In the Excel sheet below, the highlighted value at cell C23 gets its value from the above cell if the current time ( in hours as in cell C10) only if current hour is 01:00 am, but starting from the next hour e.g. 02:00 am in cell D23 the value should be the above cell value in D22 + previous hour value which in this case is C23. This logic continues so E23 = E22 + D23, that is the sum of the above and to the left value. The problem I'm facing is how to get the previous value, I tried prevalue() but it works only on tags, I also tried an analysis to reference the same variable as input and output and got a 'circular reference' error. Any ideas, please?