What 12.8kWh Usable Energy Actually Means
Real-world backup potential:
• 1.5 ton inverter AC → 6–7 hours
• Full house (fans, lights, fridge) → 10–14 hours
• Office or clinic → Extended operational continuity
This is not emergency lighting storage.
This is lifestyle continuity storage.
Net Billing Financial Reality (Lahore Case Model)
Let’s model conservatively.
Assumptions:
Retail Import Tariff: Rs 45 per kWh
Export Credit: Rs 10 per kWh
Daily Surplus Solar: 15 kWh
Daily Evening Load: 15 kWh
Scenario 1 — No Battery (Export Model)
Daytime:
15 kWh exported
Credit = 15 × 10 = Rs 150
Night:
15 kWh imported
Cost = 15 × 45 = Rs 675
Daily net gap = Rs 525
Annual leakage:
Rs 525 × 365 ≈ Rs 191,625
Under net metering, this leakage did not exist.
Under net billing, it is structural.
Scenario 2 — With SES 16.07kWh Battery
Daytime:
15 kWh stored
Night:
12.8–14 kWh supplied by battery
Grid import minimal.
Daily retail cost avoided:
~Rs 600–650
Annual savings:
Rs 220,000–240,000 (depending on load profile)
Payback Comparison Table
| Metric | Without Battery | With 16.07kWh Battery |
|---|---|---|
| Export dependency | High | Low |
| Retail import at night | High | Reduced |
| Daily arbitrage loss | ~Rs 525 | Near zero |
| Annual loss under net billing | ~Rs 190k | Avoided |
| Tariff escalation risk | High | Hedged |
| Transformer constraint exposure | Higher | Lower |
