Rising electricity prices have prompted 15% of Australians to install solar panels, according to a recent survey. Another 6% considered the move, above the 28% supported by the panel.
As costs decrease, the average system size increases rapidly. Homes now typically install 8-10kW solar systems, often with batteries; the roof area often limits the size of the system.
But does this guarantee that there will be no electricity costs in the future? No, some still pay exorbitant bills.
That's because they often feed power to the grid during peak solar power, when retailers pay low power rates of five cents per kWh or less (a response to the advent of rooftop solar). To encourage customers to use energy during these times, retailers offer generous time-of-use ("solar sponge") rates.
But the cost doubles during peak demand periods (around 6-10am and 3-11pm) when there is little to no solar output. Most solar roof owners still pay for the electricity they used at the time.
Read more: How closely monitoring a home's energy data can unlock your solar output and (supposedly) make you more money
The solution is to fix three things:
efficient equipment selection
use smart technology or a simple timer to use it in periods of abundant solar production
choose the retail power plan that best suits your usage.
How much difference can the team make?
To reduce energy costs, the starting point is to understand usage patterns.
Read more: Top 10 tips to stay cool this summer while protecting your health and your budget
Heating and cooling account for 30-45% of energy use in a typical home. Our tests at the University of South Australia show that air conditioners use more energy as they age. However, many homes have air conditioners that are over a decade old with a 2-3 star rating. Modern 6-star split systems use less than half the electricity.
Users can remotely schedule or control the air conditioner with a mobile phone to run for an hour or two before returning home. So they use cheap solar energy to create comfortable homes. The smart and convenient controller can also reduce cooling or heating when it detects an empty room or an open window.
Normally, between a quarter and a third of the energy consumption goes to heating the water. Abundant solar energy and high gas prices make heat pump water heaters the best option. With government subsidies, start-up costs are similar to conventional gas or electric systems and typically use one-third of the energy.
Again, they can be programmed to heat water during peak solar production periods and store it, thus providing almost free hot water when needed.
Read more: Heat pumps can reduce energy costs by up to 90%. It's not magic, just a clever use of the laws of physics.
There are plenty of other smart lights and devices. Induction cooktops produce fast, incredible results with very little electricity. Along with microwaves, deep fryers, and pressure cookers, you can reduce energy use. Ovens and slow cookers can be programmed to use solar energy to prepare food when we get home.
In addition to the much-loved options, washers, dryers, and dishwashers can all be easily set to run during sunny hours.
Energy efficient refrigerators also reduce costs. But while people are happy to buy these coolers, our research survey found that some coolers still last and use three to four times more electricity per drink.
Homes with a pool or spa are notorious for higher utility bills. A pond will typically use 2,000-3,000 kWh of electricity per year (depending on pump type, hours of use, and whether the pool is heated), costing AUD700-1,200. Solar pool heaters are a good alternative. A simple timer can ensure that most of the energy is consumed during the sunny hours.
A typical outdoor spa uses 5kW to heat and circulate the water. If you keep the thermostat hot all the time, a lot of heat is lost to the environment. By installing a timer, you can use the energy of the sun to heat the bathroom and prepare it for use after hours.
Use smart technology to control usage time
The key to maximizing your solar power is to avoid wasting energy and timing your electricity supply to your home's needs. An affordable smart control system, for the whole house or for individual devices, can do this.
This system can set a seven day schedule for all devices. You can turn off the lights and air conditioning after you leave the house. On a hot day, you can pull down the blinds and turn on the ceiling fan and air conditioning before heading back in, then adjust the room's temperature for a comfortable night's sleep.
With improved power demand and supply forecasting and artificial intelligence, future controllers will provide optimal power options with minimal human intervention. If smart devices aren't your thing, simple timers are under $10.
Energy storage remains the key technology to enable use at night and during the day without sunlight. A recent Conversation article talked about household batteries.
Read more: Thinking of buying a battery to power your home? This is what you need to know
Another emerging technology is thermal batteries for heating and cooling. During sunny hours, reverse cycle air conditioners produce heat or cooling to be stored in a heat exchanger (usually as hot or cold water) for later use.
A grid-connected electric vehicle will go a long way in making better use of electricity on the roof and storing it for overnight use. The battery capacity is several times higher than that of domestic batteries.
Find the best energy plan for your home
With 45 energy retailers in South and Eastern Australia offering multiple tariffs, it's no wonder consumers are confused about which one to choose. The Australian Energy Regulator provides the most reliable guidance. By uploading a few basic details, including the National Meter Identifier (NMI) that appears on your bill, you can find the best deal based on your recorded electricity usage.
With this site, my son, who already pays an $800 quarterly bill despite having a great solar system, has achieved a potential annual bill of less than $1500 simply by switching dealers. Installing a timer for your outdoor bath to run on solar energy, instead of paying 33c/kWh, will probably save you up to $5 per day. Your goal of not billing electricity has come true.
We are seeing the emergence of a new Australian dream of living in well-designed homes with rooftop solar, electric cars and energy-efficient controlled appliances. This will allow most one or two-story homes to be carbon neutral while living comfortably without a huge impact on their pockets.
