Batteries are usually the most expensive part of a solar system and the component most likely to need replacement. Choosing the right chemistry matters.
Usable capacity
Lead-acid batteries (including tubular and AGM types) last longest when discharged only partially — often around 50%. Lithium iron phosphate (LiFePO4) batteries can routinely use 80–90% of their rated capacity.
In practice, a 10 kWh lithium bank can deliver substantially more usable energy than a 10 kWh lead-acid bank.
Cycle life
Cycle life — the number of charge and discharge cycles before capacity falls significantly — is typically several times higher for LiFePO4 than for lead-acid. In Nigeria, where batteries may cycle daily, this difference largely decides replacement intervals.
Maintenance and environment
Flooded lead-acid batteries need periodic water top-ups and ventilation. Lithium batteries are sealed and include a battery management system (BMS) that protects against over-charge, deep discharge and temperature extremes.
All batteries age faster in high temperatures. Install them in a shaded, ventilated location.
Cost
Lead-acid is cheaper to buy. Lithium usually costs less per kWh delivered over its life, because it provides more usable energy per cycle and more cycles in total.
Which to choose
- Lithium suits most new installations, daily cycling and anyone who values low maintenance.
- Lead-acid may suit very tight budgets, occasional backup use, or expanding an existing lead-acid bank of the same type.
Always confirm the inverter is compatible with the battery and can communicate with its BMS.