Grundfos SQFlex pumps – the best solar-powered solution

Grundfos is a Danish company that has developed pumps for different water supply solutions. It has a vast range of options for very different needs. One of the most innovative options is a pump powered by renewable energy. The pump simply uses electricity generated by solar panels or wind turbines that have to be installed together with a pump. That allows you to get water even if in your location there is no electricity network.

The Grundfos SQFlex series is an environmentally friendly solution for the water supply industry. Grundfos SQF (SQFlex) is a series of submersible, borehole pumps. They can be produced in two versions: with a 3inch screw rotor with a high head at a low flow rate, and 4inch with a low head but high flow rate. The SQFlex system can operate on alternative energy sources like solar or wind.

SQFlex is more than just a pump, it is a complete intelligent system. Due to the built-in electronic components, the pump is compatible with both DC and AC sources, without the need to connect to an external inverter.

Development of SQFlex Pumps

Grundfos started working with renewable energy sources even before they became a popular saving tool. After the global crisis in the 70s, when humanity realized that oil reserves were not unlimited, Grundfos began experimenting with solar energy.

With the assistance of the UN in 1982, the company began testing a solar pumping station. A submersible pump with an inverter was installed, which received direct current from solar panels and turned it into alternating current, thereby starting the operation of the station. Today the project is a solar pumping system that can supply drinking water to a village with a population of up to 1000 people.

Grundfos SQFlex pumps rangeThe inverter has been praised in a World Bank report and has been recognized as a technology ahead of its time. However, the market met the new product without interest. Solar panels were bulky and ineffective for commercial applications. The company sold about 200-300 systems a year, and they were used primarily in charity missions in developing countries.

Thanks to Grundfos research, alternative energy technologies have become more efficient, cost-effective, and powerful, which has facilitated their expansion into commercial markets. Jens Frederskin, Senior Business Development Manager, notes that up to 2002, developing countries supplied 80% of solar pumping stations. Today, Grundfos solar and wind systems are widely used in industry and agriculture around the world.

SQFlex is a new stage in the development of alternative energy. In 2002, Grundfos developed the SQFlex system, which was a watershed moment in the development of alternative energy. The invention is an inverter located in the motor, which allows quick installation and easy operation of the pump.

The performance of solar systems is increasing every year. The recent development of Grundfos RSI ( Renewable Solar Inverter) enables solar energy to be used in the largest projects. While the SQFlex can handle up to 80,000 liters per day, the RSI handles over 500,000 liters. Pumps and solar pumping stations are getting bigger and more efficient. The company is optimistic about the future and actively invests in the development of alternative energy around the world.

Water Supply Solutions

The SQFlex unit is a reliable water supply system based on renewable energy sources. It is ideal for remote water supply places designed for continuous and intermittent operation.

  • Providing water to houses or structures that do not have an electricity network. Even though these houses usually have an autonomous electricity network, pumps that use solar energy greatly help to save money.
  • Farming and cattle. This is the most popular use of solar pumping systems. They have proven to be cost-effective even without the use of government incentives.
  • Quite often people start developing aquaculture. It is an area where pump power demand coincides with the peak of solar activity.

Grundfos CU200 Control Panel

Grundfos CU200 with float switchThe Grundfos CU200 control panel has been developed specifically for SQF pumps. This control unit is designed to automatically control the water level of tanks or ponds and it provides possibilities to manage the power of SQFlex pumps. The CU200 is easy to install and easy to use. The connection with a pump is performed by a long power supply cable. You do not require any other cables. It has a proper earth connection which allows you not to worry about the cable to get wet. CU200 allows you to start, restart, or stop the pump.

Besides pump monitoring, CU200 is equipped with various alarms that provide you the information on the condition of the pump. You can always know if the reservoir is full or not.

Solar Pump Selection

Based on the calculated hydraulic losses (meters) and the desired capacity (liters/min or m3/hour), you can select the required pump. All pump producers have corresponding schedules for each pump model.

When sizing solar panels, some pump manufacturers recommend increasing the panel power by 25% to compensate for power losses due to a drop in panel efficiency from high temperature, dust, aging, etc. Some solar pumping companies like Grundfos offer an online calibration tool that already takes this factor into account.

Smaller 12 and 24-volt systems of solar pumps have lesser efficiency (high losses) and tend to be more expensive. Larger pumps with solar systems that use batteries and MPPT charge controllers may be less expensive.

Selecting Solar Panels Location

The solar collection site must meet the requirements:

  • Located on the south side where there is no significant shade during the day.
  • A room or structure to house the pump, controllers, storage containers, and any other components.
  • The solar array should be as close to the pump as possible to minimize cable length and installation costs.
  • If batteries are used, they should be installed in a sufficiently dry, temperature-controlled location with adequate ventilation.
  • If water is required all year round, issues of freezing the system must be resolved. In cold climates, it is recommended to install equipment with water in heated rooms. At the same time, it is not rational to use solar panels for space heating.

Storage Tank

While installing pumps with solar systems you also need a tank to store water. A general rule of thumb is to size the tank so that there is enough water for at least three days to smooth out the changing conditions of solar activity. If the storage period is too long, water quality issues arise due to the growth of algae and the multiplication of bacteria. To prevent algae growth, it is recommended to limit the maximum storage time of water to a maximum of two days if the tank is in direct sunlight. If the tank is in the shade, the maximum storage time is recommended for no more than three days.

Float switch inside the tank

Food grade plastic containers are the most common type and are often placed at the top of the site for gravity feed to the final consumer. While these tanks are generally the most affordable option, the sun encourages the growth of algae and bacteria.

The best, but more expensive solution is underground cisterns. Tanks need to protect water from freezing and stabilizing its temperature, which allows them to minimize water quality issues. With a float switch inside any type of tank controls the pump depending on the water level. The float switch wire is passed next to the filler pipe.

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