Imagine a winter storm knocks out the grid. Your neighborhood goes dark, but your lights stay on, your fridge hums, and your Wi-Fi never drops. That’s the practical benefit of a domača sončna baterija: resilience and value. Beyond backup, batteries can lower bills under Time-of-Use (TOU) plans, enable EV charging on cheap solar, and participate in grid programs.
This guide authoritative references, clearer kW guidance, warranty traps, and a short printable buyer checklist — so a homeowner or installer can make a confident, technically correct purchase.
Kamada Power 10kWh Powerwall Home Battery
1. What Size Solar Battery Do I Need? (Capacity + Power)
Short answer: don’t only pick kWh — always pair capacity (kWh) with minimum/continuous power (kW) and an expected peak power rating (kW). Capacity tells you kako dolgo the battery can supply energy; power tells you how many or which devices it can run at once.
Sizing table (practical):
| Household | Typical daily use | Recommended capacity (kWh) | Minimum continuous power (kW) | Typical backup scope |
|---|
| 1–2 people | 10–15 kWh | 5–10 kWh | 3 kW | Lights, Wi-Fi, fridge |
| 3–4 people | 20–30 kWh | 10–15 kWh | 5 kW | Fridge, TV, small oven, microwave |
| 5–6 people | 30–40 kWh | 15–20 kWh | 8–10 kW | Whole-home (excl. heavy HVAC) |
| High demand | 40+ kWh | 20–30 kWh+ | 10 kW+ | EV charging + HVAC + whole house |
Why kW matters: A battery with 15 kWh capacity but only 3 kW continuous power won’t start a 5 kW central A/C or run multiple heavy loads at once. Example: Tesla Powerwall 3 is ~13.5 kWh and ~11.5 kW continuous per unit (scalable); manufacturers often publish both numbers — always check both.
Strokovni nasvet: If you plan to add an EV or run HVAC during outages, size for the vrh power events (surge start) and continuous rating — not capacity alone.
2. Battery Chemistry — LFP (LiFePO₄) vs NMC: which should you buy?
Spodnja vrstica: For stationary home energy storage, LFP (LiFePO₄) is the mainstream best practice in 2025 because of safety and lifecycle economics.
Key comparative table
| Metrični | LFP (LiFePO₄) | NMC |
|---|
| Typical cycle life | ~3,000–6,000+ cycles | ~800–1,500 (some sources show 1,500–3,000 depending on formulation) |
| Safety (thermal stability) | High — more thermally stable | Lower — higher thermal runaway risk |
| Energy density | Lower (bigger pack for same kWh) | Higher (lighter, smaller) |
| Cost per kWh over lifetime | Often lower due to long life (LCOS advantage) | Higher LCOS if cycled daily |
| Typical use case | Stationary storage, long life | EVs and weight-sensitive applications |
Sources and industry overviews confirm LFP 3k–6k cycles and superior thermal stability for stationary use. Use the cycle-life and LCOS numbers when comparing warranty and cost-per-kWh over the expected lifetime.
3. AC-Coupled vs DC-Coupled — pick based on new vs retrofit and efficiency
Rules of thumb
- New solar + battery: Prefer DC-coupled (hybrid inverter) for higher efficiency and better clipping recovery.
- Existing solar (retrofit): Z izmeničnim tokom is usually easier — it works with many inverters (Enphase, SolarEdge) but has additional conversions.
Efficiency comparison (practical numbers): DC-coupled systems can often reach ~95–98% round-trip efficiency, while AC-coupled systems typically range ~90–95% depending on hardware and conversion steps. The 3–7% difference compounds over years and reduces usable kWh from the same stored energy.
Compatibility note: Confirm the battery BMS and inverter communicate (CAN/RS-485, Modbus, or vendor API), especially if mixing brands or using third-party energy management.
4. Safety standards — which certifications to require
Must-check certifications:
- UL 9540A (fire/testing methodology for energy storage — check unit-level/test reports and whether your manufacturer’s unit passed relevant levels). UL published updated guidance and test clarifications in 2024–2025; this affects indoor permitting.
- UL 9540 / NFPA 855 — system & installation codes for ESS.
- IEC 62619 — cell/pack safety tests (international).
- UN38.3 — transportation safety for lithium cells.
Practical: ask suppliers for the UL-9540A test report or a statement of compliance and whether the product is permitted for indoor installations in your jurisdiction. Some AHJs (Authorities Having Jurisdiction) require UL 9540/9540A evidence before permitting indoor installs.
5. Lifespan, warranty and the fine print
What to demand in a warranty
- Years + capacity retention metric: e.g., 10 years and ≥70% SOH is a common premium benchmark.
- Cycle guarantee: explicit cycles at specified DoD (e.g., 6,000 cycles at 80% DoD).
- Warranty exclusions: temperature extremes, improper installation, unapproved charging profiles, water intrusion, or unauthorized repairs.
Watch for these traps
- Warranties voided by installation environment (e.g., “garage install above 100°F not allowed”).
- Coverage limited to the original owner (transfers may be restricted).
- Performance measured as “available energy” rather than cell capacity — read the actual metric used.
Ask supplier: “Show me your cumulative throughput and SOH guarantee, and the warranty language on temperature and installation conditions.”
6. Cost breakdown & ROI — include the tax credit reality
Federal credit (USA): Spletna stran Residential Clean Energy Credit (the Residential version of ITC) provides 30% for qualified residential clean energy property placed in service during the covered period — this includes standalone battery storage that meets the rules; verify current program dates and product ID requirements with the IRS. The credit’s rules and expiration window have been actively discussed; act with accurate timing.
How to evaluate ROI
- Uporabite levelized cost of storage (LCOS): total installed cost / total expected lifetime kWh delivered (account for cycle life and round-trip efficiency). LFP’s longer cycle life typically lowers LCOS vs cheaper chemistries.
- Model TOU savings, backup value (unquantified but real), and possible VPP payments or utility incentives.
7. Reliability: cells (Grade A) and BMS design matter
Ask for:
- Cell source and grade (Tier-1 suppliers vs generic). Grade-A automotive-class cells mean tighter specs, better matching, and longer life.
- Active vs passive balancing: active balancing + temperature management extends pack life.
- BMS features: cell-level monitoring, thermal management, overcurrent/short protection, communication logs, and firmware update policy.
Red flags: Home Battery Manufacturers that refuse to disclose cell model / manufacturer or cannot provide basic cell test data.
8. Installation & maintenance — save labor and reduce risk
Practical choices that save money and headaches
- Plug-and-play / pre-wired terminals reduce electrician hours.
- Floor-standing modular units often install faster than heavy wall mounts (less structural reinforcement).
- Verify electrician & installer credentials; improper installation can void safety certifications and warranties.
Checklist for installers: site temps, ventilation, clearance, seismic mounting (if required), conduit runs, inverter compatibility tests, BMS-inverter comms test, and firmware updates.
How to read a specification sheet
- Zmogljivost: 13.5 kWh (usable) → how long = capacity / average load.
- Continuous power: 5 kW → can run multiple loads concurrently up to 5 kW.
- Peak power: 7.5 kW (10 sec) → handles motor starts and compressors.
- Round-trip efficiency: 90–97% → higher is better (DC coupling often higher).
Compact LFP vs NMC comparison
- Cycle life (typical): LFP: ~3,000–6,000+ cycles; NMC: ~800–1,500 (varies by formulation and depth of discharge).
- Round-trip efficiency: both chemistries are similar when paired with similar inverters — system architecture (AC/DC coupling) dominates.
- Primer uporabe: LFP → stationary home/long daily cycling; NMC → weight-sensitive applications (EVs).
Buyer Quick Checklist
- kWh capacity chosen in . continuous & peak kW confirmed.
- Kemija: LFP recommended for stationary; supplier cell source verified.
- UL 9540A / UL 9540 / NFPA 855 evidence on file.
- Warranty: years + SOH % (+ exclusions) documented.
- Inverter/BMS communication protocol confirmed (CAN / RS-485 / Modbus).
- Installer credentials, permitting process, and local AHJ requirements checked.
- Confirm eligibility for Residential Clean Energy Credit (30%) and documentation to claim.
Zaključek
Selecting the right home battery isn’t just about capacity—it’s about LFP safety, precise kWh/kW matching, and verified certifications. For distributors and brands looking for custom home energy storage solutions, stopite v stik z nami, our Kamada power battery factory team provides engineering support to verify system design and ensure reliable performance before production.