Quick answer
Lithium gives four to five times the cycle life of lead-acid, about ninety percent usable depth of discharge against roughly fifty percent, and needs no maintenance. That combination means the cost per usable cycle is dramatically lower despite the higher purchase price — a lead-acid bank sized to deliver the same usable energy has to be roughly twice the nominal capacity, and it will need replacing several times over.
What you can do now
- 1Compare on usable kWh and cycle life, not on nominal capacity or sticker price
- 2Check the warranty terms — cycles, years, and the end-of-life capacity guaranteed
- 3Confirm the battery is LiFePO4 rather than another lithium chemistry, for safety and cycle life
- 4Check the BMS communicates with your specific inverter model
- 5Plan a ventilated, secure installation position out of direct heat
When to call a professional
Default to LiFePO4 lithium for any new installation. If you are being quoted lead-acid, ask for the cost-per-usable-cycle comparison over ten years and the replacement schedule in writing. Make sure the installer confirms BMS compatibility with your inverter — mismatched communication is a common and frustrating fault that only shows up after commissioning.
Typical cost in Johannesburg
5kWh lithium R45,000–R55,000
Indicative ranges only. We provide written, itemised quotes before any work.
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