Battery Comparison Table
A Common Misconception
Walk into any battery showroom and the first question is: "How many kilowatt-hours?"
A 20 kWh battery sounds impressive. Twice as good as a 10 kWh battery, right?
Wrong. A battery is not a bucket that you fill and empty. It's a system with a maximum flow rate, efficiency losses, thermal limits, and a brain (the BMS) that decides whether it will even let you use the capacity you paid for.
Here's the gap: A 20 kWh battery that charges at 2 kW is like a 1,000-litre water tank with a drinking-straw pipe. Technically large. Practically useless. It would take 10 hours to fill — but solar only peaks for 4–5 hours per day. Most of that capacity sits empty, forever.
The Analogy That Makes It Click
Imagine you're buying a water tank for your garden.
Salesman A says: "This tank holds 2,000 litres!"
Salesman B says: "This tank holds 1,000 litres, but it fills in 2 hours and has a pump that waters your garden automatically."
Most people pick the 2,000-litre tank because bigger = better. But if your roof only collects 500 litres of rain per day, the extra 1,500 litres is wasted capacity you paid for. And if the 2,000-litre tank has a clogged inlet pipe, it might take 8 hours to fill — missing the afternoon rain entirely.
Batteries work the same way. Capacity (kWh) is tank size. Max power (kW) is pipe width. Efficiency is how much water leaks out. The BMS is the pump controller. A "small" battery with high power and good efficiency often outperforms a "large" battery with low power and poor thermal management.
What this tells us: Battery manufacturers tend to highlight kWh because it's the one number that always goes up with price. kW, efficiency, and warranty terms reveal more about actual value — but receive less attention in marketing.
LiFePO₄ Batteries for Residential Solar
LiFePO₄ (Lithium Iron Phosphate): The most common battery chemistry for home solar. Safer and longer-lasting than the lithium-ion batteries in your phone, but heavier. Think of it as the "truck engine" of batteries — not flashy, but reliable for 10+ years.
| Brand | Model | Capacity | Price (€) | €/kWh | Max Power | IP Rating | Heating | Warranty | Notes |
|---|---|---|---|---|---|---|---|---|---|
| BYD | Battery-Box Premium HVM | 8–22 kWh | €4,500 | €550 | 8 kW | IP20 | No | 10 yr | HV stackable, popular |
| BYD | Battery-Box Premium LVS | 4–16 kWh | €3,200 | €500 | 5 kW | IP20 | No | 10 yr | LV stackable |
| Huawei | LUNA2000 | 5–30 kWh | €3,800 | €600 | 5 kW | IP55 | No | 10 yr | Modular, smart BMS |
| Fronius | BYD HVM (rebadged) | 8–22 kWh | €4,800 | €580 | 8 kW | IP20 | No | 10 yr | Fronius integration |
| Sonnen | Eco 8 | 8 kWh | €5,500 | €690 | 4 kW | IP54 | No | 10 yr | German brand, premium |
| Sonnen | Hybrid 9.43 | 10 kWh | €7,000 | €700 | 4.6 kW | IP54 | No | 10 yr | All-in-one unit |
| Pylontech | US2000C | 2.4 kWh | €900 | €375 | 2.4 kW | IP20 | No | 10 yr | Budget option |
| Pylontech | US5000 | 4.8 kWh | €1,500 | €310 | 4.8 kW | IP20 | No | 10 yr | Good value |
| Midea | HiEnergy HV | 5–30 kWh | €4,200 | €560 | 5 kW | IP55 | Partial | 10 yr | Good thermal mgmt |
| Deye | SE-F12 MAX | 11.8 kWh | €3,800 | €320 | 5.7 kW | IP65 | Optional film | 10 yr | Budget, heating film issue |
| Deye | RW-M6.1 | 6.1 kWh | €2,200 | €360 | 3 kW | IP20 | No | 10 yr | Low voltage |
| FoxESS | ECS2900 | 2.9 kWh | €1,100 | €380 | 2.5 kW | IP20 | No | 10 yr | Entry level |
| FoxESS | ECS4100 | 4.1 kWh | €1,500 | €365 | 4 kW | IP20 | No | 10 yr | Mid-range |
| Tesla | Powerwall 2 | 13.5 kWh | €8,500 | €630 | 5 kW | IP67 | No | 10 yr | Premium, app ecosystem |
| Tesla | Powerwall 3 | 13.5 kWh | €7,500 | €555 | 11.5 kW | IP67 | No | 10 yr | Higher power output |
| Sungrow | SBR HV | 9.6–25.6 kWh | €4,500 | €470 | 5 kW | IP55 | No | 10 yr | Modular, good value |
| LG | RESU 10H | 9.8 kWh | €5,000 | €510 | 5 kW | IP55 | No | 10 yr | Compact, reliable |
| GivEnergy | Gen 3 | 5.2–20.8 kWh | €3,200 | €450 | 3.6 kW | IP65 | No | 12 yr | UK brand, growing |
| Solax | Triple Power | 4.5–13.5 kWh | €3,000 | €400 | 6 kW | IP55 | No | 10 yr | Budget-friendly |
€/kWh: The price per kilowatt-hour of storage capacity. Like comparing price per litre when buying a water tank. Lower is generally better, but build quality matters too.
Key Metrics Explained
€/kWh
Lower is better, but not the whole story. A €300/kWh battery with poor BMS is worse than a €500/kWh battery with good thermal management.
Max Power (kW)
How fast the battery can charge/discharge. For an 8 kWp solar system, you want at least 5 kW battery power to absorb midday peaks. A 10 kWh battery with 2 kW max power takes 5 hours to charge — but solar only peaks for 4–5 hours. You'll miss the peak every day.
| Solar Size | Midday Surplus | Min Battery Power Needed |
|---|---|---|
| 4 kWp | ~2.5 kW | 2.5 kW |
| 6 kWp | ~4.0 kW | 4.0 kW |
| 8 kWp | ~5.5 kW | 5.5 kW |
| 10 kWp | ~7.0 kW | 7.0 kW |
A battery with insufficient max power is wasted capacity. Like buying a sports car with a 50-horsepower engine.
IP Rating
- IP20: Indoor only (dry basement)
- IP54: Protected against dust and splashing
- IP55: Protected against dust and water jets
- IP65: Protected against dust and powerful water jets
- IP67: Submersion protected
For under-terrace or outdoor: IP55 minimum, IP65 preferred.
Heating
- No heating: Charging stops at 0°C. Problem for cold climates. Like a phone that shuts down in winter.
- Partial heating: Maintains battery above 0°C. Basic protection.
- Heating film: Enables charging to -20°C. Essential for outdoor/cold placement.
Deye SE-F12 MAX: Heating film is OPTIONAL, not standard. Must specify when ordering.
Honest Recommendations by Budget
Budget (<€3,000)
| Option | Why |
|---|---|
| Pylontech US5000 | €310/kWh, proven, stackable |
| Deye RW-M6.1 | €360/kWh, good for small systems |
| FoxESS ECS4100 | €365/kWh, decent warranty |
Mid-Range (€3,000–5,000)
| Option | Why |
|---|---|
| BYD Battery-Box LVS | €500/kWh, reliable, widely supported |
| Sungrow SBR HV | €470/kWh, modular, good app |
| Midea HiEnergy | €560/kWh, good thermal management |
Premium (>€5,000)
| Option | Why |
|---|---|
| Tesla Powerwall 3 | €555/kWh, ecosystem, high power (11.5 kW) |
| Sonnen Hybrid | €700/kWh, German engineering, all-in-one |
| Huawei LUNA2000 | €600/kWh, smart features, IP55 |
Red Flags in Battery Specs
- [ ] Capacity unclear (gross vs. usable)
- [ ] No round-trip efficiency stated (should be >90%)
- [ ] No operating temperature range
- [ ] No IP rating (indoor-only implied)
- [ ] Warranty shorter than 10 years
- [ ] No BMS brand/manufacturer stated — the BMS is the brain that prevents overcharging and overheating. Without a good one, the battery is dangerous.
- [ ] "6000 cycles" headline without DoD context — a cycle only counts if you discharge deeply. 6,000 shallow cycles ≠ 6,000 full cycles. It's like claiming a car lasts 600,000 km but only driving it to the shops.
- [ ] Heating film "compatible" but not included — check the fine print before ordering.
- [ ] Max power < 0.5 × capacity — a 10 kWh battery should charge at least 5 kW. Less = you'll never fill it during solar peak.
Battery Sizing Guide
| Daily Consumption | Solar Size | Recommended Battery | Why |
|---|---|---|---|
| 5 kWh | 4 kWp | None | Solar covers most demand |
| 10 kWh | 6 kWp | 5–8 kWh | Covers evening peak |
| 15 kWh | 8 kWp | 8–12 kWh | Good balance |
| 20 kWh | 10 kWp | 10–15 kWh | High consumption home |
| 30+ kWh | 12+ kWp | 15–20 kWh | Large home or EV |
Weekend home: Size for 1 day of consumption, not 2. You charge all week, discharge on arrival.
HV vs LV: High Voltage (HV) batteries connect directly to the solar inverter at 400V+ — more efficient, fewer cables. Low Voltage (LV) batteries run at 48V — safer to install, more common for DIY systems. Most residential setups use HV for simplicity.
What this means in practice: Battery shopping isn't about finding the biggest number. It's about matching max power to your solar peak, capacity to your evening need, and build quality to your climate. A well-matched 8 kWh battery outperforms an oversized 15 kWh battery with a drinking-straw pipe.