The way I see it you have
server-excel-DAO

You have 150 different time series. You want to track the
min/max/current value of each time series in your DAO.
I would take advantage of Excel built in feature "Worksheet_Change"
event.
Make 3 new cells for each of the 150. (perhaps on a different sheet)
CurrentValue, MinValue, MaxValue
Then capture the
Private Sub Worksheet_Change(ByVal Target as Range)
<write code here to copy the current value and calculate the min /
max values
<trigger your app to refresh this row
End Sub