Electricity bills can feel like a maze of numbers and acronyms. In this step‑by‑step guide we’ll decode Tenaga Nasional Berhad (TNB) bills line‑by‑line and show you how to use that data to calculate the potential savings from a residential rooftop‑solar system under NEM 3.0.
1 Where to Find the Key Numbers on Your Bill
| Bill Section | What It Means | Why It Matters for Solar |
|---|---|---|
| Tariff Code (e.g. T‑NB Domestic*) | The pricing category (D, E, etc.) & any ICPT surcharge | Determines baseline RM / kWh rate |
| Billing Period | Usually 28‑31 days | Use this to normalise monthly kWh |
| kWh Used | Total energy consumed for the period | Directly drives potential PV offset |
| Maximum Demand (if 3‑phase) | Highest 30‑minute load | Peak shaving via solar + battery |
| ICPT (Imbalance Cost Pass‑Through) | Fuel‑price adjustment | Solar reduces exposure to future ICPT hikes |
| Renewable Energy Fund (RE) | 1 % levy for all users | Still payable but tiny; ignore in ROI |
Pro‑tip: Take a clear photo of two recent bills—you’ll need them for NEM 3.0 application later.
2 Calculate Your Average Daily Consumption
- Retrieve last 3 months of kWh (find under “Current Reading – Previous Reading”).
- Add them up and divide by the total days.
Average Daily kWh=Σ (monthly kWh)÷Σ (days)Average Daily kWh = Σ (monthly kWh) ÷ Σ (days) Average Daily kWh=Σ (monthly kWh)÷Σ (days)
Example:
Month 1: 450 kWh, Month 2: 480 kWh, Month 3: 465 kWh (90 days total)
Average = (450 + 480 + 465) ÷ 90 ≈ 11 kWh/day
3 Size a Residential Solar System
| Rule of Thumb | Explanation |
|---|---|
| System kWp ≈ (Average Daily kWh) ÷ 4 | West‑coast Malaysia ≈ 4 peak‑sun‑hours/day |
| 5 kWac cap (single‑phase) | ST regulator limit for NEM 3.0 |
| 12.5 kWac cap (three‑phase) | For larger landed homes |
Using the 11 kWh/day example: PV Size≈11÷4≈2.75 kWp→roundupto3 kWpPV Size ≈ 11 ÷ 4 ≈ 2.75 kWp → round up to 3 kWp PV Size≈11÷4≈2.75 kWp→roundupto3 kWp
4 Estimate Monthly Solar Generation
1 kWp in Klang Valley produces ≈ 115 kWh/month.
So a 3 kWp system ≈ 345 kWh/month (allow 10 % losses → ~310 kWh).
5 Match Solar Output to Your Bill
- Bill shows average 330 kWh/month usage.
- Solar covers ~94 % of that load.
- Under NEM 3.0, excess exports credit 1‑to‑1 (within the same month) via NOVA mechanism.
6 Compute Financial Savings
| Item | Formula | Value |
|---|---|---|
| Energy Offset | Min[ Solar kWh, Load kWh ] | 310 kWh |
| Bill Rate | Tariff D base (July 2025) ≈ RM 0.39/kWh | — |
| Gross Savings | 310 × 0.39 | RM 121 / month |
| ICPT Hedged | Assume 4 sen surcharge → 310 × 0.04 | RM 12 |
| Total Monthly Benefit | 121 + 12 | ≈ RM 133 |
7 Quick Payback Snapshot
| Financing Option | Up‑front Cost | Payback / NPV |
|---|---|---|
| Buy & Own 3 kWp (RM 20 k) | RM 20 000 | ~12 years, IRR ≈ 7 % |
| Zero‑Upfront PPA | RM 0 | Immediate RM 40‑60 bill reduction, 20‑year term |
| Green Home Loan | ~3.5 % p.a. | Cash‑flow positive from year 1 |
(Figures assume 2 % annual tariff inflation and 80 % self‑consumption.)
8 Next Steps: From Bill to Rooftop
- Collect 3 recent TNB bills (PDF or photo).
- WhatsApp them to HOMI’s solar team (+60 17‑449 7599) or email support@homifytech.com.my.
- Receive a free NEM 3.0 eligibility check + personalised ROI report in 48 hours.
Still unsure? Schedule a 15‑minute virtual walkthrough—we’ll share screen, dissect your bill live, and answer financing questions.
