Help! As usual, am baffled by matters Electric [this time re. solar pump connection]

[dinga]

I'm having trouble in getting a solar submersible pump to operate - it is powered by a single 340W solar panel; and I want a switch/breaker between the panel and the pump to be able to turn it ON and OFF (the solar panel is attached to a pontoon that floats on my pond - and the breaker is installed on a post close to the bore).

 

Solved the 1st challenge when there was no power making it to the Breaker - after one bad MC4 connection at the pontoon was fixed, achieved some 39.5V at the input side of the breaker when OFF.  Inadvertently left the breaker ON when the connection was fixed and water was being pumped from the bore until I turned the breaker OFF and then ON again.  Pumping ceased and would not restart when the breaker was reset to ON.  The reading at the breaker having dropped to 6.1V.

 

I thought there must be a problem with the breaker so I tried another one today with similar results [initial reading of 39.7V which dropped to 11.2V after the breaker was switched from OFF to ON].

 

The attached photos shows both breakers tried to date - the Red being the 1st tried, and the Green being the one tried today.

 

Greatly appreciate any & all advice - do I need just a simple switch rather than a breaker????? [seems a little odd as I installed a breaker (CHNT NXB-63) between another identical solar panel and a floating fountain pump, and all is going swimmingly (!) so far].

 

Thanks!        

[Crossy]

Assuming you had plenty of sun, could the pump have sucked something up and become stuck??

 

Are you certain you have the pump and panel polarity correct?

 

Is the pump rated to run on a single panel??

 

[georgeesarn]

For starters, you say that your panel is on a boat, what direction is the panel pointing at??

[dinga]

3 hours ago, Crossy said:

Assuming you had plenty of sun, could the pump have sucked something up and become stuck??

 

Are you certain you have the pump and panel polarity correct?

 

Is the pump rated to run on a single panel??

 

Tks Oracle Crossy!!!

 

1.  Don't think so  -  the pump stopped operating as soon as I moved from ON to OFF  -  and the Volatage drop-off occurred immediately I returned to ON.

 

2.  Yes  - my new multi-meter confirms all OK at the Panel and the pump-side of the breaker (at least as far as the reduced voltage is concerned.  As far as the pump is concerned. I've relied on the red wire and the tag that confirms it's the +ve lead.

 

3.  Sh*t - maybe that's the problem... I thought I ordered the two together but didn't (there were 2 different suppliers). 

* Panel:  340W; Voc 46.4V; Vmp 38.5V; Imp 8.9A; Max Series Fuse: 15A

*  Will need to confirm from the pump box tomorrow, but looks like:  DC 24V; 250W; 8A.  The leads from the sub-pump are 20 metres, and some 20m from the Breaker to the panel.  Is my problem the panel and pump are mismatched?  If so, how best to proceed  -  (a) replace either the pump or the panel (assume pump); (b) any other options????

 

Thanks & best regards       

[dinga]

3 hours ago, georgeesarn said:

For starters, you say that your panel is on a boat, what direction is the panel pointing at??

Pretty well due south (with a panel angle of some 15-20degrees)

[degrub]

Maybe the pump is drawing too much current on restart, dropping the voltage to below spec. , more than the panel can provide under ideal conditions even.

[georgeesarn]

how about show us a picture of the label on the pump and the label of the controller and we can see if they are correct??

[dinga]

6 hours ago, georgeesarn said:

how about show us a picture of the label on the pump and the label of the controller and we can see if they are correct??

1.  The pump is still down the bore (I'm hoping I won't need to pull it out...).  Best I can do at this stage is to attached photos of the box it came in and the following Specs from a couple of sales sites

 

https://shopee.co.th/C.T.L-ปั๊มน้ำซับเมอร์ส-DC-12V150w-24V250w-36V300w-บ่อขนาด-3-นิ้ว-ท่อออก-1นิ้ว-i.897800305.25755007784

https://www.amazon.co.uk/NDNCZDHC-3SYDC24V-Electric-Submersible-Fishing/dp/B0C9QQYFZ2

 

2.  There is no controller

 

3.  I also attached a photo of the pond set-up FYI (hubris got me until I've continue to fail to get the pump working...)

 

Any more thoughts????

 

 

  

[dinga]

14 hours ago, degrub said:

Maybe the pump is drawing too much current on restart, dropping the voltage to below spec. , more than the panel can provide under ideal conditions even.

I'm pretty well ignorant of this stuff, but I don't think that's the problem.  Correct me if I' wrong here....

 

The Specs say the Pump has  *  Power 250W; *  Current:  8A;   *  Voltage 24-36V. 

The Panel's sticker says *  340W;  *  Max Power (Vmp) = 38.5V;  *  VoC: 46.4V  * Current Imp:  8.84V 

 

I relooked at the Pump manual which says the Power from the solar panel should be 1.5 times the solar pump power  ie. for a 250W solar pump, the panel should be rated 375W.  As indicated above, the panel is actually rated 340W.  It's only a 10% difference -  could that be the problem???

 

   

[Fruit Trader]

16 hours ago, degrub said:

Maybe the pump is drawing too much current on restart, dropping the voltage to below spec. , more than the panel can provide under ideal conditions even.

 

1 hour ago, dinga said:

I'm pretty well ignorant of this stuff, but I don't think that's the problem.  Correct me if I' wrong here....

 

The Specs say the Pump has  *  Power 250W; *  Current:  8A;   *  Voltage 24-36V. 

The Panel's sticker says *  340W;  *  Max Power (Vmp) = 38.5V;  *  VoC: 46.4V  * Current Imp:  8.84V 

 

I relooked at the Pump manual which says the Power from the solar panel should be 1.5 times the solar pump power  ie. for a 250W solar pump, the panel should be rated 375W.  As indicated above, the panel is actually rated 340W.  It's only a 10% difference -  could that be the problem???

 

   

 

 

If you provide the pump with enough direct solar panel power the pump should run but its a terrible method. Solar well pumps operate best when there is a power point tracking controller in between pump and panels.

 

The video below might explain why you are having problems with your pump directly connected to a solar panel. 

 

 

 

[dinga]

2 hours ago, Fruit Trader said:

 

 

 

If you provide the pump with enough direct solar panel power the pump should run but its a terrible method. Solar well pumps operate best when there is a power point tracking controller in between pump and panels.

 

The video below might explain why you are having problems with your pump directly connected to a solar panel. 

 

 

 

 

Thanks.  Must admit to being a bit at a loss as to why the pump is designed to not require a controller.....  Also, my floating solar fountain pump operates direct from a solar panel, with a breaker in between.....[Confused!}  

 

So what do I need  -  something like these???????   

 

https://www.lazada.co.th/tag/solar-power-controller/?q=solar power controller&catalog_redirect_tag=true

 

Any specific recommendations given the info I've provided above?

Am I correct in assuming that the Breaker is no longer required if a controller is used????

 

 

 

[degrub]

Did you test the pump connected to the solar panel before you lowered it down the borehole ?

[dinga]

1 hour ago, degrub said:

Did you test the pump connected to the solar panel before you lowered it down the borehole ?

No - I was too dumb to do that.  As I said - hubris about the pontoon mounting of the panel, and confidence following the success with the fountain pump

[georgeesarn]

doing a bit of rule of thumb calculation I use a 20 - 25 % real rating of the panel as around 70 Watts so at full sun light

at 24 volts you will get around 3 amp (70 watts) output, not enough to run this pump (8 amps). assuming all connections and such are good I

would say you need at least another panel which would bring you up to 6 - 7 amps (144 W - 168 W)

My personal pool pump I use 3 450 W panels with controller and runs reliably except for rainy days..

[dinga]

9 hours ago, georgeesarn said:

doing a bit of rule of thumb calculation I use a 20 - 25 % real rating of the panel as around 70 Watts so at full sun light

at 24 volts you will get around 3 amp (70 watts) output, not enough to run this pump (8 amps). assuming all connections and such are good I

would say you need at least another panel which would bring you up to 6 - 7 amps (144 W - 168 W)

My personal pool pump I use 3 450 W panels with controller and runs reliably except for rainy days..

Thanks - apols but I'm struggling to understand why there is such a drop-off in Voltage between when the Breaker is Closed and Open.  This morning (it was very overcast), and I got the following measurements:

 

*  Breaker Closed:  Voltage +40.6V; -4.25A  [172.5W]

*  Breaker Open:    Voltage:  +3.7V; -4.27A  [15.8W]

 

If there likely something else at play here??? (realise I need to go back and relook at Fruit Traders Youtube link). 

 

Is there anything odd about the Amp readings showing Negative Numbers???

 

Seems like you're dead right about needing another panel to deliver the 8 Amp to the pump.  But if I get another one, am I still going to fall way short Voltage wise  (ie.  3.7 V X 2 = 7.4V).

 

Today's readings from my Fountain Pump [0.5HP = 370W; 24V; 13A] are also confounding  -  and this pump is performing well. 

*  31V; 3.3A = 102W.  Begs the question why the low Amp reading hasn't caused any problems.

 

Sorry to be a pest   

 

[georgeesarn]

I think you will find that whats happening is you don,t have enough current to get the pump going and you are loading down the

voltage and current, kind of like a short, remember your motor is an inductive circuit.You could confirm the solution if you had an external power supply that could put out enough current. Of course you could have a bad pump.. if you could pull it out and see if would run with no water, I think if it didn,t run you could say that it is defective or clogged.

[dinga]

11 hours ago, georgeesarn said:

I think you will find that whats happening is you don,t have enough current to get the pump going and you are loading down the

voltage and current, kind of like a short, remember your motor is an inductive circuit.You could confirm the solution if you had an external power supply that could put out enough current. Of course you could have a bad pump.. if you could pull it out and see if would run with no water, I think if it didn,t run you could say that it is defective or clogged.

Just to recap.......the Sub Pump is 250W, 24V and 8A.  The Solar Panel is 340W, 24V, Imp 8.84A

 

Attached is a page from the Pump manual which recommends a single 275W Panel for this Pump.  Based on this recommendation, I shouldn't need a second Panel.  Could it be that I need to buy a 275W Panel to replace the current (sic) 340W Panel????

[georgeesarn]

You even say your measured output current is only 4.2 amps from the one panel????

I think if you want to save money on this, pull up your pump and see what happens then you know for sure.

What are you using to measure the current with?