Solar with a home battery: what it really adds
The calculator compares the same house with and without a battery. Change the capacity and see how much the saving grows.
Yearly saving on your bills
PLN 4,189
5,250 kWh produced · 64 % used on site
| Used directly and from the battery | 3,337 kWh |
| Exported to the grid | 1,727 kWh |
| Deposit (×1.23) | PLN 553 |
| Deposit spent on energy | PLN 405 |
| Overpayment refunded | PLN 135 |
| Deposit forfeited | PLN 13 |
| Bill before / after | PLN 4,373 / PLN 319 |
| Pays back in 10 years up to | PLN 41,889 |
Hourly model of an average day in each month; surplus priced at the last 12 months of RCEm (PSE) plus the gain from negative RCE counted as zero. An estimate, not an offer; fixed charges excluded.
| No battery | 10 kWh | |
|---|---|---|
| Used on site | 32 % | 64 % |
| Exported | 3,579 kWh | 1,727 kWh |
| Yearly saving | PLN 3,039 | PLN 4,189 |
| Gain from the battery | – | PLN 1,150 |
| PME grant (30%, ≤ PLN 800/kWh) | – | PLN 8,000 |
A home battery stores the midday surplus and releases it in the evening and at night, instead of sending it to the grid. Under net-billing this makes economic sense, because energy used from the battery saves the full bill price, about PLN 1.09 per kWh, while the same energy exported gives a deposit valued at RCE that only pays the energy part of the bill. For 6 kWp in Warsaw and 4,000 kWh of use, a 10 kWh battery raises the share of output used on site from 27 % to 55 %, and the yearly saving from PLN 3,425 to PLN 4,323, an increase of PLN 897. A battery costs well over ten thousand zloty, however, so it pays back more slowly than the panels. The Przydomowe Magazyny Energii programme covers 30% of its price, at most PLN 800 per kWh and PLN 16,000. The calculator above compares both options for your municipality and use.
Checked by Radif Partners · Editorial policy · Method
What each extra kilowatt-hour of capacity adds
| Battery | Used on site | Exported | Saving | Gain from battery |
|---|---|---|---|---|
| no battery | 27 % | 4,603 kWh | PLN 3,425 | – |
| 5 kWh | 50 % | 2,994 kWh | PLN 4,198 | PLN 773 |
| 10 kWh | 55 % | 2,639 kWh | PLN 4,323 | PLN 897 |
| 15 kWh | 55 % | 2,639 kWh | PLN 4,323 | PLN 897 |
The gain grows more and more slowly, because the battery charges only from surplus and discharges only up to the night-time use. Once capacity exceeds what the house uses from evening to morning, the extra kilowatt-hours sit empty.
A battery helps most where nobody is home in the daytime
| House | No battery | With 10 kWh battery | Difference |
|---|---|---|---|
| out during the day | PLN 3,148 | PLN 4,315 | PLN 1,167 |
| working from home | PLN 3,732 | PLN 4,331 | PLN 599 |
In a house that is empty during the day, the surplus is large and the battery has plenty to move to the evening. When someone works from home, the house already does part of that job. The home battery grant calculator works out the grant and the programme rules, and the prosumer deposit page shows what exported energy is worth without a battery.