How can I use my TNB bill to decide if Solar ATAP is suitable?

Start by charting 6–12 months of kWh usage from your TNB bills, then estimate how much of that usage happens during the day versus at night. If you have moderate to high and relatively stable daytime consumption, Solar ATAP is more likely to be suitable, especially when system size is matched to your real load profile rather than your roof’s maximum capacity.

What is the risk of oversizing a Solar ATAP system?

Under Solar ATAP, exported energy for homes is credited only against the Energy Charge portion of the bill and any unused credits expire at the end of each billing cycle with no rollover. Oversizing can therefore lead to a significant portion of generation providing little or no financial benefit, particularly in months with lower usage or limited daytime consumption.

Why are self-consumption and daytime usage more important under Solar ATAP than under NEM 3.0?

Unlike NEM 3.0, which allowed export credits to roll over for up to 24 months, Solar ATAP resets credits monthly and restricts their use to energy charges. This makes real-time self-consumption and a strong daytime load critical for maximising savings, because excess exports beyond what can be used within the month may not reduce your bill further.

Solar Knowledge · Malaysia · 2026

Solar ATAP Malaysia Sizing Guide: 3 Simple Charts to Decide If Your TNB Bill and Usage Really Suit a Rooftop System

Updated February 22, 2026 · Homi Solar Malaysia

Solar ATAP Sizing Guide TNB Bill Analysis Avoid Oversizing

Solar ATAP Malaysia Sizing Guide: 3 Simple Charts to Decide If Your TNB Bill and Usage Really Suit a Rooftop System

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If you can understand three simple charts, you can already decide whether Solar ATAP suits your home—and how big your system should be.
Under Solar ATAP, **export credits only offset the Energy Charge and expire every billing cycle with no rollover**, which makes precise sizing and daytime usage far more important than under NEM 3.0. [web:33][web:44][web:57] Instead of just asking “How many kW can fit on my roof?”, the smarter question is “Does my TNB bill and day/night pattern support a system that will actually pay off?” [web:33][web:259]

This article introduces three charts that HOMI uses in our sizing reports. Once you understand them, you will know whether Solar ATAP is a good fit and which capacity range makes sense for you.

Chart 1: Your Last 6 Months of TNB Usage

The first chart is simply your **last 6 (or 12) months of kWh usage** from your TNB bills. [web:62][web:259]

How to build it yourself:

Take the kWh figure from each bill (usually labelled “kWj used”). [web:124]
Plot month vs kWh as a simple bar or line chart.

What HOMI looks for in Chart 1:

Is your usage stable (e.g. 500–600 kWh every month), or very seasonal (300 kWh some months, 900 kWh others)? [web:248]
Did CNY or recent heatwaves push usage much higher in certain months?
Are you often in the higher TNB blocks where each kWh is more expensive, so solar has more value? [web:259]

If your usage is very low (e.g. always below 300 kWh), Solar ATAP might still work—but the “sweet spot” system size will be small, and chasing a zero bill usually does not make sense. [web:124][web:259]

Chart 2: Daytime vs Night-Time Usage Split

Solar ATAP rewards **daytime self-consumption**, because that is when your PV is generating. Credits that rely on export are energy‑only and are lost if not used in the same month. [web:33][web:44][web:62]

How to approximate Chart 2 (without a smart meter):

List key daytime appliances: air‑cond, fans, WFH laptops, pool pump, etc.
Estimate how many hours they run between 9am–5pm and their kW rating.
Roughly calculate daytime kWh vs night‑time kWh.

Pattern	Example Profile	Solar ATAP Fit
Strong Daytime Usage	Retirees, WFH, young family at home, 1–2 AC rooms in afternoon.	Excellent: plenty of self‑consumption potential. [web:33][web:206]
Evening-Heavy Usage	Everyone out 9–6, most AC and cooking at night.	Needs careful sizing; oversizing will export too much at low value. [web:33][web:57]
Weekend Peaks	Big usage on weekends/holidays, moderate on weekdays.	Still workable; HOMI will size to your typical patterns, not just roof size. [web:33]

If your Chart 2 shows very small daytime usage and almost everything at night, Solar ATAP is a **maybe** rather than a clear yes—and the system should be smaller than what many “max roof” quotations suggest. [web:33][web:57]

Chart 3: Self-Consumption vs “Wasted” Export for Different kW Sizes

The third chart is the most important under Solar ATAP. It compares, for example, a 3 kW, 4 kW and 5 kW system and shows for each: “What percentage of generation is self‑used, how much offsets energy charges, and how much is potentially unused credit?” [web:33][web:62]

Conceptually, Chart 3 answers:

If I install 3 kW, maybe 80–90% of solar is self‑consumed; export is small. Efficient
If I install 5 kW, maybe only 50–60% is self‑consumed, and exports may saturate my Energy Charge each month. Risk of wasted credits

Because Solar ATAP credits reset monthly and cannot offset non‑energy components, pushing too high in kW can create a “waste tail” of generation that does not meaningfully reduce your TNB bill. [web:33][web:44][web:204]

How HOMI actually builds Chart 3 for you:

We use your TNB kWh history (Chart 1) and estimated day/night split (Chart 2). [web:206]
We apply Malaysian yield benchmarks (1 kWp ≈ 4–5 kWh/day) to simulate 2–3 system sizes. [web:206][web:230]
We overlay Solar ATAP rules: self‑consumption first, energy‑only credits, no rollover. [web:33][web:44][web:62]

Interactive: Quick Solar ATAP Feasibility Check

Solar ATAP Feasibility Snapshot (For Homeowners)

Use this to get a quick sense of whether Solar ATAP is likely a good fit—and a rough “just right” kW range.

Average Monthly TNB Usage (kWh):

Daytime Share of Usage (%):

Roof-Quota / Installer-Quoted Size (kWp):

This tool uses 4.5 kWh/day per kWp and simple thresholds. HOMI’s full report uses half‑hourly simulations where available and more conservative assumptions. [web:206][web:230][web:33]

Why “Just Right” Beats “Maxed Out” Under Solar ATAP

Under NEM 3.0, big systems could store value via long‑life credits; Solar ATAP removed that safety net. Credits offset energy charges only and are erased each month if unused. [web:33][web:44][web:57]

If Chart 3 shows that a 4 kW system already offsets most of your Energy Charge, jumping to 6 kW may not reduce your bill much further. [web:33]
Extra kW then mostly becomes “export noise” with weak financial value.

That is why HOMI’s advice to “comparison shoppers” is simple: if a quotation only talks about “maximum kW we can fit” but not about your Chart 1–3 story, you are not getting a serious Solar ATAP design.

How HOMI Turns Your TNB Bills into a Proper Sizing & Savings Report

When you send HOMI your TNB bills (PDF or clear photos), we generate a customised report built around these three charts.

Chart 1: 6–12 month kWh trend, with hot-season highlights.
Chart 2: Estimated day vs night usage, including weekend/holiday peaks. [web:206][web:248]
Chart 3: Self‑consumption vs export vs potential credit wastage for 2–3 system sizes (e.g. 3.5 kW, 4.5 kW, 5.5 kW). [web:33][web:62]

We then recommend a **capacity range**, not a single magic number, so you can decide based on budget and future plans (EV, more AC, parents moving in, etc.), without stepping into obvious oversizing risk.

Upload My TNB Bills for a HOMI Solar ATAP Sizing & Self-Consumption Report

FAQ: Charts, TNB Bills & Solar ATAP Feasibility

Do I really need 6–12 months of TNB bills to decide on Solar ATAP?

Three recent bills are enough for a rough estimate, but 6–12 months capture seasonal patterns and festive peaks like CNY. [web:206][web:248] Because Solar ATAP credits don’t roll over, understanding how your usage changes month by month is crucial for choosing the right system size. [web:33]

Why is the daytime vs night-time split so important under Solar ATAP?

Solar ATAP credits are energy‑only and reset every month, so systems deliver the best value when a large fraction of generation is used in real time during the day. [web:33][web:44][web:62] If most of your usage is at night, a smaller system may be more sensible than a “maxed out” design, because exported energy has limited value once the Energy Charge is fully offset.

Can I use TNB’s own solar estimator instead of a custom HOMI report?

TNB’s online solar tools are useful for high‑level estimates and show how bill savings relate to system size. [web:259] HOMI goes deeper for Solar ATAP specifically, modelling self‑consumption vs export and potential credit wastage using your detailed usage profile and updated ATAP guidelines. [web:33][web:62]

Want HOMI to review your TNB bill?

Send your usage pattern and HOMI can estimate whether Solar ATAP makes sense for your home or business.

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