Powering Grundfos A/C Pump in off-grid application

[Texas Wellman]

You have SQ confused with SQ Flex. There is a difference.

The SunPumps controller that I have is a voltage booster that goes up to 30V (I think) and it is not really useful for anything besides controlling the SunPumps brush-type DC pumps.

The reason why I was interested in the SP series of pumps is because they are much cheaper than the SQ series. Specifically, I found one online for $6xx (it was one of the first results in a Google search). Thus, the inverter cost (just under $900) plus the pump is less than the cost of the SQ series pump. The other issue with the SQ series pumps is that I would not be able to run it off of my batteries due to the increased voltage required.

Regarding the power consumption: 550W seems like it could be within the realm of possibility (granted, it's definitely on the low end!); so it seems like my assumption about the number of impellers = the number of "stages" is correct.

Thanks for the response.

Chris

[cjb80]

The SunPumps controller that I have is a voltage booster that goes up to 30V (I think) and it is not really useful for anything besides controlling the SunPumps brush-type DC pumps.

The reason why I was interested in the SP series of pumps is because they are much cheaper than the SQ series. Specifically, I found one online for $6xx (it was one of the first results in a Google search). Thus, the inverter cost (just under $900) plus the pump is less than the cost of the SQ series pump. The other issue with the SQ series pumps is that I would not be able to run it off of my batteries due to the increased voltage required.

Regarding the power consumption: 550W seems like it could be within the realm of possibility (granted, it's definitely on the low end!); so it seems like my assumption about the number of impellers = the number of "stages" is correct.

Thanks for the response.

Chris

[Texas Wellman]

Do you use a controller for your sun pump and if so is the controller compatible with their brushless line of DC pumps? I would recommend you look into one of sun pumps brushless pumps if they will work with your controller.

Here is the breakdown for you on what a submersible motor consumes by Horsepower:
1/2 HP = 600-950 watts
3/4 HP = 940-1300 watts
1 HP = 1200-1600 watts.
Source: http://www.franklin-electric.com/aim...l/page-13.aspx

These numbers will vary depending on manufacturer and pumping conditions. The amps are dependent on the amount of water you are moving. With a high water level you're going to have max. flow and thus max amps.

If you're dead-set on using an AC pump look at the Grundfos SQ series that use a 3" pump/motor and have built-in soft start. They have one available for 115V and they are all 2-wire. The 115V Grundfos SQ is the only pump that I am aware of that will start on a Honda EU2000i. The inverter you mentioned will probably not start any other pump due to the surge amps.

FYI a 3-wire pump normally pulls about 1/2 the starting power that a 2-wire pump will so I suggest you stay away from any 2-wire models except either the Grundfos SQ or CentriPro (Goulds) 2-wire which uses a PSC (capacitor start). Franklin motors (most common) use a biac switch and pull 2x the starting load.

The best solution is probably the Grundfos SQ Flex. Wire the panels in Series to get above 90V and you will really move some water. The pump will cost you about $2K but has built in MPPT (no controller needed). You can add controllers that only act as an interface with level etc. but they have multiple models.

I currently have a SunPumps T-135 well pump in an well that is positioned 50 feet down. The water level in the well is essentially at grade and the well is a part-time artesian well. The pump fills a 2600 gallon tank that I use as a buffer for a much bigger pump that pressurizes a drip irrigation system. The T-135 pump is a brush-type DC pump that (IIRC) consumes something on the order of 150W or so; however, the pump is apparently dying according to the readings that I have taken with my volt-meter and the advice from SunPumps. I have 4 T-105 batteries wired in series (24V), ~5.4 Kwh of storage. I have 3 285W (36V) panels charging the batteries - they are wired in parallel, and I have a Xantrex C40 charge controller.

To make a long story, less long, I need to increase my flow rate from the well to fill the tank so that we can do two waterings per day. The well will support the increased flow rates, but the current pump is no capable of doing that and it's dying anyways. The increased fill rate will enable us to do two waterings per day and also the filling of the tank will occur during daylight hours. We are targeting a flow rate of 6-7 GPM, an increase from ~1.5-2 GPM using the T-135.

I have been looking at the Grundfos SP pumps because they are much less expensive than DC brushless pumps. This will require an inverter, obviously, and I have initially chosen the Samlex SA-2000K-124, 24V Pure Sine Inverter as it is 24V and relatively cheap and I have another Samlex inverter that has been working really well for the last year or so.

I am looking to use the 7S05-11 pump, 115V 2 wire. The Pump's documentation can be found here: http://us.grundfos.com/content/gpu/e...-SP-PG-001.pdf on page 22 and 23. This should meet my flow rate requirements and has a reasonable cost.

OK, so that's the background. Here's the questions:

1) In the pump's documentation it shows the power consumption "per stage", but the documents never define what a stage is. I am assuming that the number of stages = the number of impellers. Thus, the peak steady-state power consumption of the 7S05-11 should be ~ 0.05 * 11 = 0.55 Kw = 550W. This sounds about right, assuming that the pump is extremely efficient (i.e., that is only about 100W more than a DC brushless pump with equivalent capabilities). Does this sound right? Is my assumption about stages = # of impellers correct?

2) Would a 2Kw inverter (4Kw surge) have any issues with this pump? Can I go with a smaller inverter (e.g., 15000W).

3) Are there other A/C submersible well pumps with similar efficiency?

4) Assuming that the panels produce a "real world" 600W (855W nameplate) then it seems like the panels should be sufficient to run the pump and keep the batteries topped off. Does this seam reasonable?

Thanks!

PS - I realize that this pump will be a huge load on the batteries. The irrigation pump is panel-direct, so in low light conditions it will not pump out of the tank. Thus, the only time the tank should drain is when the sun is shining. In theory, the power should "pass through" the batteries and they should be fully charged much of the time. In any case, if this doesn't turn out to be true then I realize that I will need to replace the battery bank. The last watering of the day starts at 1 PM, so the tank should be filled again by approximately 4:30 PM. Finally this is only running during the summer, and there is still light out at 9:30 PM here in the summers.

[cjb80]

I currently have a SunPumps T-135 well pump in an well that is positioned 50 feet down. The water level in the well is essentially at grade and the well is a part-time artesian well. The pump fills a 2600 gallon tank that I use as a buffer for a much bigger pump that pressurizes a drip irrigation system. The T-135 pump is a brush-type DC pump that (IIRC) consumes something on the order of 150W or so; however, the pump is apparently dying according to the readings that I have taken with my volt-meter and the advice from SunPumps. I have 4 T-105 batteries wired in series (24V), ~5.4 Kwh of storage. I have 3 285W (36V) panels charging the batteries - they are wired in parallel, and I have a Xantrex C40 charge controller.

To make a long story, less long, I need to increase my flow rate from the well to fill the tank so that we can do two waterings per day. The well will support the increased flow rates, but the current pump is no capable of doing that and it's dying anyways. The increased fill rate will enable us to do two waterings per day and also the filling of the tank will occur during daylight hours. We are targeting a flow rate of 6-7 GPM, an increase from ~1.5-2 GPM using the T-135.

I have been looking at the Grundfos SP pumps because they are much less expensive than DC brushless pumps. This will require an inverter, obviously, and I have initially chosen the Samlex SA-2000K-124, 24V Pure Sine Inverter as it is 24V and relatively cheap and I have another Samlex inverter that has been working really well for the last year or so.

I am looking to use the 7S05-11 pump, 115V 2 wire. The Pump's documentation can be found here: http://us.grundfos.com/content/gpu/e...-SP-PG-001.pdf on page 22 and 23. This should meet my flow rate requirements and has a reasonable cost.

OK, so that's the background. Here's the questions:

1) In the pump's documentation it shows the power consumption "per stage", but the documents never define what a stage is. I am assuming that the number of stages = the number of impellers. Thus, the peak steady-state power consumption of the 7S05-11 should be ~ 0.05 * 11 = 0.55 Kw = 550W. This sounds about right, assuming that the pump is extremely efficient (i.e., that is only about 100W more than a DC brushless pump with equivalent capabilities). Does this sound right? Is my assumption about stages = # of impellers correct?

2) Would a 2Kw inverter (4Kw surge) have any issues with this pump? Can I go with a smaller inverter (e.g., 15000W).

3) Are there other A/C submersible well pumps with similar efficiency?

4) Assuming that the panels produce a "real world" 600W (855W nameplate) then it seems like the panels should be sufficient to run the pump and keep the batteries topped off. Does this seam reasonable?

Thanks!

PS - I realize that this pump will be a huge load on the batteries. The irrigation pump is panel-direct, so in low light conditions it will not pump out of the tank. Thus, the only time the tank should drain is when the sun is shining. In theory, the power should "pass through" the batteries and they should be fully charged much of the time. In any case, if this doesn't turn out to be true then I realize that I will need to replace the battery bank. The last watering of the day starts at 1 PM, so the tank should be filled again by approximately 4:30 PM. Finally this is only running during the summer, and there is still light out at 9:30 PM here in the summers.