Export to grid payments

I am new to solar and learning a lot. I do find it difficult to understand a lot of the information available in the app. Is there a manual available that breaks down everything, explains the relevance of the various metrics etc.
Also does anyone know how often Octopus pay for exported energy to the grid. Is it random or a fixed period in the year?
I keep a daily record of the energy exported daily taken off the Givenergy app. on my iPad. There is a variance between the number I have and the total export (it's greater) shown in the Givenergy app on my MAC. As the information is derived from the same source (i assume) I expected the numbers to be the same.

CJI there are a lot of topics on here that cover your points, but in summary:

• have a look at the KB: https://kb.givenergy.cloud/ or the unofficial wiki: https://wiki.terravolt.co.uk/ which should help break down all the info in the app and portal

• Octopus will usually add a credit on to your monthly bill - make sure you sign up with them ASAP as the process can take a while to complete

• there will be a difference between the GivEnergy import/export figures and those from your supplier - they're not the same source as your supplier uses your meter (which is certified) and GE use a CT clamp attached to your meter tails which have a small tolerance and will not reflect 100% the same as your meter. Take the GE stats with a pinch of salt and don't use them for billing purposes.