We can confirm the results produced by Excel PV function http://tadxl.com/excel_pv_function.html by performing online NPV calculation http://njinstruments.com/financial/npv-calculator.html

For the first example when costs are incurred immediately

=tadPV( 3%, 0%, 0%, 20/5, -1000, 0, 1, 0, 1, 5, 1 )
$3,248.56

NPV = 3,248.56
How net present value was calculated
Present value of cash flows
DCF1 = #### 1000 x (1+3%)-0 #### 1000 x 1.00000 #### 1,000.00
DCF2 = #### 0 x (1+3%)-1 #### 0 x 0.97087 #### 0.00
DCF3 = #### 0 x (1+3%)-2 #### 0 x 0.94260 #### 0.00
DCF4 = #### 0 x (1+3%)-3 #### 0 x 0.91514 #### 0.00
DCF5 = #### 0 x (1+3%)-4 #### 0 x 0.88849 #### 0.00
DCF6 = #### 1000 x (1+3%)-5 #### 1000 x 0.86261 #### 862.61
DCF7 = #### 0 x (1+3%)-6 #### 0 x 0.83748 #### 0.00
DCF8 = #### 0 x (1+3%)-7 #### 0 x 0.81309 #### 0.00
DCF9 = #### 0 x (1+3%)-8 #### 0 x 0.78941 #### 0.00
DCF10 = #### 0 x (1+3%)-9 #### 0 x 0.76642 #### 0.00
DCF11 = #### 1000 x (1+3%)-10 #### 1000 x 0.74409 #### 744.09
DCF12 = #### 0 x (1+3%)-11 #### 0 x 0.72242 #### 0.00
DCF13 = #### 0 x (1+3%)-12 #### 0 x 0.70138 #### 0.00
DCF14 = #### 0 x (1+3%)-13 #### 0 x 0.68095 #### 0.00
DCF15 = #### 0 x (1+3%)-14 #### 0 x 0.66112 #### 0.00
DCF16 = #### 1000 x (1+3%)-15 #### 1000 x 0.64186 #### 641.86
DCF17 = #### 0 x (1+3%)-16 #### 0 x 0.62317 #### 0.00
DCF18 = #### 0 x (1+3%)-17 #### 0 x 0.60502 #### 0.00
DCF19 = #### 0 x (1+3%)-18 #### 0 x 0.58739 #### 0.00
DCF20 = #### 0 x (1+3%)-19 #### 0 x 0.57029 #### 0.00
NPV (Annuity Due) T= 0 to N-1 #### $3,248.56

For the second example when costs are incurred at the end of 5 year period

=tadPV( 3%, 0%, 0%, 20/5, -1000, 0, 0, 0, 1, 5, 1 )
$2,802.24

NPV = 2,802.24
How net present value was calculated
Present value of cash flows
DCF1 = #### 0 x (1+3%)-1 #### 0 x 0.97087 #### 0.00
DCF2 = #### 0 x (1+3%)-2 #### 0 x 0.94260 #### 0.00
DCF3 = #### 0 x (1+3%)-3 #### 0 x 0.91514 #### 0.00
DCF4 = #### 0 x (1+3%)-4 #### 0 x 0.88849 #### 0.00
DCF5 = #### 1000 x (1+3%)-5 #### 1000 x 0.86261 #### 862.61
DCF6 = #### 0 x (1+3%)-6 #### 0 x 0.83748 #### 0.00
DCF7 = #### 0 x (1+3%)-7 #### 0 x 0.81309 #### 0.00
DCF8 = #### 0 x (1+3%)-8 #### 0 x 0.78941 #### 0.00
DCF9 = #### 0 x (1+3%)-9 #### 0 x 0.76642 #### 0.00
DCF10 = #### 1000 x (1+3%)-10 #### 1000 x 0.74409 #### 744.09
DCF11 = #### 0 x (1+3%)-11 #### 0 x 0.72242 #### 0.00
DCF12 = #### 0 x (1+3%)-12 #### 0 x 0.70138 #### 0.00
DCF13 = #### 0 x (1+3%)-13 #### 0 x 0.68095 #### 0.00
DCF14 = #### 0 x (1+3%)-14 #### 0 x 0.66112 #### 0.00
DCF15 = #### 1000 x (1+3%)-15 #### 1000 x 0.64186 #### 641.86
DCF16 = #### 0 x (1+3%)-16 #### 0 x 0.62317 #### 0.00
DCF17 = #### 0 x (1+3%)-17 #### 0 x 0.60502 #### 0.00
DCF18 = #### 0 x (1+3%)-18 #### 0 x 0.58739 #### 0.00
DCF19 = #### 0 x (1+3%)-19 #### 0 x 0.57029 #### 0.00
DCF20 = #### 1000 x (1+3%)-20 #### 1000 x 0.55368 #### 553.68
NPV (Ordinary Annuity) T= 1 to N #### $2,802.24