SQFlex data booklet

5. System sizing
Sizing of an SQFlex system
Grundfos has an online tool for the sizing of SQFlex
systems.
See Grundfos Product Center. The sizing tool covers both
solar- and wind-powered systems.
For sizing the proper SQFlex system, the following
parameters are required:
• location of installation
• maximum head
• quantity of water.
Regarding the size of a correct solar-powered SQFlex
system, there are six regions:
• North America
• South America
• Australia and New Zealand
• Asia and the Pacific
• Southern Africa
• Europe, Middle East and Northern Africa.
Each region is divided into a number of zones according to
the solar radiation in kWh/m
2
(kWh/ft
2
) per day.
Voltage effect on pump efficiency
The pump efficiency can vary depending on the input
voltage. This chart shows the dropoff in efficiency as the
voltage gets lower. For example, if you have two systems
with the exact same wattage rating, but System A is running
at 120V and System B is running at 35V, System A will
produce 20 % more water than System B.
SQ Flex optimal efficiency
Panel output voltage (% loss in gallons/day)
120 - 300 V - 0 %
90 V - 5 %
60 V - 10 %
35 V - 20 %
Solar panel wiring
Methods of solar panel wiring
Solar panels can be connected in the following methods:
1. series wiring
2. parallel wiring
3. series/parallel wiring.
The Grundfos SQFlex pump is most efficient at 120 V and
above, up to a maximum of 300 V. To maximize pump
performance, connect panels to obtain at least 120 V.
Series wiring
All solar panels have a negative (-) and a positive (+)
terminal.
When wiring panels in series, voltages add and amperage
stays the same.
To wire panels in series, connect the positive terminal of one
panel to the negative terminal of the next one.
1 2 3 4
TM062377
Solar panel wiring in series
Pos. Description
1 Panel #1
2 Panel #2
3 Panel #3
4 Panel #4
Panel voltages add in series, so if the panels in fig. Solar
panel wiring in series are rated at 70 V (GF100), then the
total voltage is the following:
70 + 70 + 70 + 70 = 280 V
Panel amperage remains the same, so if each panel
produces 1.43 A, then the total current is 1.43 A.
Panel wattage always adds, so if each panel is rated at 100
W, the total wattage (Watts = Volts x Amps) output is the
following:
100 + 100 + 100 + 100 = 400 W
SQFlex
5
24
System sizing