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:


mustbethrifty house

The batteries are HERE

So I came home on Friday to these babies:

Enphase batteries Enphase batteries are AC-based (rather than DC) and hence integrate really well with our AC microinverter system. It has many pluses, such as compact sizing, modularity and, according to Renew Economy, ‘a depth of discharge greater than 95 per cent, an ambient operating temperature range of -20°C – 45°C and a warranty of up to 10 years or 7300 cycles.’ After 7300 cycles, Cheap Geek expects them to still be operating at 80% capacity.

Install took just over 5 hours (1 hour per battery) and the batteries were charged by the end of the day. We now have somewhere between 5.7 kW and 6 kW to draw from during sunless periods. It’s too early for us to tell whether the batteries will remove our need for coal-powered grid electricity completely, so watch this space…

Footnote Frivolity***, Going Green, mustbethrifty house, Reviews, Uncategorized

Goodbye gas, we’re NOT going to miss you (part 1)

Over the Christmas break, Cheap Geek spent a lot of time crunching numbers. He downloaded a year’s worth of electricity usage data from the power company, poured over utilities bills, and trawled through solar panel specs in an attempt to determine the whens and hows of breaking even with solar panel technology. At the end of it, he figured that

  • it would take us 9.5 to 10 years to recoup the initial estimated outlay*;
  • based on our consumption patterns, we could only achieve this if we also installed battery technology; and
  • getting rid of gas would effectively pay for 80% of the solar panels within ten years.

This project was of immense interest to him, so much so that he spent much of the next few months telling everyone and anyone about the financial merits of switching over to solar power. He even convinced my dad, a big Liberal, no-Greens-hogwash supporter, that solar power plus batteries was the way to go.

As of this Thursday, we are officially gas appliance free. These last couple of months have been a frenetic mess of tradesmen replacing gas hot water, gas ducted heating, and gas stove with reverse-cycle heating and cooling, induction stove, and hot water heat pump. Apart from reverse-cycle cooling, most of these technologies are still as fresh as the fresh air fanned out of a heat pump (brrrrr), and the average John Smith/Jane Doe might feel uncomfortable adopting them. Ripping out the gas stove sounded particularly traumatic to some of our acquaintances (especially the wok-loving ones)**.

So the rest of this post will be about my thoughts on changing over from various gas to electric appliances, starting with the


Disconnected gas stove

Before: Bosch gas cooktop

After: AEG induction cooktop

Tradie costs: $165 (plumber) and $370 (electrician)

As per above, switching over from gas cooking to induction is the greatest mental hurdle. Cooking is so very personal and seeing flames lick the sides of a pot must fulfil some Neanderthal need within us. I’ve even had greenies ask me whether I miss my stovetop or not.

FYI: I don’t use a wok much as it is not conducive to batch cooking. I usually cook casserole-style dishes, soups, and roasts. I’ve just newly discovered pressure cooking, which really suits my one-pot mindset (less pots to clean) and doesn’t even require a stove. When  I do use the induction stove, I use it to make sauces, soups, stews. I fry eggs sunny side up, make an omelet, boil water/stock, cook meat.

What I love about the induction stove is the evenness and control. It is superior to gas when needing to cook food at low temperatures: heating milk, cooking eggs and fish. Sausages also cook more evenly.

The AEG stove that we bought also has some fancy eco functions. For instance, it will tell you if you can use the residual heat on the stove as a ‘keep warm’ function, and it can turn off power to an element just before the end of a timed cook, using the residual heat to continue cooking the food.

What I find hard to adjust to is the speed in which a pan will heat up. You can’t leave an empty pan heating on the stove (I manage to burn butter for the first time by heating up an empty saucepan and then dropping the butter into it). This could be overcome by using a heavy cast iron pot; these take much longer to heat up than my Baccarat Bio+***.

There also is a lot more steam produced; you can’t cook without turning on the exhaust fan. And you need to hold onto your lightweight pans when stirring the pot, so that the pans don’t move around, scratching the cooktop surface. Regular cleaning is also important: the bases of pots and pans need to be properly cleaned of grime/residue and the cooktop needs to be wiped down with a soft, damp cloth after each use.

In the next post, I’ll talk about our experience with reverse-cycle heating and cooling, and hot water heat pumps.

*This estimated outlay included new energy-efficient electric appliances, solar panels, batteries, electrical work to get solar power ready, plumber work needed for the removal of all gas appliances, and various installation costs.

**It didn’t take too long for me to find a new home for the gas stove, whereas the gas hot water and gas ducted heating seem destined for the scrap heap.

***You may need to upgrade your pots/pans if you don’t already own induction-compatible ones.