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

[Engineer54]

Hi to all you solar chappies,

Need a little advice on a 11KW stand alone PV irrigation pump installation.

Not done much at all with PV installations and trying to get some of the information i need off the internet is proving difficult especially as it all takes loads of time going through the bamboo internet wall from over here...lol!!

The pump i'll be working with is a 3 phase 11kw Franklin Electric submersible, working from about 550 feet of a 600 foot well. The areas i'm trying to gain some information on, is suitable panels, PV string configuration and connection diagram(s) showing PV combiners and PV disconnects etc, a suitably rated 3 phase output PV controller and expected overall system loses to take into account.....

If anyone can give me some internet links relating to the above and/or any useful comments based on experience of such an installations i'd be very much obliged??

 

[jason121]

Could you explain further on what you are trying to achieve

 

[Engineer54]

Yes, basically raising water from a deep well, using PV power for irrigation purposes...

 

[PVMatt]

Its not going to be cheap to do so, Need to look at the start currents of the pump and how frequent you would like to use it. SMA Sunny Island option might be a good one, fairly plug n play and easy to put into three phase.

 

[Gavin A]

are you absolutely certain that it needs a 3 phase pump, and can't be run from a direct DC pump?

as you're introducing all sorts of expensive and lossy components by using 3 phase, though for a 600 foot well, I suppose maybe you do need that.

anyway to the question, I'd think you'd need to be looking at something like a 1000AH 48V battery bank, and 3 x sunny island / sunny back up inverters to give you the 3 phase, but is it 11kW per phase or total? They only come in max 8kW units. Can PM you the tech support contact details for SMA's design team who specialise in this kit if you want.

ALternatively maybe victron do some bigger units, but I don't really know how their range works.

Once you've got that sussed out, then work out about the panel requirements IMO.

 

[Engineer54]

are you absolutely certain that it needs a 3 phase pump, and can't be run from a direct DC pump?

as you're introducing all sorts of expensive and lossy components by using 3 phase, though for a 600 foot well, I suppose maybe you do need that.

anyway to the question, I'd think you'd need to be looking at something like a 1000AH 48V battery bank, and 3 x sunny island / sunny back up inverters to give you the 3 phase, but is it 11kW per phase or total? They only come in max 8kW units. Can PM you the tech support contact details for SMA's design team who specialise in this kit if you want.

ALternatively maybe victron do some bigger units, but I don't really know how their range works.

Once you've got that sussed out, then work out about the panel requirements IMO.

No batteries on this little project, this is a straight stand alone system that fills a large storage tank, irrigation is by gravity feed from the tank. The 11KV 3 phase submersible pump is a fairly new unit that was temporarily used at another deep well location, and is being put into use for this installation. Any links you may have to the information requested in OP will be much appreciated...

 

[Worcester]

No batteries on this little project, this is a straight stand alone system that fills a large storage tank, irrigation is by gravity feed from the tank. The 11KV 3 phase submersible pump is a fairly new unit that was temporarily used at another deep well location, and is being put into use for this installation. Any links you may have to the information requested in OP will be much appreciated...

Without a battery backup in the system you're on a hiding to nothing as the pump will have all sorts of requirements with regard to start up currents and voltages as well as running voltages and currents in order to pump the water, you won't be able to just take that direct from the panels and inverters.

 

[jason121]

Why not use a diesel or LPG generator

 

[SibertSolar]

You could consider combining a diesel generator with an AE Smart Hybrid control system (https://www.dropbox.com/s/679yvjkwnymnor2/20140610_AE_ProductLineEN-RZ-V02-WEB.pdf?dl=0). Use an AE 3phase 10kW inverter and the smart hybrid will balance the PV/diesel genny output such that diesel use is minimised whenever the PV inverter is generating.

 

[Worcester]

Remember (I'm guessing) this is a field in remote area of china.. Appropriate technology..

 

[jason121]

My area is very remote and most if not all the irrigation is done by diesel pumps
Not cost effective to use standalone renewables yet

 

[SibertSolar]

Fair point Gordon

 

[Gavin A]

No batteries on this little project, this is a straight stand alone system that fills a large storage tank, irrigation is by gravity feed from the tank. The 11KV 3 phase submersible pump is a fairly new unit that was temporarily used at another deep well location, and is being put into use for this installation. Any links you may have to the information requested in OP will be much appreciated...

as gordon indicates, if this is a 3 phase pump then you'll need batteries and inverters to overcome start up currents and actually generate what the pump expects to be given power and voltage wise.

so yes batteries will need to be involved, unless your description of the pumps isn't accurate - have you got a link to the datasheet?

 

[jason121]

I would think the pump would start by a variable speed drive.
This stops the pipes from blowing joints.
So start current would be low

 

[Engineer54]

Without a battery backup in the system you're on a hiding to nothing as the pump will have all sorts of requirements with regard to start up currents and voltages as well as running voltages and currents in order to pump the water, you won't be able to just take that direct from the panels and inverters.

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.

 

[Engineer54]

The PV pumping system is replacing a diesel pumping station that has been nothing but trouble to the owner with continuous brake downs and maintenance costs since it's original conception over 20 years ago, in which time he has replaced the diesel pump sets 3 times. The cost of fuel and the ongoing regular maintenance required for these type of pumps is also another aspect he is looking forward to enjoying being without!! The owner knows full well that the installation is going to be an initially costly proposition, and is more than happy having a payback period of 10 years or so., not that it'll be anywhere near that time...

A quick calculation puts irrigating with brought in water, at around 8000+ Euros per year and seems to get more expensive every year....

 

[mechelec]

I guess you can pump all the water required during daylight hours with the system you have designed? One thing about irrigating at night in hot countries is less evaporation than during the day.Diesel sets at least run when you want them to.

 

[jason121]

Non standalone Solar PV works with grid tied inverters, so that means there must be connected to the grid to wk.
If you don't have a grid near buy,you will need batteries to the make the PV work. I assume you will need around 30kw of PV, but I am no expert regarding off grid PV

 

[Worcester]

@Engineer54,, PV doesn't provide constant power, it is dependant upon, time of day, date (in the year) weather - sun / cloud. What you have therefore is a highly variable supply with no gaurantee that it can pump the water when needed.

You are filling a water tank so that the water can be drawn as and when needed, which will be variable flows for variable periods of time, effectively your water tank is a "battery" of water.

In this case your power supply - the sun is exactly the opposite, a variable flow (power) for varaible periods of time, however your pumps needs to be able to draw what it needs, when it needs, so you need a 'tank' of electricity aka battery.

You won't get 11kW out of an 11kW PV Array, on occasions you'll be lucky to get even 500W...

If you've been running pumps direct of generators, I'm not suprised both have given trouble over time, they almost certainly have been abused by each other.

 

[Worcester]

Here's you're problem graphically (this is a snapshot of one of our systems three lines, generation, consumption, import/export,) if we didn't want to import / weren't connected to the grid, we would have to put a battery in place to store what we are currently exporting: