Scheduled refresh failure - Memory error: Memory Allocation failure

Hi, 

Hoping someone will be able to give some advice on what may be causing this issue. 

I have a report built up which links to 2 locations both in a SharePoint folder

1 is a direct link to an excel file looking up employee details

2 is a document library where the query combines multiple files of raw data all small size nothing over 1mb probably about 49 columns in total.

There are a few conditional columns and a couple of customer columns in the combine query but nothing too complex, there is only 1 relationship between the 2 files aligning a serial number from the employee details to the raw data.

When I refresh in the desktop absolute no issues it's a bit slow but it goes through however it throws back the following error everytime I refresh in the service.

Any advice on why or how I can resolve this would be great.