Solar Pump Question

jimjones26

Solar Enthusiast
Joined
Aug 20, 2020
Messages
74
I recently bought a solar pump. The specs are as follows:
  • Maximum pump voltage: 65V DC
  • Maximum motor current: 3 amps DC
  • Maximum wattage: 360W
I have an extra solar panel I'd like to use, but I don't want to mess up the pump. Solar panel specs:
  • Max Power - 250W
  • OCV - 37.6
  • Voltage at Pmax - 30.3
  • Short-circuit current - 8.85A
  • Current at Pmax - 8.27
I think the panel I have would be ok, but just wanted some more experience folks to chime in. Thanks!
 

OzSolar

Started out w/nothing & still got most of it left
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Jan 5, 2021
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Southwest MO
It's fine. Did the pump come with a controller?

Diagram or some other style of positive displacement pump I assume?

In my experience when a pumps say "max watts" what they really mean is the most it will use.
 

DThames

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Nov 22, 2019
Messages
2,297
Do you have a link to the pump? I helped a friend install one recently. The pump motor was 24v but it could take 40v input, ran directly from solar. Our testing was that this pump would pump with less than rated power. Your 250w panel might make 200w and for the 360w (max) pump should pump some water. It would be better if you had two of those panels. We put two large used panels that together would just make over 400w.
 

jimjones26

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Joined
Aug 20, 2020
Messages
74
Do you have a link to the pump? I helped a friend install one recently. The pump motor was 24v but it could take 40v input, ran directly from solar. Our testing was that this pump would pump with less than rated power. Your 250w panel might make 200w and for the 360w (max) pump should pump some water. It would be better if you had two of those panels. We put two large used panels that together would just make over 400w.
I do not have a link, but I do have another panel I could hook up.
 

MichaelK

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Mar 21, 2020
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Is the specs on the panel for the one that came with the kit, or the one you are considering adding? Assuming their specifications are the same, would you be wiring them in series or parallel? The Vmp would go up to about 60V, but the Voc might be ~ 75V. Not knowing anything about this pump kit, is the 65V limit the Vmp or Voc?
 

schmism

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Joined
Jul 13, 2020
Messages
1,238
Location
Central IL, USA
I recently bought a solar pump. The specs are as follows:
  • Maximum pump voltage: 65V DC
  • Maximum motor current: 3 amps DC
  • Maximum wattage: 360W
I have an extra solar panel I'd like to use, but I don't want to mess up the pump. Solar panel specs:
  • Max Power - 250W
  • OCV - 37.6
  • Voltage at Pmax - 30.3
  • Short-circuit current - 8.85A
  • Current at Pmax - 8.27
I think the panel I have would be ok, but just wanted some more experience folks to chime in. Thanks!
These are just DC motors that spin a pump. SO you can feed it any voltage you want up to some point at which point you burn out the windings (and or some other component that isn't rated for that high of a voltage). so at 12v its spins at roughly 1/5 the speed it does at 60v. Power output is a bit more different, the old P=I²R says that for any given power output the current squared. (this is why DC stuff at half current is frequenly 1/4 the power output) so you may think it would still "work" at low voltage and perhaps it does spin but its ability to pump any water (head pressure) is going to be significantly limited by the available current (which is a function of the amount of sun on the panel, remember that virtually any light on the panel with generate panel voltage, but it takes "real" sun to produce any real current)
 

jimjones26

Solar Enthusiast
Joined
Aug 20, 2020
Messages
74
These are just DC motors that spin a pump. SO you can feed it any voltage you want up to some point at which point you burn out the windings (and or some other component that isn't rated for that high of a voltage). so at 12v its spins at roughly 1/5 the speed it does at 60v. Power output is a bit more different, the old P=I²R says that for any given power output the current squared. (this is why DC stuff at half current is frequenly 1/4 the power output) so you may think it would still "work" at low voltage and perhaps it does spin but its ability to pump any water (head pressure) is going to be significantly limited by the available current (which is a function of the amount of sun on the panel, remember that virtually any light on the panel with generate panel voltage, but it takes "real" sun to produce any real current)
With my one panel it is pumping 5 gallons per minute over 400 feet at a 16 foot positive elevation change. That's enough for what I need it for, not going to bother adding another panel.
 
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