Solar Pool Pump on cloudy days

[Timothy]

I was using 4 460 Watt 40V panels to run a pool pump. It was running fine on sunny days, but not on cloudy days.

So I added 4 more of the same panels, but now learned from the installer that this would overpower the mppt pump controller which is max. 100V / 15 Amps.

I was assuming that the pump controller would only pull the amps needed, but according to the installer, the panels would push all amps generated to the controller and damage it on a sunny day.

Is there any way to make this work with the 8 panels? Is there a device like a limiter so it would use all energy generated on a cloudy day, but only let pass the 15 Amps max. on a bright sunny day to not destroy the pump controller?

I now have 8 460 Watt panels and according to the installer can only use 4. He couldn't provide any solution other than buying a new pump controller that would allow for higher amperage.

Any other solution to make use of all 8 panels?

 

[timselectric]

Panels don't push current. They just make it available.
Some of cheaper charge controllers may not have the ability to adjust the demand. They just take all that's available.
So, it comes down to the ability of the charge controller.
I would recommend a MPPT charge controller.
Does this system have a battery? Or, does it just send the power directly to the pump?

 

[Timothy]

Thanks for your reply.

That's exactly what I thought. Even told the installer that an outlet also provides 20 Amps, but it's possible to connect something using milliamps. He said that AC is different and that the panels are DC and push the Amps to the controller. As I'm a noob, I wanted to verify this before continuing discussion with him. The pump is using an MPPT controller rated at 90V and 15 Amps. So would it be possible to put 2 X 4 panels in parallel and the 2 4 packs in series to have 80 Volts available for the MPPT? Would the MPPT just take the Amps it needs without going above his rated 15 Amps or is there any risk of it getting damaged being provided amperage above it's rating as my installer says?

The panels go directly to the MPPT controller of the solar pump. There is no battery. That's why I added 4 more panels in order to make the pump work on cloudy days. But now the installer said it wouldn't work.

 

[Wet1]

More details on both are needed. Post the specs and/or part numbers.

 

[Timothy]

Attached are the specs of the 8 Peimar solar panels, the solar pump controller and the solar pump connected to the controller.

I think the question comes down to if the panels make the amps available like a transformer would or if they push them onto the controller.

 

[DThames]

Thanks for your reply.

That's exactly what I thought. Even told the installer that an outlet also provides 20 Amps, but it's possible to connect something using milliamps. He said that AC is different and that the panels are DC and push the Amps to the controller. As I'm a noob, I wanted to verify this before continuing discussion with him. The pump is using an MPPT controller rated at 90V and 15 Amps. So would it be possible to put 2 X 4 panels in parallel and the 2 4 packs in series to have 80 Volts available for the MPPT? Would the MPPT just take the Amps it needs without going above his rated 15 Amps or is there any risk of it getting damaged being provided amperage above it's rating as my installer says?

The panels go directly to the MPPT controller of the solar pump. There is no battery. That's why I added 4 more panels in order to make the pump work on cloudy days. But now the installer said it wouldn't work.

Not saying that I know it will work fine but...... any pump will draw X amps and those amps can change with the load on the pump. Pumps will be rated to pump with a specific "head" or lift distance which when run at rated voltage will keep the amps inside the design limits of the motor. Unless you block the output flow or raise the head, the pump will only pull normal amps.

So the amps are limited by the pump motor design and the load applied to the pump.

Funny story...someone I knew had a car wash and burned up one motor after another. He asked me for any help that I might provide. I listened to his story and he told me that he had upgraded his carwash with new 5hp pumps. Previously he had 2hp pumps. So he had put 5hp pumps on 2hp motors. The motor had a load in excess of its design and tried to do that work which caused the amps to go up, burning up the motor. Again, the load governs the amps (for a given design).

 

[Maitake]

Truth is you probably don't need circulation on a cloudy day.
Less solar chlorine loss, less oxidation loss.

 

[timselectric]

Thanks for your reply.

That's exactly what I thought. Even told the installer that an outlet also provides 20 Amps, but it's possible to connect something using milliamps. He said that AC is different and that the panels are DC and push the Amps to the controller. As I'm a noob, I wanted to verify this before continuing discussion with him. The pump is using an MPPT controller rated at 90V and 15 Amps. So would it be possible to put 2 X 4 panels in parallel and the 2 4 packs in series to have 80 Volts available for the MPPT? Would the MPPT just take the Amps it needs without going above his rated 15 Amps or is there any risk of it getting damaged being provided amperage above it's rating as my installer says?

The panels go directly to the MPPT controller of the solar pump. There is no battery. That's why I added 4 more panels in order to make the pump work on cloudy days. But now the installer said it wouldn't work.

Shouldn't be any problem with this.
Current is Current, AC or DC makes no difference.

 

[DThames]

Attached are the specs of the 8 Peimar solar panels, the solar pump controller and the solar pump connected to the controller.

I think the question comes down to if the panels make the amps available like a transformer would or if they push them onto the controller.

If you put a pump on there that runs at 25 amps, then controller should only output 15amps. Controller amps out is what controllers ratings are for. Not what the source amp capacity. There needs to be more education in the business.

 

[Timothy]

Truth is you probably don't need circulation on a cloudy day.
Less solar chlorine loss, less oxidation loss.

I use a saltwater chlorinator. It beeps on low flow. But you're reply is sort of off topic anyway. But thanks for the hint

 

[Timothy]

If you put a pump on there that runs at 25 amps, then controller should only output 15amps. Controller amps out is what controllers ratings are for. Not what the source amp capacity. There needs to be more education in the business.

I hear what you're saying. But does that mean the 8 panels can be used or better not?

 

[DThames]

I hear what you're saying. But does that mean the 8 panels can be used or better not?

On the back of the panels what is the Voc and the Impp, the Open Circuit Voltage and the Max power amps?

Are the panels in series or parallel? With 40v panels in 100v max input, surely they are not in series.

Edit added....Recently I learned that on some inverters the solar input is "rated" at some max amps. The real truth is that there is a reverse polarity protection diode across the inputs that will short the input in the event that someone connects positive to negative for the PV input. The diode will short out the panel output in an effort to keep reverse voltage off of the internal circuit. That diode can only handle X amps, so a max input rating that relates to reverse polarity connections.

 

[740GLE]

Prob doesn’t run pool pumps on sun freezing temps.

What’s the ISC of the pump controller?

Would all the panels be facing the same direction? Maybe have 4 to the east and 4 to the west spread out the peak generation and stay within the controllers specs.

 

[frogeyepete]

I should have read this thread before starting a new one, although I guess my question was slightly different. I doubled up on the recommended number of panels 4x450w instead of 2x450w. I did it on the assumption that a device only draws the current that it needs from the supply, be it AC or DC. There seems to be confirmation of this in this thread. My 500w pump has been running for nearly a week now and all seems OK (touch wood). It does run the pump on cloudy days (all be it slowly). The pool guy even managed to clean the pool withe a partially obscured sun.