Product Guide

Solar panel wiring
SQFlex
4
23
4. Solar panel wiring
Methods of solar panel wiring
Solar panels can be connected in one of three
methods:
1. Series wiring
2. Parallel wiring
3. Series/parallel wiring (a combination of the two)
The Grundfos SQFlex pump is most efficient at
voltages of 120V and above, up to a max of 300V. To
maximize pump performance connect panels to obtain
at least 120V.
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 panel.
Fig. 21 Solar panel wiring in series
Panel voltages add in series, so if the panels in fig. 21
are rated at 70V (GF100), then the total voltage will be:
70 + 70 + 70 + 70 = 280V
Panel amperage remains the same, so if each panel
produces 1.43 amps, then the total current will be 1.43
amps.
Panel wattage always adds, so if each panel is rated at
100W the total wattage (Watts = Volts x Amps) output
will be:
100 + 100 + 100 + 100 = 400W
Parallel wiring
When wiring panels in parallel, results are the opposite
of series wiring, that is, amperages add and voltage
stays the same.
To wire panels in parallel, connect the positive terminal
of each panel to the positive terminal of the other
panels and negative terminal of each panel to the
negative terminal of the other panels.
Fig. 22 Solar panel wiring in parallel
Panel voltage remains the same, so if the panels in
fig. 22 produce 70V each, then the total output will be
70V.
Panel amperage adds in parallel, so if the panels in
fig. 22 are rated at 1.43A, then the total current will be:
1.43 + 1.43 + 1.43 + 1.43 = 5.72A
Panel wattage always adds, so if each panel is rated at
100W the total wattage (Watts = Volts x Amps) output
will be:
100 + 100 + 100 + 100 = 400W
Series/parallel circuits
A series/parallel circuit is simply two or more series
circuits that are wired together in parallel.
Fig. 23 Solar panel wiring in series/parallel circuit
In fig. 23 two separate pairs of panels have been wired
in series and each of these series pairs have been
wired together in parallel.
To determine the total voltage and amp output of this
array, consider first each pair of panels wired in series.
Think of each pair as a single panel. Each panel has a
rating of 70V, 1.43A and 100W. Remember that in
series, voltage adds, while amperage remains the
same. Pair #1 provides 70 + 70 = 140V and 1.43A.
Pair #2 provides the same (continued on next page).