The document discusses the potential for solar PV tube wells in Pakistan. It estimates that there are over 1 million existing tube wells, 70-80% of which currently run on diesel engines. Solar PV tube wells could potentially replace much of this diesel usage. The economics are promising, with estimated payback periods of 3 years for solar PV systems compared to operating costs of 25 cents/kWh for diesel. Various business models are proposed to encourage the adoption of solar PV for tube well irrigation, which could significantly reduce fuel costs for farmers and diesel imports.

1. PROPLAN ASSOCIATES
Potential and Economics of
Solar PV Tube Wells
Akhtar Ali
March 2013
Draft Working Paper

2. Potential and Economics of Solar PV Tube Wells
Solar PV modules prices have come down drastically low over the past two years and the trend is
expected to continue into the future. It appears that the target of USD 1 per Watt would be achieved
much earlier than 2020.Recent bids in California for Solar PV ground mounted utilities have been
received as low as 8 cents per kWh. Similarly in India, bids of as low as 11 cents per kWh have been
received. It is predicted that Solar PV mat compete with conventional electrical sources by 2017.Even
now, Solar PV is cheaper than Diesel based applications in day time, where storage requirement is not
there.
The total potential of Solar PV has been estimated at 6- 8000 MW for about one million existing
Diesel and electricity operated tube wells. If the entire potential is to be implemented, it will
take 10 years at the rate of 6-800 MW (60-80,000 pumps) of installations per year. Even if we
make allowance for 40% of tube well capacity to be non-operating or operating under capacity,
there would still be a potential of some 4800 MW, out of which PEPCO confirms electrical tube
wells to be consuming 2-3000 MW.
One important point to be noted is that Diesel Tube wells operate for 150-200 days per year on
the average. As Diesel Engines are comparatively cheap and Diesel oil being expensive, there is
pressure on the user to minimize its use. In case of Solar Pumps, there would be pressure for
maximization of usage, as all cost is sunk cost. This means that 2kW of Diesel Capacity may be
replaced by 1 kW Solar PV. The typical HP range is 5, 10,15,20,22 and 25 H.P., with an average
of 17 H.P. Also the most common water table depth is between 20 and 50 ft mostly in Punjab.
In Balochistan, however, the depth can go as much as 200 ft.
Tube Wells appear to be the readiest application of Solar PV; as there are a large number of
tube wells, 1 million plus; 70-80% of which run on Diesel Engines. Diesel based electricity at
currently high oil prices cost around 25 cents per kWh. On the other hand (see table ),Solar PV
,based on 1600 hours of operations per year, costs around 10 cents per kWh, as per market
prices as these prevail for Chinese origin systems. The payback period for Solar PV tube wells
has been estimated at about 3 years. Noting this, the market of Solar PV tube Wells has already
picked up without any support or incentives. PV Tube wells system (solar panels, controls and
submersible DC pump)of various capacities, ranging from 4 kW to 10-15 kW are being marketed
at a price range of )0.4 to 1.5 Million Rs.

3. Table 1 :Micro-economics of Solar PV in Tube well visa-vis Diesel
Engine
Case study of a 15 kW Solar Tube well replacing diesel engine
Item
units
Amount/Value
Solar PV capacity
kW
15
Capacity factor
hours
1600
Annual Electricity produced
kWh
24000
Replacement cost of Diesel
Rs/kWh
25
Annual Diesel replacement
Rs/yr
600000
CAPEX Solar PV and Pump
Rs
1800000
Investment Payback Period
years
3
Equity @30%
Rs
540000
Loan
Rs
1260000
Repayment period
years
10
interest rate
%p.a
14
Annual Debt servicng
Rs
$241,559
Annual saving for first 10 yrs
Rs
$298,441
Equity payback Period
yrs
$1.81
Present Value of 25 yrs saving
Rs
$5,446,224
Net Present Value @10%
Rs
$3,646,224
IRR
%
33.31
Electricity cost in1-10 years
Electricity cost in11-25 years
Rs/kWh
$10.06
0
At a micro level, it has been estimated that every two Acres of land requires on the average 1
KW of Solar pumping power. Keeping in view, the capital requirements, one would expect that
initially very large farm owners-cultivators would go for solar, installing several pumps each. At
a mean level, a 20-Acre farm would require 10 kW system costing around Rs.1.2 Million
currently. A 5 Acre farm would require Rs 0.3 Million. The prices are expected to go down at
about 7-10 percent per year for several years.
In search of Business Models
Conversion of Electric Tube Wells may partly replace expensive oil based electricity generation
by IPPs and GENCOs, while conversion of Diesel Tube Wells saves oil and refining capacity
directly. A number of business models may be examined to meet this demand;
 User installed off-grid
 Utility installed on-grid or Micro grid

4. 
User(community) installed on-grid or Micro grid
User installed off-grid business model is already under practice due to high prices of Diesel and
may continue to keep capturing large land owners market segment. It is an open question
whether our grid system would be able to operate in two way system integrating small PV
inputs of 10-20 kW. Utilities or Local governments may be able to install micro grids(AC or DC)
just to share Solar PV electricity generated by user systems. The concept of micro grids is fast
expanding specially for remote application. In developing countries, Micro Grid may be installed
even in close by locations for making use of and sharing user generated electricity.
Alternatively, excess water extracted through continuous daylight operation of Solar PV tube
wells, can be diverted to water courses and canals. In the U.S. irrigation districts have been
created which operate like a legal entity. Irrigation districts are installing Solar PV tube wells
and distributing water. In Pakistan, the equivalent may be the Water Users Associations. The
task being huge and economics being so attractive, all possible institutional arrangements and
business models may be put into use.
Table 2 : Possible Business Models Solar PV tube Wells








User Financed off grid
Leasing or agricultural loan schemes
Third Party PPA/WPA
Utility owned on or off-grid(micro-grid)
Community owned /Water users Association]
Irrigation district(Water distribution)
Tube well plus other uses(micro-grid)
Water Markets
Source:Author

5. Table 3 : Tube well irrigated land and potential for Solar PV
____________________________________________
 Total number of Farms+8.26 Million
 Total Farm Area =52.91 Million Acre
 Total Cultivated Area=42.6 Million Acre
 o/w irrigated by canal and tube wells both=13.89 Million Acre
 and irrigated by tube wells only=6.08 Million Acres
 Estimated coverage of Tube wells=12 Million Acre
 @0.5 kW per acre, Solar PV potential=6000 MW
________________________________________________
Author’s Estimate, data source; Agricultural Census of Pakistan 2010
Table 4 :Existing Tube Well Statistics and Solar PV Potential









Total number of Tube Wells = 1 million plus
o/w Diesel based =834905(11000 MW)
and Electric =250,000(3000 MW)
Average HP per Tube Well=17 H.P.(12.68 kW)
Typical Capacities:10,15,20,22,25 HP
Diesel, number of days of operation=125 days per year
Electric, number of days of operations=184 days per year
Solar PV ,optimal number of days of operation=300 days per year
Estimated number of obsolete pumps(installed
before1994)=400,000
 Estimated Solar PV demand for 300 days of operations=8000 MW
 Assumed Target 50% conversion in 10 years=4000 MW
 Yearly conversion =400 MW(40,000 solar pumps)
________________________________________________
Author’s Estimate, data source; Agricultural Census of Pakistan
2010;Agricultural Machinery Census

7. Table 5 :Tube wells by Horse Power Capacity and power source(2004)
Pakistan
Capacity(H.P.)
Diesel
< 10
5760
>10<15
122575
>15<20
586097
>20<22
13165
>22<24
14107
>25
93207
Total
834911
RoG %p.a.upto2004
7%
Wt.Avg.HP
18
Provincial Distribution
Punjab
697156
Sindh
64128
KpK
4223
Balochistan
11872
Total
777379
http://www.pbs.gov.pk/sites/default/files/agriculture_statistics/publications/Agricultural_Statistics_
of_Pakistan_201011/t
PRIVATE TUBEWELLS & LIFT PUMPS BY
PURPOSE OF INSTALLATION
Total
number of
tubewells/
lift pumps
Administrative
Unit/ Type of
Tube-Wells
Punjab:
Tubewells
Lift Pumps
Sindh:
Tubewells
Lift pumps
KPK:
Tubewells
Lift Pumps
Balochistan:
Tubewells
Lift Pumps
Pakistan:
Tubewells
Lift Pumps
Number of Tubewells/Lift pumps by Purpose of Installation
Supplementing
Irrigation of
Replacement of
Canal water
Barani/Sailaba land
wells/karezes
Number
% of
Number
% of
Number % of
Total
Total
Total
829437
5415
587146
731
70.78
13.50
194765
3811
23.48
70.37
57681
914
6.95
16.87
38330
7809
34125
6877
89.02
88.06
4055
713
10.57
9.13
283
260
0.73
3.32
18705
2186
3289
379
17.58
17.33
14630
1551
78.21
70.95
925
263
4.94
12.03
19172
1134
637
170
3.32
14.99
9912
767
51.70
67.63
9296
203
48.48
17.90
905644
16544
625197
8157
69.03
49.30
223362
6842
24.66
41.35
68185
1640
7.52
9.91
.
Source : Pakistan Agricultural Machinery Census - 2004.

8. USE AND RENTING OUT TIME OF PRIVATE ELECTRIC & DIESEL TUBEWELLS/LIFT PUMPS DURING
LAST 12 MONTHS
Total
No. of
tubewells/
lift pumps
Administrative
Unit
Punjab:
Electric
Diesel
Sindh:
Electric
Diesel
KPK:
Electric
Diesel
Balochistan:
Electric
Diesel
Pakistan:
Electric
Diesel
Average use of time
Days
Hours
per
per
year
day
Renting out time
Number of Average
Average
tubewells/
Hours
Hourly
lift pumps
rented
rate
per year
(Rs.)
61931
771642
183
124
6
5
22174
143308
619
315
110
114
3449
42691
151
123
7
6
513
6502
468
311
112
111
9829
11020
152
108
4
5
2350
2583
431
380
106
122
10659
9552
227
189
7
5
681
611
532
259
120
121
85868
834905
184
125
6
5
25718
153004
597
316
110
114
Source : Pakistan Agricultural Machinery Census - 2004.
DIESEL TUBEWELLS BY TYPE OF PUMP
GOVERNMENT
WELL
CENTRITURWELL
CENTRIWITH
FUGAL
BINE
WITH
FUGAL
PUMP
PUMP
4
5
6
7
8
ADMINISTRATIVE UNIT
CENTRIFUGAL
TOTAL
TURBINE
1
2
3
PAKISTAN
784006
21572
12199
277
120
75
783729
21452
12124
N.W.F.PROVINCE
PUNJAB PROVINCE
SINDH PROVINCE
BALOCHISTAN PROVINCE
2957
744303
32763
3983
2920
15501
915
2236
2850
5196
1556
2597
6
111
139
21
14
25
81
2
13
60
2951
744192
32624
3962
2906
15476
915
2155
2848
5183
1556
2537
Water Table
PRESENT DEPTH OF
WATER TABLE
1
TOTAL *
TUBEWELLS
2
PAKISTAN
UPTO
10 FEET
22466
11
TO 20 FEET
125382
21
TO 30 FEET
224027
31
TO 40 FEET
188707
41
TO 50 FEET
116750
51
TO 75 FEET
94999
76
TO 100 FEET
59965
101
TO 150 FEET
31053
151
TO 200 FEET
11053
201 FEET AND ABOVE
12378
PRIVATE
TURWELL
BINE
WITH
PUMP
9
10

9. Pump Head or Power Calculations;
: GPM x TDH / 3960 = WHP



GPM = Gallon per minute at the best efficiency point
TDH = Total discharge head (measured in feet), as shown on the pump
curve ; at the best efficiency point)
WHP = Water horse power or the amount of horse power the pump is
generating.
Doing the same thing in the metric system we would get:


M3/ HR = Cubic meters per hour of capacity as measured at the best
efficiency point on the pump curve.
TDH = Total discharge head, in meters, at the best efficiency point.
WKW = Water kilowatts of power being generated by the pump
PV Panel Selection
1. The power of solar panel=power of pump X 1.3, the voltage of
solar panel=the voltage of pump, the controller should be
matched
Pump kW calculations
Pump#1
Daily Consumption
Number of hours per day
Hourly Flow
Dynamic Head
Efficiency
Motor Power Reqd
CM/d
hrs/d
CM/hr
Meters
%
KW
1000
8
125
10
60
5.79
Pump#2
Pump#3 Pump#4
1500
2000
2500
8
8
8
187.5
250
312.5
20
20
15
60
60
60
17.36
23.15
21.70