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Solar Slowpump from Energy Matters

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article image Solar Slowpump

Solar Slowpump is a commercially available low power solar pump.

Solar Slowpump was developed by Windy Dankoff in 1983, in response to those who said that is impossible.

Thousands of Slowpumps have been installed worldwide by ranchers, homeowners, missionaries, health workers and government agencies.

Slowpump is not submersible, but can draw water from shallow wells, springs, cisterns, tanks, ponds, rivers and streams, and push it as high as 450 vertical feet and through miles (kilometers) of pipeline.

Slow pumping minimises the size and cost of the solar array, wire and piping. Slowpump is less expensive than submersible DC pumps, and made in a much wider range of sizes.

Construction and features

  • Rotary vane mechanism (positive displacement) made of forged brass, carbon-graphite and stainless steel
  • NSF approved for drinking water
  • Handles sea water, dissolved minerals
  • Survives most freezes
  • Permanent magnet, DC motor
  • AC models use a low-surge PM motor that greatly reduces starting surges, inverter and wire size requirements
  • Installation and service manual is highly detailed and illustrated

Suction capacity

  • 20 vertical feet (6 m) at sea level– subtract 1 ft. for every 1,000 ft. altitude (1 m for every 1,000 m). Pump should be placed as low as possible.

Filtration requirement

  • Solar Slowpump cannot tolerate dirt. Water must be filtered clear. If water is dirty, improve the source or consider a different pump.

PV-Direct (non-battery) requirements

  • The rated power of the PV array must exceed pump watts by 20% or more.
  • A linear current booster (controller) is required to start and run in low light.
  • Solar Tracker (optional) will increase daily yield (40-55 % in summer)


  • 300/1400 series: 1/2” female
  • 2500/2600 series: 3/4” male

Dimensions (1300/2500 Series)

  • 5.7 x 15.5” (14 x 39 cm)
  • Weight 16 lbs (7 kg)

Solar Slowpump is available from Energy Matters.

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