are as many ways to do it as skinning a cat, but I wouldn't advocate that.

If you end up desperate for LoRa units, send me your address and I'll post a pair to you. I converted back to using a spare CAT5 cable because the reception between my house and the workshop was poor.

Tim The thing I love about solar/battery systems is that the more you learn the more you realise you dont know, sigh!

mrand31 Wow thats a very helpful offer thanks. I'm hoping my installer will emerge from the mists this week and then I'll know if anything is still missing.