2021: Hot water to instantaneous gas

<<< 2017 – Suppliers Strike Back

2022 – Battery? >>>

First an update….

Thermann Gas Hot waterOur electricity supply has been plugging along since the last post a couple of years ago, with no big changes other than switching our hot water to gas.

After the failure of our electric hot water storage tank (fed from a solar heater on the roof, and supplemented by grid electricity) we have switched over to a gas-powered instantaneous hot water system. Not necessarily saving too much money, but we now never run out of hot water. And it doesn’t heat any water when we don’t need it – like when we are away on holidays.

I see this as a temporary solution until we can get our hot water heated by solar generated electricity. Though that might be a while yet.

In the meantime it is worth checking in to see how our electricity bills are going. So here is a summary of the journey so far…

A quick re-cap

Remember that this journey started in 2007:

    • we were consuming 5750 kWh of electricity each quarter (65kWh per day);
    • paying 12c per kWh;
    • Total cost per quarter (Spring): $695

By 2009 we had reduced our consumption:

    • 4439 kWh per quarter (50kWh per day);
    • cost had increased to 18c per kWh;
    • Total cost per quarter (Spring): $791

So, although we reduced our consumption by 23% our costs increased by 13%.

Go figure.

In subsequent years our steadily decreasing consumption of electricity from the grid wasn’t resulting in decreasing costs. The only option left was to get off the grid, and produce our own electricity.

in 2015 we installed solar panels on our roof:

    • our consumption from the grid reduced to 1729 kWh per quarter (19kWh per day)- that’s a 61% decrease in consumption from the grid.
    • the cost of grid electricity increased to 22c per kWh
    • our total net cost per quarter (Spring) for electricity: $380

Comparison graphs

In 2017 our consumption had plateaued:

    • we used 1730 kWh of grid electricity per quarter (Spring):
    • the cost of grid electricity had increased to 31c per kWh;
    • our total cost of electricity for the Spring quarter: $536

By 2021 we have unhooked our hot water from the electricity supply, upgraded all our lighting to energy efficient LED lights, though we have installed ducted reverse cycle air conditioning (mostly for heating) and our permanent resident family size has reduced:

    • we used 788 kWh of grid electricity in the Spring quarter (9kWh per day) – that’s an 86% decrease in electricity consumption from the grid since 2007;
    • the cost of grid electricity is 22c per kWh;
    • we now pay $1 per day grid supply charge;
    • net cost of grid electricity (including solar feed-in rebate): $236

Even though our usage has dropped 86% since 2007 – we have reduced our grid electricity consumption, we use solar generated electricity during the day, our solar panels export excess electricity back to the grid – our costs have only dropped 65%, partly because the suppliers now include a daily supply charge of around $1 per day, regardless of how much or how little electricity we consume from the grid.

Also remember that we are feeding excess electricity, not consumed during the day, back into the grid at the rate of $0.05 per kWh, which we are then purchasing back from the supplier at the rate of $0.22 per kWh.

How do we get our energy costs down to zero?

Battery?The obvious answer is to install a battery, to store the excess energy we produce during the day, to be consumed at night, rather than paying $0.22 per kWh to buy it back from the supplier.

The Tesla Powerwall 2 can store 13.5 kWh of energy. But, in 2021, we are only returning around 5.5 kWh to the grid each day from our solar panels. And we don’t have any space on the roof for more panels!

So, is a battery worth the cost? More research required.

<<< 2017 – Suppliers Strike Back

2022 – Battery? >>