Going Green

Nerdy numbers

I’ve been meaning to post up some data about our usage patterns, etc. ever since we removed the gas, put in the solar panels, and started using batteries. So here it goes:

Switching over from gas/electric to all electric has resulted in nearly a doubling in electricity consumption, ranging from a 156% increase (December) to a 237% increase (November).

2015 and 2016 daily electricity consumption – in 2016, our electricity requirements were higher because all gas appliances were replaced by electrical appliances.

The solar panels have generated 3868kWh (3.86MWh), since going online (5 August 2016-22 December 2016). That’s an average of 27.63kWh of green electricity generated per day, using a 8.48kWh system in Melbourne. Holy crapcakes!

While we had solar panels, we shifted our electrical load to daytime use as much as possible. The dishwasher, hot water service, and washing machine all had timers or delay functions so we were able to run them during the middle of the day, making the most of the sun while it was out. For 100 days while we waited for our battery install, we consumed 771.73kWh, 390.48kWh of which was from the grid and 381.25kWh was from our solar panels. In other words, our solar panels supplied just under half of our energy needs.

Breaking down the daily electricity consumption – during the period of August 2016 to October 2016, our solar panels significantly reduced our grid power imports.

And how does our current daily grid power consumption compare to 2015 figures for August to October? 

Hardy ha ha, another geeky graph:

2015 versus 2016’s daily consumption of grid power – very similar figures. 

In 2015, we used gas for our our hot water service, stovetop cooking, and heating. Since our 2015 and 2016 daily grid power imports are very similar, the solar power we consume on site is roughly equivalent to our heat pump, induction cooktop and split-systems’ energy needs.

But the million-dollar question is: how have the Enphase batteries affected the numbers? We installed Enphase batteries on 13 November 2016; our power usage has dropped considerably since. In the first half of November, we imported an average of 2.22kWh per day from the grid. In the second-half, post-batteries, this number dropped to 0.8kWh per day. And in December, as summer shines down on our roof, we are now drawing an average of 0.644kWh per day.

We will always be drawing a small amount of power from the grid, as the batteries aren’t designed to take all of the immediate load like an uninterruptible power supply (i.e. offgrid systems), but 0.644kWh is pretty darn good.

So, pretty exciting stuff.

And finally, here’s a lovely table from our Powershop account which is our year in review:


3 thoughts on “Nerdy numbers

  1. i wonder if the govt allows you to sell the electricity u generate to the power companies. that way u dont need the batteries. u sell the surplus to the company and that off sets the amount u take from them at night. you might even find that u make a profit on it as u may sell more electricity to the company than u buy from them.

    1. You can’t sell directly to the power companies in Australia but there is new technology coming out (i.e. Reposit) which allows for you to sell electricity that you’ve stored in your batteries to the grid when prices are high. Exciting times.

  2. Everything we feed in is automatically supplied to our electricity retailer (Powershop) who pays us 10 cents per kWh rather than the electricity generators (who would pay much less as they would then on-sell it to the retailers). Unfortunately net feed-in (what you feed in offsets what you use when you aren’t producing) isn’t supported in Victoria. That would be great as we consume only 20-30% of what is generated and would mean we’d have no bills other than the service charge. Having said that, we are now on a time of use tariff so most of our consumption at night is at low prices like 15 cents per kWh given that we draw mostly from our batteries. As you can see what we export more than covers the cost of the service charge and what we draw from the grid.

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