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Latest bill received - now have just shy of a year's total billing with the new provider, using the Powerwall.
I'd predicted the summer bill to be about $1.20 a day (similar to winter, but with more sun comes more export $$$) and it came in 8% under that.
So, across the year, my actual spend on electricity: 51 cents per day. That's inclusive of all usage and the daily connection fee etc.
The other way to look at it is on an energy cost basis i.e. removing the 3 referral fees I received as credits, as well as the application fee I paid to join this retailer.
We then come out around 73 cents per day.
Given the connection fee is about $1 inc GST, I'm pretty much laughing.
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it'd also be interesting to see if/when the ROI date changes and what drives that. Like you noted earlier changes in tariffs and export rates add something else to the mix.
But that daily average spend is mental ha ha, even if you convert to kiwi peso's
Our place is a north facing sun trap and while we don't have plans to move in the next 2-3 years it's probably too big of an capital investment (given our area etc).
Have you connected with anyone on the education/schooling front about your site/tech and data? It'd be awesome to have kids looking into solar alongside the science and maths. Some awesome learning opportunities in what you are doing. I'd almost swap that topic for my go-to primary topic of polar bears!
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@Paekakboyz I did a presentation to my son's school (Year 6 = last year of primary). The slides I used for that are going into a video for my YouTube channel so I can share that if you're happy to show Australian-language version
@Kirwan said in Solar Power and Storage - a nerd's view:
That's awesome. Does that give you enough data to map out a break even date?
Effectively, yes. My power bill for the year prior was about $2300. This year it will be (total including all fees and referrals) approx $280.
Year 1 is approximately $2000 savings.
If we make the fairly solid assumption that system performance degradation (normal with lithium) is roughly cancelled out by increases in electricity tariff* then we can assume that amount of $2000 will roughly continue.
System cost is $18K, including the new panels I added in October. So ordinary ROI is about 9 years.
HOWEVER - and this is the thing I don't broadcast on the blog - because of the PR I did for the installer, I got a $1k discount on Day 1. The extra 1.5kW of panels I got for free, which was another $1300 worth. So I really only paid $15,800.
NTA payback is therefore under 8 years
The breakdown of savings I've worked out to be roughly the following:
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50% is due to solar panels - particularly the practice of shifting certain activities e.g. dishwasher into daylight hours
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25% could be directly contributed to the battery itself in terms of allowing me to use solar at night AND charing the battery with off-peak power to save peak power (tariff arbitrage). This is a key because if the system knows a cloudy day is coming up, it'll give me power that it holds until the evening, as one example.
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15% is due to change in habits reducing overall consumption (waste). Once I was getting a data feed, I started to understanding where my pain points were, and could mitigate them. The stats page on the blog lists my system lifetime consumption as around 16kWh per day. Previously it was closer to 20 on average.
Note also on that page that the battery (top graph "Last 3 days") has started charging with some off-peak rate to get me ready for tomorrow. Which is meant to be shitty hot (41C).
- 10% of the savings is due to chage in retailer, by my early estimations. However, that was comparing my single-rate power to the old retailer ($2300 guys). Now I'm on Time Of Use that calculation is a little funny. The smart controller hooked up to my system "games" the rate e.g. the offpeak charging of the battery in order to get me the best financial result.
I really need to change over the APIs that feed that page - they come from the inverter hardware and are a little fuzzy by my estimation. The Smart Controller has much more detailed stats, but its a bit less mature to retrieve (tokens, not api key) and a hell of a lot more complex in its detail.
- Note that electricity tariffs in Australia have increased rapidly in the last two decades. In some places e.g. Queensland, messy administration and back room matesy deals between the government and regulator have jacked up prices by as much as 60% over 10 years.
For every 2 cents per kWh (< 10%) that my power price goes up, my system wins even harder.
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@Crucial interesting stuff. A few bus fleets are looking at retrofit of gas-electric setups as well
Wife has a car with her work, and the fleet contract is up for renewal. I've told her to tell the fleet manager to sign a short term deal so that they can wait until Tesla is doing the Model 3 in quantity next year
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Of course, the upshot of going full EV on your fleet is that electricity retailers now need to find you some more juice.
On-premises parking with charging stations could help offset solar / wind spikes, which the big generators see as a genuine threat to the system: fluctuation of power.
There is a persistent belief that, because our grid is built to handle certain frequencies (e.g. 50Hz) in order to make sure things don't blow up down the chain. However, with a big enough battery and inverter you can mitigate that.
The other side of it is the Duck Curve, which I cover here as part of a thing I entered.
http://unleashthepowerwall.com/2016/12/21/climate-change-risks/
500-700 words was a little limiting for my frothing enthusiasm, but the basic premise is the same: the industry needs to undergo change.
Baseload isn't even a thing if you ask the Chinese. There is a technological answer for anything.
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@NTA said in Solar Power and Storage - a nerd's view:
Effectively, yes. My power bill for the year prior was about $2300. This year it will be (total including all fees and referrals) approx $280.
Oh. I just realised that I'd miscalculated something there.
My actual out of pocket for electricity bills this year:
$175
So I guess all the haters - who said "it's not worth the money!" - can tuck into that bag of steaming cocks they no doubt keep in their pantry.
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Those tariffs ended in NSW and SA this year. And the conditions on the QLD ones are quite interesting - can't move house, can't alter the size of the system.
The state government were simply too stupid (or uninformed) about how, once people saw what they were getting for the investment, they decided they'd never move house.
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@NTA said in Solar Power and Storage - a nerd's view:
@NTA said in Solar Power and Storage - a nerd's view:
Effectively, yes. My power bill for the year prior was about $2300. This year it will be (total including all fees and referrals) approx $280.
Oh. I just realised that I'd miscalculated something there.
My actual out of pocket for electricity bills this year:
$175
So I guess all the haters - who said "it's not worth the money!" - can tuck into that bag of steaming cocks they no doubt keep in their pantry.
So without having to read/endure your blog. What's the short answer here on investment payback. How many years now you have some actual results to work off?
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It would be 9 on the full price of my system. But under 8 for what I paid.
However, the new powerwall would chop it down to below 7 even at full price I reckon - more storage, more output.
As I've said before: savings not ALL in the battery, but spread across the whole system.
Everyone could probably save 25% off their bill right now if they looked for a better deal, and took some efficiency measures in their current house.
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@NTA said in Solar Power and Storage - a nerd's view:
It would be 9 on the full price of my system. But under 8 for what I paid.
However, the new powerwall would chop it down to below 7 even at full price I reckon - more storage, more output.
As I've said before: savings not ALL in the battery, but spread across the whole system.
Everyone could probably save 25% off their bill right now if they looked for a better deal, and took some efficiency measures in their current house.
Not all of us would get overly anal on saving power though as well. For example those still getting the occasional bit between the sheets may be happy for the missus to use the oven
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Awnings over particularly hot windows don't cost much.
Knowing you can run your air con at 25C instead of 23C without dying.
Getting TOU power and putting as much heavy stuff as you can there.
Going and getting a better deal - and understanding how you pay, and what that actually means - is the biggest thing. -
@dK yesterday was $2.57 (out of a predicted $2.95)
Today so far I've been alerted to dispatch $2.45 (2.54kW) to help support the grid. Started about 1715 hours but I had the air con running so might not make all of that.
I've been following the NEM on Twitter the last few hours. The situation earlier today - predicting blackouts from 5-6PM across NSW - has eased.
Also this from AusGrid:
Solar Power and Storage - a nerd's view