Solar hot water
in Greener Homes on 23 August 2009
With generous rebates available, it’s time to tap into efficient hot water.
“To save money on your bills, solar hot water is the best investment you can make – after you’ve done simple things like changing light bulbs,” says Nick Brass from renewable energy supplier Energy Matters. “You can save 75 per cent of the energy you need to heat your water.”
According to Mr Brass, households that now have electric water heaters stand to gain the most. Replacing a system that runs on peak-rate electricity can mean savings of up to $1000 per year. “If you’ve got an electric hot water unit you should go solar right now, without even considering it for a second longer,” he says.
Efficient hot water units cost more up front, but will cut your carbon footprint and save you money in the long term. To encourage you to switch, there’s a generous (but highly complex) set of state and federal rebates on offer.
The Federal Government will stump up $1600 for householders who replace electric systems. If you’re not eligible for the national scheme, the Victorian Government will pay up to $1500 in metropolitan Melbourne and $2350 in the regions – the most efficient units attract the highest rebates. Including extra dollars for Renewable Energy Certificates and Victorian Energy Efficiency Certificates, the total cash-back can be well over $3000. For more detailed guidelines, visit the Sustainability Victoria website.
Three kinds of hot water systems are eligible for the rebates. Flat-plate solar collectors have water pipes set inside a clear-fronted, airtight box, with a storage tank perched above. Evacuated tube systems use a row of glass tubes, each with a water pipe inside (in a vacuum), and no rooftop tank. Electric heat pumps work like a refrigerator in reverse, using warmth in the air to heat water. They’re not solar powered, but they’re highly efficient.
Which one is right for you?
Prices vary with rebates and installation costs, but Energy Matters estimates that the grand total will range from $2000 to $3500 installed, depending on the system. Heat pumps are cheapest upfront, followed by flat-plate, then evacuated tube. For ongoing costs, the systems rank in the reverse order.
“We recommend that if you’ve got a roof with solar access, you should use solar,” Mr Brass says. “If you don’t, then you should use a heat pump.”
Of the two solar systems, Mr Brass promotes evacuated tube. “The technology is very good. It’s easy to install, inherently frost-protected, and requires very little maintenance,” he says. “It’s more efficient. Because the tubes are curved, they passively track the sun all day. Flat-plate systems generate the greatest heat in the middle of the day.”
You’ll also need to back up your solar heaters for the times when sunlight isn’t enough. “Instantaneous gas is best,” Mr Brass says. “The only time the water gets boosted is when it passes into the home, so there’s no waste.”