26kWh Solar Farm for Pumping Water

G’day Guys,
How can I configure a 26kW Solar Farm for Pumping Water, so that if/when the Grid goes down we will still be able to use power from the solar panels to operate the Pumps ?

We have 3phase power running to the pumps, and have a 50KW pump motor, so I think we have a 50KW power lines. When we pump we use from 150~200kwh power per day.

I have been told that in a blackout situation, normal grid connected inverters will disconnect from the grid for safety reasons for linesmen working on the lines.

So if a blackout happens during the day, what equipment do I need to install so the Solar power can be used during the blackout ?

We want to remain grid connected to get an income from the Solar when not being used ?


Good question, this is one for @commodoresolar

Hi Skippy,

In this case what we would recommend is a three phase pump drive inverter and Solar array to power your 50kW pump. When you’ve got Solar available your system will run from Solar, if you’re connected to mains we can set it up for you so that it will automatically switch to mains power when there isn’t enough Sun. This pump drive inverter also has a generator input so if you need to pump but there isn’t enough sunlight you can run it from a generator, it also has the capability to set the generator up with an automatic transfer switch so that the generator will kick in when the Solar isn’t enough. Feel free to yell out if you have any more questions.

Solar will be on a ridge over 200m away from the dam and doing our own trenching down to the dam, where the power lines run to.
We have been told it be better to convert Solar DCV to 3phase ACV at the solar panels, as running AC wiring long distances is better & wiring is cheaper ?

Not interested in using a generator or batteries, as if we go with solar we will only pump during the day!

Not clear on what type of inverter you talk about, is it one inverter that allows solar to be used to pump water, when the grid fails, and export when working, so it does everything ?

Yes running AC wiring will have less voltage drop and be more economical.

That’s fine regarding not wanting to use generator or batteries, it is a capability of the pump drive inverter but its your choice whether you use it.

The pump drive inverter I’m referring to is a Commodore brand it is something that we have developed in house exactly for this purpose of larger scale pumping with Solar. The inverter doesn’t export back to the grid but it will run your existing pump from Solar when the sun is shining, if you have a grid connection it will automatically changeover to mains when Solar is running low whilst not needed in this case it has the capability to run off a generator either manually or if wired correctly for the generator kick in automatically.

We have a small gen-set at the house & sheds, it has an auto transfer relay switch that stops & starts if/when the grid goes down, but does not export & we don’t need it to, as fuel costs somewhat more than the grid power.

We need an inverter &/or system that will do both ?

  1. Obviously we needs to Pump water with solar during the day.
    We understand that we require a large 3phase inverter to operate the pumps on solar …when there is enough power.
  2. We just need an inverter that will disconnect the Solar power from the Grid in a blackout, but still allow the solar to keep pumping, or it becomes a useless system!

I don’t know if I explained that correctly the first time.

I was told we could install two separate inverters, one at the solar & one at the pumps, but still researching our options, but don’t know anyone that’s done that yet.

Mate say when the grid goes down, there House solar does also.
I understand batteries act like a private grid, but is sounds stupid that Solar cant be used in a blackout, & exported when power is back on …or have I got that wrong!?

Hey mate, I think the only system out there capable of doing what you are asking would be a Selectronic select sun 20 or 40kw Solar inverter feeding 3x selectronic SP Pro’s with the multiphase expansion cards. The system would give you a grid connected 3 phase hybrid system with instantaneous changeover from grid to off-grid in the event of a blackout. each of the SP pro’s would be able to have a significant amount of battery storage as-well if you wanted to add batteries later. I don’t want to scare you but you would be looking at $30000+ just for the equipment. It is not something you can just do yourself.

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If your current solar inverter is 3 phase then i believe it will still work with the 3SP Pros it will just be a ‘dumb’ system as there will be no talk from the inverter to the sp-pros