Battery Guide – LiFePO₄ vs AGM Solar Batteries | The Sun Pays
🔋 Battery Guide for Solar Systems: Why Lithium is the New Standard
Choosing the right battery for your solar system is critical. While lead-acid batteries (AGM/Gel) were common in the past, LiFePO₄ lithium batteries have become the preferred choice in modern solar installations — especially for off-grid and hybrid systems.
⚡ Lithium (LiFePO₄) Batteries – The Modern Standard
- ✅ Longer lifespan – 10+ years or 3000–6000 cycles (80% DoD)
- ✅ Higher usable capacity – up to 100% DoD on quality models
- ✅ Lighter and more compact – high energy density
- ✅ Low maintenance – built-in Battery Management System (BMS)
- ✅ Safer chemistry – LiFePO₄ is one of the safest lithium types
- 💰 Higher upfront cost — but lower long-term cost per cycle
Important Tip: Always choose a lithium battery with a built-in BMS to prevent overcharging, deep discharge, or overheating.
🔋 What About Lead-Acid (AGM/Gel) Batteries?
AGM and Gel batteries are older technologies that:
- 👎 Last only 2–4 years (fewer than 1000 cycles)
- 👎 Must not be discharged below 50% of their capacity
- 👎 Are heavy and bulky
- 👎 Require external battery balancers (not plug-and-play)
These may be suitable for very small, low-budget systems — but offer poor performance over time.
⚙️ How to Calculate the Energy Storage You Need
Energy (Wh) = Voltage (V) × Capacity (Ah)
Example:
A 48V, 100Ah lithium battery stores:
48V × 100Ah = 4800Wh or 4.8 kWh
With 80% usable capacity: 4.8 kWh × 0.8 = 3.84 kWh usable
⏳ How Long Will a Battery Last on Load?
Example: 1x 48V 100Ah LiFePO₄ battery @ 80% DoD
(Includes inverter losses and Peukert effect)
Load on Inverter | Runtime Estimate |
---|---|
2500W | ~1 hour |
1270W | ~2 hours |
630W | ~4 hours |
410W | ~6 hours |
230W | ~10 hours |
150W | ~14 hours |
130W | ~16 hours |
90W | ~20 hours |
Add batteries in parallel to increase runtime.
🧠 Why We Recommend Lithium for Most Systems
- 🔋 More usable power per Rand spent over time
- 🔄 Faster charging and more charge/discharge cycles
- 🧠 Built-in smart protection (BMS)
- 🏡 Safer for indoor or outdoor installation
- 📉 Lead-acid is being phased out in most quality solar systems
🔌 Smart Inverter Settings for Lithium Batteries
Many modern off-grid or hybrid inverters allow you to:
- ⚙️ Limit charge and discharge rates to protect batteries
- 🔋 Set battery protection thresholds (for longevity)
- 🔁 Automatically switch to the grid or generator if needed
We also offer inverters that operate without batteries for solar-only or grid-tied applications.
✅ Need Help Choosing the Right Battery?
Our team will help you select the correct size, voltage, and configuration for your solar system — with safe, affordable, and long-lasting lithium solutions.
👉 Contact us at sales@thesunpays.co.za or browse our lithium batteries here.