Hi all,

My girlfriend is using an old centrifugal water pump powered from the grid and I am looking at the possibility of adding the option of powering from solar in addition to the grid. Below is the diagram showing how I think the whole thing will connect (based on research on the web).

The pump details are as per below, so if I understand it correctly I need the panels to produce ~ 1.76 kW (220Vx8A) , so I think 4 x 600 w panels can cover the voltage requirement but I am not clear about the 8A requirement. Can someone more experienced shed some light on that?

Secondly is an inverter like below adequate for what I want to achieve?
https://www.thaiagrotech.com/product/259/solar-pump-inverter-controller-1-2-2-kw-1-3hp-1-3%E0%B9%81%E0%B8%A3%E0%B8%87-1ph-220vac-%E0%B8%AD%E0%B8%B4%E0%B8%99%E0%B9%80%E0%B8%A7%E0%B8%AD%E0%B8%A3%E0%B9%8C%E0%B9%80%E0%B8%95%E0%B8%AD%E0%B8%A3%E0%B9%8C%E0%B8%84%E0%B8%B8%E0%B8%A1%E0%B8%9B%E0%B8%B1%E0%B9%89%E0%B8%A1%E0%B9%82%E0%B8%8B%E0%B8%A5%E0%B9%88%E0%B8%B2%E0%B9%80%E0%B8%8B%E0%B8%A5%E0%B8%A5%E0%B9%8C%E0%B9%83%E0%B8%8A%E0%B9%89%E0%B9%84%E0%B8%9F%E0%B9%84

Thanks

The pump controller/inverter you link to certainly looks like it's the answer and enables operation from either solar or grid power.

To be sure it would be a good idea to locate and download the manual for the beast (when you find it post a link here).

Of course you would wire it according to the manual.

Solar panels are a peculiar power source and are certainly not constant power, they need to feed into a MPPT (Maximum Power Point Tracking) system for efficiency and safety. The Suoer box has a suitable controller. The destructions for the controller should recommend suitable panels for your particular application.

Crossy has answered your specific question, but I have others to determine if it’s the right approach.

What is the purpose of the water pump? Can it be run only when solar is available? Eg does it fill a storage tank? Does it feed your taps and so variable and periodic in nature? Is it for a swimming pool?

Have you considered grid-tied, no export inverter?

@Crossy

I have found the manufacturer's website, not much of a manual but at least some details of it
https://www.suoerinverter.com/pv100-2r2g-ss-solar-pump-inverter-single/three-phase-suoer-15kw-22kw-pump-inverter-price

I have found also this which seems to be the same
https://www.lazada.co.th/products/handuro-dc-acdc-750w-1100w-1500w-2200w-3000w-i4347976201-s24577797496.html?

and here are its specifications
https://www.handurothailand.com/ac-dc-hybrid-2/

I came across these also which are a bit more pricy but will allow me to drive the pump for now but also to expand the system in the future (that was in the plan anyway).

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(Manufacturer: https://www.sunrayups.com/MPS-VIII-ECO-Series-Hybrid-Solar-Inverter-pd42726729.html)

@JBChiangRai
The pump is used for irrigation of the girlfriend's and MIL garden in the land around the house (~ 1 rai) , they are feeding a mazze (sic) of blue pipes with sprinklers that are sectioned off (not all the land is watered in the same time). Usually they use it 1 time per day for a period of 1 hour or so (from what I saw I believe they are restricted to one time per day as it is a constant fight of fixing a broken/leaking pipe or a connection or a sprinkler 😁).

my 2c. Your 8amp quoted maybe constant running.

Crossy question.🤔

Don't we need to take into account the inrush when starting which will be more than 8 Amps ? It could be quite high.

Or maybe it simply starts very slowly as the sun rises ?🤔 Or there is an on-board Lithium battery to take care of the pump inrush. Or are we starting the pump on grid power and switching to solar when running.

11 hours ago, capriole said:

Usually they use it 1 time per day for a period of 1 hour or so

Then IMHO the better solution is a grid-tied, no export inverter. This will give you a better ROI and provide additional benefits outside of that 1 hour window.

12 hours ago, VocalNeal said:

my 2c. Your 8amp quoted maybe constant running.

Crossy question.🤔

Don't we need to take into account the inrush when starting which will be more than 8 Amps ? It could be quite high.

Or maybe it simply starts very slowly as the sun rises ?🤔 Or there is an on-board Lithium battery to take care of the pump inrush. Or are we starting the pump on grid power and switching to solar when running.

Centrifugal pumps are low torque at low speed so not too heavy with start up demand and react well to a low current soft start.

As mentioned (@JBChiangRai) , a budget grid tie inverter would likely be a better solution to lowering operating cost. Solar pumps are great for off grid situations.