Running a Hot Tub Filter Pump with Excess Sunlight

rpvietzke
rpvietzke Registered Users Posts: 48 ✭✭
in General Solar Power Topics #1
Hi,

I have a 24Volt system - 12 T105RE's/Schneider CSW4024/ 6 250W panels, Combox and an MPPT60 controller at my weekend cabin. Their is PLENTY of capacity for our loads (today) and most of the time the system barely cycles during the weekdays.

I'm refurbishing and installing an old-style wood hot tub, 6'x4' barrel with a 3/4 HP pump that will run at 220V with a high and low speed. There is also a small ozonator / water purifier that needs to have water pushed across it a few hours a day on average. Between the ozonator and the filter, the tub should be "clean" when we are there. Ideally the pump would run a few hours every day, but I'm told 4 hours 3-4 times a week would be plenty, especially with our limited use of the hot tub.

I'd like to set the timer on the pump to run this a small number of hours every day, but ideally would also turn it on whenever there was excess sunlight for a little "extra" filtering. My question is, is there a way to setup a relay that would close whenever the batteries were fully charged? IE, how could I start the pump whenever there was sun power that wasn't needed in the batteries? I'm thinking some sort of voltage controlled switch set to the float charge voltage setting and a relay at the pump, but maybe there is a fancier way. Also figured when the pump first starts it might draw more than its share of solar power and it might drag the batteries down and loop/confuse a voltage controlled switch.

I am currently not using the Combox relay setting, but I am using the MPPT60 relay to run my battery-box fan.

Ideas?

Rob

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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Relays themselves... The simplest would be to use a diode to (or from) the relay for each control source. Also known as "diode OR" function. You have two controllers--One a simple voltage switch, the other a timer. When one "turns on" it supplies current to the relay through a diode. And the second controller has its own diode--This prevents power from feeding back to the controller.

    A second is to power the relay from +12 volts. And the controllers connected to "ground". When either controller "turns on"--It shorts the relay to ground to turn the relay on. This is a "wire OR" function.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #3
    The SW4024 has a aux port also does it not? The XW does. Your project does not state if the heater will come on which is the real load to recon with.
    Your solar capacity would never run this safely unattended or at least I would not advise it.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • rpvietzke
    rpvietzke Registered Users Posts: 48 ✭✭
    #4
    Heater will be propane and doesn't require electrical power. The tub can go "cold" during the months it will be full (9 months) and I'm really just worried about green water :-) !

    As far as I know the CSW4024 does not have any aux relays. It has Xanbus and Battery Temperature readings, but not any sort of relay that I know of...

    Is there a stand-along voltage controlled switch, (or a Xanbus aux relay?) that could be triggered on charge state or availability of excess power?

    Rob
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  • rpvietzke
    rpvietzke Registered Users Posts: 48 ✭✭
    #5
    Curious if other folks on the Forum have ideas about how to know when my batteries are fully charged and I have "extra" energy. Are there any voltage-controlled relays out there that would do this? Any other ideas?

    Rob
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