Quick Panel Count Calculator
Enter your average monthly TNB electricity bill to get an instant recommendation.
3 Ways to Calculate Your System Size
Use whichever method you have data for. All three should give you a similar answer — if they don't, the roof-based method caps your maximum.
Method 1: Bill-Based (Quickest)
Divide your average monthly TNB bill by RM50 to get your approximate system size. Example: RM300 bill ÷ 50 = 6kWp system = 12 panels.
The 120 Factor: Why We Use It
Malaysia receives 4.0–5.4 peak sun hours per day depending on location (Klang Valley: 4.5-4.8, Penang: 4.2-4.6, Johor: 4.6-5.0, Sabah/Sarawak: 4.8-5.4). A 1kWp system generating 4.5 kWh/day yields roughly 135 kWh/month. We use 120 as a conservative estimate to account for panel soiling, inverter losses, temperature derating, and cloudy-day reductions — typical for Malaysian conditions.
Panel Count by TNB Bill Size
Find your typical monthly bill in the table below. All savings calculated using TNB tariff 2026 and Tier 1 panel pricing (JA Solar, Jinko, LONGi at 580W).
| Monthly Bill | System Size | Panels | Monthly Savings |
|---|---|---|---|
| RM 100 | 2 kWp | 4 | RM 80-100 |
| RM 200 | 4 kWp | 7 | RM 160-180 |
| RM 300 | 5-6 kWp | 10 | RM 230-270 |
| RM 400 | 8 kWp | 14 | RM 330-370 |
| RM 500+ | 10 kWp | 18 | RM 400-460 |
Panel Count by House Type
Malaysian house types have different typical electricity consumption, roof areas, and constraints. Find your home type below.
Apartment / Condo
RM 100-200/mo
Most condos prohibit roof panels. Check management rules. Some allow balcony-mounted panels (1-2kWp).
Single-Storey Terrace
RM 150-300/mo
Single phase (4.5kWp max). Roof often has water tank and vent obstructions. Usually enough for a meaningful system.
Double-Storey Terrace
RM 200-400/mo
Single phase limits to 4.5kWp (9 panels). Many owners upgrade to three-phase to unlock 6-8kWp potential. Larger south-facing slope available.
Semi-Detached House
RM 300-600/mo
Usually three-phase already. Ample roof for 8kWp. Check for shared wall setback requirements with adjoining unit.
Bungalow
RM 500-1,200/mo
Three-phase essential for systems above 4.5kWp. Bungalows can fully offset their bills. Consider battery storage to capture overnight self-consumption.
Inverter selection matters too. For houses with complex multi-slope roofs (L-shaped, U-shaped), consider micro inverters or power optimizers. Each panel operates independently, maximising yield even when different slopes face different directions. Read our inverter comparison guide for details.
Don't Oversize Under Solar ATAP
This is the most common and costly mistake Malaysian solar buyers make.
The Solar ATAP Sweet Spot
Roof Area Requirements in Detail
The 10m² per kWp rule is a starting point. Here is how to calculate your real usable roof space.
Common Roof Obstructions in Malaysia
- 1Water tanks (1.5–3m² each, plus 1m clearance all around)
- 2Roof vents / ventilators (0.3–0.5m² each, 1m clearance)
- 3Solar water heaters (2–4m²)
- 4Satellite dishes (0.5m² + shadow zone)
- 5Ridge vents (full ridge length × 0.5m)
- 6Air conditioning condenser units (1–2m²)
- 7Chimney stacks (1m clearance all sides)
Pro Tip: When You Can't Fit Enough Panels
If your roof area is limited, switching from 400W panels to 580W+ Tier 1 panels (JA Solar JAM72D40, Jinko Tiger Neo) gives you 40–45% more power per panel. A 5-panel roof that would have been 2kWp at 400W can now be 2.9kWp at 580W — without installing any extra panels.
Quick Roof Area Reference
Single Phase vs Three Phase: System Size Limits
Your home's electrical connection type determines the maximum system size you can install under Solar ATAP.
Max 4.5 kWp → 9 panels (500W) or 8 panels (580W)
Most terrace houses, apartments, and smaller landed properties. Your meter box will have a single-phase MCB.
Max 12.5 kWp → 25 panels (500W) or 22 panels (580W)
Semi-detached houses, bungalows, and most commercial premises. Your meter box has three-phase MCBs.
Can I Upgrade to Three Phase?
Yes, but it involves a TNB application and an additional cost of RM3,000–6,000 for the upgrade (wiring, new meter, new MCB). For a bungalow with a RM500+ bill wanting a 10kWp system, this upgrade cost is easily justified by the extra generation capacity.