Opportunities for solar powered pumping

There are as many opportunities for using solar power for agricultural water pumping as there are pumping tasks. 

The pumping task can be small, for example, to replace a windmill on a remote stock watering point, or it could be very large, for example, to meet the bulk water transfer needs of an entire irrigation district. 

Naturally, different sizes of solar system and complexity of project are involved, depending on the amount of energy required, the kinds of pumps used, and whether of not the solar array is integrated with general farm electricity supply and grid connected. 

Integrated solar pumping packages are on the market for small pumping tasks. These include a solar array and an electric pump that has been matched to the array. These off-the-shelf solutions may be the simplest way to implement a small scale solar pumping solution and are worth considering. It is important to understand, however, that there is no such thing as a “solar pump”, which is how such systems are typically marketed. Your existing electric pumps and/or electric pumps not marketed as solar may be well suited for use in a solar powered pumping project. 

What ever the size of the project, we recommend that farmers gain familiarity with the technology, assess a range of options and make return on investment comparisons. 

Why use solar power?

Generating electricity on farm using solar Photovoltaic (PV) technology can be an important step towards increasing the resilience and sustainability of your business.

Solar PV is scalable. Additional modules can easily be added to systems. Solar technology is proven, well understood and widely adopted across Australia and internationally.

On most farms, solar PV can provide cost effectively at least some proportion of energy needs. Benefits to implementing solar as a source of power for irrigation pumping include: 

  • Reduced bills for mains electricity and diesel;
  • Reduced connection and infrastructure costs when new power lines and poles can be avoided if fully replacing mains electricity;
  • No noise, fumes or fuelling runs if replacing diesel;
  • Scalable – additional panels can be added to increase output;
  • Flexible – solar power can be integrated with mains electricity supply, if desired;
  • Low maintenance. Aside from tracking systems, traditional solar generators have no moving parts and are generally very reliable; and
  • Protection from rising energy costs. Sunshine is free so generating energy on farm reduces exposure to rising electricity and diesel prices.

What pumping tasks suit solar power? 

Solar PV arrays provide power whenever the sun is shining. Designed properly, solar PV systems can ensure a steady and reliable power supply, even on cloudy days. 

Solar has potential to reduce your pumping energy bill and maintenance costs if any of the following apply: 

  • You already use electric pumps for irrigation and are grid connected;
  • You pump water to header tanks for stock or domestic use;
  • You have the potential to load shift (eg. use solar during the day to reduce total electricity demand and enable a more favourable tariff structure); 
  • You have substantial and efficient water storage (solar is ideal for transfer pumping tasks); and
  • You have a discrete day-time pumping task as part of your broader irrigation system that is suitable for a solar power solution. 

Livestock drinking-water supply 

The necessity to provide continuous (year-round) water supply for livestock, and the relatively small volumes required for stock watering makes this a pumping task well suited to solar PV power. Water can be pumped during the daytime from a bore, dam or stream into a stock dam or elevated tanks for on-demand supply to troughs. 

Sheep station near Griffith, NSW. A PV system provides power to a bore pump to lift water to storage tank. Water from the storage is gravity-fed to drinking-water troughs for cattle (NSW Farmers, 2014).
 

Domestic water and cleaning farm buildings 

Installing solar PV to meet all, or some, domestic and cleaning pumping needs can provide significant savings to most farms. In typical installations solar is used to transfer water to header tanks during the day. If pressurised water is needed at night time, a grid connection or battery storage will also be needed to power pressure pumps. 

Domestic solutions can be commissioned solely for water pumping but often are specified to supply total domestic electricity as part of an integrated system. 

Irrigation pumping – lifting and distributing bulk water 

The cost of pumping bulk water using mains electricity or diesel has become a significant burden on Australian agricultural productivity with most irrigation farmers having to cover six figure energy bills. 

Irrigated agriculture produces more than 20 percent of the total value of Australian agricultural production on less than one percent of agricultural land. To achieve this, approximately five million megalitres (ML) of irrigation water is applied every year in NSW alone (ABS, 2014). Diesel or grid-connected electric pumps are used to lift water from rivers and ground water, and to pressurise distribution systems. 

While electricity is more efficient for pumping than diesel, high network charges and connection costs in rural areas have inhibited growth in the electrification of irrigation pumping. Increasingly, therefore, irrigators across all farming systems are looking to solar power for solutions. 

Technically, there is no limit to the volume of water that can be pumped using solar power as a solar array can be sized to meet any scale of power demand. The business case for solar powered irrigation on a given farm depends on factors including the number of months of pumping per year, the time of day when irrigation occurs and the potential to export and sell unused energy. 

A solar PV system capable of providing the required amount of energy for an irrigated farming enterprise can entail significant investment and detailed site-specific analysis. 

Irrigation water requirements vary markedly, depending on the crop to be watered. Orchards, for example, typically require year-round irrigation, with increased water requirements during fruit production. Solar pumping solutions are naturally well suited to such horticultural irrigation systems, especially if the crops grown need more water during summer months, such as blueberries and fruit trees. For example, see Fig. 2: The water requirements of a blueberry tree (L/day per plant). 

The water requirements of a blueberry tree (L/day per plant).
 

Irrigation for broadacre crops usually occurs during certain periods of the year. Some broadacre crops, such as rice and lucerne, require irrigating over six to eight months of the year whereas the irrigation period for crops such as wheat and mung beans is shorter. 

When pumping is seasonal or irregular, it is essential to identify how your solar power will be used when it is not needed for irrigation. If you do not have other uses for electricity on farm, or the ability to export and sell unused power, consider installing a smaller system that is integrated with another power supply. 

A great strength of solar is its ability to be integrated with electricity from other sources. This means that it is not strictly necessary to install a system that is large enough to meet your peak seasonal irrigation load. Solar can be used to supplement mains power, reducing bills in high-tariff periods. Alternatively, a free standing system (not grid connected) could be sized to meet year round base load, with diesel generation used to top up total power in peak load periods. 

There are many possible configurations and site specific analysis is essential to identifying the optimal design and size for your particular property and farming system. 

The water requirements of a cotton crop with an irrigation scheme that runs for approximately six months of the year (Source: WATERpak, Cotton Research and Development Corporation).
 
 
 
 

Is solar pumping right for my farm? If so, which configuration is likely to be most suitable? 

To help you decide whether solar pumping is a technically feasible and financially viable option for your farm, consider the following questions. 

  1. Are your current pumps suitable? Diesel pumps cannot be integrated with solar power and would need to be replaced, incurring extra costs. However, there are good opportunities to integrate solar with diesel generators. 

  2. What is the cost of operating your existing pumps? Solar power has high up-front costs but low operating costs. A solar PV system can result in significant savings over the life of the system. Integrating solar with your existing power supply can substantially reduce operating costs. 

  3. How far from the electricity grid is the proposed pump site? Solar can be used to power pumps that are far from the grid. Such solar pumps can transfer water to locations near the electricity grid for grid-powered pumping or pressurisation. 

  4. How often is the pump used? Solar pumping suits applications requiring regular operation. It may be more economical to employ mobile fuel generators for pumps that are used for only a couple of periods a year. 

  5. At what time of day do you need water? A solar PV system powers pumps only during daylight hours. For applications that require water at night or on-demand, consider combining solar with water or battery storage. It may also be more economical to use a different pump technology. 

  6. Is there existing water storage? Solar pumps are well suited to pumping water to some form of water storage (such as a dam or tank) where it can be used when needed. 

  7. Will the water be pressurised? Pressurised systems require consistent energy sources. Combining solar with battery power could provide this otherwise integration with other power will be necessary. 

  8. How much water must be pumped? Solar can provide power for large volumes of water; however, with such applications, it may be more economical to install solar to reduce the size of the main energy source rather than as your sole power source. 

 

Energy

Comments

Error | AgInnovators

Error

The website encountered an unexpected error. Please try again later.