Solar system cuts costs

More than six months ago, Doug and Lyn Crosby and their sons Bill and Bob installed a single-wall evacuated tube high-temperature dairy solar hot water system and, based on its performance, believe it will pay for itself in 2.5 years.

The custom-designed system is used to wash down their two robotic dairy machines and rinse out milk lines.

The collector system that is mounted to the roof of the dairy comprises 32 single-walled vacuum glass tubes, each 2.2 metres long.

Inside the clear 100-millimetre diameter evacuated tubes are absorber fins coated with aluminium nitride selective coating to ensure high absorption of the sun’s rays.

Each of the 32 tubes are plugged into a heat exchanger which feeds into a 320-litre ground-based tank, pre-heating water up to 85 degrees Celsius for a 400L electrically boosted main storage tank.

The water is heated by the solar radiation collected by the tubes and can reach temperatures of up to 85 degrees C depending on the time of the year.

An electric power booster in the main storage tank is used to reach the required temperatures to be used in the dairy, between 80 and 100 degrees C.

With the latest investment, the Crosbys have continued their strong track record of innovation.

Four years ago, they were the first dairy in South Australia to install robotic milking machines to minimise labour needs.

They are milking about 150 cows with the two Lely robots and continue to work part-time off-farm.

Doug said he was not immediately convinced about investing in the solar thermal hot water system.

“I couldn’t see how it was going to work but now we can see it does,” he said.

He is now a strong advocate of the Australian Sun Energy hot water system, and works out that by reducing power usage by about 30 kilowatts a day, farms can make savings of about $10 a day.

Bill says it is a case of spending a little money to save some in the long term.

“If we can cut costs with our energy bill we can be more profitable,” he said.

“If we can take out or reduce a $60,000 expense it may allow us to pay ourselves a wage whereas, at the moment, we are not taking much out of the farm.”

Mount Gambier-based Australian Sun Energy is a national distributor for Greenland solar hot water systems.

Sales manager Peter Taylor and business manager-director Roslyn Pasfield set up the company more than four years ago.

Their company now supplies energy reduction systems and equipment to domestic and commercial customers across the country.

Their product range includes solar tracking skylights, pipe insulation, digital self-heating home systems and modular stainless steel water tanks.

Mr Taylor said the solar thermal hot water system would work on cloudy and sunny days.

It even worked when it rained and when there were frosts.

These systems are also used in Europe, where it snows.

“There is always solar energy hitting the ground during the day,” he said.

“We are storing the energy from the sunlight in the water so it can even be used at night.”

Mr Taylor said solar evacuated tube hot water systems were distinctly different from the photovoltaic solar panels designed to produce electricity.

The system was much more efficient at harvesting energy year-round.

“Most photovoltaic solar panels work at 15% energy conversion and in winter and on a rainy day, the other solar hot water flat plate systems aren’t doing anything whereas with the solar evacuated tube system we are averaging 68-72% conversion,” he said.

Mr Taylor and Ms Pasfield expect the collectors to last more than 20 years – similar vacuum tubes in Europe and Asia are performing after 20 years, with only a 1-2% reduction in efficiency.

All the materials in the tubes are fully recyclable.

Mr Taylor said he saw enormous potential for the system in dairy sheds where hot water for cleaning is a daily requirement.

Dairyfarmers faced huge energy bills because heating water and milk refrigeration costs made up a large percentage of their running costs.

“A lot of farmers are conscious of their inputs such as cows and feeding costs, but have less of a handle on the importance of energy in their costs and just how much hot water they are actually using,” he said.

Mr Taylor said that all consumers should see it as risk management for rising electricity costs.

“You can’t do much about rising energy costs but you can reduce your energy usage using equipment like this,” he said.

“It is not only environmentally sustainable but also good for the hip pocket, producing clean, efficient energy.”

Ms Pasfield, who has a background in the financial industry, said the equipment was a solid investment.

“Taking the Crosby farm’s calculation savings of $10 a day and the expected lifespan of the system (20 years) they can expect their system to save at least $178,000 in energy costs during this period.” she said.

“This calculation assumes electricity increases at about 8% per annum.

She said a $12,000 investment (at today’s rates) for 20 years at 5% with monthly compounding interest, that would amount to $32,552.

Australian Sun Energy has set up a splash monitoring system to check on the performance of its solar hot water system and power usage.

This enables it to show that its solar hot water systems work, especially in the southern parts of Australia.

The Crosbys’ system can be seen live at www.splashmonitoring.com/ system/mtgambier