PV field irrigation system using a 3 phase pump...

[whinmoor]

Go to the China Hi-Tech Fair in Shenzhen from 16-21 Nov. You might find a local company able to help you out with this.http://www.chtf.com/english/

 

[Gavin A]

your issue here is that what you're trying to do is to use inverters to run directly off the solar PV to power a specific load directly on 3 phase, which is a pretty unusual situation, and I'm not aware that such inverters exist, primarily because if you were going to do this from scratch you'd use a direct PV powered variable drive pump, not a 3 phase pump.

Stick a battery in the mix and you have a fairly standard set up with a wide range of inverters to choose from, plus you can be sure that the pump will actually have the power to pull the water to the surface when needed, as opposed to potentially only having he power to pull the water half way up for an entire day, which is no use to anyone.

 

[Engineer54]

The system is going to be installed in Cyprus, not China. Now in Cyprus it is sunny from middle of March all the way through to October. You can almost guarantee no rain in that period. so you stand more chance of losses through high PV panel temperatures than the system suffering from lack of sun to power the system. The irrigation system isn't required much at all between November and March, plenty of rainfall in the winter months....

The system is a daylight only operation that supplies a large raised storage tank. The well water level has remained pretty much constant over the last 6 years, in fact the well passes through 2 water courses the first is at 230 feet the other at 560 feet.....

I'm just waiting for a couple of system component quotes, one from a UK company and one from a Cyprus based company!! So we'll see if these batteries are needed or not. The two companies have the full details of the pump motor and it's controller which i believe has a soft start or some other form of efficiency control, As i say, i'm waiting myself for the full details of the pump motor...

 

[Worcester]

Unless i'm missing something here, why would you need battery backup if the PV system is sized correctly to the pump and it's requirements??

At the moment i'm waiting for confirmation of the pumps rating (eg if its 11 KW or 11HP.)
there is a little confusion going on there.

My response is pretty clear as to why you would need batteries.

We need the spec of the pump, as it won't have a constant supply available to it, Voltage "constant" available current "variable". to pump from 550 ft below ground, your pump loads are going to be quite high. - pipe pressure will be in the order of 20 bar at the bottom of the well (where the pump is)

Despite what everyone is saying on this thread, you are obviously convinced what you are doing is spot one, so it seems we have something to learn - could you post up a link to your design spec - a simple sketch with component specs on it would do (and links to the component datasheets)

kW or hp it's only 34% difference the question remains over the design not PV array sizing...

 

[solarfred]

Have you considered the Lorentz systems? Complete kits for well pumping direct off solar. Let me know if you need more direction or design options.

Lots of information here....https://www.lorentz.de/en/products/submersible-solar-pumps.html

 

[Marvo]

Over the years I've installed many solar bore hole pump systems in remote locations for the UN and a couple of other charities so I have some experience.

Because of the particular environment we operate in we try to keep the systems very simple and as low-tech as possible because there's never local access to skills and spares etc sometimes for over a thousand Km. It's possible to run smaller pumps reliably directly from solar without battery storage but after a certain size the technology required to ensure reliable starting and the complexity it introduces outweighs the benefits of being without batteries for us. This might not be the case however in Cyprus which might be considerably more first world.

I'd ask you to take a step backward and go back to the actual water volume requirement of your system. By standards an 11kW pump is very large. What is the daily water volume required for irrigation? What type of irrigation system is it ie is it impact sprinklers or porous pipe below ground etc? Finally how much tank storage do you have available?

I agree that generators and pumps are a mix that's very difficult to get reliable from both sides and also a generator / PV hybrid system will become a control nightmare plus you end up using the generator regularly at a small fraction of its full capacity which introduces a whole new set of problems as well as the fuel to power output efficiency will plummet. Neither of these options would be my first choice.

 

[Gavin A]

nice one Marvo, I wrote a post pointing out that we need to know the volume per day of water required, and tank storage volume as well, but apparently didn't post it up.