Smart Zigbee switch in metal consumer unit

I have an 30Amp AGA which I've traditionally run on Economy 7. But now I've also got an EV I've shifted to Intelligent Octopus which gives me 6 hours of cheap rate 7.5p and the other 18 hours at 30.23p. But IO also allows for additional cheap rate time slots depending on what Octopus has available. Under ECO7 I had a terminal 5 which flagged up when cheap rate was active and this was fed to the AGA which then knew when to start charging but this isnt available with IO. So I'm looking at running Home Assistant pulling tariff data from Octopus and then programming the feed to the AGA for the 6 hours +any extra hours.
I've bought a Home Assistant Yellow unit and am planning on installing a smart DIN rail mounted Zigbee switch in the consumer unit to take the place of the Terminal 5 line and control the AGA charging.
As it happens I'm also about to have a consumer unit upgrade and this will have to be a metal case unit to meet current regs. So what I'm after advice on is how well will the Zigbee Connector in the HA see a Zigbee smart switch in the metal consumer unit? I could add a router very near/adjacent to the consumer unit and look to the mesh functionality to sort it out. But does anyone know if the signal would penetrate a metal consumer unit which I presume will be earthed (Faraday Cage?). Alternatively anyone out there able to advise on what is likely to work?

BarryForde Your unlikely to get much through the metal box. Hi for metal consumer unit with an adjacent plastic housing with a DIN rail to house the Zigbee.

BarryForde You could install a contractor within the consumer unit with a low power 240V ZigBee switch in an external DIN housing. Alternatively, if Terminal 5 is nothing more than a 240V off-peak sensor, then any mains powered Zigbee switch capable of supplying the 240V signal adjacent to the AGA, or the meter if that's where the existing connection comes to would work. Doesn't need to be DIN rail, just a ZigBee switch in an enclosure.

Tim Yes that sounds sensible. Its just that historically my wiring is a mess, first the eco7 installation with a separate little consumer unit, then the Solar/Battery system with the meters in yet another box and finally the EV charger with its own consumer unit. Makes spaghetti junction look neat... I was hoping to get a nice clean new install with everything in a single neat consumer unit with either RCBOs or AFDDs on every feed (still trying to decide and see if piggy bank can bear it). But looks like the AGA feed will need to be outside of that, still its only one!

Tim contractor

Ah shucks! You could install a contractor, but he might need feeding and watering. A contractor on the other hand would be just the job.

Tim But by the time I cover auto enrollment pension costs and NHI I think it might be too expensive!

Tim flipping autocorrect really likes contactors!

Just to bring you all up to date...
I got the new consumer unit installed, FuseBox F2029MX and yes its metal. I asked the electrician to try installing the smart Zigbee switches directly in the unit to see how things went. Pleasantly surprised to find that I am getting LQI 104, RSSI of -74 and the control from HA is working flawlessly! I have a number of other Zigbee plugs and stuff around the house including a couple within a few metres of the consumer unit so perhaps its the mesh stuff thats doing it. Anyway got everything in the one neat unit in the end.