The winter power problem
Energy when it matters most.
How self-determined a building is does not only depend on how much energy it generates. It depends on when — and on whether that energy can be stored.
02 The problem
In winter, demand rises. Photovoltaics deliver less.
A building needs the most energy in the heating season. At the same time, photovoltaics deliver far less than in summer.
The result: dependence on the grid rises at exactly the time when power of your own would be most valuable.
The chart shows it for an example building, month by month: heat demand at the top, power from photovoltaics and from COR.gen below.
Heat demand and power generation over the year
Model calculation for an example building, values per month
Model calculation, not measured values. Example building: refurbished detached house with 200 m² and four occupants in St. Pölten, Austria, 10 kWp of photovoltaics, one COR.gen, one COR.stor. Values rounded. COR.gen runs heat-led — mainly in the heating season, in summer only for hot water. How much power is actually generated depends on running time and building.
| Month | Heat demand · kWh of heat per month | Photovoltaics, 10 kWp | COR.gen (heat and power plant) |
|---|---|---|---|
| January | 3,800 | 390 | 860 |
| February | 2,800 | 850 | 620 |
| March | 2,000 | 1,000 | 460 |
| April | 1,300 | 1,300 | 310 |
| May | 1,100 | 980 | 260 |
| June | 290 | 1,600 | 90 |
| July | 300 | 1,300 | 100 |
| August | 300 | 1,300 | 90 |
| September | 390 | 1,100 | 110 |
| October | 1,100 | 760 | 270 |
| November | 2,000 | 480 | 460 |
| December | 3,200 | 450 | 710 |
03 The answer
Need heat. Generate power at the same time.
COR.gen, the heat and power plant inside COR.set, uses the heat demand that is there anyway: it heats with wood pellets and generates up to 2.2 kW of electrical output at the same time — not in addition, but while it is heating.
Combined with COR.stor, energy is stored: 70 kWh usable, expandable to 210 kWh usable. That keeps the power available even when it is not needed at the very moment it is generated.
04 The proof
Timing makes the difference.
At 8 operating hours a day that is up to 17.6 kWh of electricity (2.2 kW × 8 h), at 12 hours up to 26.4 kWh — on days when the heating is running.
That is the calculation at rated output. The model calculation in the chart further up works differently: with the heat-led running time over the whole month — on cold days the system runs longer in the model, but often at part load.
How much that adds up to over a full heating season depends on your system’s running hours — we work that out for your property in the initial consultation.
- up to 2.2 kW electricity
- 92.5% overall efficiency