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I am a mechanical maintenance person who is looking to design a standalone solar pumping system (3kW pump) for my farm. It will be running on solar and batteries, no generator or grid. When doing demand calculation, I would like to find out the power consumption for the "EasySolar-II GX 48/3000VA/35-32"? Would the consumption be in AC or DC? The datasheet seems confusing to read. What voltage shall my solar panels be to interface to this unit?
As per the spec sheet this unit includes a MPPT 250/70 - so max panel voltage (allowing for cooler weather peaks etc) is 250V.
https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-charge-controller-MPPT-250-60-and-250-70-EN.pdf
Also, since you mentioned a 3kW pump - this is a 3kVA inverter so max 2400W. Do not plan to sustain this load as the unit will likely derate depending on temperatures. If your load is a genuine 3kW, excluding start-up surges, you would be better off with a larger inverter like a 5kVA.
Requirements depend on your pump, does it soft-start can you fit one to it?
How long will it run and how often, is it by day only or 24/7?
a 5kVA should be fine, it can deal with brief surges (within reason) but the battery will also take the brunt of this.
You will need to do a calculation for total pump consumption, you can then work out what size array would be optimal, taking into account weather etc.
For a 3kW motor you will need a way bigger inverter and/or a soft starter. I don't think a 5kVA inverter will be enough.
A motor needs up to 8 times the normal current to start.
Is it a 3 phase motor? If yes you need 3 inverters for that.
To calculate the needed PV power and battery capacity you need to know how much energy the pump needs (power x time).
Is that pump also running at night? What can happen if the pump can't run because the battery is empty (bad weather for a few days)?
Depends how reliable you need the system to be and where you are, among many other things.
In the southern UK in summer you would on a sunny day get at most about 6kWh generated per kw of panels installed which (neglecting losses) would run a 3 kW pump for 2 hours.
If the pump only runs intermittently then it might be cheaper to install a smaller pump which would run for longer periods, the total power consumed would be much the same so you would need the same number of panels but you could get away with a smaller and cheaper inverter.
In the limit, since you have got energy storage available in the form of the water tank, do you need batteries and an inverter at all? You could just run a DC pump straight off the solar panels whenever there is enough sun.
The pump is single phase with no soft starter. I am thinking it will run intermittently throughout a 24 hrs period for a total of 5 hours everyday. The location is semi tropical on an island with plenty sun. I like to allow 2 days/week worst case scenario to run off batteries.
You can buy pumps that run of a few panels via a mppt-pump controller. No batteries or inverter needed.
How much water needs to be pumped?
What head / height does the water need to be pumped?
Does the pump need to run outside of daylight hours?
