farm solar

Solar for Hydroponic Farming

The cold conditions at Dalgety in southern New South Wales have not deterred a former aircraft-flight engineer from constructing a solar powered greenhouse for the production hydroponic herbs.

Damien and Carol Doyle are growing a variety of herbs from the better-known basil through to Asian species such as Japanese Shiso."We were quite sick of going and buying cut herbs in supermarkets, taking them home and being lucky enough for them to last two days," said Mr Doyle who has been a flight engineer in the Australian Navy, Air force and Britain's Air force.

"By the time we got home they had wilted and lost all their flavours."

So they set about addressing the problem on just over four hectares of land, on the outskirts of the small town. Dalgety is on the banks of the Snowy River on the New South Wales/Victorian border. The herbs are grown under 'solar weave' which covers an area of sixteen metres by three metres.

Water with nutrients is dragged from a 1,000 litre tank which is located at a higher point than the greenhouse. Gravity enables the water to flow down to the channels where the herbs are grown.Depending on the time of the year, the water temperature either cools the enclosure or warms it during the cooler month. After the thin film of water has flowed down through the herbs it is then gathered at the bottom and then pumped back up the rise to the tank for recycling.

With winds in the winter months often at speeds of between 60 and 80 kilometres per hour and at times gusting to 120 kilometres per hour, the Doyle's concentrate their efforts on a few months of the year."Our growing season is in the summer months. Growing in the winter months is near on impossible. The more hardier plants will grow but their growth rates are reduced somewhat and that makes it hard to guarantee supply" Mr Doyle explained.

"We are on standalone solar power. We have limited supply of electrical power and of course any heating elements are a hell of a draw-down on batteries. "When the herbs are available they are extremely popular with the people who flock each weekend to the local farmers' markets which are held in Canberra. Another way of ensuring that there is a steady supply of the herbs is to take some of the farm's infrastructure to the outlets.

A number of restaurants in the town of Cooma also use the herbs after Mr Doyle installed a mini hydroponic system to enable the cooks to have fresh herbs readily available. "We put a small system in a cafe as the plants need to have their roots in a little bit of water for them to survive so people buying them are getting them fresh." Mr Doyle said. "You can take the plant home. It is living. You can put it in a saucer or vase, keep the water up to them and they can last a week. We had one person tell us he had the basil plant for more than a month!"

Listening to customers plays a major role in deciding what to grow, which was the case with the Japanese Shiso. "A Japanese lady came past one day and asked if we had it. We had to say no. But we went home and immediately looked up to see what it was and how it was grown. We ordered some seed and started to grow it and it has been quite a success. "Different types of cress which are distantly related to the water cress, such as an American variety which has a more peppery flavour, have proved a success along with dill and various mint varieties. However the woodier herbs such as marjoram, oregano and sage "don't seem to respond" to the particular techniques the Doyle's use.