What means it: - 0.00375 - 0.000875 - 0.04
Yes, this would be totally awesome to be implemented to native Energy dashboard as energy used as savings in house using entity as current electricity price like can be used for calculation on used energy for grid and sold energy to grid and shown and reduced from total sums in Sources…
Since your electricity consumer price seems to be 0.57 EUR / 6.17 kWh = 0.092 EUR/kWh, should not be the “Solar savings” amount be -8.6 kWh * 0.092 EUR/kWh = -0.79 EUR ? I mean what you save is the consumer price, right?
Calculating savings from solar PV (and batteries) is a bit of a dark art.
That’s because the tariff plan you would choose without solar PV (and/or battery) would likely be different, and also because the consumption patterns are going to be different with solar PV than without.
When you have solar PV you naturally shift discretionary loads to the daytime, which may have a different grid tariff to when it would have normally been run if you did not have solar PV, e.g. overnight.
IOW assigning the saving to the avoided grid tariff at time of consumption is a bit misleading. It really needs to be compared with what you would have done had you not had solar. And that’s all but impossible.
e.g. with solar PV our pool pump and water heating runs in the daytime. Without solar they would be run at other times when grid tariffs are cheapest. So in reality I’m offsetting the cost of consumption at the time of day they would have run, not when they actually run.
Sure, if you have a totally flat rate tariff then it will work but as soon as you move into the realm of time based tariffs and consumption patterns are altered, well then it starts to become little more than a feel good guesstimate.
I agree there are multiple ways of ‘accounting’ for solar/ battery benefits, but the savings are real so should be quantified.
I don’t think it is impossible, but there is some complexity.
My Default Market Offer 6 price for my region (Energex) is $2,052 for 4,600 kWh ~ 44.6c / kWh, so without solar/ batteries and on the default offer 10 kWh of water heating will have an operating cost of $4.46, lets call this the maximum savings as if you shop around you can do better than the DMO, but it is a benchmark. A simple assumption would be that my solar/ battery saves me ~ 44.6c / kWh.
If my solar system is generating and I don’t consume from the grid, I could export 10 kWh with a default 5c/ kWh feedin and generate 50c revenue or I could use that 10 kWh to heat my hot water, forego the 50c revenue and I have saved $4.46 - $0.50 = $3.96 against the DMO. If I’m on a spot price the feedin might be 1c for 5 kWh and 3c for the other 5 kWh, so the forgone revenue is $0.20 and my operating cost savings against the DMO are now $4.26.
If I consume 50/50 from the grid (5 kWh @ 44.6c/ kWh = $2.23) and solar (5 kWh @ 5c/ kWh = $0.25), then the operating cost savings are $4.46 - $2.23 - $0.25 = $1.98. If I consume 100% from the grid (10 kWh @ 44.6 c/ kWh = $4.46) then savings are $0.
The same can apply for a battery, costs can be the feed in price (say 5c/ kWh) of forgone revenue from not exporting and savings can be the cost of energy is you source from the battery (say 44.6 c/ kWh).
As I said this is just one method of accounting, which accommodates variable spot pricing and time-shifting loads, which I have implemented through a series of calculations and formula, which gives me a dashboard in Home Assistant.
There are other methods of accounting, and they have different assumptions and models, so lets get them implemented and reviewed so people can use the system that suits them.
I guess it comes down to what the purpose of the numbers are.
If you just want feel good numbers to brag about, then fine. But if it’s actually meant to be an honest appraisal of the real $ benefits of solar PV and/or battery, then it’s a misleading approach.
No one in their right mind is on the DMO, nor would someone with an electric water heater in the Energex region have it operating on the DMO peak tariff. It would most likely be on a controlled load off-peak tariff (T31 or T33), or at worst operating outside of the peak tariff period.
Using DMO as a baseline is just generating feel good numbers, the sort of tactic dodgy salesmen use to inflate the benefits of solar/batteries.
If you are going to compare water heater energy consumption costs, then at least use the baseline tariff most commonly used for heating water.
The comparison should be the bill difference between the optimal tariff plan for each scenario:
- What the bill would have been had you not had solar PV and/or battery
- What the bill actually is with solar PV and/or battery.
In each case people will have different consumption patterns and choose different tariff plans.
e.g. Because I have an EV I have access to a plan with super off-peak (i.e. free) energy in the middle of the day, so my middle of the day grid imports are high as I “load up” in that period. If I compared that altered consumption pattern with a regular tariff plan (let alone the DMO), then the cost differential would be large. I must be saving a lot, right?
But of course if I did not have access to a super off-peak tariff then I would not consume energy in the same manner. I would instead choose to consume it at other off-peak times.
So my savings are really the difference between those cheapest options in each case.
Likewise if I have a home battery and charge it with super off-peak power and then discharge it during peak period (which inevitably has an inflated peak tariff as that’s the way they work), my saving is not the difference between those tariffs. It’s has to be compared with the tariff plan I would have chosen if I did not have the battery, which would of course not have as high a peak tariff.
It would appear that some household are paying well above the DMO.
Whilst I don’t disagree that it should be easy to switch to a lower rate tariff the report would indicate that many don’t.
They are either vulnerable, lazy, or don’t care. Only the former I have sympathy for.
Yes, that was just quick mockup with paint to give an example, so savings in EUR was not correct 
So the self used energy savings would be calculated with same sensor as is currently used calculating current price from grid per hour:
What kind of sensor is this? : sensor.amber_vs_dmo_savings_daily
This value represents how much money I’m saving with my retailer vs the default offer.
The Default Market Offer for my location (Qld) is about 42c / kWh.
With my wholesale retailer I pay around 5c-10c/ kWh for energy during the day and around 20c-50c/ kWh for energy overnight.
So for example if I consume 10 kWh from the grid during the day (@10c/ kWh) it would cost $1.00, but at the Default Market Offer (@42c/ kWh) it would cost $4.20, thus this represents a $3.20 savings.
If I consume 10 kWh from the grid at nighttime (@42c/ kWh) it would cost $4.20, at the Default Market Offer (also 42c/ kWh) it would cost $4.20 so there are no savings.
As my pricing changes every thirty minutes I use an integral sensor to multiply the current energy consumption by the current price throughout the day which is recorded in sensor.amber_vs_dmo_savings and I use a utility meter helper to generate the daily savings: sensor.amber_vs_dmo_savings_daily, which resets to zero at midnight each day.
That’s exactly what I’m after! I’m surprised this isn’t calculated by default since the grid export calculation worked immediately when pointed to the correct sensors.
Where do you store the code? I’m so lost along the sensors, helpers, templates, 50+ yaml files you need an add-on to be able to access which all throw error messages at you and refuses to boot/start. From the dashboard, where do you go to add your code to where?
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