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).

daily-consumption-for-electricity
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.

solar-vs-grid-power-3-months
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:

grid-power-consumption-2015-vs-2016
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:

powershop-account-review-2016

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Footnote Frivolity***, Going Green, mustbethrifty house

Going electric in the garden

Now that we have surplus free clean electricity from our solar panels, it makes sense to power our garden tools with batteries instead of petrol. Cheap Geek took advantage of the Masters fire sale and bought an electric lawnmower and line trimmer. He’s used both a few times now. The mower was used on regularly cut buffalo grass while the trimmer was used on a neighbour’s neglected garden as well as our somewhat neater yard. Here are his thoughts:

LAWNMOWER

The electric lawn mower is quieter and lighter than its petrol equivalent*. It also doesn’t have a pull cord and therefore does not require muscle to start; if you can make a fist with your hand, you can turn it on. Cleaning is easier too: no need to worry about petrol leaking or accidentally burning yourself against a hot engine.

The height adjuster on the electric mower is not as fine as the old petrol mower, but it is good enough for domestic use on buffalo grass.

LINE TRIMMER

The electric line trimmer is also quiet to use. The noise mainly comes from the sound of the trimmer line hitting the grass. It is, however, heavier than petrol models due to the weight of the battery. This particular model comes with a shoulder strap, which can take some of the load off the arms when necessary.

AND ANOTHER THING

The batteries provided ample juice for our block (and some of the neighbour’s garden as well), and you can buy bigger batteries where needed. When the batteries run out, the tool just stops; there is no noticeable decline in power before this happens. Recharging takes about 1 to 1.5 hours, and should be done while the sun is shining.

Our old petrol garden tools are still in good working order. My dad gave these to us when we first moved into the Mustbethrifty House; they were old models that he had repaired/serviced. Dad will be taking these back and sending them onto family who don’t have solar panels. I’m not sure what to do with the jerrycan though.

jerrycan


* ‘The average gas powered lawn mower is approximately 90 dB…these cordless mowers are almost 100 times less noisy compared to the gas mower’ (Todd Fratzel from Toolbox Buzz on ‘Best Cordless Lawn Mower – Head to Head Comparison’).