Comparison of 48V Solar PCU with Lithium battery 51.2V
The difference between Tubular lead Acid battery and lithium-ion battery is already explained in this blog https://suvastika.com/difference-between-tubular-and-lithium-battery/
In this blog we will discuss about the use of tubular lead Acid battery and lithium-ion battery for the inverter/UPS application and solar PCU application and we will try to cover the comparison of 4 tubular batteries of 200 Ah and Lithium LifePo4 battery of 51.2Volts having 100 Ah capacity.

MPPT Solar PCU 5.5KVA
BIS certified : Su-vastika 5.5kVA Hybrid Solar PCU is certified by the Bureau of Indian Standards which gives assurance to the user for the safety standards being followed by the Su-vastika.
Here’s a detailed comparison of Tubular lead-acid batteries (C20) and lithium-ion batteries (C1) for inverter/UPS backup systems, focusing on critical factors like backup time, cycle life, maintenance, size, cost, and reliability:
1. Backup Time
Factor | Tubular Lead-Acid (C20 or C10) | Lithium-lifePo4 (C1) |
---|---|---|
Nominal Capacity | Example: 200Ah @ C20 or C10 (48V system) | Example: 100Ah @ C1 (51.2V system) |
Total Energy | 200Ah × 48V = 9,600Wh | 100Ah × 51.2V = 5,120Wh |
Usable Energy (DoD) | 50% DoD → 4,800Wh | 95% DoD → 4,864Wh |
Real-World Performance | Capacity drops under high load (C1 vs C20). | Maintains full capacity even at high discharge. |
Backup Time @ 1kW Load | ~4.8 hours | ~4.9 hours |
Key Insight:
- Both provide similar usable energy, but lithium performs better under high loads due to stable C1 capacity. Lead-acid’s capacity reduces if discharged rapidly (e.g., during high-power appliance usage).
2. Cycle Life
Factor | Lead-Acid | Lithium-Ion (LiFePO4) |
---|---|---|
Cycle Life | 1,200–1,500 cycles at 50% DoD | 3,000–5,000 cycles at 90% DoD |
Calendar Life | 2-4 years | 5–7+ years |
Degradation | Faster degradation with deeper discharges. | Minimal degradation even at high DoD. |
Key Insight:
- Lithium lasts 2–3x longer in cycles and doubles the calendar life, making it ideal for daily cycling (e.g., frequent power cuts).
3. Maintenance
Factor | Lead-Acid | Lithium-Ion |
---|---|---|
Requirements | Regular watering, terminal cleaning, ventilation. | Maintenance-free. No fluids or gases. |
Sensitivity | Risk of sulfation if left discharged. | Built-in BMS prevents overcharge/discharge. |
Key Insight:
- Lithium is maintenance-free, while lead-acid requires periodic upkeep and monitoring.
4. Size & Weight
Factor | Lead-Acid | Lithium-Ion |
---|---|---|
Weight | ~70–75 kg per 200Ah unit (bulky). so total weight will be around 300Kg with mounting Iron stand it will be 350 Kgs | ~50–60 kg per 100Ah unit (compact). |
Space | Requires large installation space. | 30–40% smaller footprint. |
Key Insight:
- Lithium is 5x lighter and space-efficient, ideal for tight spaces or rooftop installations.
5. Cost
Factor | Lead-Acid | Lithium-Ion |
---|---|---|
Upfront Cost | Lower initial cost (e.g., ₹30k–₹40k for 200Ah) | Higher initial cost (e.g., ₹80k–₹1L for 100Ah) |
Lifetime Cost | Higher due to replacements and maintenance. | Lower due to longevity and efficiency. |
Key Insight:
- Lithium’s long-term ROI is better despite higher upfront costs.
6. Reliability
Factor | Lead-Acid | Lithium-Ion |
---|---|---|
Efficiency | 70–85% (energy loss during charging). | 95–98% (minimal losses). |
Voltage Stability | Voltage sags under load. | Stable voltage even at high discharge. |
Temperature | Performance drops in cold. | Wider operating range (-20°C to 60°C). |
Key Insight:
- Lithium offers superior reliability in diverse conditions and faster recharge times.
7. Environmental Impact
Factor | Lead-Acid | Lithium-Ion |
---|---|---|
Recyclability | Recyclable but contains toxic lead. | Recyclable with lower toxicity (LiFePO4). |
Safety | Risk of acid leaks and gas emissions. | Safer (no leaks/emissions; BMS protection). |
Summary: Which to Choose?
- Choose Lithium-Ion (LiFePO4) If:
- You prioritize long lifespan, low maintenance, compact size, and high reliability.
- You experience frequent/long power cuts and need daily cycling.
- Choose Tubular Lead-Acid If:
- Budget is tight, and usage is occasional (e.g., backup for infrequent outages).
- You can manage maintenance and have ample installation space.
-
Solar Hybrid PCU MPPT With LifePo4 Lithium Battery (51.2V).
- For solar applications, lithium-ion batteries (LiFePO4) and tubular lead-acid batteries have distinct advantages and limitations. Here’s a breakdown of extra benefits lithium offers over lead-acid in solar setups, along with niche advantages of lead-acid:
1. Depth of Discharge (DoD) & Usable Energy
- Lithium (LiFePO4):
- 90–100% DoD: Fully utilize stored solar energy daily without degrading the battery.
- Example: A 10kWh lithium battery provides ~9–10kWh usable energy.
- No “partial cycling” penalty: Frequent partial discharges don’t harm lithium.
- Lead-Acid (Tubular):
- Limited to 50% DoD for longevity.
- Example: A 10kWh lead-acid system delivers only ~5kWh usable energy.
- Must avoid deep discharges: Repeated deep cycling drastically shortens lifespan.
Solar Benefit: Lithium maximizes solar energy utilization, especially critical for off-grid systems or cloudy days.
2. Cycle Life & Longevity
- Lithium:
- 3,000–6,000 cycles at 80–90% DoD (8–15 years of daily use).
- Minimal capacity degradation over time (retains ~80% capacity after 3,000 cycles).
- Lead-Acid:
- 1,200–1,500 cycles at 50% DoD (3–5 years with daily cycling).
- Degrades faster if discharged beyond 50% or left undercharged.
Solar Benefit: Lithium’s longevity aligns better with Solar’s 25+-year panels, reducing replacement costs.
3. Charging Efficiency
- Lithium:
- 95–98% efficiency: Almost all solar energy is stored and used.
- Charges faster (1–2 hours at high C-rates), ideal for limited sunlight hours.
- Lead-Acid:
- 60-70% efficiency: Significant energy loss during charging.
- Slow charging (10-14 hours) due to lower charge acceptance.
Solar Benefit: Lithium captures more solar energy daily and recharges quickly during short sunny periods.
4. Temperature Resilience
- Lithium:
- Operates efficiently in -20°C to 60°C (with BMS protection).
- Minimal performance drop in cold weather (unlike lead-acid).
- Lead-Acid:
- Performance plummets below 0°C: Capacity drops by 30–50% in cold.
- Overheats above 40°C, accelerating degradation.
Solar Benefit: Lithium suits extreme climates (e.g., mountain cabins, deserts) where lead-acid struggles.
5. Maintenance & Monitoring
- Lithium:
- Zero maintenance: No watering, terminal cleaning, or equalization.
- Built-in BMS prevents overcharge, over-discharge, and thermal issues.
- Lead-Acid:
- Requires monthly maintenance (water topping, terminal checks).
- Sensitive to improper charging (sulfation risk if undercharged).
Solar Benefit: Lithium is ideal for remote solar installations where maintenance is impractical.
6. Weight & Space
- Lithium:
- 50–60% lighter (e.g., 100Ah lithium = ~15 kg vs. 100Ah lead-acid = ~30 kg).
- Compact design allows vertical stacking or wall mounting.
- Lead-Acid:
- Heavy and bulky (requires sturdy racks and ventilation space).
Solar Benefit: Lithium saves space and simplifies rooftop or small-room installations.
7. Scalability
- Lithium:
- Modular design: Easily expand capacity by adding batteries in parallel.
- No “charge balancing” issues between old and new units.
- Lead-Acid:
- Mixing old and new batteries causes imbalance and reduces efficiency.
Solar Benefit: Lithium allows gradual system expansion as energy needs grow.
8. Self-Discharge Rate
- Lithium:
- 1–3% monthly self-discharge: Holds charge longer during low-sun periods.
- Lead-Acid:
- 5–15% monthly self-discharge: Requires frequent solar top-ups.
Solar Benefit: Lithium is better for seasonal or backup-only solar systems.
9. Environmental Impact
- Lithium:
- Recyclable (95% materials recoverable).
- No toxic fumes or acid leaks.
- Lead-Acid:
- Recyclable but involves hazardous lead/acid handling.
- Risk of soil/water contamination if improperly disposed.
Solar Benefit: Lithium aligns better with eco-conscious solar users.
10. Voltage Stability
- Lithium:
- Flat discharge curve: Maintains stable voltage (e.g., 51.2V ±2V) until ~90% DoD.
- Ensures consistent inverter performance.
- Lead-Acid:
- Voltage drops steadily during discharge (e.g., 48V → 42V at 50% DoD).
- Inverters may shut off prematurely due to low voltage.
Solar Benefit: Lithium avoids unexpected power cuts during critical loads.
When Lead-Acid Might Still Work
- Budget constraints: Lower upfront cost for small, infrequently used systems.
- Low cycling needs: Backup for occasional grid outages (not daily solar cycling).
- Non-critical applications: Sheds, workshops, or seasonal setups.
Final Recommendation for Solar
Choose Lithium (LiFePO4) if:
- You prioritize long-term ROI, daily cycling, or off-grid reliability.
- Space, weight, or maintenance are concerns.
Choose Lead-Acid if:
- Initial cost is critical, and usage is infrequent (e.g., backup-only systems).
Lithium’s efficiency, longevity, and maintenance-free operation make it the superior choice for most solar applications, especially paired with long-lasting solar panels.
- Lithium (LiFePO4):
Final Verdict
While lead-acid batteries have a lower upfront cost, lithium-ion (LiFePO4) is the future-proof choice for inverter/UPS systems due to its longevity, efficiency, and hassle-free operation. Over 5–10 years, lithium’s total cost of ownership often becomes cheaper than lead-acid. https://lithiuminverter.in/inverter/advantages-and-disadvantages-li-battery-vs-tubular-battery-using-a-48v-solar-power-conditioning-unit-pcu-with-a-lithium-battery-compared-to-a-tubular-battery/
Here’s a detailed comparison of four 200Ah tubular lead-acid batteries (48V system) and a 51.2V 100Ah lithium (LiFePO4) battery, focusing on backup time, life, maintenance, size, and reliability:
1. Backup Time
- Lead-Acid (48V 200Ah, C20, 50% DOD):
Total energy = 48V × 200Ah = 9,600Wh
Usable energy = 9,600Wh × 50% = 4,800Wh
Backup time at 1kW load = ~4.8 hours.
Note: Capacity drops significantly under high discharge rates (C1 vs. C20 rating). - Lithium (51.2V 100Ah, C1, 90% DOD):
Total energy = 51.2V × 100Ah = 5,120Wh
Usable energy = 5,120Wh × 95% = 4,808Wh
Backup time at 1kW load = ~4.9 hours.
Note: Maintains rated capacity even at high discharge rates (C1).
Verdict: Similar usable energy, but lithium performs better under high loads due to stable C1 capacity. Lead-acid may underperform in real-world high-discharge scenarios.
2. Life (Cycle and Calendar)
- Lead-Acid:
- ~1,200–1,500 cycles at 50% DOD.
- Calendar life: 3–5 years (even with light use).
- Degrades faster with deeper discharges.
- Lithium (LiFePO4):
- ~3,000–5,000 cycles at 90% DOD.
- Calendar life: 8–10+ years.
Verdict: Lithium lasts 3–4x longer in cycles and doubles calendar life.
3. Maintenance
- Lead-Acid:
Requires regular electrolyte checks, water topping, terminal cleaning, and ventilation.
Sensitive to under/overcharging. - Lithium:
Maintenance-free. No fluid checks, gas emissions, or corrosion risks.
Built-in Battery Management System (BMS) protects against overcharge/over-discharge.
Verdict: Lithium wins hands-down for ease of use.
4. Size and Weight
- Lead-Acid (4x 200Ah units):
- Weight: ~280–300 kg (total).
- Volume: Large footprint (e.g., 4x bulky batteries).
- Lithium (1x 100Ah unit):
- Weight: ~50–60 kg.
- Volume: ~30–40% of lead-acid’s space.
Verdict: Lithium is 5x lighter and far more compact, saving space and installation effort.
5. Reliability
- Lead-Acid:
- Prone to sulfation if left discharged.
- Lower efficiency (70–85%), slower recharge, and voltage sag under load.
- Temperature-sensitive (performance drops in cold).
- Lithium:
- Stable chemistry with 95–98% efficiency.
- Faster recharge, minimal voltage drops, and no memory effect.
- Wider temperature tolerance (with BMS protection).
Verdict: Lithium is more reliable for deep cycling, efficiency, and environmental adaptability.
Summary
Factor | Lead-Acid (48V 200Ah) | Lithium (51.2V 100Ah) |
---|---|---|
Backup Time | ~4.8h (50% DOD) | ~4.6h (90% DOD) |
Cycle Life | 1,200–1,500 cycles | 3,000–5,000 cycles |
Maintenance | High | None |
Size/Weight | Bulky (240+ kg) | Compact (40–60 kg) |
Reliability | Moderate | High |
Final Recommendation
Choose lithium for:
- Longer lifespan, minimal maintenance, compact size, and reliable performance.
- Comparable usable energy despite lower nominal capacity.
Choose lead-acid only if:
- Initial cost is a critical constraint, and maintenance/space are not issues.
Lithium’s superior lifecycle, efficiency, and maintenance-free operation make it the better long-term investment.
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