Sustainable solar pumping: how drives put the sun to work | ABB

By Torben Poulsen, Business Development Manager for Drives and Pumps, ABB Motion

Amid the dual crises of climate change and population growth, the need for sustainable agriculture and water management has never been more critical. Essential to this effort is not only the clean energy harnessed from the sun to nourish crops and livestock, but also innovation in water conservation and smart usage.

Water is a precious resource, and its correct treatment, allocation, and usage are essential in supporting sustainable farming practices. To move water, a pump system is required. In fact, pumping systems are so vital that all the pump systems in the world account for an estimated 20 percent of the world’s energy consumption, according to the Hydraulic Institute. To be sustainable, pumping must be done in a way that maximizes productivity and minimizes energy usage, particularly in remote areas.

In such regions, traditional water pumping - simply extracting water from the ground - is insufficient. The process must evolve towards intelligent solar-powered solutions that maximize efficiency and minimize waste. Here, solar drives come into play, combining solar panel technology with pumps to create autonomous systems that smartly pump, store, and distribute water.

This not only fosters effective crop irrigation but also supports the broader vision of food security intertwined with environmental protection. It ensures that every drop of water and ray of sunshine contributes to a more resilient and food-secure future. Alongside, the role of drives in water treatment processes further establishes their value in sustainable agriculture.

The demand for solar pumping

This demand for off-grid water movement has given rise to solar pumping – where a pump is powered completely by photovoltaic (PV) power. The benefits of solar-powered pumps are that they reduce energy costs, cut emissions, and can operate without a grid connection. Modern technology is improving efficiency even further in solar pumping, making it a system that’s become extremely viable for irrigation in remote areas as an alternative to pumps powered by diesel generators.

As a result, it’s a solution that’s gradually gaining in popularity all across the globe, but especially in regions that contain areas of extreme aridity. It’s also a growing market in the Middle East where, in some cases, it can be cheaper to get 1 kilowatt hour (kWh) of energy from solar panels than from oil. There has also been significant growth in Europe, where getting a reliable grid connection is becoming more and more problematic – an issue that will only get worse as demand for electricity increases, with more sectors aiming to decarbonize through electrification.Indeed, an efficient, off-grid water pumping system could become a global necessity in the years to come.

What you need to consider when installing a solar pump

There are certain obvious limitations to solar pumping – for instance, cloudy days and hours of darkness. So, solar pumping works best when operators decouple the processes of storing up and using water. This involves a mindset shift from traditional pumping.

So, rather than pumping water only when it is needed, use daylight hours to move as much water as possible to where it can be most easily and efficiently stored. Essentially, this means using excess energy to fill a tank or reserve, then using it when it is needed. Pumping excess water to a higher elevation means that gravity then provides power to distribute the water later.

Furthermore, operators should consider which direction to install PV panels, depending on which hemisphere they’re located in. They should be south facing if located in the northern hemisphere, and north facing if located in the southern hemisphere. This maximizes the energy production over the course of summer and winter.

Solar pump drives: taking the efficiency even further

To make solar pumping even more efficient, solar pump drives have been developed. These maximize the useful power of the sun – from dawn until dusk. In fact, various features in modern drives enable more than 98% of the available PV power to be used for pumping.

For example, Maximum Power Point Tracking (MPPT) adjusts the pump motor’s speed according to sunlight conditions to ensure maximum power output from the pump. This is because insolation varies both gradually during the day and instantaneously due to cloud cover.

Selecting a drive with a wide input voltage range means the drive can still operate even when the voltage supplied by the solar panels drops off. This effectively means that the pump can start very early in the day and stop very late in the evening. It also means the whole system is less affected by variations in sunlight.

A modern solar pump drive can also be controlled remotely so that the pump can start and stop without any manual intervention. It can be programmed for specific start and stop times – with MPPT handling variations in flow during the day. For example, with level sensors fitted to tanks, the system can be programmed to start and stop pumping to avoid overfilling or underfilling the tank without any human input. Drives can also deliver useful data like calculated, total, daily, and hourly flows.

Drives also boost the reliability of the solar pump. Dry run protection, for example, can use an in-pump sensor to see when the inlet water flow is running low or simply detect minimum load current which can also signal when there is no water in the system so it can cease pumping and ensure components don’t overheat from dry running. Pump cleaning settings mean the drive quickly operates the pump in forward and reverse to push out any unwanted material that might cause blockages.

If more power is required than is available from the PV panels, then solar pump drives can draw additional power from a generator or a grid connection.

Case study: Doubling irrigation hours for pistachio crops in Spain

An agricultural business in Herencia, Spain, had a problem with the irrigation system on its pistachio plantations – and in a country where production is increasing exponentially, with the potential to reach 25,000 tons of pistachios every year within the decade, faults and inefficiencies lose money incredibly fast.

This crop’s irrigation needs aren’t especially high and are normally carried out by water pumped directly from the subsoil with submerged pumps. This particular business had a solar installation with photovoltaic cells, a solar frequency converter, and a submerged pump with a nominal power of 7.5 kW. However, the system was experiencing a lot of downtime and, when it was working, the pump could only run during hours when solar irradiation was highest.

With advice from the installer, Electrotécnicos Manchegos, the company installed a new solar pump drive from ABB, ACQ80. The new drive includes features like MPPT to maximize output and performance from solar power. It also has a proportional integral derivative (PID) control function to achieve the desired water pressure at the output in the irrigation system.

The result was a huge improvement in the solar pump system’s performance. System availability increased by 100% and the company saw a doubling of the usable hours of solar irradiation compared to the previous year.

A sustainable answer to irrigation

Solar pumping is an ideal irrigation solution for remote regions. By making use of the sun, a solar pump saves energy, reduces costs, and doesn’t rely on a grid connection.

By pairing solar pumps with high-performance drives, efficiency is increased even further – a solution that could become even more important in the coming years as vast areas of land become hotter and drier than ever.

Discover more about solar pump drives: https://new.abb.com/drives/low-voltage-ac/industry-specific-drives/acq80-solar-pump