Big discrepancy between the usage graphs and the actual meter readings

Good point @Emmanuelle_OVO definitely worth checking. 

I have been struggling to understand my energy usage with OVO. I have been residing in my current house for almost a year, but I have been receiving weird bills. Some months, such as be my energy bill was around £60, while in other months, it spiked to £220, despite only having two people living in the house. I am puzzled by the significant fluctuations in usage, which have occurred without any changes to our lifestyle. Additionally, I noticed that the daily usage from the 20th to the 27th of the month is exactly the same, which seems like a system glitch. Same as 5th to 19th, not sure why the usage was dramatically lower than others. Has anyone else experienced a similar issue? I am incredibly frustrated and struggling to make sense of my energy usage.

Hi @HeadbuJJ and welcome to this customer based forum. There is a change of usage over the months especially over winter of course. 
If you look at your meter readings to check if they’re all accurate that might help as sometimes readings can be estimated. 
https://account.ovoenergy.com/meter-readings

Other than that, if you have a smart meter with readings set to record every 30 mins you could see when any extra usage occurs

I do understand that winter season may entail greater consumption, however, the captured data is of April. Would it be necessary for me to submit readings periodically? I am already using a smart meter

If you check on your account you will see what readings are being used. Smart meters do drop connection occasionally. If there are estimated readings for a few days you can give manual readings to keep things on track

How can I properly submit the readings from previous days?

You don’t need to. OVO use what they call a live billing system so any meter readings given now would correct any previous estimates

Something fishy is going on with the usage days. I have solar panels with battery so it's not uncommon for my electricity usage to be pennies (as seen in screenshots from early last week). But then for a similar amount of kWh usage, for some reason the app is saying we owe £1. What's more if I go into the weekly view, it's saying we've used over 5kWh for those days, which not only doesn't line up with the daily view, it also doesn't align with the meter readings or the solar battery readings and would be an incredible outlier. I know the usage data goes buggy from time to time but very concerned it's for 3 days now recording 100 x the actual usage. 

Mine is showing an incorrect amount for Monday this week it shows our use as 0.29p usually we are approx £1.50 per day it fluctuates but never as low as Mondays results. I’m sure it’ll sort itself. 
I also notice our free hour of elec registers but our readings are slightly off makes me wonder if we are getting much benefit from this scheme. Can we trust our smart meters. 

The free elec scheme will be entirely credit based, you won't see any effect of it on your usage.

Spoke to customer services today and they've confirmed there's a data problem with our end, but on their end the readings are what I would expect.  They are working on a fix but do wish they'd put an info bar up when stuff like this happens.