I wrote an earlier post about how my electricity company actually provides a decent API. Unfortunately it turns out that even though the API is OK, the data is bad. Data fetched for daily consumption is sometimes completely wrong. Re-fetching data for the same interval at a later time gives different results. I can see that some of the data is wrong, but I have no method to decide which data is correct. So currently the data is more or less useless.
This is is extra worrisome since I don't know if the invoicing will be based on correct data. So far I can't put the full blame on the company though. It could possibly be the meter (that's owned by a different company) that's acting up. I'm currently waiting for access to the P1 port so I can compare the data being recorded by the meter to the data reported back by the provider.
I've reached out to support, but is still waiting for an answer.