Solar water pumps: cheaper, easier but routinely underestimated

Despite specialising in off-grid systems, water pumps have been large part of Commodore Australia’s business since it was founded in 2005 in Victoria. The company sends out between 30 to 35 pumps domestically and internationally each week, Commodore’s Marketing Manager Matt Miller told pv magazine Australia.

Commodore recently crunched the numbers on how much customers, primarily farmers in this case, save by opting for a solar water pump over diesel, petrol or mains-connected pumps. It found at the largest end of the scale, savings could reach $44,837 per year.

Few farms would need a pump that big however, so their savings wouldn’t reach such epic proportions. Nonetheless, Commodore found that for a mid-sized solar pump, the customer could save $1,793 in a year – paying off the bare running costs of a diesel pump in 2.77 years. Compared with a mains-connected grid, customers would save $1,404 and meet the running costs in 3.54 years. 

These numbers, Miller noted, don’t even include the costs of travel for diesel or maintenance, which can be significant.

Lack of awareness about solar pump efficacy

“[Solar pumps] are a renewable source, it’s also a cost effective source,” Miller said. Be that as it may, solar pumps are routinely underestimated, he says, adding that there’s a real lack of awareness about how effective solar pumps are. “That’s quite often a misconception.”

That is, most farmers or other customers don’t expect solar-powered water pumps to have anywhere near the pumping capacity they do. For instance, a small 0.75 kW pump Miller says can in fact deliver 10,000 to 20,000 litres of water per day, dependant on head hight (which means how high up the water needs to travel). On the other end of the scale, the biggest solar pumps can draw up to 100,000L per hour. “It’s an enormous amount of water,”  Miller said, noting the pumps are not at all not supported by mains electricity supply.

Naturally, solar pumps only run in the daytime and continue to perform well even on cloudy days. The ground mounted solar arrays which power the pump can also be located in premium positions, with Miller pointing to a recent job where the solar array sat around 300 metres away from the pump, connected via cable.

Batteries can also be fitted to the pumps so they can be used on command. Miller says only around 10% of the solar pumps Commodore installs include batteries though.

While water pumps are most commonly used by farmers to irrigate crops, Commodore has fitted pumps in remote parts of Papua New Guinea as part of humanitarian projects bringing water to dry villages. Part of the beauty of solar pumps is they require far less maintenance compared to diesel pumps and require no fuel, which makes them far better suited for developing and remote communities.

In the last six months, solar pumps have also began integrating remote app access and monitoring, allowing customers to stop and start the pump and irrigations on their phones.