Solar methods of rural bore water extraction have become more and more viable as technology, the same used in electric vehicles and solar power stations, improves

Turn sunshine into water

by Andy Bryenton

A new generation of solar-powered deep-bore pumps is getting rid of the need for a generator in an old tin shed placed over far-flung wellheads. With improvements in battery and controller tech, there’s no reason why even the most out of the way water source can’t be utilised, reticulated and harnessed to help out in the dry weather when rain is not forthcoming.

Here’s the scenario; you’ve located water in a deep aquifer, far out on the part of the farm where it would be great to have some troughs for the herd or a backup supply for irrigation. Mains power is so far away that rigging all that wire makes the job a cost to benefits nightmare. In the old days, the answer was to permanently relegate an old diesel or petrol generator to duties over the wellhead, powering a submersible pump with enough juice to bring water to the surface. The grim realities of hydrodynamics and physics meant that solar power was sometimes too weak a motive force to impel good clean H2O up a bore and into the pipe, troughs and tanks.

There have been changes afoot. Now, there are plenty of places online and in your local area who will sell a solar-powered submersible pump system able to achieve a flow rate of more than 10 litres a minute at a depth of up to 85 metres. That rate will, of course, increase from a trickle to a flood if the bore is shallower. The great thing with a solar pump is that, so long as the sun rises in the morning, it will work all day, pumping with better efficiency, these days than most windmills. Photovoltaic technology has few moving parts, so as long as the panels are pointed up, the pump will continue to work with the absolute minimum of maintenance.

This fairly hefty pump example, which works in any bore more than three inches, takes only a single 1,100 watt panel to keep it turning over. The attached controller will turn it off when it fills an adjacent tank, and the whole system can be augmented with a secondary panel and batteries to work all night as well. The best part is, you can control such pumps by tablet or smartphone with the right adaptors, meaning that there’s no need to ride out to the boundaries with diesel and tools to ensure a drink for the livestock.

Check the level, flip the switch and monitor flow from wherever you are. A combination of brushless motors, better photovoltaic efficiency and more compact batteries means that a complete solar pump system can cost less than the equivalent generator and pump, considering that well drilling costs will be the same for both units. Considerably less, if you factor in a lifetime of fuel.