Proposed DIY solar power station

[tumbi1]

Looks like a Voltronics clone. 4kW (5kVA) with max 145V solar MPPT.
I have a similar clone unit but mine has lower solar PV input voltage limit (105V) and is PWM, not MPPT.

Hard to know how it would go with your pump. You'd really need to know the characteristics of your pump, or measure it with power meter that can assess surge rating. Perhaps consider a pump soft starter.

Mine runs a pool pump which starts with 900W cycle for 5-min before reverting to all day cycle at ~320W but it has a soft start up and doesn't seem to have a high current surge demand at all.


Can't connect those batteries in series. 12V systems only.


That's a better choice - the specs say these can be connected in series. I can't vouch for their quality though, just that the specs say you can connect in series.

I dunno, maybe consider a pre-made 48V battery?


While they are better panels, you need to be careful about panel choice Voc ratings and how that works with your choice of inverter/charge controller. These have a Voc at 25°C of 41.2V, so allowing for a chilly morning west of Kempsey you are looking at a Voc of ~45V.

I think you would be safe to have those panels in a 3S arrangement with that inverter, 2S would also work. But no more or less per string.

Not sure you'd want put all that on a trolley really. Seems more of a wall mount job to me.

Many thanks,

I'm learning rapidly - I spotted the limitation with those batteries - there are pitfalls here and there you can easily fall into! I will investigate the pump further to see what I can do.

 

[wattmatters]

My cheap (3kW, 24V) Chinese knockoff will take an 800W load for quite some time - like hours - with no apparent strain... except the fans go whoof all the time.

An 800W load is no issue. The issue is it's a pump and the wattage rating is only telling us the running power demand, not start up surge power demand.

A pump can draw a start up surge current up to 10 times it's running demand. How high the surge demand is varies by pump. Some pump start up cycles are brutal on electrical supply equipment, while others have a softer start (sometimes with starter electronics to help).

We don't know what the surge demand of tumbi1's pump is. Also, if the pump's normal surge demand cannot be met but the supply is still high enough to start the pump, albeit more slowly, this is not good for the pump's longevity.

There is a fair chance the 5kVA unit will manage but it would be wise to get a better understanding of the actual start up demand of the pump.

 

[tumbi1]

An 800W load is no issue. The issue is it's a pump and the wattage rating is only telling us the running power demand, not start up surge power demand.

A pump can draw a start up surge current up to 10 times it's running demand. How high the surge demand is varies by pump. Some pump start up cycles are brutal on electrical supply equipment, while others have a softer start (sometimes with starter electronics to help).

We don't know what the surge demand of tumbi1's pump is. Also, if the pump's normal surge demand cannot be met but the supply is still high enough to start the pump, albeit more slowly, this is not good for the pump's longevity.

There is a fair chance the 5kVA unit will manage but it would be wise to get a better understanding of the actual start up demand of the pump.

I've been researching the pump, but there is no extra information in regards the surge demand in the manual unfortunately, and I can't find it for any comparable pumps either. I've also been looking for a module/device to provide a 'soft start' for it, but nothing I can find that the pump can just plug into - they all seem to be wired modules. The pump is under the house, and is plugged into a normal wall type socket. Maybe the safest thing is to invest a bit more and get a higher rated AIO?

 

[Rednecktek]

but nothing I can find that the pump can just plug into - they all seem to be wired modules

Wire a male plug on one end and a female on the other and stick it between the pump and the wall?

 

[tumbi1]

Just a follow up on this one - I have completed the build and tested it ok. One 'foible' that came up was one I couldn't know from the Vevor description as it wasn't mentioned - it doesn't support using lithium batteries! No problem, I bought 16 second hand Yuasa UXH-125-6FR batteries for $100 each, to give 48V 250Ah. The batteries, although second hand, are barely used and in very good condition. I looked them up online and they are built to last 10 years. I am using Trina solar panels, and 100A copper tinned cables throughout. I have the batteries housed in an old cupboard that was damaged and would have been thrown out, to stop mice etc getting in.

One question; I have a 48V circuit breaker between the batteries and the Vevor, but the batteries add up to 53V, given the extra voltage you get from fully charged batteries. Will that still work? I'm not sure what else to use as breakers only seem to come in a small number of standard sizes like 12V and 48V.

 

[wattmatters]

it doesn't support using lithium batteries!

It may not have default lithium battery settings but you can chose the User definable battery settings to set appropriate voltages. It will work just fine.

I have mine working with LiFePO4 batteries, indeed mine are a hybrid of LiFePO4 and Sealed Lead Acid.