So­lar trial works won­ders

So­lar ir­ri­gation means the best of both worlds

The Northern Star - Northern New South Wales Rural Weekly - - NEWS - Cindy Ben­jamin Aus­tralian Cane­grower

WHEN grow­ers try to re­duce pump­ing costs by ir­ri­gat­ing at night, there can be sig­nif­i­cant im­pacts not just on pro­duc­tiv­ity, but on the grower’s health and well­be­ing as well.

Feel­ing con­strained to night ir­ri­gation times to re­duce elec­tric­ity costs means grow­ers of­ten de­lay ir­ri­gation and fre­quently do not ap­ply the quan­tity of wa­ter re­quired to maximise pro­duc­tiv­ity in a sup­ple­men­tary grow­ing re­gion such as Bund­aberg.

Chas­ing wa­ter winches at night also dis­rupts sleep and can be dan­ger­ous.

To over­come these prob­lems many grow­ers have looked for and im­ple­mented al­ter­na­tive ir­ri­gation sys­tems.

While so­lar en­ergy has sig­nif­i­cant ad­van­tages and po­ten­tial cost sav­ings, stand-alone so­lar sys­tems can have op­er­a­tional lim­i­ta­tions.

A new three-year re­new­able en­ergy project in Bund­aberg, which is funded by the Aus­tralian Re­new­able En­ergy Agency (ARENA) and ad­min­is­tered by the Bund­aberg Re­gional Ir­ri­ga­tors Group (BRIG), is in­ves­ti­gat­ing the fea­si­bil­ity of us­ing a unique hy­brid so­lar and grid en­ergy sys­tem to pro­vide all the con­ve­nience of grid elec­tric­ity and the sav­ings of­fered by so­lar.

Bund­aberg Sugar Ser­vices spe­cial projects of­fi­cer, Mau­rie Haines, said the so­lar ar­ray at the demon­stra­tion ir­ri­gation site had been liv­ing up to ex­pec­ta­tions since it was com­mis­sioned in mid-Jan­uary this year.

“This sys­tem is de­signed to be a hy­brid ir­ri­gation sys­tem that blends so­lar and grid power to main­tain seam­less op­er­a­tion be­tween clear or cloudy day­time con­di­tions or night-time op­er­a­tion,” he said.

“Un­like most so­lar farms, this sys­tem does not feed so­lar en­ergy into the grid. All the de­ci­sions the grower makes are based on whether the crop needs wa­ter, and not how much it will cost.”

Dur­ing peak so­lar ra­di­a­tion con­di­tions, the so­lar pan­els can power the pump with­out draw­ing on the grid sup­ply.

In the early morn­ing and late af­ter­noon, the sys­tem draws as much so­lar en­ergy as is avail­able and draws the rest from the grid. In the evening, the cheaper night tar­iffs are used if re­quired.

The demon­stra­tion site is lo­cated on the Killer fam­ily farm at Sharon, west of Bund­aberg.

Rod­ney and his son Josh have 58 hectares of cane on this block and use high­pres­sure wa­ter can­nons to ir­ri­gate.

Other op­tions, such as low-pres­sure lat­eral booms, are not a fea­si­ble op­tion for the un­du­lat­ing and oddly shaped farm.

Josh said the new pump sys­tem had given them a much greater in­cen­tive to wa­ter when they knew it would be ben­e­fi­cial, with­out wor­ry­ing about the cost of elec­tric­ity.

“This year we have ir­ri­gated ra­toons much ear­lier than we usu­ally would and we are con­fi­dent that look­ing after them dur­ing the dry win­ter and early spring will pay off in higher yields at har­vest next year,” he said.

The other big ben­e­fit for Josh has been the re­duced work stress sur­round­ing ir­ri­gation. Josh lives about 45 min­utes from the farm with the so­lar demon­stra­tion so start­ing and stop­ping pumps and check­ing wa­ter winches was time con­sum­ing.

“Be­fore the so­lar sys­tem was oper­at­ing I would need to get to the farm early to shut the pumps off and stay late in the af­ter­noon be­fore start­ing the pumps so that we only wa­tered on the night tar­iff,” he said.

“Now I can turn the pump on and off re­motely, know­ing that there is a safety mech­a­nism to shut ev­ery­thing down if there is a prob­lem.

“I can re­ally man­age my time a lot bet­ter be­tween our two farms and can get the most out of ev­ery day.”

The Killers are now able to ir­ri­gate all day and all night if nec­es­sary dur­ing peak wa­ter use pe­ri­ods, to keep their crops grow­ing and make the most of the avail­able sun­shine and warmth in spring and early sum­mer par­tic­u­larly.

They are also us­ing the ex­tra flex­i­bil­ity with ir­ri­gation to wa­ter in fer­tiliser so they elim­i­nate volatil­i­sa­tion losses and get the full ben­e­fit of the ap­plied nu­tri­ents. Josh has found that the so­lar sys­tem has changed their whole

mind­set when it comes to the ap­pli­ca­tion of wa­ter.

The equip­ment in­stalled at the site in­cludes a 240-panel so­lar ar­ray (81.6kW), 45kW elec­tric mo­tor and cen­trifu­gal pump de­signed to op­er­ate at vary­ing speeds, and a VSD Eco­drive con­troller to man­age both so­lar en­ergy (DC power) in­put as the pri­or­ity en­ergy source with grid sup­plied (AC power) as a sup­ple­men­tary source. The Eco­drive con­troller also man­ages the in­put wa­ter pres­sure to maximise pump ef­fi­ciency.

A new pump was in­stalled as part of the demon­stra­tion project but it has the same ca­pac­ity as the one it re­placed.

The changes have cen­tred on im­prov­ing pump ef­fi­ciency.

The be­fore-and-after en­ergy us­age com­par­i­son shows the so­lar/grid pump­ing demo sys­tem uses ap­prox­i­mately 78 per cent less en­ergy than the grid-only sys­tem it has re­placed.

The VSD Eco­drive power blend­ing sys­tem mon­i­tors the wa­ter in­flow pres­sure and man­ages the mo­tor speed to main­tain a con­stant pres­sure to the winch ir­ri­ga­tor.

This means the pump is al­ways oper­at­ing at max­i­mum ef­fi­ciency and not wast­ing power, un­like the pre­vi­ous sys­tem, which re­lied on a check valve to con­trol pres­sure to the winch while con­tin­u­ing to op­er­ate the mo­tor at max­i­mum speed and en­ergy use.

“Un­like some so­lar sys­tems, this one never cuts out and does not sim­ply switch to the grid if the so­lar in­put drops be­low the thresh­old re­quired to run the pump,” said Mau­rie.

“The pri­or­ity-so­lar with grid back-up sys­tem max­imises the ben­e­fits of so­lar elec­tric­ity.

“Given that many grow­ers in the Bund­aberg area only use 50 per cent of their wa­ter al­lo­ca­tion, due in part to con­cerns over pump­ing costs, there is plenty of room for ad­di­tional pro­duc­tiv­ity from the cur­rent crop area,” he said.

“Avoid­ing crop stress in July and Au­gust and tak­ing ad­van­tage of longer days in sum­mer will both pay off in ex­tra yield.

“The more the grower uses a sys­tem like this the bet­ter off they will be.”

The mod­u­lar de­sign of this demon­stra­tion so­lar farm is one of the key fea­tures that makes it a vi­able op­tion for other grow­ers.

It is pos­si­ble to start small, in­stalling the Eco­drive sys­tem to ini­ti­ate greater pump ef­fi­cien­cies and then add ex­tra so­lar pan­els as funds per­mit, un­til the ar­ray has the ca­pac­ity to run the pump on so­lar en­ergy alone dur­ing clear day­time con­di­tions.

Over and over again, Mau­rie has seen the ef­fect of grow­ers mak­ing a change to their ir­ri­gation prac­tices and reap­ing the dou­ble ben­e­fit of bet­ter pro­duc­tiv­ity and re­duced costs.

“It is so of­ten the case that the pro­duc­tiv­ity gains even out­weigh the sav­ings in en­ergy costs,” he said.

To as­sist with ir­ri­gation sched­ul­ing, there are soil mois­ture probes and an au­to­mated weather sta­tion in­stalled on the Killers’ prop­erty. These also con­trib­ute data to the area-wide weather mon­i­tor­ing sys­tem in Bund­aberg, pro­vid­ing grow­ers with more lo­calised weather in­for­ma­tion.

This demon­stra­tion project aims to pro­vide grow­ers and their lend­ing in­sti­tu­tions with re­li­able and field-tested data to sup­port in­vest­ment in sim­i­lar sys­tems.

“These sys­tems in­volve large cap­i­tal out­lay and grow­ers need to be con­fi­dent that they will de­liver pro­duc­tiv­ity gains and cost sav­ings,” Mau­rie said.

“An­other com­po­nent of this project is to col­lect lo­cal in­for­ma­tion about how much so­lar en­ergy is avail­able through­out the year and how that might vary across the dis­trict. This will help grow­ers de­ter­mine if they can ex­pect the same out­comes or bet­ter than what we are achiev­ing at the demon­stra­tion site.”

All the data col­lected through the three-year project will be avail­able on the BRIG web­site (, in­clud­ing how much so­lar and grid en­ergy is con­sumed for each me­gal­itre of wa­ter pumped and all op­er­a­tional costs.

“This in­for­ma­tion will be of enor­mous ben­e­fit to grow­ers if they get Bund­aberg Sugar Ser­vices Ltd to con­duct a Farm En­ergy and Ir­ri­gation In­for­ma­tion Au­dit for their farm,” Mau­rie said.

“This will cre­ate a pow­er­ful de­ci­sion-mak­ing tool for farm en­ergy and farm wa­ter use plan­ning in the lead-up to the 2020 tar­iff changes and be­yond.”


STEP­PING UP: Rod­ney Killer and his son Josh were on board with the trial.

HIGH-TECH: The equip­ment in­stalled in­cludes a 240-panel so­lar ar­ray (81.6kW), 45kW elec­tric mo­tor and cen­trifu­gal pump de­signed to op­er­ate at vary­ing speeds.

The so­lar pump on the Bund­aberg prop­erty.

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