Grundfos solar water pumps run straight off a solar array, with no separate inverter, batteries or power line, and every one of them also runs on a generator or the grid.
SQFlex submersibles cover wells from 3 in casing up: helical rotor pumps for deep water to 820 ft of head, high-speed and 4 in centrifugal pumps for volume to 100 GPM. CRFlex surface pumps move pond, creek and tank water to 141 GPM. RSI solar inverters run three-phase Grundfos pumps from 2 to 250 HP.
All share built-in MPPT, a 30-300 VDC or 90-240 VAC supply on the same two wires, and protection against dry running, overload, overheating and bad voltage.
Grundfos publishes a 24-month limited warranty from the date of installation.
Available to order with the CU 202 controller, IO 101 generator switch box, DC protection and replacement hydraulic ends.
Send us your total head, daily water need and location for engineering-led sizing: 1-888.510.4036 or sales@watermainsupply.com.
Well and surface pumps that run straight off a solar array — no separate inverter, no batteries, no power line. 16 SQFlex submersibles to 820 ft of head, 9 CRFlex surface pumps to 141 GPM, and RSI solar inverters for three-phase pumps from 2 to 250 HP. Every one of them also runs on a generator or the grid.
820 ftDeepest SQFlex Head
30-300 VDCOr 90-240 VAC, Same Wires
24 MonthsGrundfos Limited Warranty
Since 2002SQFlex in the Field
1-888.510.4036Talk to a Person
Grundfos has built pumps since 1945 and solar pumping systems since the 1980s. The SQFlex, launched in 2002, put the inverter inside the motor: a permanent-magnet motor with built-in electronics that takes 30-300 VDC or 1 x 90-240 VAC on the same two wires, tracks the maximum power point of the array by itself, and protects itself against dry running, overload, overheating and bad voltage. The CRFlex applies the same idea to a vertical multistage surface pump, and the RSI renewable solar inverter turns an array into three-phase power for conventional Grundfos pumps.
We supply the complete Grundfos renewables range on the 2026 U.S. price list — pumps, replacement hydraulic ends, the CU 202 controller, the IO 101 generator switch box, DC disconnects and surge protection — with engineering-led sizing on every enquiry. Send total head, daily water need and location to sales@watermainsupply.com or call 1-888.510.4036. Supplied for installation in the United States. Genuine Grundfos equipment, factory-new in original packaging — sold and supported by Watermain Supply, an independent industrial supplier.
Three Systems, One Idea
Put the power electronics where the pump is, accept whatever clean power the site has, and store water instead of electricity.
SQFlex Submersible
16 ModelsTo 820 ftTo 100 GPM3 in or 4 in Well
Stainless steel AISI 304 well pump on the MSF 3 permanent-magnet motor. Helical rotor models for high head and small flow, centrifugal models for volume.
Five 3 in helical rotor pumps, 3 SQF-2 to 11 SQF-2
Five 3 in high-speed centrifugal pumps, 300 W to 2500 W
Six 4 in centrifugal pumps, 16 SQF-10 to 75 SQF-3
Water level electrode on the motor cable stops the pump before it runs dry
IP68, submerged to 500 ft below static level
Best forStock water, remote homes and cabins, village supply, irrigation from a well, any well without a power line.
24 Sizes2 to 250 HP208-240 V or 380-440 VIP66 to 50 HP
Off-grid inverter that converts array DC to three-phase AC for Grundfos CR, SP, NB, NK, MTR, CM and TP pumps, with four MPPT algorithms and a built-in motor library.
1.5 to 160 kW, 5.6 to 310 A rated output
Grid or generator input as backup
Dry-running and level switch inputs
Setup wizard, detachable operating panel, operating history
Optional sine-wave filters
Best forDuties past one SQFlex: irrigation wells, large ranch and community supply, and solarizing a three-phase pump already in the ground.
The whole range against the questions that decide it: where the water is, how far it has to be lifted, and how much of it you need.
SQFlex Helical Rotor
SQFlex High-Speed
SQFlex 4 in
CRFlex
RSI + 3-phase pump
Water source
Drilled well
Drilled well
Drilled well
Pond, creek, cistern, tank
Well or surface
Minimum well
3 in
3 in
4 in
Not applicable
By pump
Charted head
To 820 ft
To 525 ft
To 230 ft
To 492 ft
By pump
Charted flow
To 12.7 GPM
To 45 GPM
To 100 GPM
To 141 GPM
By pump, 2 to 250 HP
Motor input P1
1400 W
300, 1000 or 2500 W
1400 W
880 or 1730 W
1.5 to 160 kW
Supply
30-300 VDC or 1 x 90-240 VAC
30-300 VDC (100-300 on 2500 W) or 1 x 90-240 VAC
30-300 VDC or 1 x 90-240 VAC
30-300 VDC or 1 x 90-240 VAC
Array DC to 400 or 800 V; 3-phase AC backup
Controls
CU 202 or switch box
CU 202
CU 202 or switch box
IO 50 or IO 101; level switch to motor
Built into the RSI
Generator or grid backup
Yes — IO 101
Yes — confirm box on 2500 W
Yes — IO 101
Yes — IO 101
Yes — AC input
Start here when
The water is deep and the need is modest
The well is 3 in and you need more flow
The well is 4 in and you need volume
You can see the water
One SQFlex cannot do it
Quick ruleCasing under 4 in: helical rotor or high-speed. Deep water, small daily volume: helical rotor. A 4 in well and a lot of water at modest head: 4 in centrifugal. Surface water within 20 ft of lift: CRFlex. More than any of those can move: an RSI on a three-phase pump. The calculator below does this sort for you.
Warranty, Reliability and Where This Came From
The first things buyers ask. Grundfos publishes the warranty, the reliability is engineered into the motor, and SQFlex has been in the ground since 2002.
Grundfos limited warranty
As published by Grundfos Pumps Corporation
Period
24 months from the date of installation, and not more than 30 months from the date of manufacture
Who is covered
The original user
What is covered
Defects in material and workmanship. Grundfos repairs or replaces the product at its option, F.O.B. its factory or a Grundfos service station
What is outside it
Costs of removal, installation and transportation; damage from abnormal operating conditions, accident, abuse, misuse, or alteration or repair by others; and products not installed to Grundfos printed installation and operating instructions
How a claim runs
Through the seller. For equipment bought from us, send proof of purchase, installation date, failure date and the installation data, and we take it to Grundfos
Five things that protect the pump and the claim1. Write down the installation date and keep the invoice — the 24 months run from installation. 2. Install to the Grundfos instructions, with the pump fully submerged and the water level electrode 12 to 24 in above it. 3. Ground the system, and fit external lightning protection where lightning is common; the motor itself is surge-tested to 6 kV. 4. Keep sand under 50 ppm on SQFlex and 20 ppm on CRFlex. 5. Stay inside the voltage window — never more than 300 VDC open circuit into a Flex motor.
Protection is inside the motor
Dry running: the water level electrode stops the pump and restarts it five minutes after the water returns. Over- and undervoltage: stops and restarts on its own. Overload: slows down first, then stops for 30 seconds and tries again. Overtemperature: stops at 185 °F, restarts at 165 °F. No starter, no control box, no protection relay to buy or fail.
Few parts, none of them consumable
Permanent-magnet motor, carbon / ceramic bearings, stainless steel AISI 304 throughout, IP68. Grundfos states that under normal operating conditions the pumps and controls are maintenance-free — maintenance is confined to cleaning the solar panels.
Soft on the well and the pipe
The starting sequence charges, positions the rotor and ramps up; there is no across-the-line start and no limit on starts per hour. In weak sun the pump simply turns slower and keeps delivering.
What does wear, and what we do about it
Sand is what shortens the life of any well pump, and a helical rotor and stator are the parts that see it. Grundfos lists replacement hydraulic ends for eight SQFlex models, so a worn pump end goes back on the existing motor.
Is There Electrical Backup? Yes — Every Way There Is
Flex motors do not care what feeds them. Solar by day, a generator in a cloudy week, the grid if it is there.
Source
How it connects
What to know
Solar array
Direct to the pump, through a switch box or CU 202
Wire for 120 V or more. Grundfos states 0 % daily loss at 120-300 V, 5 % at 90 V, 10 % at 60 V, 20 % at 35 V for the same wattage
The pump runs from the generator when it is started and returns to solar automatically when it stops or runs out of fuel. Size the generator at pump input power plus 50 %, never less than plus 10 %
Utility grid
1 x 90-240 VAC on the same two terminals
Useful where power exists but is unreliable or costly; an IO 101 handles the changeover
Batteries
30-300 VDC, maximum 8.4 A
Array at 60 to 110 VDC through a 48 V charge controller. At 48 VDC the pump is limited to about 403 W. For pressure systems, automatic waterers and very low-yielding wells
Wind
e300i turbine with pump control interface
SQFlex Wind and Combi systems store wind, or wind and solar together, as water
RSI systems
Three-phase AC input, 208-240 V or 380-480 V
Grid or generator takes over during solar disruptions; also lets you commission on shop power before going to site
The cheapest backup is a bigger tankGrundfos builds its systems around storing water, not electricity. Three days of water in a tank rides through most cloudy spells with no generator, no fuel and no batteries to replace. Add the IO 101 for the week that does not end.
Why Solar, and Why These
Six reasons ranchers, growers and rural homeowners move a well to the sun, and when not to.
No power line to the well
Trenching or poles to a remote well is priced by the foot and can cost more than the whole pumping system.
No fuel, no utility bill
A generator pump needs fuel hauled, oil changed and someone to start it. Sun arrives by itself.
Water is the battery
Pump into a tank while the sun shines and draw from it all night. Tanks do not wear out after a few hundred cycles.
It pumps in weak sun
MPPT and variable speed mean the pump starts early, runs late and keeps delivering under cloud. A CRF 1-9 begins pumping at 40 W against 16 ft.
Fits wells other pumps cannot
Ten of the sixteen SQFlex pumps are 2.9 in diameter and go down a 3 in casing.
Watch it from anywhere
The CU 202 adds Bluetooth setup from the Grundfos GO app and remote monitoring over Wi-Fi, GENIbus or Modbus.
When solar is the wrong toolA pump that must deliver full flow on demand at 2 a.m., with no room for storage, wants grid power or a generator. A very large daily volume from great depth can need more array than the site justifies. And if utility power already reaches the wellhead, a conventional pump costs less to buy — see the comparison. If that is your site, we will say so.
Solar Pump Sizing Calculator
Estimating tool for this range only. It turns a daily water need into a flow, stacks up the head, and shows which SQFlex or CRFlex models cover the duty. It is not a selection — we confirm every system with the Grundfos sizing tool before it ships.
Step 1 · How Much Water a Day
Enter gallons directly, head counts, or both — they add. Head counts use hot-weather planning figures: 30 gal per cow-calf pair, 20 per stocker, 15 per horse, 3 per sheep or goat, 75 per person.
Irrigation, tank fill or a known figure
Step 2 · Where the Water Is
A well means a submersible; surface water within suction lift means a CRFlex.
Pump off for an hour or more
Leave 20 if unknown, then test it
Lowest water level of the year
Step 3 · Where the Water Goes
Rise is measured to the highest point of the fill line, usually the top of the storage tank.
Zero for an open tank or trough
Step 4 · Sun, Storage and Backup
Peak sun hours are yearly averages. If you need full water in winter, pick one line lower.
If nothing happens when you press the button, email the numbers to sales@watermainsupply.com and we will run them.
Daily Water—Gallons per day
Design Flow in Full Sun—GPM
Total Dynamic Head—ft
Array, Estimating—Watts of panel
Storage Tank—Gallons
Head term
Value
Where it comes from
Candidate
Listing
Max flow at this head
Your flow, % of max
Input power, est.
Method: design flow = gallons per day ÷ (peak sun hours × 60). Head = lift + rise + Hazen-Williams friction in plastic pipe with a 20 % fitting allowance + outlet PSI × 2.31. Capability and input power come from the Grundfos Product Center flow-versus-input-power curves — nine points on every head Grundfos charts — for all 16 SQFlex models and 8 of 9 CRFlex models (CRF 10-2 from the data booklet curves): the calculator reads the two charted heads either side of yours and the two curve points either side of your flow, so the watts shown are an estimate between published points, not a published figure. Array = input power plus 25 %, rounded up to 50 W. Well yield, water quality and shading are not modelled.
Performance — Documented Duty Points
Grundfos Product Center curve points, as published. Head is what the pump adds: 1 ft of water is 0.433 PSI, 1 PSI is 2.31 ft.
SQFlex submersibles — helical rotor, high-speed and 4 in listings. The end of the Grundfos curve at the highest and lowest head charted for each model, with the input power P1 at that point — the watts the array has to deliver for the pump to reach it. The product pages carry all nine points of every head curve.
Model
Pump type
Min. well
Motor rating
Highest head charted
Lowest head charted
Part No.
3 SQF-2
Helical rotor
3 in
1400 W
2.7 GPM at 395 ft on 420 W
2.8 GPM at 35 ft on 200 W
95027332
3 SQF-3
Helical rotor
3 in
1400 W
2.7 GPM at 655 ft on 590 W
2.8 GPM at 260 ft on 350 W
95027333
5 SQF-80
High-speed centrifugal
3 in
300 W
2.1 GPM at 130 ft on 300 W
9.4 GPM at 15 ft on 300 W
98842520
5 SQF-200
High-speed centrifugal
3 in
1000 W
6.5 GPM at 230 ft on 910 W
16.9 GPM at 65 ft on 920 W
99596874
6 SQF-2
Helical rotor
3 in
1400 W
5.3 GPM at 395 ft on 690 W
6 GPM at 35 ft on 220 W
95027334
6 SQF-3
Helical rotor
3 in
1400 W
4.6 GPM at 820 ft on 1350 W
5.9 GPM at 295 ft on 550 W
96834840
11 SQF-2
Helical rotor
3 in
1400 W
10.3 GPM at 395 ft on 1400 W
12.7 GPM at 15 ft on 240 W
95027335
16 SQF-10
4 in centrifugal
4 in
1400 W
13.2 GPM at 230 ft on 1400 W
21.8 GPM at 100 ft on 1400 W
95027350
15 SQF-290
High-speed centrifugal
3 in
2500 W
7.8 GPM at 525 ft on 2110 W
19.9 GPM at 195 ft on 2290 W
99858157
25 SQF-3
4 in centrifugal
4 in
1400 W
28.4 GPM at 50 ft on 720 W
40 GPM at 7 ft on 720 W
95027351
25 SQF-7
4 in centrifugal
4 in
1400 W
18.7 GPM at 185 ft on 1400 W
39.6 GPM at 35 ft on 1380 W
95027353
22 SQF-220
High-speed centrifugal
3 in
2500 W
17.4 GPM at 330 ft on 2480 W
35.3 GPM at 65 ft on 2180 W
99465259
35 SQF-4
4 in centrifugal
4 in
1400 W
19.2 GPM at 115 ft on 940 W
58.1 GPM at 15 ft on 1100 W
98994960
30 SQF-160
High-speed centrifugal
3 in
2500 W
18.3 GPM at 260 ft on 2230 W
44.8 GPM at 65 ft on 2450 W
99595463
45 SQF-3
4 in centrifugal
4 in
1400 W
44 GPM at 80 ft on 1300 W
74.6 GPM at 15 ft on 1410 W
98994951
75 SQF-3
4 in centrifugal
4 in
1400 W
30.9 GPM at 80 ft on 1210 W
106 GPM at 15 ft on 1440 W
98994964
Flow-versus-input-power curves from the Grundfos Product Center for each part number, at the heads Grundfos charts in its SQFlex data booklet 92552657, NA 60 Hz, 07/2021. Flow rounded to 0.1 GPM, power to 10 W. The small helical rotor pumps are at full speed well below the 1400 W motor rating — a 3 SQF-2 needs about 420 W at 395 ft — so size the array on the watts in the table, not the rating. 75 SQF-3 is printed as 77 SQF-3 in Grundfos data booklets; same part number. 16 SQF-10, 25 SQF-3 and 25 SQF-7 are 4 in pumps even where a price list groups them with 3 in models. Grundfos curve conditions: mean values, typical deviation ±15 %, water at 68 °F, not guarantee curves.
CRFlex surface pumps. Flow against electrical input power P1 at the motor, which is less than the array nameplate except in full sun.
Model
Motor
Ports
Begins pumping
Mid-range head, end of curve
Lowest head, end of curve
Highest head charted
Part No.
CRF 1-9
880 W · 1 HP
1 in NPT
35 W at 16 ft
13.9 GPM at 131 ft on 920 W
17.7 GPM at 16 ft on 840 W
4.8 GPM at 263 ft
98419320
CRF 3-5
880 W · 1 HP
1 in NPT
45 W at 16 ft
22.9 GPM at 82 ft on 830 W
29.8 GPM at 16 ft on 780 W
9.5 GPM at 148 ft
98419327
CRF 5-2
880 W · 1 HP
1-1/4 in NPT
30 W at 7 ft
39.2 GPM at 33 ft on 610 W
50.8 GPM at 7 ft on 630 W
19 GPM at 59 ft
98419329
CRF 10-1
880 W · 1 HP
2 in NPT
70 W at 13 ft
61.7 GPM at 33 ft on 730 W
82.7 GPM at 13 ft on 720 W
38.9 GPM at 46 ft
98419330
CRF 1-17
1730 W · 2 HP
1 in NPT
85 W at 66 ft
12.1 GPM at 328 ft on 1750 W
17.1 GPM at 66 ft on 1590 W
5 GPM at 492 ft
98424448
CRF 3-11
1730 W · 2 HP
1 in NPT
35 W at 16 ft
23.9 GPM at 164 ft on 1730 W
30.6 GPM at 16 ft on 1540 W
7.9 GPM at 328 ft
98424474
CRF 5-6
1730 W · 2 HP
1-1/4 in NPT
45 W at 16 ft
43.9 GPM at 98 ft on 1790 W
57.4 GPM at 16 ft on 1700 W
19 GPM at 181 ft
98424476
CRF 10-2
1730 W · 2 HP
2 in NPT
80 W at 16 ft
74 GPM at 49 ft on 1460 W
89 GPM at 16 ft on 1360 W
52 GPM at 82 ft
98424480
CRF 15-1
1730 W · 2 HP
2 in NPT
130 W at 20 ft
113 GPM at 39 ft on 1650 W
141 GPM at 20 ft on 1750 W
65.2 GPM at 59 ft
98424484
Product Center curve points for eight models; CRF 10-2 read from the vector curves in Grundfos data booklet 98619370, 01/2020, until its export is in hand. The CRFlex product page carries every point of every head curve, plus the shaft seal, gasket and chamber stack service kits by Grundfos part number. For a duty point in between, request the manufacturer curve and we will send it with the sizing.
How to Size a Solar Pump
A grid pump is sized on gallons per minute. A solar pump is sized on gallons per day, because the sun sets.
1. Daily water
Add up what the site uses on the hottest day of the year: head counts, people, irrigated area. Storage covers the peaks, so the pump only has to make the daily total.
2. Peak sun hours
The hours a day the site receives the equivalent of full sun — about 5.5 across Texas as a yearly average, lower in winter. Design flow = gallons per day ÷ (sun hours × 60).
3. Total dynamic head
Pumping water level (static plus drawdown) + rise to the top of the tank + pipe friction + any outlet pressure × 2.31. Size on the pumping level, never the static level.
4. Pick the family, then the model
Casing size and head choose the family. Inside it, take the model whose chart covers your flow at your head with some room — a pump at 80 % of its maximum fills the tank on a hazy day too.
5. Array
Input power at the duty point plus about 25 % for heat, dust and wiring. Wire the strings for 120 V or more and never over 300 VDC open circuit on a cold morning. 2500 W models need at least 100 VDC.
6. Storage and controls
Three days of water in the tank. A level switch on a CU 202 stops the pump when it is full; the water level electrode stops it when the well is low. Add an IO 101 if a generator will ever be plugged in.
Worked example — stock water from a deep well50 cow-calf pairs and 4 horses: 50 × 30 + 4 × 15 = 1,560 gallons a day. At 5.5 peak sun hours: 1,560 ÷ 330 minutes = 4.7 GPM. Static level 180 ft, 20 ft of drawdown, 25 ft up to the tank, 400 ft of 1-1/4 in poly plus the drop pipe: 200 + 25 + about 3 ft of friction = 228 ft, which is 99 PSI. A 4 in casing allows every family. At 228 ft the Grundfos curves put the 6 SQF-2 helical rotor at 5.7 GPM, so 4.7 GPM is 82 % of what it can do — a fit. Reading the same curves, that flow takes about 370 W into the motor, so roughly a 500 W array wired for 120 V or more. Tank: 3 days × 1,560 = 4,680 gallons. Controls: CU 202 with a level switch, or a plain switch box and a float valve. It is the default case in the calculator above.
Motor must suit a VFD; match 208-240 V or 380-440 V
Specifications at a Glance
From the Grundfos data booklets. The product pages carry the full tables: dimensions, weights, materials, terminals and cable sizing.
SQFlex
CRFlex
RSI
Supply
30-300 VDC (100-300 on 2500 W) or 1 x 90-240 VAC, 50/60 Hz
30-300 VDC or 1 x 90-240 VAC, 50/60 Hz
Array DC; 3 x 208-240 or 3 x 380-480 VAC backup
Maximum input
300, 1000, 1400 or 2500 W
880 or 1730 W
1.5 to 160 kW output
Maximum current
8.4 A; 12 A on 2500 W
4.6 A or 8.9 A
5.6 to 310 A output
Enclosure
IP68
TEFC / NEMA 3 (IP55)
IP66 / NEMA 4X to 37 kW; IP54 / NEMA 12 above
Liquid
32 to 104 °F, pH 5 to 9, sand to 50 ppm
32 to 248 °F, pH 5 to 9, sand to 20 ppm
—
Array voltage window
Best at 120 V and above, 300 VDC maximum
30 to 300 VDC
MPP 290-336 VDC (400 max) or 530-615 VDC (800 max)
Solar Against the Grid Pumps We Also Sell
If utility power already reaches the water, a conventional pump is usually the cheaper buy. These are the ones we would put against a Flex pump, and where each wins.
3 to 15 GPM and 110 to 370 ft nominal TDH on the 10 SQ; family 5 to 30 GPM
1/2 to 5 HP and 126 to 1,225 ft nominal TDH on the 10S; family 7 to 77 GPM
5 to 25 GPM, 1/2 to 5 HP, stainless steel, built-in check valve
Wins when
There is no power at the well, or the power is unreliable
Power is at the well and the casing is 3 in; SQE for constant pressure
High head or high flow on grid power
Power is at the well and the job is a household 4 in well
Verdict: on a powered site the grid pumps cost less and deliver on demand day and night, and the A.Y. McDonald 24000 is the straightforward household choice. SQFlex wins wherever the wire does not reach — and it is the only one here that runs on either.
Vertical multistage, variable speed by available power
Constant-pressure booster with integrated VFD
Self-priming cast-iron sprinkler pump, 1 to 2 HP
Convertible jet, shallow or deep well, 1/2 to 1 HP
Wins when
The water is nowhere near a power line
A building needs constant pressure
Lawn irrigation from a pond with power nearby
A house on a well to about 120 ft, NSF/ANSI 61 and 372
Verdict: the CMBE is the better pressure booster and the A.Y. McDonald pumps cost a fraction of a CRFlex. The CRFlex is for the pond in the back pasture.
RSI or CUE?Both are Grundfos drives for three-phase pumps. The CUE is a grid-powered variable frequency drive for constant pressure and process control. The RSI takes solar DC, tracks the maximum power point and falls back to AC. If the site has reliable power, buy the CUE; if the point is to get off it, the RSI.
Controls, Protection and Parts
Everything else on the Grundfos renewables price list, each on its own listing.
Monitoring and control for the full SQFlex range: keypad and LED display, level or pressure start and stop with soft start, speed limit to match well yield, Bluetooth for Grundfos GO, Wi-Fi, GENIbus and Modbus.
80 VDC turbine, 30 ft tower, pump control interface and adaptor for SQFlex Wind and Combi systems.
Genuine Grundfos parts only. CRFlex shaft seal, gasket and chamber stack kits are tabulated by part number on the CRFlex listing. Level switches, dry-running switches, sine-wave filters and zinc anodes are available on request.
See It in the Field
A Texas water well contractor on the SQFlex, and the Grundfos installation walkthroughs for a solar and a wind system.
Grundfos SQFlex with Ferguson Water Well, Edna, Texas
How to Install Grundfos SQFlex Solar
How to Install Grundfos SQFlex Wind
Size It on Your Phone — Grundfos GO Solar
The free Grundfos app that sizes an SQFlex, CRFlex or RSI system from what you have in hand.
Three ways to size: from a pump you already have, by scanning its barcode; from the number of solar panels available; or from the application — head, flow, well depth, pumping distance and location. The app lists the models that fit, estimates the number of panels, pairs an RSI with the three-phase Grundfos pumps it can drive, works offline and syncs with the Grundfos Product Center.
A built-in calculator estimates daily water demand for homes, crops, livestock and community supply. Size it in the app or with the calculator above, then send us the result and we confirm it before it ships.
Grundfos GO Solar is a free app from Grundfos Holding A/S. The CU 202 controller pairs with the separate Grundfos GO app for commissioning over Bluetooth.
Why Buy It Here
Engineering-led sizing
Head, daily volume, sun hours, array voltage and cable loss worked out before anything ships, and checked in the Grundfos sizing tool.
Multi-brand honesty
We sell grid pumps from Grundfos and A.Y. McDonald too. If solar is not the right fit for your site, we will say so.
The whole system on one order
Pump, controller, generator switch box, DC disconnects and surge protection together, matched to each other.
The U.S. build
60 Hz, NPT threads, UL-listed CU 202 — the part numbers on the Grundfos U.S. renewables price list.
Account terms
Ranches, contractors, utilities and growers can buy on account. Ask when you call.
Parts and aftermarket
Hydraulic ends, controls and service parts by Grundfos part number, from a company based in Houston and serving the Gulf Coast.
Questions Buyers Ask
If yours is not here, call. Sizing conversations are the part of this we are good at.
What is the warranty on a Grundfos SQFlex, CRFlex or RSI?
Grundfos Pumps Corporation publishes a limited warranty to the original user against defects in material and workmanship of 24 months from the date of installation, and not more than 30 months from the date of manufacture. Grundfos repairs or replaces at its option; removal, installation and freight are outside it. A claim runs through the seller, so for equipment bought from us, send proof of purchase, the installation date, the failure date and the installation data.
How reliable is a solar pump, and what maintenance does it need?
Grundfos states that under normal operating conditions the pumps and controls are maintenance-free; maintenance is confined to cleaning the solar panels. The motor protects itself against dry running, overload, overheating and over- or undervoltage and restarts on its own. SQFlex has been in the field since 2002.
What happens at night and on cloudy days?
The pump slows as the light drops and stops when there is not enough power, then restarts by itself. That is why solar systems pump into storage: size the tank for about three days of water. For water on demand at night, add a generator, the grid or batteries.
Is there electrical backup?
Yes. SQFlex and CRFlex motors accept 1 x 90-240 VAC on the same two wires as solar DC. An IO 101 switch box runs the pump from a 115 V or 230 V generator when it is started and returns to solar automatically when it stops. RSI inverters take three-phase grid or generator power.
Do I need batteries?
No. The pump runs directly from the array and the tank stores the energy as water. Batteries are an option on SQFlex, at 30 to 300 VDC, for pressure systems, automatic waterers and very low-yielding wells.
How many solar panels do I need?
Enough to deliver the pump input power at your duty point plus about 25 %, wired in series for 120 V or more and never above 300 VDC open circuit. A deep stock well is often 400 to 900 W; a 2500 W high-speed pump needs correspondingly more. The calculator on this page estimates it.
How deep can an SQFlex pump from?
The 6 SQF-3 helical rotor pump is charted to 820 ft of total head, and any SQFlex can be set up to 500 ft below the static water level.
Will it fit a 3 in well?
Ten of the sixteen models do: the five helical rotor pumps and the five high-speed centrifugal pumps are 2.9 in in diameter. The six 4 in centrifugal pumps need a 4 in well.
Can a solar pump pressurize a house?
Yes, with a pressure tank and a pressure signal to a CU 202 — but only while there is power. Most off-grid homes pump to an elevated tank, or add batteries or a generator for the night.
Is there an app for sizing a solar pump?
Yes — Grundfos GO Solar, free on iOS and Android, sizes SQFlex, CRFlex and RSI systems three ways: from a pump you have, from the panels available, or from the application. It estimates the panel count and works offline. Details and store links are in the app section above.
What else do I need besides the pump?
Solar modules and racking, a switch box or CU 202, DC disconnect and surge protection, drop cable, pipe, a safety rope, a storage tank and a level switch. The pump part number covers the pump and motor with its motor cable only.
Ready to Size It
Send the well or pond details, the daily water need and the nearest town. We come back with the pump, the array size, the controls and the reasoning.
Technical data on this page is taken from Grundfos product literature and is subject to change by the manufacturer. Confirm against the current installation manual before specifying. Estimating figures from the calculator are not a selection. Grundfos, SQFlex, CRFlex, Grundfos GO and Grundfos GO Solar are trademarks of Grundfos Holding A/S. A.Y. McDonald is a trademark of A.Y. McDonald Mfg. Co. Used here for product identification only. Watermain Supply is a DBA of E4 Industrial LLC, an independent industrial supplier based in Houston, Texas.
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