November energy bill came. I changed energy provider mid month, which lowered the margin a bit. I changed also the other car in the family from diesel to electric and charging the two electric cars is heavily shifting the total consumption to the lowest priced hours. October and November actual price is now about 50% below spot average thanks to the load from charging the cars. Night time cheapest spot time is around 1-2 cents, so driving is really cheap this way, especially as we only charge at home. Total savings 382€ this year so far. Looking really good.
In Germany, we’ve had a “Dunkelflaute” in Nov and Dec, i.e. very little wind and sun, resulting in high spot market prices.
Here’s my December month-to-date report from “the Day After” 24/12/12 where we had peak prices of 900+ €/MWh all over Europe. “Vergleichstarif” below was Tibber i.e. what you would have paid with an unmanaged spot market price per kWh.
Still paid less than the average 2023 cost was (35,xx per kWh).
Our neighbors have solar panels and they are actually shoveling the snow from the panels (after he has done the shoveling from the front yard, though). He’s point is not to get the couple of minutes of sunlight during these darkest months but to get the production ongoing like a month earlier in the spring.
They also have a battery and they sell their excess production back to the grid and sometimes when the prices have big peaks up and down also buy when its cheap to load the battery and then sell it back with much bigger price.
This year they started to pay for the electricity in mid-October, the money they got for selling covered the costs until that.
Their stuff is extremely hard core, the guy also has 20 motor valves to automate the watering of their green house, flowers and grass.
Yes that’s more or less what I did and do, too, i.e. pre-charge the battery from the grid when cheap.
Except for that we don’t have snow and that in Germany we cannot sell back at higher prices because those are regulated and fixed (“EEG Vergütung” in my picture).
(unless you’re member of a private community to share electricity, but that in turn usually isn’t worth the fixed cost)
That plus suppressing to heat during the most expensive hours made up for the 2,7ct difference of Vergleichstarif (spot price) - Strompreis avg (my cost).
Here’s a new dump of our savings. I’ll post this in two parts because we changed the contract type from the beginning of August this year.
This first post is the 24 month period that we had a hybrid contract (aka kulutusvaikutusopimus in Finnish). In this contract type there is a fixed base fee +/- delta, where the delta is the difference to the monthly spot average.
Month
Consumption, kWh
Spot average c/kWh
Own average, c/kWh
Delta, c/kWh
Delta, %
Actual price, c/kWh
Actual monthly price, EUR
Discount, EUR
Total with spot contract, EUR
Diff EUR
2022-08
518
32.4
22.5
-9.9
-30.56%
4.9
25
-51
119
-93
2022-09
625
26.6
18.6
-8.0
-30.08%
6.8
43
-50
119
-76
2022-10
873
14.1
8.9
-5.2
-36.88%
9.6
84
-45
81
3
2022-11
1034
24.2
20.2
-4.0
-16.53%
10.8
112
-41
213
-101
2022-12
1503
27.1
24.2
-2.9
-10.70%
11.9
179
-44
370
-191
2023-01
1369
8.9
6.9
-2.0
-22.47%
12.8
175
-27
100
75
2023-02
1570
8.82
6.0
-2.8
-31.75%
12.0
188
-44
101
88
2023-03
1723
8.16
5.7
-2.4
-30.00%
12.4
213
-42
105
108
2023-04
975
6.66
4.7
-2.0
-30.03%
12.8
125
-20
49
75
2023-05
890
3.28
2.2
-1.1
-33.54%
13.7
122
-10
23
99
2023-06
719
4.24
3.4
-0.8
-20.00%
14.0
100
-6
27
73
2023-07
596
4.08
2.9
-1.2
-29.41%
13.6
81
-7
20
62
2023-08
704
8.23
5.1
-3.2
-38.40%
5.7
40
-22
39
2
2023-09
672
4.08
2.3
-1.8
-44.36%
7.1
48
-12
18
30
2023-10
1319
4.67
2.4
-2.3
-49.25%
6.6
87
-30
37
50
2023-11
1642
8.63
2.8
-5.8
-67.21%
3.1
51
-95
53
-2
2023-12
2012
9.46
8.1
-1.4
-14.59%
7.5
151
-28
171
-20
2024-01
2320
13.18
10.8
-2.4
-17.98%
6.5
151
-55
260
-109
2024-02
1587
6.4
5.7
-0.8
-11.72%
8.1
129
-12
96
33
2024-03
1456
7.36
6.1
-1.3
-17.80%
7.6
110
-19
94
16
2024-04
1225
6.07
4.6
-1.4
-23.72%
7.4
91
-18
62
30
2024-05
986
4.37
1.9
-2.5
-56.52%
6.4
63
-24
23
41
2024-06
713
4.47
2.6
-1.9
-42.73%
7.0
50
-14
21
29
2024-07
828
2.09
1.2
-0.9
-44.02%
8.0
66
-8
13
53
2483
-725
2211
272
So during the 24 month period, we got a 725 EUR discount with the hybrid contract. A pure spot price contract (last two columns) would have been 272 EUR cheaper during this 24 month period.
Next post will contain the status from 2024-08 onwards when we have had a pure spot price contract.
Here’s the dump from August - November 2024 when we have had a pure spot price contract where we pay the market price + 0.38 c/kWh.
So during these 4 months we have saved 76 EUR compared to spot average (Our 0.38 c/kWh margin is included in the calculation of the total savings).
Month
Consumption, kWh
Spot avg, c/kWh
Own avg without margin, c/kWh
Delta, c/kWh
Delta, %
Monthly total, EUR
Savings vs. spot avg
2024-08
901
1.57
0.73
-0.84
-53.50%
10
-4
2024-09
787
7.03
3.82
-3.21
-45.66%
33
-22
2024-10
1150
5.11
2.32
-2.79
-54.60%
31
-28
2024-11
1461
5.69
3.78
-1.91
-33.57%
61
-22
-76
I also calculated the year-to-date consumption-weighted average (assuming that we would have had a spot price contract all the time).
YTD total consumption: 15426 kWh
YTD total price w/ margin: 964 EUR
YTD avg price, c/kWh: 6.25 c/kWh
I believe the best fixed fee prices a year ago were on the ballpark of 8.8 c/kWh. So if we compare to that, the total cost would have been 1357 EUR. So if that would be the comparison point, the YTD savings would be 393 EUR.
Just came across that, hadn’t seen it at that time.
Are you still around and willing to share some knowledge?
Actually I’m looking for openHAB code (DSL or JS) to compute how much one would have paid with current spot prices (from Entso-E binding) and a H0 SLP, i.e. the German standard consumer load profile.
I already do the math for my (shifted) consumption in my EMS, see my post up,
but I’m eager to know how much shifting ultimately saved me in € and ct, i.e. what I would have paid without an energy management system.
It’s not that difficult, when the automation takes care of it, lol. Our February was 41% below spot average (excluding margin) and 35% below if margin is included.
We had a Välkky hybrid agreement to the end of July 2024. Our year-to-date average is currently 5.97 c/kWh. If we would have hade a pure spot price agreement for the whole 12 month period the YTD average would be 4.81 c/kWh.
I don’t think the difference will be explained by the parameters that I’m using for optimizing the heating. It’s most probably other usage patterns that are different between your household and ours.
Besides heating, the biggest loads for us are:
Heating domestic hot water. The ground source heat pump takes on average 45 mins per day for this (we have allowed the cheapest 1 hour) and the external 300 liter boiler takes on average 1.5h per day (we have allowed the cheapest consecutive 2 hours, but it typically hits the thermostat upper limit after about 1.5h of heating.
The biggest reason why our average gets this low is the charging of our electric vehicle. We don’t need to charge it every day, only a couple of times per 2 weeks - sometimes more frequently. But when we do charge, it’s typically very cheap hours, which then brings our monthly average down quite a bit because there is huge peak of consumption with very low price.
But since you asked, the heating parameters that we use are
// Heat pump compressor will always have 1 hour, even during summer, for heating domestic hot water
parameters.numberOfPeriods = 4; // Number of heating periods in a day.
parameters.heatCurve = [ // Heat curve:
{temperature : -25, hours: 24}, // - Average temperature -25°C, heat 24h / day
{temperature : 13, hours: 1} // - Average temperature +13°C, heat 1h / day
];
// These parameters are fixed for me
parameters.dropThreshold = 2;
parameters.flexThreshold = 1;
parameters.shortThreshold = 0.5;
parameters.shiftPriceLimit = 2;
// I have items for these parameters
parameters.periodOverlap = items.getItem('HeatingPeriodOverlap').numericState;
parameters.flexDefault = items.getItem('HeatingPeriodFlexibility').numericState;
parameters.gapThreshold = items.getItem('HeatingGapThreshold').numericState;
parameters.heatingNeedAdjustment = items.getItem('HeatingNeedAdjustment').numericState;
I usually don’t have a need to adjust the parameters that I have items for, but especially now that there starts to be days when there is quite a lot of passive heating from the big south-facing windows, I sometimes use the HeatingNeedAdjustment and adjust the other parameters so that there is less (or none) heating during the days when the prices are typically higher.
Here is the total result for 2025. We live in a the arctics and our space heating is based upon a ground source heat pump. We have heating, EV charging, Dish Washer and Washing machine under spot price optimization.Total energy consumption 2025 was 16,5 MWh. There is an increase of about 3 MWh from 2024 which is accountable to the fact that we swapped also our other car to an EV. Even with the added energy consumption we spent 150€ less on energy in 2025 than in 2024. We saved a whopping 763 € against the local energy company prices and 211 € against average spot price. Further, the average annual realized cost of energy was 25% below the spot annual average. This is a remarkable result and a proof of how well @masipila s algorithms work. Without automation it is nearly impossible to even reach spot average in the long term.
