WATSAN COORDINATION MEETING
UNICEF Kampala July 7,2005
SOLAR &
DIESEL MOTOR
PUMPS
APPRAISAL
Alessandro Galeota
(galeota@coopi.org)
SOLAR PUMPING SYSTEM




The solar system comprises: stationary
or tracking solar array; controller;
electric motor and pump
The system pumps water with the use
of power generated by the sunlight
Solar electric cells convert sunlight
directly into DC power (photovoltaic
process)
The controller converts the variable DC
voltage into three phase voltage to run
a brushless pump
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Aloi camp solar scheme
solar & motor diesel pumps appraisal
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DIESEL MOTOR DRIVEN PUMP




Diesel motor
Discharge and
drive head (1)
Driveshaft (4)
Rotor/stator
pumping
element (6)
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Pabbo camp diesel motor
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STRENGTHS
Solar system
Diesel system
Ideal for remote &
unattended locations:
•
No fuel & little or no
maintenance
•
No need of pump or
motor attendants
Little maintenance of the
pump
Solar pumping system are
noise and pollution free
Ease of inspection &
maintenance of motor
drive head
Reliability and ease of use
Wide range of applications
• Capacity 10-1700 l/min
•
Total head 15 – 450 m
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WEAKNESSES
Solar system
• High capital cost
• Restricted daily
flow
• Limited storage
capacity due to
above
• Daily flow reduced
with increase in
total head
Diesel system
• High O&M costs
• No operation due
to shortage of fuel
• Power losses
through drive head
& shafting
• Greenhouse gas
emission
• Human factor
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OPPORTUNITIES for both systems
To address the water demand of
a large number of IDPs
 To store water
 To use tap stands with less effort
for collecting water and reduced
queueing time
 To increase access to safe
drinking water

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POTENTIAL THREATS
Solar system
• Lower flow rate
due to rainy
season
• Theft of solar
modules
• Broken modules
• Disconnection of
electrical wiring
Diesel system
• Lack of
maintenance
• Theft of fuel
• Unavailability of
spare parts
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Steps towards solution
Solar system
Lower flow rate due
to rainy season
• GPS Tracking Array
• Additional array
oversizing (30%)
• Increased water
storage
Diesel system
Lack of maintenance
• Keeping a service
book
• Check of service
book
Theft of fuel
• Limited storage &
proper planning of
delivery
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Steps towards solution
Theft of solar
modules
• Solar array placed
on high stand and
connected with
large size bolts
Broken panels
• Solar assembly
metal backed. No
grid is suggested
Availability of spare
parts
• Local authorized
distributors and
dealers
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Steps towards solution
Disconnection of
electrical wiring
• The wires are
placed inside iron
pipes
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MONO PUMP COMPUTER AIDED SOLAR
SIMULATION
Country : Uganda
Location :Tororo (Latitude 0° 60' / Longitude 34° 20')
Static head : 35 m
System size : 1200 Watts
System efficiency : 56%
Array type :Tracking
TYPICAL PERFORMANCE AT 1000 W/m 2
Month
January
February
March
April
May
June
July
August
September
October
November
December
Average
Daily Flow
44,4
43,1
43,4
39,9
38,2
37,1
34,4
36,0
42,7
44,0
42,4
44,7
40,9
Horizontal Irradiation
2
KWh/m day
5,6
5,5
5,6
5,2
5,0
4,9
4,7
4,9
5,5
5,6
5,4
5,6
5,3
Average flow rate for January
(Mono Pump solar simulation)
7.
00
8. AM
00
9. AM
00
10 A
.0 M
0
11 AM
.0
0
12 AM
.0
0
1. AM
00
2. PM
00
3. PM
00
4. PM
00
5. PM
00
PM
100
90
80
70
60
50
40
30
20
10
0
Flow rate (l/min)
Aloi camp solar scheme
(oversized solar array)
WATTS
POWER SUPPLY
450
400
350
300
250
200
150
100
50
0
410
410
410
410
240
220
140
7.30
AM
8.00
AM
12.00
AM
4.00
PM
TIME
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5.30
PM
6.00
PM
6.30
PM
Cost-Benefit Analysis





System’s daily flow of 40 m3
System’s lifetime of 10 years
Benefit: revenue from water fees
Capital cost and Operation &
Maintenance costs
Life-cycle costs and benefits are
discounted to the present value
using 10% discount rate
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O&M costs breakdown
Diesel pump: Fuel consumption 1 l/h –
Discharge rate 10 m3/h
•
•
•
Cost of diesel (216,000 USh/month)
Cost of lubricant (15% of fuel) (32,400
USh/month)
Wages of two pumps operators (150,000
USh/month)
•
Kit of spare parts for pump – over 3 years (gland
packing, vee belts, drive shafting assy, rubber column
stabilizer, final connecting shaft) (122,467 USh/year)
•
Engine service kit (2000 hours) (363,658
USh/year)
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O&M costs breakdown
Solar pump: replacement of
pump & controller after 5 years
of service
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Solar Pump Life-Cycle Costs
SOLAR PUMP LIFE-CYCLE COSTS
YEAR
0
1
2
3
4
5
6
7
8
9
10
CAPITAL
COST
13432
OPERATION &
MAINTENANCE
COSTS
0
0
0
0
0
0
2320
0
0
0
0
Remark:
The unit output cost is attained dividing
TOTAL
COSTS
(EURO)
13432
0
0
0
0
0
2320
0
0
0
0
PRESENT VALUE
FACTORS
PRESENT
(discount rate
VALUES OF
10%)
TOTAL COSTS
1,00
13432
0,91
0
0,83
0
0,75
0
0,68
0
0,62
0
0,56
1299
0,51
0
0,47
0
0,42
0
0,39
0
TOTAL LIFE-CYCLE COST
14731
3
the total life-cycle cost by 40 m 3, which is UNIT OUTPUT COST (Euro/m )
solar pump's daily flow with a given 35 m
of total head
368
Diesel Pump Life-Cycle Costs
YEA
R
0
1
2
3
4
5
6
7
8
9
10
OPERATION &
CAPITAL MAINTENANC
COST
E COSTS
7607
0
2394
2394
2394
2394
2394
2394
2394
2394
2394
2394
Remarks:
The unit output cost is attained
dividing the total life-cycle cost by 40
m3 which is diesel motor pump's daily
flow with a given 80 of total head
TOTAL COSTS
(EURO)
7607
2394
2394
2394
2394
2394
2394
2394
2394
2394
2394
PRESENT
VALUE
FACTORS
PRESENT
(discount rate
VALUES OF
10%)
TOTAL COSTS
1,00
7607
0,91
2179
0,83
1987
0,75
1796
0,68
1628
0,62
1484
0,56
1341
0,51
1221
0,47
1125
0,42
1005
0,39
934
TOTAL LIFE-CYCLE COST
22306
UNIT OUTPUT COST (Euro/m3)
558
(SOLAR PUMP UNIT OUTPUT COST: 368 Euro/m 3 )
DISCOUNTED CASH-FLOW
FOR SOLAR PUMP
OPERATION
CAPITAL
&
COST
MAINTENANCE
YEAR BENEFITS (EURO)
COSTS
0
0
13432
1
6636
0
2
6636
0
3
6636
0
4
6636
0
5
6636
0
6
6636
2320
7
6636
0
8
6636
0
9
6636
0
10
6636
0
TOTAL
COSTS
13432
0
0
0
0
0
2320
0
0
0
0
PRESENT
VALUE
CASH-FLOW FACTORS
(BENEFITS - (discount
TOTAL
rate
DISCOUNTED
COSTS)
10%)
CASH FLOW
-13432
1,00
-13432
6636
0,91
6039
6636
0,83
5508
6636
0,75
4977
6636
0,68
4512
6636
0,62
4114
4316
0,56
2417
6636
0,51
3384
6636
0,47
3119
6636
0,42
2787
6636
0,39
2588
NET PRESENT VALUE
Remarks:
1 litre of water is assumed to cost 1 USH
40000 litres x 1 USH x 365 days = 14600000 / 2200 = 6636 Euro
26014
DISCOUNTED CASH-FLOW
FOR DIESEL PUMP
CAPITAL OPERATION &
MAINTENANCE
COST
COSTS
YEAR BENEFITS (EURO)
7607
0
0
2394
6636
1
2394
6636
2
2394
6636
3
2394
6636
4
2394
6636
5
2394
6636
6
2394
6636
7
2394
6636
8
2394
6636
9
2394
6636
10
PRESENT
VALUE
CASHFACTORS
FLOW
(BENEFITS - (discount
DISCOUNTED
rate
TOTAL
TOTAL
CASH FLOW
10%)
COSTS)
COSTS
-7607
1,00
-7607
7607
3860
0,91
4242
2394
3521
0,83
4242
2394
3182
0,75
4242
2394
2885
0,68
4242
2394
2630
0,62
4242
2394
2376
0,56
4242
2394
2163
0,51
4242
2394
1994
0,47
4242
2394
1782
0,42
4242
2394
1654
0,39
4242
2394
NET PRESENT VALUE
18439
(Net present value of solar pump: 26014)
Remarks:
1 litre of water is assumed to cost 1 USH
40000 litres x 1 USH x 365 days = 14600000 / 2200 = 6636 Euro
Conclusions



Solar system is sustainable and
reliable: no fuel, no need of operator,
pump and controller are maintenancefree
Solar system is cost-effective: 4 times
the hand pump’s daily flow with
negligible recurrent cost
Diesel system has high pumping & lift
capacity: 3 times the solar system’s
daily flow
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Conclusions


Over 10 years of service, unit output
cost of diesel pump is higher than
solar: 558 Euro against 368 Euro
For a better analysis of field data
(i.e. maintenance), the appraisal
should be extended over a longer
period of service-time
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PUMP PERFORMANCE Grundfos:
(HT=6 Kwh/m2 day
20° northern latitude)
H(m)=30~Q(m3/day)=26 H=60~Q=16 H=80~Q=13
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PUMP PERFORMANCE Mono diesel pump mod. 620 Pump
speed 1200 rpm H=30~Q=3.55 H=60~Q=3,48 H=80~Q=3,3
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