Using Panels directly to 12V Shurflo pump

lazzalazza Solar Expert Posts: 330 ✭✭✭
HI

We recently provided the following item http://www.solar-electric.com/2088-514-145.html to a Belgian couple... we were told by the supplier that it could be used directly from the panels for solar pumping.

However, looking at the specs, it appears that this is not the case--- and as the 12V panels could give up to 17V at Pmax... i'm concerned that this could damage the pump.

They wish to have a system without a battery. Therefore, does anyone know of a kind of voltage stabilizer that would go between the panels and the pump to maintain the voltage around 12V... it would have to cope with up to 8A.

Thanks for any pointers
Larry

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,058 admin
    Re: Using Panels directly to 12V Shurflo pump

    I am not sure if it is a problem or not--Probably try contacting NAWS or Sureflow directly for more information.

    Otherwise, look for a "Linear Current Booster"... Sort of like MPPT for water pumps.

    NAWS has a bunch of different versions--But here is one basic one that may work:

    http://www.solar-electric.com/7amplincurbo.html

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Using Panels directly to 12V Shurflo pump

    I'm using a 65w 12V panel and a linear current booster to drive a 1gpm shurflo pump directly without batterys. Been running fine for 6 years when the suns out with no over voltage issues. Replaced the pump twice now but that was likely from wear and freezing.

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • lazzalazza Solar Expert Posts: 330 ✭✭✭
    Re: Using Panels directly to 12V Shurflo pump

    HI thanks for the replies.

    The solution seems to be as expensive as the pump, i was hoping for less than 50€ of extra expense... any cheaper solutions?
  • machinemanmachineman Solar Expert Posts: 129 ✭✭✭
    Re: Using Panels directly to 12V Shurflo pump

    Email Shurflow and see if it can handle 17V and put a inline fuse size based on the current load shown in the specs per feet of head your pumping up to.

    Off Grid Cabin, 24V 440ah 6V GC battery bank, Xantrex MPPT60-150 CC, Magnum MS4024 inverter-charger, >1200w Solar bank

  • lazzalazza Solar Expert Posts: 330 ✭✭✭
    Re: Using Panels directly to 12V Shurflo pump

    I called them- they seemed to think it may be problematic at higher voltages... the only way i suppose is to see really what voltage is being supplied once the motor is running- it could be that the load brings it down to 14V say.

    I have read somewhere that the 24V version can go direct... but this topic seems a very grey area, no one really seems to know whether they can be used directly or not
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: Using Panels directly to 12V Shurflo pump

    The Shurflo spec is no doubt based on the assumption that the power source is some sort of regulated voltage. As a result the pump's current, being a more or less linear load, will go higher as it is driven with higher voltages. However, that is not the case if connected directly to a PV module. The PV has limited current and the pump is going to load down the PV to some lesser voltage. I bet you'll be alright.
    On the other hand, I don't know which Shurflo pump you are talking about, but many of them are not designed to run continuously. Especially at "overclocked" speeds. They are all PM motors with brushes, and can wear out fast. Plus, having killed my share of diaphram type pumps in submersible wells, I don't believe in trying to get by with low cost setups in that application anymore.
  • lazzalazza Solar Expert Posts: 330 ✭✭✭
    Re: Using Panels directly to 12V Shurflo pump

    It is a premium model for continuous use, model 2088-514-145 http://www.solar-electric.com/2088-514-145.html ... so maybe it will be alright- i guess the only way is to test it and see how it runs and what voltage its pulling when the pump is on.

    My understanding of how motors work is very limited :blush:

    What damages motors? is it too much or too little current, or too much or too little voltage?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Using Panels directly to 12V Shurflo pump
    lazza wrote: »
    What damages motors? is it too much or too little current, or too much or too little voltage?

    All of those.
    In this case the main problem will be Voltage above about 14 which when applied to the fixed resistance of the motor causes an increase in current above the level it was designed to handle.

    It should not be too difficult to come up with a Voltage limiting circuit here. Perhaps a small PWM controller used as a 'dump' controller so that any Voltage over say 14.2 on the pump & PWM input would connect (pulsed) to a load on the controller output.

    Or even something simpler with a Zener diode and resistor.
  • lazzalazza Solar Expert Posts: 330 ✭✭✭
    Re: Using Panels directly to 12V Shurflo pump

    HI Cariboot, thanks for the reply

    As the panels will give about 8A maximum and the maximum current of the pump is 9A.... then surely overcurrent will not be a problem if panels are current-limited.

    What about too little current... will this damage the motor?
  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: Using Panels directly to 12V Shurflo pump

    What is the application for this pump? We have a little pond setup with a fountain and it has a solar direct pump. We used a 500 GPH 12V bilge pump for a boat and the thing runs continuously six or seven hours a day in the summer. I found that a 50W panel seemed to wear the pumps out rather quickly, I think the voltage was climbing up north of 15V and spinning the motor too quickly. My first solution was to put a rheostat from a car headlight dimmer in series with the pump and that worked well until I found a couple underperforming 15W amorphous panels to use for the application. Boat bilge pumps are cheap, the cartridges only run $30 or so. Under-current doesn't seem to affect them as they just spin slowly without pumping until the sun gets high enough. They will only do a few feet of head and definitely won't pressurize a tank but perhaps one would work for your application.
  • lazzalazza Solar Expert Posts: 330 ✭✭✭
    Re: Using Panels directly to 12V Shurflo pump

    Thanks Volvo Farmer, that's very interesting.

    Could you send me a link to the type of rheostat you are talking about.

    So it seems from your experience that it is the excess voltage not under voltage that creates problems

    Cheers
    Larry
  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: Using Panels directly to 12V Shurflo pump
    lazza wrote: »
    Thanks Volvo Farmer, that's very interesting.

    Could you send me a link to the type of rheostat you are talking about.

    So it seems from your experience that it is the excess voltage not under voltage that creates problems

    Cheers
    Larry

    Over voltage was a problem with our boat bilge pump. There is no load on the motor at start up though. A diaphragm pump like a Shurflo is a whole different beast.

    If you want a rheostat like I used, you need to go to the junkyard and find a 1979 Ford Courier, and pull the headlight dimmer switch out of it.
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