Is there a way to limit output in a pv direct system without a fuse so one could use a larger array

Discussion in 'Power Electronics' started by Duncan 8, Oct 2, 2017.

  1. Duncan 8

    Thread Starter New Member

    Oct 2, 2017
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    in order to take advantage of inexpensive larger output panels in low light circumstances for water pumping purposes?
     
  2. KeepItSimpleStupid

    Distinguished Member

    Mar 4, 2014
    2,781
    492
    Limit what parameter? The inverter usually has a range of operation. I trouble shot an issue where the inverter would start, but immediatey shut down. It was going on since the install. The install was for "show". They were able to re-connect the array in another series parallel configuration to make it work.

    You may be able to load it using a different sensor to select the load. e.g. A series/parallel load.
     
  3. Duncan 8

    Thread Starter New Member

    Oct 2, 2017
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    I have a Shurflo submersible pump that presently runs on two 40 watt 12 volt pv panels wired for 24 volts. There is a linear current booster to help the pump start in low light and a 7.5 amp automotive fuse. In the winter months we could certainly use more water. One of the large commonly available panels which put out 24 volts and about 300 watts in full sun would probably run the pump quite well in low light but would blow the fuse in full sun....so anyway to solve that?
     
  4. dendad

    Well-Known Member

    Feb 20, 2016
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    It sounds like you do not have a charge controller. One is really needed to prevent battery over charging or discharging.

    "linear current booster"???
    More details? What fuse?
    Please post a connection diagram.
     
  5. wayneh

    Expert

    Sep 9, 2010
    14,708
    5,228
    The short answer is yes, there are ways to prevent the panel from supplying over-voltage to the pump or battery if you have one. If the panel voltage cannot exceed the pump specs, then you don’t need anything. The load will take the current it needs and no more.

    We’d need more details to say more.
     
  6. Duncan 8

    Thread Starter New Member

    Oct 2, 2017
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    There is no battery in this system, the pump is directly powered by the pv panel, similar to a Solar hot water system that has a small panel to power a circulating pump and I have seen some fridges that are set up to run directly too (they have a block of coolant to get through the night)
    The linear current booster I think works somewhat like an mppt charge controller to increase current by reducing voltage in order to start the pump in low light .
    Panel - linear current booster - fuse - pump
     
  7. dendad

    Well-Known Member

    Feb 20, 2016
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    I just Googles "linear current booster" and they all appear to be switch mode. A confusing name!
    As I have no experience with them, it is hard to say. What is the rating of your booster? I would assume it would have current limiting and output voltage limiting built in. If it does not, toss it and get a better one.
    It may be your booster is outputting more volts that the pump is designed for so excess current is drawn.
    And once again, we cannot help with vague spotty info.
    What are the devices in your setup (make and model) with specs and technical diagrams if you can supply them.
    Have you measured the input volts and output volts over various sun conditions? All this sort of thing will help us help you.
    If you are running a 12V pump on 24V panels without voltage regulation you are asking for trouble.
    There is no reason you could not run your pump on even 1KW worth of panels with the correct controller.
     
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