I have a large spreadsheet with more than 76,000 rows.

In this spreadsheet I have 3 columns, namely Date, Time and kWh.

The kWh column gives half hourly electricity consumption values based on the Date and Time interval.

I need to roll up the date and time columns into a 24 hour period so I can get daily electricity consumption figures. What I would like is have a new column with the date such as 2018/06/01 and a 2nd corresponding column giving the corresponding total kWh for that day based on the half hourly data points in the original kWh column.

My question is what formula do I need to roll up the dates into a 24 hour period and total the kWh for that period?

Thanks

Regards