Fronius Reserva 15.8 vs VARTA element backup 18
Usable capacity: Fronius Reserva 15.8 15.79 kWh, VARTA element backup 18 17.6 kWh. The Fronius Reserva 15.8 is better on 5 of 8 comparable points.
Who wins where
- Fronius Reserva 15.8
- VARTA element backup 18
Biggest differences
| Fact | Reserva 15.8 | element backup 18 |
|---|---|---|
| Min. operating temperature | -20 °C | 5 °C |
| Charge power (continuous) | 16.38 kW | 4 kW |
| Discharge power (continuous) | 16.38 kW | 4 kW |
| Warranted cycles | 6,000 | 4,000 |
| Nominal capacity | 16.71 kWh | 19.5 kWh |
| Weight | 187 kg | 215 kg |
Score per area = position (0–100) relative to all 130 models in this category; higher is better.
| Technical specifications | FroniusReserva 15.8 | VARTAelement backup 18 |
|---|---|---|
| General | ||
| Cell chemistry | LFP 1 | – |
| Performance | ||
| Usable capacity | 15.79 kWh 1 | 17.6 kWh ✓ 2 |
| Nominal capacity | 16.71 kWh 3 | 19.5 kWh ✓ 2 |
| Charge power (continuous) | 16.38 kW ✓ 1 | 4 kW 2 |
| Discharge power (continuous) | 16.38 kW ✓ 1 | 4 kW 2 |
| Efficiency | ||
| Round-trip efficiency | 95 % 1 | – |
| Electrical | ||
| Coupling | DC-coupled 1 | – |
| Phases | – | 3 2 |
| Backup power | Yes 1 | – |
| Dimensions & weight | ||
| IP rating | IP65 1 | – |
| Min. operating temperature | -20 °C ✓ 1 | 5 °C 2 |
| Width | 772 mm 1 | 600 mm 2 |
| Height | 1,640 mm 1 | 1,176 mm 2 |
| Depth | 176 mm 1 | 500 mm 2 |
| Weight | 187 kg ✓ 1 | 215 kg 2 |
| Warranty & lifespan | ||
| Warranted cycles | 6,000 ✓ 1 | 4,000 2 |
| Warranty | 10 years 1 | 10 years 2 |
Sources
- The Fronius storage solution, V09 Sep 2026 — Fronius International GmbH · accessed 29 Sept 2026
- VARTA element backup, DB178038DACHDE005 — VARTA Storage GmbH · accessed 29 Sept 2026
- CEC approved solar batteries (Australia) — Clean Energy Regulator (Australian Government), CC BY 4.0 · accessed 29 Sept 2026