Charting item aggregate value or Sum by day

Setup, Configuration and Use Items & Sitemaps
1

Is it possible to chart by an aggregate value .
eg If I write hourly can I sum for a daily chart?

2

There are not a lot of details to go on here, but in general create a separate Item to store the daily sum. At midnight (or there about) trigger a rule to calculate the daily total and update the daily sum Item.

3

Clarification, I’m persisting a item every hour, however I’d like to chart by day but sum the values.
ie I’m logging kwh every hour and would like see daily totals over the month.

4

Same answer. If you want to chart by day, you gotta save the data by day in a different Item (or change your existing Item to only save once per day).