🌟 TAWANAI ENERGY
🌟 Empowering Pakistan with Smart Solar Storage Solutions
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📞 +92 343 270 2932
🔋 THE ULTIMATE GUIDE TO LITHIUM BATTERY STORAGE:
Understanding Depth of Discharge (DoD) & The True Cost Per Cycle
When selling Dyness Lithium Batteries, customers often only look at the Upfront Price and Total Capacity. But the true measure of a battery’s value is its Cost per kWh per Cycle (Levelized Cost of Storage).
This brochure breaks down exactly how Depth of Discharge (DoD) impacts battery life, and proves mathematically why larger batteries are the smartest long-term investment for Pakistani homes.
📉 PART 1: What is Depth of Discharge (DoD)?
Depth of Discharge (DoD) refers to the percentage of the battery’s total capacity that you actually use before recharging it.
Think of a lithium battery like a fuel tank:
- 100% DoD: You drain the battery to absolute zero. (Highly stressful, damages the battery’s chemical health over time).
- 80% DoD: You use 80% of the battery and leave a 20% “buffer” at the bottom. (The industry standard for daily solar use).
- 50% DoD: You only use half the battery before recharging. (Very gentle, drastically extends the battery’s lifespan).
⚖️ The Golden Rule of Lithium Batteries (The Trade-Off)
There is a direct tug-of-war between Daily Usable Backup and Total Lifespan (Cycles):
- Shallower Discharge (e.g., 50% DoD): The battery experiences less stress, so it will last for more cycles (more years). However, you get less usable backup power per day.
- Deeper Discharge (e.g., 80% DoD): You get maximum daily backup during loadshedding, but the battery experiences more stress, resulting in fewer total cycles over its lifetime.
🧮 PART 2: Calculating the “Cost Per kWh Per Cycle”
To find out how much it actually costs to store and use one unit (kWh) of solar energy, we use this formula:
Total Selling Price ÷ (Capacity × DoD × Expected Karachi Cycles) = Cost per Unit/Cycle
Note: The “Expected Karachi Cycles” below are heat-adjusted. Lab tests assume a perfect 25°C. In Pakistan’s ~35°C+ indoor environments, cycle life is realistically adjusted to 4,000 cycles (for 6k-rated models) and 5,500 cycles (for 8k-rated models) at 80% DoD.
📊 Step 1: Expected Lifespan (Cycles) by DoD
Because shallower discharges reduce stress, the battery survives more cycles.
|
Battery Model Type |
50% DoD (Gentle) |
60% DoD |
70% DoD |
80% DoD (Standard) |
|---|---|---|---|---|
| 1.2 / 5 / 10 kWh (6k-Rated) |
~7,600 Cycles |
~6,000 Cycles |
~4,800 Cycles |
~4,000 Cycles |
| 14.3 / 16 kWh (8k-Rated) |
~10,450 Cycles |
~8,250 Cycles |
~6,600 Cycles |
~5,500 Cycles |
💰 Step 2: Dyness Selling Prices & Cost Per Cycle Matrix
|
Battery Model |
Tawanai Selling Price |
Cost @ 50% DoD |
Cost @ 60% DoD |
Cost @ 70% DoD |
Cost @ 80% DoD |
|---|---|---|---|---|---|
| 1.2kWh IP65 | Rs 59,850 |
Rs 13.13 |
Rs 13.85 |
Rs 14.84 |
Rs 15.59 |
| 5kWh IP66 | Rs 278,250 |
Rs 14.64 |
Rs 15.46 |
Rs 16.56 |
Rs 17.39 |
| 10kWh IP66 | Rs 535,500 |
Rs 14.09 |
Rs 14.88 |
Rs 15.94 |
Rs 16.73 |
| 14.3kWh IP21 | Rs 609,000 |
Rs 8.15 |
Rs 8.60 |
Rs 9.22 |
Rs 9.68 |
| 16kWh IP21 | Rs 645,750 | Rs 7.72 | Rs 8.15 | Rs 8.74 | Rs 9.17 |
💡 PART 3: How to Read This Data (The Sales Pitch)
1. The “Karachi Sweet Spot” is 60% to 80% DoD
While 50% DoD offers the cheapest per-cycle cost, it requires the customer to buy double the battery capacity just to get the same daily backup. If you can get along with 50% DOD and do not need long duration storage or have a generator backup in case you really need long duration power then this is better for battery life and reducing costs of electricity via storage.
60% to 80% DoD is the perfect balance for many Pakistani homes. It provides enough backup to survive 4-6 hours of loadshedding while keeping the battery healthy for 10+ years. This is provided that the storage size is based on 4 to 5 hours of usage capacity.
If you run air conditioners on the inverter, and do not want to be bothered to worry about depth of discharge, then set the DOD to 50% and use an auto start generator beyond that.
2. The Ultimate Upsell: Bigger Battery = Cheaper Electricity!
Look closely at the 80% DoD column.
- A customer using the 5kWh battery is paying Rs 17.39 in battery wear-and-tear for every 1 unit (kWh) of solar power they store and use.
- A customer using the 16kWh battery is paying only Rs 9.17 for that exact same 1 unit of power.
The larger battery is almost HALF the price to operate per cycle! Because the 16kWh uses larger, higher-capacity cells (like 280Ah/314Ah) and undergoes less relative stress per cycle, its lifetime energy throughput is massively superior.
3. The Utility Comparison (The Closer)
With K-Electric and WAPDA grid rates frequently crossing Rs 40 to Rs 60+ per kWh (including taxes, peak-hour rates, and fuel adjustments), storing solar power in a Dyness battery is a massive money-maker.
- WAPDA Cost: Rs 45.00 / unit
- Dyness 16kWh Storage Cost: Rs 9.17 / unit
- Customer Savings: Rs 35.83 per unit, every single day, for the next decade.
TAWANAI ENERGY Explanation for customers
Many people just look at the upfront price of a 5kWh vs a 16kWh battery and think the smaller one is cheaper. But let’s look at the math for Karachi.
If you buy the 5kWh battery, every time you store and use 1 unit of solar energy during loadshedding, it costs you about Rs 17.39 in battery degradation. But if you step up to the 16kWh PowerBrick, that same 1 unit of energy only costs you Rs 9.17. You are literally buying electricity at half the wear-and-tear cost! Plus, the utility is charging you Rs 45+ per unit. By installing the larger Dyness bank with Tawanai Energy, you aren’t just buying a battery; you are locking in a Rs 9 per unit electricity rate for the next 10 to 15 years.
You can also set the small battery to 50% DOD and get the cost per cycle down to about PKR 13.
TAWANAI ENERGY
Your Trusted Partner in Solar Innovation
🌐 remote-support.space/wordpress/tawanai-energy-main-page/
📞 +92 343 270 2932
Disclaimer: Cycle life estimates are based on LiFePO4 degradation curves adjusted for South Asian ambient indoor temperatures (~35°C).
Actual results may vary based on installation environment, inverter settings, and maintenance.
