Heat pump and solar: how much the roof really covers
Enter your municipality, house, pump and solar size. The calculator adds the pump’s power to the house’s use over the heating season.
Heat pump + solar: yearly heating cost
PLN 3,164
without solar PLN 4,641 · solar covers PLN 1,477 of the pump’s power
| Heat needed per year | 13,200 kWh |
| Heat pump electricity | 4,258 kWh |
| Solar output | 8,400 kWh |
| Used on site with / without pump | 2,805 / 1,533 kWh |
| Solar saving with / without pump | PLN 4,932 / PLN 3,455 |
Heat pump power spread over October to April; winter sun is weak, so most of that energy goes through the deposit, which covers only the energy part of the bill. An estimate.
A heat pump and solar panels fit together less well than adverts promise, but better than either alone. The pump uses most power from November to February, when the panels produce least: an 8 kWp system in Warsaw gives about 1,100 of its 8,400 kWh a year in those four months. Under net-billing, summer surplus does not come back in winter as energy but as a deposit that pays the energy part of the bill. For a 120 m² house at 110 kWh/m², a pump with SCOP 3.5 uses about 3,771 kWh of power a year, costing PLN 4,123. With 8 kWp and house use of 3,500 kWh, solar saves PLN 4,846 a year with the pump and PLN 3,455 without it. The difference, PLN 1,390, is the part of the pump’s bill the roof covers. Much of it comes from deposit that, without the pump, would partly be lost. The calculator above works this out for your municipality.
Checked by Radif Partners · Editorial policy · Method
How much the roof covers at different sizes
| Solar size | Output | Saving without pump | with pump | Solar covers of pump bill | Deposit lost without pump |
|---|---|---|---|---|---|
| 4 kWp | 4,200 kWh | PLN 2,512 | PLN 3,054 | PLN 543 | PLN 0 |
| 6 kWp | 6,300 kWh | PLN 3,264 | PLN 4,006 | PLN 743 | PLN 20 |
| 8 kWp | 8,400 kWh | PLN 3,455 | PLN 4,846 | PLN 1,390 | PLN 585 |
| 10 kWp | 10,500 kWh | PLN 3,646 | PLN 5,648 | PLN 2,002 | PLN 1,150 |
| 12 kWp | 12,600 kWh | PLN 3,834 | PLN 6,427 | PLN 2,593 | PLN 1,713 |
The last column explains why the pump and the panels complement each other. Without a pump, a large system builds up a deposit the house has nothing to spend on, and part of it is lost. The pump creates winter use on which that deposit is spent. That is why the saving with a pump grows faster with size than without one.
When the combination works best
When the house is insulated and the pump runs at a low flow temperature: it then uses less power, and more of that power falls in March, April and October, when the panels are already producing. When the pump also heats hot water in summer, since that use falls in production hours. And when the prosumer is settled at RCE, which has a higher refund cap. The heating cost calculator shows the cost of pump heating alone, without panels, and the prosumer deposit page how the deposit works.