1. Battery Type: Lithium vs Lead-Acid

The first decision is choosing between lithium-ion and lead-acid batteries.

Battery Type	Cycle Life	Depth of Discharge (DoD)	Maintenance	Cost
Lithium-ion (LiFePO₄)	6,000–10,000 cycles	80–100%	Low	Higher upfront, lower lifetime cost
Lead-acid (AGM/GEL)	500–1,500 cycles	50–70%	High	Lower upfront, higher lifetime cost

Recommendation: For home users seeking long-term performance and minimal upkeep, lithium batteries are generally the better option.

2. Storage Capacity (kWh)

Battery capacity determines how much energy can be stored and used during periods with no sunlight. To estimate your needs:

Daily load (kWh) × Days of autonomy = Total battery capacity needed

For example, if your home consumes 10 kWh per day and you want 2 days of backup:

10 kWh × 2 days = 20 kWh of usable battery capacity

Don't forget to consider the battery's DoD. If the battery supports 90% DoD:

20 kWh ÷ 90% = ~22.2 kWh total rated capacity needed

3. Power Output (kW)

Storage isn't everything—power output matters too. It determines how much energy can be discharged at once. A higher power rating ensures the battery can handle high-demand appliances (like air conditioners or water pumps).

• Continuous Output: The maximum sustained power the battery can deliver.
• Peak Output: Short bursts for starting motors or appliances.

Tip: Match the inverter's capacity to the battery's output capabilities.

4. Battery Lifespan & Warranty

Lifespan is typically measured in:

• Cycle life (number of full charge/discharge cycles)
• Calendar life (years before performance declines)

Look for batteries offering:

✅ 6,000+ cycles
✅ 10+ year warranties
✅ Reliable manufacturers with proven track records

Lithium batteries often provide >10 years of service, making them ideal for long-term residential systems.

5. Safety & Certification

Safety should never be compromised. Key certifications to look for:

• UN38.3 / IEC 62619 – Safety and transport of lithium batteries
• UL1973 / UL9540 – U.S. standards for stationary batteries
• CE / RoHS – European compliance

Avoid untested, uncertified batteries that may risk fire or system damage.

6. Compatibility with Solar System

Ensure the battery integrates with your inverter, charge controller, and monitoring systems.

• Communication protocols: MODBUS, CAN, or RS485 for real-time control
• Hybrid inverter compatibility: Most lithium BESS pair best with hybrid or off-grid inverters.

Ask your installer or supplier to confirm full compatibility before purchase.

7. Installation Environment

Different batteries perform better in different environments:

Environment	Best Battery Type	Considerations
Indoor garage	Lithium-ion	Stable temp, low maintenance
Outdoor enclosure	Sealed AGM / Outdoor-rated Lithium	Waterproofing, ventilation
Hot/cold climates	LiFePO₄ with BMS	Temperature-tolerant, BMS must include thermal protections