Excel does not have any way to do this.
The result of a formula in a cell in Excel must be a number, text, logical (boolean) or error. There is no formula cell value type of "empty" or "blank".
One practice that I have seen followed is to use NA() and ISNA(), but that may or may not really solve your issue since there is a big differrence in the way NA() is treated by other functions (SUM(NA()) is #N/A while SUM(A1) is 0 if A1 is empty).