48V pump connected directly to MPPT

gregapex

Question:  I have an MPPT controller https://www.amazon.com/dp/B0719PGGBS?psc=1&ref=ppx_yo2ov_dt_b_product_details.  I have a pump https://shop.rpssolarpumps.com/products/2-hp-eco-steady-booster-pump™-system.  I have 4 solar panels specs: LG Electronics

LG26081C-G3

Vmpp 31.17V

Impp 8.35A

Voc 38.56V

Isc 8.82A

Max System voltage 1000V(IEC), 600V(UL)

Max series fuse 15A

 

Panels connected in series.

 

I want to connect the pump directly to the MPPT controller.  

 

Q:  The MPPT is 12-48V so can I simply pigtail a 48V outlet to match my pump and voila?

Q:  Any suggestions where I can purchase the 48V outlet? 

 

gregapex

to clarify - second link - I only have the 2HP pump

gregapex

BB.

Question--Are you planning on having a 48 volt battery bank? Or trying to use without a battery bank. From your controller link:

TIPs

1. Always connect battery first!!! Make sure enough batteries’ voltage let controller recognize the right system voltage. The disassembly sequence is contrary to the wiring order. NEVER connect the solar panel array to the controller without a battery
2. DO NOT connect any Inverter/ wind/ Alternator or Charger into the charge controller! connect the Inverter directly to the battery.
3. Ensures solar input voltage higher 3V or more than batteries’ voltage and total input power in the range. if input power is too low for max input power, it may be appears to have been discontinued., the charging current almost be zero when controller is floating charge.

So, yes you can connect your pump to a 48 VDC battery bank (wiring should be protected by a Fuse/Circuit breaker rated for cable).

Need to know the pump specifications (current, starting current if pumping against pressure for displacement type pump) and the run time (xxx Watts * y Hours per day) to figure out if your array is sufficient for your needs (location, hours of sun by season, etc.).

Once you know the pump current--You can figure out if the 20 amp (or whatever) 240 VAC (or whatever) plug and socket...

Many people will use twist lock connectors (120/240/etc.) instead so there is no chance of plugging into the wrong outlet (nobody has twist lock plugs around their home).

If you no 240 VAC to accidentally plug into (NEMA 6-15 -- 208-250 VAC @ 15 amps--It will work. Just label the socket and cord end that this is 48 VDC (and get polarity correct for pump/pump rotation).

-Bill

gregapex

Hi Bill.

Yes...I was hoping to connect the irrigation pump directly to the MPPT controller.

Yay or nay?  Its a 12A, 48V pump. 

BB.

Solar charge controllers, in general, need a working battery to 1) power the CPU, typically around 9 volts minimum and 2) the bank voltage to figure out if 12/24/48 volt battery bank.

An issue is that solar charge controllers are not a "regulated voltage supply". If they are connected to the solar array first, the output voltage will be (effectively) uncontrolled output voltage without a battery bank to buffer the controller's DC output)... And the out put voltage rise high enough to damage the battery side electronics in the solar charge controller (i.e, 72-150 volt solar array input to MPPT controller and 12-48 volt battery bank output and uncontrolled rise to Vpanel input voltage).

So, answer for this MPPT controller is NO, it can ruin your controller and it will not function correctly, or possibly, at all.

Regarding your array, if the Array is Vmp~48-60 volts, and the pump is a universal motor (Brushed motor), you could try directly connecting the solar array to the motor and see what happens.

If the pump motor has some sort of electronics, connecting to the solar array may be a bit iffy (possibly damage electronics in motor).

There are devices called Linear Current Boosters:

https://www.solar-electric.com/sunpumps-solar-pump-controller-pca-60-bls-m2s.html (an example)

They take the solar array power, run it through an MPPT type circuit, and then drive the DC pump motor in an "optimal" manor for the motor (i.e., take high voltage/low current from the array and down convert to low voltage/high current to start the pump turning in "morning light" (vs just stalled with array trying to output 48 volts at 1 amp, vs (example) 12 volts @ 4 amps--DC brushed motors, the torque is mostly proportional to the input current--more current, higher torque).

The issue seems to be is that most LCB are almost as expensive as adding a solar charge controller and "golf cart" battery bank. And with LCBs, they pumps only run when the sun is up (vs a battery bank that can supply home water pressure 24x7 from the sun or battery bank).

-Bill