Mismatch in electricity imported on my solar PV app compared to my smart meter and OVO online account?

I assume your top picture is from your solar app? In most cases they measure the current flow from a CT clamp on your meter tail and these aren't very accurate. While it's not impossible that your smart meter is incorrect it's far more likely that your solar app is wrong.

My solar app always reads at least 10% low.

Report from the Solar app:

As mentioned above some will say this is less accurate, Ovo says for March we have spent 417.46Kw but the solar app is reporting 207.26Kw bought from the grid (just under half of what Ovo says, which is quite a difference and not a minor clamp inefficiency)

Not to hand sadly. The high export days on the 10/11th March seem about right (we were away for the weekend)

For these dates it’s pretty comparable and what I’d expect for the +/- mismatch

Solis: 10th 3.77, 11th 1.88

OVO: 10th 4.11, 11th 1.96

Yeah we have the 30min reporting form the smart meter enabled to try track whats going on.

Looking on the 13th March

Solis: 4.65 (from grid)

OVO: 11.53

Ok that’s useful. There are significant times when your consumption looks more than your generation/self use and the evening peaks are all from the grid rather than solar or battery. You can see the difference between the green line and the orange. 
There’s a lot of detail there so when I get chance I’ll look closer but I’m now wondering if there’s something else amiss like the battery demanding power from the grid if it’s at its lower limit

All meters are independently validated - they are not OVO’s as such and so have to be calibrated separately. You can do a check if you can turn most things off and just turn on a known load for a certain time, checking meter readings before and afterwards. 
There are some strange looking pieces .. as I said, your export level is a bit high if I compare to others I’ve seen. There’s also an early peak which suggests it’s import to charge the battery which is why I’m wondering if there’s some setting which is making the system charge from the grid more often than usual. 

That might help. If you look at 13th, there is a spike around 5am which looks like it’s battery demand (charging from the grid). Generally the batteries have a limit at 10% of their charge when they stop supplying but also if the charge drops below 10% they can ask for a charge from the grid. The level is to stop problems with the batteries and is quite typical. The level is adjustable and so you might want to check what it’s set at. It’s usually called ‘Cut Off’

Just giving an update for anyone that may still see this thread.

 

2 weeks on and it seems our useage from the Ovo app is pretty unchanged and on somedays even more useage than history. (Started solar from 7th March, some days seem to report correct around 1-5Kw, especailly if we were away for the weekend) but still feels the ‘smart’ meter is not recording only the electricity from the Grid

Feb:
 

March:
 

 

Just looking at this again, bit by bit, while I appreciate that the above detail is not complete, if I add all the March figures together I get 193.13 kWh which is close to the 207 you have from the solar app. Not sure where the 417 kWh comes into it?