6.21 Suppose you are setting up a little fountain for a pond using a PV-powered
DC pump. Shown below are pump curves for various voltages along with
a system curve including a static head of 10 in. The PV I-V curve and
hourly insolations are also shown.
Head (inches of Hâ‚‚O)
80
70
16 V
60
14 V
50
System curve
20 V-
gal/min = ?
40
12 V
10 in.
18 V
30
20
10 V.
PV
10
Pump
0
0
1
2
3
4
Flow rate (gal/min)
2.2
2.0
1.8
1-sun I-V
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Time
0 2 4 6 8 10 12 14 16 18 20 22
Voltage (V)
8 Α.Μ. 9 10 11 12
Insolation (kW/m²) 0.4 0.5
gal/min = ?
1
0.7 0.9 1.0 0.9 0.7
2
3
0.5
4 P.M.
0.4
FIGURE P6.21
Suppose the electrical characteristics of the pump can be modeled as a
simple 10-Ω resistance. Find the hourly flow rates (gal/min) and estimate
the total gallons pumped in 1 day (assume insolation is constant over each
1-h interval).
