Understanding Batteries
Battery Basics for Solar
Understand battery types, sizing, and what to expect for backup power in the Philippines.
8 min read
Simple and practical
Beginner level
No solar background needed
PH context
Made for local homes
What you will understand
Visual Learning Map
Lesson Guide
Why Add Batteries?
In the Philippines, batteries provide:
- Brownout backup during power outages
- Nighttime power from stored solar
- Peace of mind during typhoon season
Battery Types
Lithium (LiFePO4) — Recommended
- 3,000–6,000 cycles
- 80–90% usable capacity (DoD)
- Lighter, longer lifespan
- Higher upfront cost
Lead-Acid (AGM/Gel)
- 500–1,500 cycles
- 50% recommended DoD
- Cheaper upfront
- Shorter lifespan, heavier
Key Terms
- kWh: Total energy storage (like a fuel tank size)
- Ah (Amp-hours): Another capacity measure
- DoD (Depth of Discharge): How much you can safely use
- Cycles: How many charge/discharge lifetimes
PH Example
For 4 hours backup on 500W critical load: 500W × 4h = 2,000 Wh = 2 kWh usable With 80% DoD: need 2.5 kWh battery minimum
Frequently Asked Questions
Lithium or lead-acid?
Lithium (LiFePO4) for most PH homes — better lifespan in heat, more usable capacity.
How many hours of backup?
Depends on battery kWh and load. A 5 kWh battery powers 500W for about 8 hours.
Do batteries need maintenance?
Lithium: minimal. Lead-acid: check water levels and terminals quarterly.
Can I use car batteries?
Not recommended. Car batteries aren't designed for deep cycling and will fail quickly.
How hot is too hot for batteries?
Keep batteries below 45°C. PH heat is a factor — ensure ventilation or indoor placement.
Common Mistakes to Avoid
Deep discharging lead-acid below 50%
Kills battery life fast. Use a BMS or inverter with low-voltage cutoff.
Mixing old and new batteries
Always replace battery banks as a matched set. Mixed ages cause imbalance.
Undersizing for aircon backup
Running aircon on battery requires large capacity (10+ kWh). Size realistically.