PV Charge Controller with diversion aux output

cdre
cdre Solar Expert Posts: 78 ✭✭
in Advanced Solar Electric Technical Forum #1
I'm designing a new system to replace my cobbled together off-grid system.

Basic specs: 5.3kw consumption daily, PV primary supply, generator backup. Probably around 1300w of panels.

I have been considering the Outback FP1-1 system which includes the inverter/charger, PV charge controller, and associated integration hardware. I like the outback's automatic gen start system, but I'm not satisfied with the auxiliary output on its PV charge controller, which has me leaning toward a more custom solution once again.

What I want out of the Charge Controller is the ability to divert excess power when the batteries can't take everything the PV array can supply. I'd like to divert that power to a 12v or 24v solar water pump controller and on to the pump. I'd use this to provide irrigation to a yard during the "dry season" when rain is scarce while sun is plentiful. I'm looking for a controller that will basically split the power, prioritizing battery charging obviously.

Outback's charger has an aux circuit which can be used to switch a relay, but then the load has to be powered from the battery back. From my understanding, this limits operation time to the set relay operation threshold and potentially taking more from the batteries than the array is sending. Outback's 80amp unit costs $600.

Blue Sky has a unit, which will actually send up to 20amps to a diversion load whenever it has current the batteries will not accept. This is great, but Blue Sky's unit is only rated to 30 amps. Cost is $350.

With 1300w of panels, I'll need a unit rated to at least 60 amps.

I supposed I could buy to Blue Sky units and combine the aux outputs....

Any other manufacturers I should look at? Any other thoughts?
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Comments

  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
    #2
    Re: PV Charge Controller with diversion aux output

    Look here: http://forum.solar-electric.com/showthread.php?t=6858
    But, since you want to power the motor instead of simple resistive load like I did, this ciruit will not work. It will work if you only drive the transistor either fully on or fully off, but not in PWM mode. Another problem, is that FM-60's PWM diversion algorithm is a little buggy. It often goes into really annoying oscillation when PWM duty cycle goes beyond 50%.

    To use your pump motor in PWM mode, you will need separate PWM motor speed controller, capable of taking 0 - 5 V DC (or 0 - 12V) as throttle input. Then you should be able to average PWM output from FM-60 into continuous DC of varying voltage and use that as source to drive your motor controller throttle input.
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  • cdre
    cdre Solar Expert Posts: 78 ✭✭
    #3
    Re: PV Charge Controller with diversion aux output

    I'm thinking I would use a solar pump controller, as they are already designed to compensate for rising and falling voltage in feeding the motor.
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  • System2
    System2 Posts: 6,290 admin
    #4
    Re: PV Charge Controller with diversion aux output

    Does not Coleman Air makes those Diversion Controllers? I thought I bumped into it a while ago and it actually had multiple modes of diverting excess energy, one went by minutes and another by battery discharge percentage. I am pretty sure it called a Diversion Controller.
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