By Electrify 2515 volunteer Denise Aubourg
The cheapest electricity you can get in Australia is the electricity generated from your rooftop solar system. Since we installed a 6.6kW system 18 months ago, our two-person household is saving $1600 on energy bills a year (from $500 down to $100 a quarter – an 80% reduction!) and we expect to pay off the system in about three years.
Of course we still use power from the grid so we tried to determine how to make the most out of our rooftop solar. Currently on our plan we are paying 38c / kWh to buy power from the grid, and only get paid 12c kWh to put excess solar power back into the grid. So, it makes sense to use as much of the energy we generate ourselves during the day and minimise the amount we draw from the grid.
What we do to take advantage of solar was:
• Put a timer on our electric hot water system so it heats up during the day.
• Run the dishwasher, washing machine, oven and other household appliances during the day wherever possible (many modern appliances have auto-timers).
We’ve also been trialling a monitoring system called Clipsal Cortex as part of the Electrify 2515 project which has helped us understand our energy usage patterns. For instance, this is what 2nd May 2023 looked like on the Clipsal Cortex monitoring system.
You can see the fridge cutting in and out throughout the 24-hour period. The mid-morning session baking sourdough bread is totally powered from solar (yup, I’m still hooked on the Covid sourdough fad!).
Solar does not quite cover the energy needed for the hot water system on this day and a smallish amount of electricity was drawn from the grid to cover this. The afternoon got cloudy, so the solar generation was a bit sporadic. Even so, when we turned on our reverse-cycle heating mid-afternoon, most of the power was covered by the solar system. In the evening we continued to have the reverse-cycle heating on and had the cooking dinner peak in the early evening.
Even on this late autumn day that clouded over and got cool in the afternoon, the yellow sections show there was plenty of excess solar generated. This was fed back to the grid to help offset some of the cost for electricity we draw from the grid outside daylight hours.
If you have rooftop solar, the new “off-peak” is between 9am and 3pm when your electricity is effectively free!
I volunteer with the community group Electrify 2515 who have a Solar Rollout Program for all Illawarra residents to support more local households to join Australia’s solar revolution.
About the writer
Denise Aubourg is enjoying an active retirement in Coledale after many years as an IT Project Manager. Denise volunteers with Electrify 2515. She is inspired by Saul Griffith’s practical guide on how households and communities can play a significant part in the transition to renewable energy and reduce our living costs. Denise is also a keen golfer, cyclist, gardener and campervanner.
