Battery types explained
The two battery types and two wiring methods — explained in plain terms so you can ask the right questions.
Battery specifications can feel overwhelming. This guide explains the distinctions that are worth understanding before you read a quote.
LFP vs NMC chemistry
Most home batteries use either lithium iron phosphate (LFP) or nickel manganese cobalt (NMC) chemistry. LFP batteries have a longer cycle life, tolerate being left fully charged, and are more stable. NMC batteries can achieve higher energy density (more kWh in a smaller box). For a home installation, LFP is generally the preferred choice — the longevity advantage outweighs the density benefit in a fixed installation.
AC coupling vs DC coupling
AC-coupled batteries connect to your home's AC circuit — they can be added to any solar system, new or existing. DC-coupled batteries connect directly to the solar panels and share the inverter, which is slightly more efficient but requires compatible equipment. If you are adding storage to an existing system, AC coupling is simpler. If you are buying a new system and want storage from the start, DC coupling is worth discussing.
Usable capacity vs total capacity
Manufacturers sometimes quote total capacity; what matters is usable capacity — how much you can actually charge and discharge without damaging the battery. This is typically 80–90% of total capacity for LFP and slightly less for NMC. Always check which figure an installer is quoting.
Cycle life and warranty
A cycle is one full charge and discharge. A battery rated for 6,000 cycles at one cycle per day would last around 16 years. Most manufacturers guarantee a minimum retained capacity (often 70% or 80%) after a set number of cycles or years. Read the warranty carefully — it sets the floor for long-term performance.
Key takeaways
- LFP chemistry is generally better suited to home installations than NMC — longer life, more stable.
- AC-coupled batteries can be added to any existing system; DC-coupled batteries are slightly more efficient for new installations.
- Always ask for usable capacity, not total capacity.
- Check the warranty for guaranteed retained capacity over time — this is the real performance guarantee.
This guide is for general information only. It is not a substitute for a survey of your home or professional advice. Solar Help Centre does not install solar equipment or produce the final design for your home.
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