New heating system but struggling to get the right tariff

I concur:
  

Best of British ​@BPLightlog!

There’s a bit of confusion over naming these heaters, probably because the separate ‘Solar’ range seems to have been discontinued and the Plus varieties (i.e. Wi-Fi-enabled) have the same capability as only the Solar ones had before. It seems to come down to a control device, ‘G-Control’, that provides “Efficient management of surplus energy in photovoltaic installations.”  The manual will with any luck make it clear whether this control unit is essential to making use of solar power to charge the heaters. 
  

@Viv1966 The little display inside your black box (which is actually a mini-consumer unit just for the solar panels) is a very neat little meter. There’s a tiny button in its bottom right-hand corner that when pressed repeatedly will show you all sorts of data. It seemed to be showing the power factor of the supply when you took the picture - I’d leave that one to the experts! You should be able to get readings, though, of power generated so you can keep your own records. This is a fairly detailed description of the beast: 
DEM1A Series; what the numbers you see on the display mean is listed in part 3 of the document.

​@juliamc is very probably right that the inverter is up in the loft. You will of course take great care if you go hunting for it, won’t you!

Isn’t technology getting complicated 😳

I’d thought the inverter was in the outside cupboard where the old oil boiler was - but it’s got to be somewhere !!

Honestly i think you are all amazing!  Thank you for all your finding out and explaining to someone who doesn't know the first thing, its much appreciated! So these figures in the junction box are they what you would normally see on the inverter?  Don't worry i won't be searching in the loft for anything....i have a spider phobia and not wonderful with heights!  Its interesting what you are saying about charging because at the moment, although the heaters do seem to work  but they don't seem to have any charge in the battery and at the moment it says on the LCD display that they are programmed to charge during the day?! I probably need to re-programme it to charge at night. So i do have the solar heaters then!

Am i right or have i completely misunderstood?

​@BPLightlog  i filled a form in online requiring the "Don" information  and "MCS" certificate with Octopus on 10th April. They said it takes 14 days to register which brings is to about now -ish. So how will i know when its been registered?

You should get notification from them giving you a ‘start’ date for the scheme. 

I would suggest you hang on before changing anything ​@Viv1966 until we can see how this is supposed to work .. obviously the solar feed is only live during the day (no sun at night) but then you also mention batteries. 
^
[ I haven’t caught up on the manual yet - I was rather busy yesterday]

Ok, the heaters are ‘traditional’ storage design 

they use bricks to store heat which slowly gives heat out later

The standard fitting assumes an off peak tariff but this can be set to other situations 

The solar part can also be defined from the app 

but I’m assuming that ‘solar alone’ won’t be sufficient heat during winter.

I really think the installation team should have walked through all this and made sure it was set up to match your situation and needs.

But the bottom line is you probably need an off peak tariff - that’s where your other appliances matter ​@Viv1966 as there is also a peak time for this which means during other times you pay more for your energy.

That is why ​@juliamc was asking about other appliances 

Well thank you for all this info ​@BPLightlog . One good thing to note  is that the Compliance Team from my housing association are visiting on Friday to see how the heating situation is going.  The batteries i mentioned, are diagrams on the LCD display indicating that  they are empty.