Well pumps · SQFlex
Grundfos SQFlex for solar and remote supply
SQFlex is Grundfos’s renewable-friendly submersible family: built-in AC/DC drive, MPPT-aware solar behavior, and motors that accept a wide DC or AC window. It is for remote / off-grid / hybrid water supply — not a drop-in replacement for a grid SQE constant-pressure house kit.
What SQFlex is good at
- Wide input — roughly 30–300 VDC or 1×90–240 VAC (model-dependent; higher-power motors tighten the DC floor). Polarity-tolerant DC connection on many kits.
- Built-in electronics — VFD/MPPT behavior, soft start, dry-run and motor protection without a separate solar pump inverter in the basic case.
- Helical rotor and centrifugal variants — helical for higher head / lower-medium flow; centrifugal for shallower head / higher flow (within published ranges).
- Hybrid energy — solar primary with generator or grid AC backup is a common pattern; batteries and charge controllers appear in some architectures.
Typical applications (and non-applications)
| Fits | Usually not the first pick |
|---|---|
| Off-grid cabin or ranch stock tank with daytime fill + storage | Suburban house that already has reliable 230 V and wants CU constant pressure (use SQE) |
| Community / school / clinic water where fuel delivery is painful | “Quiet night pressure” with zero storage and zero battery — solar pumps sleep when the sun does |
| Conservation / pond / floating intake (with proper kit) | High simultaneous indoor demand without a reservoir or large storage strategy |
Sizing honesty
Solar yield is seasonal. Design for the worst month of irradiation that still must meet daily demand, plus total head (static lift + drawdown + friction + discharge elevation). Use Grundfos Product Center / SQFlex tools — or a solar-pump-experienced contractor — not HP anecdotes. Grid SQ / SQE sizing still starts with GPM and head; SQFlex adds energy and storage.
Controls you will hear about
- IO 50 — simple on/off switch box for service or “no water needed.”
- CU 202 — status / reservoir-full cutout with level switch when storing water as the battery.
- Charge controllers and battery banks when the design stores electricity instead of (or in addition to) water.
Hard water after the well
Remote wells still deliver iron and H₂S. Treatment order does not change because the pump is solar — see iron and H₂S.
Final pump selection needs your well data and a published performance curve. Talk to a licensed well contractor for design, pull/replace, and code compliance. For product questions, you can also contact R.E. Merrill & Associates.
Hard-water cross-links
- Iron in well water — treatment order after the well can deliver flow
- Rotten-egg / H₂S — smell is not a pump feature
- Size softener by GPG — once pressure and yield are stable