What about solar power for irrigation & specifically


solar water pumps? Across many parts of Africa, the Middle East and Asia, solar power for irrigation has become the norm. In these markets, diesel was the only choice for power but has now been replaced by solar. Large- scale flood irrigation with single systems pumping 1 million gallons per day are now not uncommon. Across North Africa, whole areas are being changed from deserts to productive fields by using full-size center pivots and solar pumps. Both the pivot and pumps are powered from the sun.


Modern solar pumping systems are smart, smaller systems using high-efficiency motors (direct current brushless) to allow them to operate effectively as the available energy from the sun changes. Remote monitoring and management are features of the best- of-breed systems offering the capability of managing a remote plot from afar.


The larger systems all have variable speed drives included, and there are even hybrid systems that will blend together solar and power from a generator to give backup power when the sunlight is not sufficient to achieve the desired flow, pressure or level. This allows for constant pressure, level or flow to be achieved using hybrid solar- powered pumping systems.


Holistic irrigation solutions


The best solar irrigation solutions look at the crop’s requirements, soil type and water availability and then find the irrigation method that fits best. Changing an existing irrigation pump to solar might not give satisfactory results unless all factors have been taken into consideration.


Best results come from changing irrigation methods and habits to better meet the daytime pumping requirement. An example of this is using subsurface drip irrigation for fruits, trees and nuts. By using subsurface irrigation during the daytime, losses due to evaporation are minimized. Studies carried out in the Middle East show that production can be increased by reducing watering levels using subsurface precision irrigation.


This center pivot in Sudan utilizes solar- powered pumps and pivot in a field growing alfalfa for livestock and crops


eight to nine times per year. Photo credit: BERNT LORENTZ GmbH & Co. KG


16 Irrigation TODAY | April 2018


Does solar always make


sense for irrigation? If you are paying $0.08 per kilowatt-hour for electricity, have a short irrigation season and require 24-hour pumping, then solar- powered irrigation would typically be financially unattractive. But, there are many scenarios where solar irrigation becomes interesting:


• You have a plot where there is no power, and the electric company wants $50,000+ to connect power.


• In areas where you are running a generator for pumps — with all the trouble and cost of refueling and servicing — solar will be cheaper and much easier.


• There are scenarios where “growing green” can add value to your product. Think about the next step beyond organic where you have carbon neutral production.


• Investing in solar can provide interesting financial returns.


• If the existing power grid has reliability or quality issues that continuously shorten the life of pumping equipment, it can jeopardize the availability of the water supply.


Eric Macias is the chief operating officer for LORENTZ US Corp. During his career, he has worked in the irrigation industry in customer service, sales, training and marketing, until discovering his passion for pumping water using renewable energy.


What is a solar water pumping system?


A typical solar water pumping system has three components:


solar generator – This includes one or more photovoltaic modules that convert photons (light from the sun) to electricity. These modules will produce electricity whenever there is light. The brighter the light source the more electricity is generated. The PV modules have a long life, are robust and typically have a warranty of 25 years.


pump controller – The controller monitors the system; provides inputs for sensors such as run dry, pressure or level measurement; and performs voltage and frequency conversions (like a variable frequency drive) to match the available power from the PV modules.


electric pump – Motors optimized for solar are variable speed, may have different windings for specific “solar friendly” voltage ranges and are high efficiency. Permanent magnet motors (electronically commutated direct current) are often used because of their superior efficiency.


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