Billing Awesomeness Powerwall Style

As I’ve been hinting for a while, the first bill has landed – Billing Awesomeness Powerwall Style! The guys at Natural Solar and I have been jumping out of our skins to get this moving, but all good things in time.

Natural Solar

I’d better come clean – technically this isn’t the “first” bill. I actually got one over a month ago, which only covered 35 days due to various scheduling issues with the meter changeover and reading.

And don’t get me wrong: that 35 days was a very small amount, particularly as my last summer bill was $660 (!!!), but I felt it best to wait and see.

Now that we have a quarterly amount, which also lines up roughly with the same billing period last year, I (and everyone watching) can compare apples more easily to apples.

Let’s go to the numbers, courtesy of my poor quality photography. Here is the bill from the “Autumn” quarter last year:


Of course, I’m a fine and upstanding citizen (stop giggling), so I paid on time to get the appropriate discount under my plan.

And here is the bill from “Autumn” quarter this year – this amount also includes the pay-on-time and direct debit discounts:

Billing Awesomeness Powerwall Style

Ninety per-freaking-cent reduction!

Not too shabby, but as always, it isn’t the whole story.

The 2015 bill overlaps the 2016 period by a few days at each end, so this is only a fair comparison if we look at the number of days on each bill. Hey let’s do that to FOUR decimal places!

Year Days Cost $ / Day
2015 99 $490.38 $4.9533
2016 86 $50.39 $0.5859

So… yeah… that’s 59 cents per day for electricity. And if you recall my ROI/payback article from April, you’ll know that under Diamond Energy single rate plan I pay a tick over 82 cents per day for connection, so I’ve even reduced the connection fee by a fair whack.

That makes it pretty clear that I was smashing out the solar power with extreme prejudice from my 5kW array. The final number was a tick over 3 kWh exported for every 1 imported. Always going to look good when you’re getting 8 cents for export, from the legends at Diamond Energy.

I will throw in here: that bill doesn’t contain a single GridCredit sale, either. Nor does it contain any off-peak (TOU) power. That is pure, single-rate, import versus export.

And I think I could do better, but we’ll get to why that is later.

Billing Awesomeness Powerwall Style – Factors

I suppose it was a pretty mild weather period, but then in Sydney for the Autumn period that’s not unexpected.

Looking at the energy consumed per day is also helpful:

Year Days kWh consumed kWh / Day
2015 99 1777 17.9495
2016 86 1180 13.7209

Note that because I don’t see how much I consume on the bill, I’m having to use the data generated by the SolarEdge API. In my experience so far it is fairly accurate, though it has a small degree of variance due to updating on the quarter-hour, as I understand it.

A good reduction in usage, due in part to having a couple of new devices we needed to replace, like the oven. The old one was listing badly to port, in naval terms.

That reduction is also about learning my consumption patterns via the SolarEdge and Reposit Power portals, and coming up with the best way to eliminate waste.

I’m also paying a bit less for my power overall since changing providers, but as I’m only importing around 3kWh per day, that is of negligible effect on terms of cents per day. The connection fee is only a tiny percentage different.

Critics will be quick to jump in at this point, with smugness, clamouring that its NOT just the Powerwall.

While that is a fair point, at the same time, they should not be dismissive of the lessons the system has taught me.

To digress into simile for a moment: I went to University, and it cost me a lot of money, but it didn’t get me a job; it gave me a mindset, problem solving skills, and the experience of those who were my educators.

Likewise, I have not just purchased a battery, but an entire solar PV system with smarts. With it, I have been given the opportunity to generate, store, and export that energy. I can access new energy trading markets such as GridCredits.

Most importantly, I have a new way of thinking, evidence to track my progress, and help from a range of people across the industries involved.

The battery, by itself, doesn’t deliver miracles, not was it ever intended to. I’ve made it very clear from early on that there were tangible benefits to the Powerwall.

The power shifting aspect of the battery is extremely important to reducing my import requirements. I don’t get Gross Tariffs, so moving what I can to the daytime is great.

BUT we don’t get to spend our whole day at home (the kids would drive me up the wall), so there needs to be other ways to reduce or offset that cost. That’s where the Powerwall takes over.


The ROI blogs I’ve written state quite clearly that any household could save money by making simple changes. Smarter devices. Better practices. Maybe a new billing provider. It didn’t matter whether they had even had solar PV, much less a battery.

A household with Solar PV on Net Tariffs has probably learned some of these lessons already. For them, the cost of a battery is a marginal prospect today but is certainly on the radar.

A household with Solar PV and Gross Tariffs in NSW is probably looking for “what next” as they lose those benefits at the end of the year. Perhaps they haven’t had to think about these factors, but they probably will (and I know some who are), once they start actually importing power at a cost ratio which reverses Gross Tariff costs.

I just look at the FACTS: I’m saving about 90% on my power bills. I’m making my household greener than it was, through waste reduction and buying green power. I’ve been asked to relate my experiences at conferences, schools, and work places.

People are interested in this technology, and want to see it in action before they commit. Hopefully this kind of real-world data, even if its only one site, will help.

As a side note, based on this one bill, the return is in the order of 10%. Extrapolating that, factoring degradation versus increase in power costs, the 10 year window on my warranty is looking pretty safe.

And I’m not done.

The next arrow out of the quiver is my upcoming move to time-of-use
billing. That way, I can start really getting the most out of the Reposit Power software to drive those costs down even further.

Energy Networks
This lighting really makes me look good…

Billing Awesomeness Powerwall Style, away!