Dealing with an unreliable energy supply

Tall Trees is an established nursery in Balnarring Victoria, wholesaling native trees and plants for new suburban developments to roadside verges and revegetation projects. Their plants help keep Melbourne’s vast suburbs and built environment cooler than they would be without tree cover.

For over 10 years, Tall Trees has had access to, and been using, recycled water to propagate their plants. This is water that would have otherwise been released at the sewage outflow near Gunnamatta Beach.

Whilst the security of water supply has been beneficial over recent years, Tall Trees has had to deal with another issue that threatens nursery viability – power. The nursery has access to an abundant water supply,  but if the power goes out, then so do the pumps that distribute that water through the nursery. Although this part of the Mornington Peninsula’s power supply is becoming increasingly reliable, the risk of summer outages and impact on irrigation water supply is still unacceptable to operations.

Diesel generators trialled at their nursery were unreliable and cumbersome. This led to the decision by Tall Trees management to invest in some real power security and put control back into their own hands.

The solution – solar and batteries

Installed on the north facing roof of the newly built dispatch shed, is an array of over 100 solar panels (with a combined generation capacity of 35 kW) harnessing the sun’s radiant energy. Solar energy is stored in battery banks (with a storage capacity of 50 kWh) meeting the nursery’s energy requirements, most importantly the irrigation system, at any time of the day or night.

Tall Trees can run a full watering cycle of the nursery on one complete charge of the batteries. Two recently installed potting machines, electric vehicles and an aerator operating in the dam are also powered from the solar system during the day. They also have 3 mini-solar stations set up to power (without backup) the front gate and two fuel bowser pumps. An additional 5 kW system was recently installed onto the office roof to provide a little extra boost to the office only circuit.

The independence and security of the 40 kW solar array and battery backed system was more than a financial decision. General Manager, Joel Vanderuit, notes that without some form of contingency, the nursery would face an unacceptable level of risk. Given their operational situation, Joel wanted to install the best, most reliable system at Tall Trees, that they could afford.

‘Despite the initial expense, the savings on electricity and feed-in-tariff received for excess power fed back to the grid, equates to an investment pay-back period of around 8 years’ says Joel.

As for usage/consumption and savings, Joel provided the following data for Tall Trees energy generation and consumption, drawn from their monitoring system:

* prior to the recent addition of the 5 kW unit

Tall Trees nursery inverters, controls and battery bank

If this case study is of interest, try out Sustainability Victoria’s Energy Upgrades Tool, designed to help you work through the energy upgrades process, even in the planning and scoping stages. It is suitable for both on-farm and off-farm agricultural businesses.