new solar pump

scoot scoot

I am wanting to use a solar pump that requires 72-144 volts and 800-1500 watts. I am wanting to use Canadian Solar CSI CS6P-235PX 235W Solar Panel. My problem is i don't know how many panels and what configuration I need to meet the middle of the road requirements of this pump. Any help is appreciated

BB.

Re: new solar pump

What brand and model of pump? Need to know more about its input power requirements. Solar panels are not very "accurate" or "stable" in their voltage/current output. Their voltage changes with temperature and loads.

-Bill

scoot scoot

Re: new solar pump

Ok Lets try again if a pump calls for 72 volts and 1300 watts, how would you configure solar panels with Imp of 7.66 and Voc of 30 volts? If you hooked parallel 6 panels at 230 watts you would have 1380 watts but only 30 volts. If you hooked 3 panels in series you would have 90 volts but only 230 watts. How would you match both requirements of the pump?

westbranch

Re: new solar pump

again, what model/make of pump so one can look up the power ( Amps and Volts) needed by the pump and to compare to the various configurations of the panels.

HTH

BB.

Re: new solar pump

solar pump that requires 72-144 volts and 800-1500 watts. I am wanting to use Canadian Solar CSI CS6P-235PX 235W Solar Panel

Panel spec. appears to be:

Pmax=235W
Vmp=29.8V
Imp=7.90A
Voc=36.9V
Isc=8.46A

So, say the pump will accept a Vmp range of 72-144 volts:

• 72 volts pump min / 29.8 volts Vmp-stc = 2.4 panels in series
• 3 panels (whole number) * 29.8 Vmp = 89.4 volts Vmp-stc

The amount of power in such a string:

• 89.4 volts Vmp * 7.90 Amps Imp = 706.3 watts per string

As a real rough approximation, assume panels + wiring will run at 80% of rated output (dirt on panels, age, voltage drop):

• 706.3 watts * 0.80 derating = 565 watts "nominal" output power on typical warmish day

So, you would need around 2 to 3 parallel strings of panels to operate the pump.... ASSUMING that the Vmp/Imp requirements are met, and the Voc-cold does not exceed the pump's maximum input voltage.

You could do the same thing with 4 panels in series:

• 4 panels (whole number) * 29.8 Vmp = 119.2 volts Vmp-stc
• 119.2 volts Vmp * 7.90 amps Imp * 0.80 derating = 753 watts nominal per string.

The reason we are asking about the pump itself is many pumps have electronic switching power supplies the input to better match the IV curve of the solar panels to the IV load curve of the pump motor.

A 4 string panel can easily exceed 144 volts on a cold day with no load (say water tank is full), and could damage your pump controller/electronics.

-Bill