Seeking advice for battery backup on well pump

Famtraveler24

New Member
Can anyone point me to a resource for establishing an automatic transfer from grid power to solar charged batteries during a power outage?

I assume there is a way to do this.

The well pump is my sole application for the solar array.

Thx.
 

DThames

Photon Sorcerer
Running well pumps off an inverter is a fairly common questions. Motor starts often require a lot more power than they do just to run. This makes it hard to properly size an inverter. Look for an inverter with UPS mode or a pass through with automatic transfer switch. Here is one that would work on smaller pumps. How small/large, I don't know. You would also need a battery if you want to run in poor sun or at night.
 

Rednecktek

Solar Enthusiast
You'll also have to know the wattage of the pump and if it's single or split phase as both of those will help determine the size of the inverter.

Next step is to guesstimate how long it'll need to run to figure out battery capacity.

Not difficult, just potentially expensive. The MPP and Growatts are pricy but you pretty much just need to pick the size, connect the batteries, and program it for UPS/Grid First mode. Boom, done.
 

Famtraveler24

New Member
You'll also have to know the wattage of the pump and if it's single or split phase as both of those will help determine the size of the inverter.

Next step is to guesstimate how long it'll need to run to figure out battery capacity.

Not difficult, just potentially expensive. The MPP and Growatts are pricy but you pretty much just need to pick the size, connect the batteries, and program it for UPS/Grid First mode. Boom, done.
Awesome. Thx. Do you have a similar system? If so, what inverter did you choose?
 

Rednecktek

Solar Enthusiast
I don't, and unless I win the lotto I won't be able to due to a 300ft deep well pump and needing to build up and feed a 6Kw system. I'll just fire up the generator for the 3-5minutes it takes to top up the pressure tanks.

Granted that is at my camp and it gets about 150 minutes of run time a year. :)
 

pvdude

Solar Enthusiast
Here is what we did to run our well pump.
The LRA (Locked Rotor Amps) for our pump motor is 41A, so @ 240volts, needed an inverter that
would supply 10kw for a second or two.
After starting, the motor uses about 8A
The pump only runs long enough to fill a pre-charged pressure bladder tank.

The inverter we use decides where to get the electricity to run the pump.
If it is sunny, the pump is powered from the PV panels.
No electricity is used from the grid or batteries.

If it is cloudy, the inverter will take what it can get from PV, and supplement from the grid.
The inverter uses the batteries as a last resort.

When the grid goes down, the inverter powers the pump from the PV and batteries.
When the grid comes back up, the inverter switches back to normal operation.
 

Famtraveler24

New Member
Here is what we did to run our well pump.
The LRA (Locked Rotor Amps) for our pump motor is 41A, so @ 240volts, needed an inverter that
would supply 10kw for a second or two.
After starting, the motor uses about 8A
The pump only runs long enough to fill a pre-charged pressure bladder tank.

The inverter we use decides where to get the electricity to run the pump.
If it is sunny, the pump is powered from the PV panels.
No electricity is used from the grid or batteries.

If it is cloudy, the inverter will take what it can get from PV, and supplement from the grid.
The inverter uses the batteries as a last resort.

When the grid goes down, the inverter powers the pump from the PV and batteries.
When the grid comes back up, the inverter switches back to normal operation.
Could you share details about your inverter and setup? This sounds like exactly what I need. Thx.
 

pvdude

Solar Enthusiast
We used a Schneider Conext XW Pro 6848 inverter.
it is rated at 6800watts continuous, 12000watts for 30 seconds.

A Schneider Conext XW+ Mini Power Distribution Panel was used for the electrical connections to the battery & grid & loads.

Schneider Conext Gateway for management and remote access.
Schneider Conext Battery Monitor
Schneider Conext XW MPPT 100-600 Charge Controller connects the PV array to the inverter & batteries.

16 REC Solar Alpha REC365AA yields about 5840watts (there are newer, more powerful PV panel options available now)

8 Rolls S6 L16-HC 445Ah FLA (Flooded Lead Acid) batteries provide enough storage to run overnight, if needed.

solar_installation_complete.png
 
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Porch

Solar Enthusiast
Can anyone point me to a resource for establishing an automatic transfer from grid power to solar charged batteries during a power outage?

I assume there is a way to do this.

The well pump is my sole application for the solar array.

Thx.

We need to know what pump size and current draw to suggest anything.

3HP (might be 5HP, I forgot) well pump on twin OutBack 3648 here. Pump is a 3 phase and I run a VFD to convert the split phase to 3 phase. The VFD has a slow ramp up, so that gets around the startup surge issue and makes everything last longer.
 

Chip

New Member
I don't know if this helps? But you can get 12,24,48 volt well pump. Mine is 24volt I set the pressure on the grid pump to 30 on 50 off
and set the 24volt pump to 25 on 50 off. I connected it direct to the battery. That way I don't need to use an inverter/converter the way I see it less things to go bad, and less power usage from inverter/converter
 
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