Family House Vejvanov
The heating system is implemented through a combination of radiant panels ECOSUN, underfloor heating foils ECOFILM F and ceiling foils ECOFILM C, ECOFLOOR underfloor heating, and ECOFLEX convectors. The total installed electric heating power is 29.2 kW.
In October 2022, a PV system with a total capacity of 19.8 kWp was installed on the house, along with an HES battery storage system with a capacity of 41.1 kWh. The PV system is divided into two identical parts of 9.9 kWp each. One group of photovoltaic panels is connected to the HES storage as standard, while the other group is connected to a separate Fronius grid inverter directly to the building’s consumption. The excess from this part of the production is handled by the battery storage system in AC coupling mode. This part of the PV system is mainly used in the winter season to increase overall production during the heating season. In the summer of 2024, this part of the PV system was deactivated, and only the part connected directly to the HES storage was in use. The reason was to prevent unwanted feed-in during periods of frequent negative prices on the spot market.
Previous years' summary data on electricity consumption and costs are available:
| Period | Off-peak Consumption (kWh) |
Peak Consumption (kWh) |
Total Consumption (kWh) |
Total Payment (CZK) |
Unit Price (CZK/kWh) |
|---|---|---|---|---|---|
| 2016/2017 | 20 390 | 714 | 21 104 | 57 384 | 2,72 |
| 2017/2018 | 23 824 | 1 262 | 25 086 | 68 747 | 2,74 |
| 2018/2019 | 22 760 | 1 674 | 24 434 | 73 232 | 2,99 |
| 2019/2020 | 20 931 | 1 170 | 22 101 | 77 069 | 3,48 |
| 2020/2021 | 26 526 | 2 590 | 29 116 | 93 306 | 3,20 |
| 2021/2022 | 25 346 | 1 027 | 26 373 | 116 848 | 4,43 |
| 2022/2023 *) | 21 120 | 3 963 | 25 083 | 156 340 | 6,23 |
*) The amount of consumed energy influenced by the activation of the PV system
From January 2024, the house transitioned to a mode of purchasing and selling electricity based on spot prices (optimized by an algorithm within the HES storage system). Since then, more detailed monthly billing has been available:
| Period | Total consumption (kWh) |
Grid consumption (kWh) |
PV production (kWh) |
Grid feed-in (kWh) |
Grid consumption (CZK) |
Grid feed-in (CZK) |
Electricity costs (CZK) |
Achieved price (CZK/kWh) |
|---|---|---|---|---|---|---|---|---|
| 01/2024 | 4 442 | 3 827 | 756 | 141 | 17 763 | 216 | 16 947 | 3,82 |
| 02/2024 | 3 283 | 2 678 | 722 | 117 | 11 354 | 122 | 11 232 | 3,42 |
| 03/2024 | 2 798 | 1 438 | 1 815 | 455 | 6 346 | 405 | 5 941 | 2,12 |
| 04/2024 | 2 069 | 556 | 2 248 | 735 | 3 116 | 364 | 2 752 | 1,33 |
| 05/2024 | 1 000 | 85 | 2 053 | 1 138 | 1 230 | 1 417 | -187 | -0,18 |
| 06/2024 | 649 | 226 | 1 030*) | 607 | 1 719 | 1 654 | 65 | 0,1 |
| 07/2024 | 657 | 129 | 1 200*) | 672 | 1 364 | 1 783 | -419 | -0,63 |
| 08/2024 | 1 100 | 98 | 2 954 | 1 952 | 1 382 | 3 681 | -2 299 | -2,09 |
| 09/2024 | 1 039 | 164 | 2 204 | 1 329 | 1 570 | 2 422 | -852 | -0,82 |
| 10/2024 | 1 962 | 1 066 | 1 273 | 377 | 5 661 | 640 | 5 021 | 2,56 |
| 11/2024 | 3 234 | 2 731 | 656 | 153 | 16 365 | 623 | 15 742 | 4,87 |
| 12/2024 | ||||||||
| Total | 22 233 | 12 998 | 16 911 | 7 676 | 67 870 | 13 327 | 54 543 | 2,45 |
*) External inverter with 10kWp PV system turned off.
Prices are inclusive of VAT.
Preliminary results for 2024 show that the PV system with HES battery storage, efficiently managed according to spot price trends, is capable of achieving average prices comparable to those from 2016/2017.
