Custom Query/Function to convert UTC to EST

Hi all

Struggling with some datetime conversions in PowerBI Desktop and Service. Seen this topic all over the internet with no great answer. I'm hoping someone has a simple function I can invoke to solve this, as I have many datetime columns to convert.

I am pulling datetimes from a number of sources, which are mostly in UTC. In PowerBI Desktop I'm using ToLocal to display these in EST, which is my local time, and is how my end users need to see the data.

However this does not work in the report after publishing to the PowerBI service, which seems to use UTC as its local time.

If I take 18:00 UTC, ToLocal has no effect on the data -- it is still shown as 18:00  in the PowerBI Service.

A simple solution would just be to subtract X hours from my UTC times in PowerQuery. The data would "looks" like EST in PowerBI Desktop, and will "look" like EST in the PowerBI service (even though PowerBI thinks it is a UTC time).

However this does not account for daylight savings at all. It doesn't help of course that DST start/end changes every year.

So I'd like an M function that can...

-> Read in a DateTime that is in UTC

-> Check if that DateTime falls into Daylight Savings

-> If yes, subtract 5 hours

-> If no, subtract 4 hours

Any ideas?? Surely this has been solved somewhere!