Commercial Solar Malaysia: Rooftop Solar for Offices, Hotels, Retail and Warehouses

Who commercial solar is for

This page is written for the person who signs off on a TNB bill for a business property — a facility manager, finance director or owner of an office, hotel, retail unit, shop-lot or warehouse. If your building runs on a domestic tariff, the residential process applies instead; if it runs on an industrial tariff (manufacturing, a plant with shift patterns, or a maximum-demand charge that dominates the bill), the industrial and factory pages below are the better starting point.

The common thread across office, hotel, retail and warehouse buildings is that the electricity bill is driven almost entirely by the energy charge — how many kWh you consume — rather than by a maximum-demand charge. That's what makes the sizing and savings method on this page different from the industrial pages, and it's covered in the next two sections.

How TNB charges a commercial account

Low-voltage commercial accounts on Tariff B pay a combined marginal rate of RM0.5068/kWh, made up of energy, capacity and network charges, plus a RM20 monthly retail charge and a 1.6% KWTBB renewable-energy fund levy on the bill. That schedule is stamped 2025-01-01 — see TNB Commercial & Industrial Pricing & Tariffs for the current published rates, and note that the ICPT surcharge component resets roughly every six months regardless of the base schedule.

Larger buildings on medium-voltage tariffs — Tariff C1 (general) or Tariff C2 (time-of-use) — carry an additional maximum-demand (MD) charge, billed per kW against the single highest half-hourly demand recorded in the billing month, on top of the energy and network components. Tariff C2 also splits the energy rate into a peak period (08:00–22:00, Monday to Friday) and a cheaper off-peak rate for all other hours. We don't publish medium-voltage RM/kW figures on this page, because that schedule resets on its own cycle — read the exact rate off the "Maximum Demand" line of your own TNB bill, or bring the bill to your first assessment and we'll read it with you.

How much can rooftop solar save an office, hotel, retail or warehouse business?

The honest answer is a formula, not a fixed percentage: monthly saving equals the kilowatt-hours your solar system generates and you consume on site, multiplied by your marginal Tariff B (or C1/C2 energy) rate. There is no single number that applies to every building, because the variable that actually moves the outcome is how much of your daytime load overlaps with the solar generation curve — not the size of the system alone.

An office that empties out by 6pm and sits idle on weekends will self-consume a smaller share of a large system than a warehouse running pick-and-pack shifts five or six days a week. The load-pattern section below sets out typical self-consumption ranges by building type, and the worked example directly below shows the full calculation for one case, step by step, so you can see exactly where the number comes from.

Sizing a commercial system: method and worked example

Sizing starts from whichever constraint binds first: your maximum demand, or your available roof and car-park area. Under Solar ATAP (GP/ST/No. 60/2025 §8.3), a non-domestic system is capped at 100% of your maximum demand in kWac, with a hard ceiling of 1,000 kWac per installation (§8.5) — DC-oversized, battery-buffered designs are permitted provided the inverter's AC output still fits inside that cap. In practice, most office, hotel and retail buildings are area-constrained long before they reach the MD cap.

The generation estimate itself uses Trexon's standard proposal-engine assumption: 94.6 kWh of monthly generation per installed kWp (30 days × 3.8 peak-sun-hours × an 83% performance ratio, which accounts for heat, soiling and cabling losses on a typical Malaysian rooftop). The worked example below applies that assumption to a single illustrative case.

Why your load pattern decides self-consumption — and what happens to weekend surplus

Self-consumption is not a fixed property of solar — it's a property of when your building uses electricity. Trexon's modelling assumes an office self-consumes about 95% of a correctly-sized system's output (weekday, daytime-heavy load), a warehouse about 92%, a shopping or retail premises about 80%, and a 24/7 hotel — where a large share of demand shifts to evenings and early mornings — about 75%, all at roughly 30% solar penetration with no battery. These are model assumptions for sizing, not a promise for any specific building.

The uncovered share of generation — a closed office on a Sunday, for instance — doesn't simply vanish. Under Solar ATAP, surplus is exported to the grid and credited at a System Marginal Price (SMP)-based rate under a 10-year contract, with no rollover of unused credit into future months. We don't quote the SMP rate itself here because it moves with the wholesale market; what matters at the sizing stage is that a building with a large weekend or evening gap between load and generation should be sized to its weekday self-consumption, not to its roof area alone — oversizing past that point buys export credit, not full-value savings.

Own, borrow, instalment or PPA: how to structure the purchase

There are four common ways a Malaysian business funds a commercial solar project, and the choice affects who owns the asset, who can claim the tax incentives in the tax incentives section, and how the cash flow lands against your existing bill.

Tax incentives for commercial solar

Solar PV installed for your own consumption can qualify for a Green Investment Tax Allowance (GITA) Asset claim at Tier 2, subject to MGTC approval — an allowance equal to 60% of qualifying capital expenditure, which can be offset against up to 70% of your company's statutory income in a given year of assessment, under a window that currently runs to 31 December 2026. See the GITA tax incentive guide for the full claim process.

Where GITA isn't claimed or doesn't fully apply, solar equipment can also qualify as plant and machinery under standard capital allowance rules — a 20% initial allowance in the first year of assessment plus a 14% annual allowance, both of which reduce the income on which corporate tax (24% for non-SME companies) is charged. See capital allowance for solar panels in Malaysia for the mechanics and worked figures.

Indicative only. Subject to MGTC/MIDA approval, applicable tax law and confirmation by the customer’s licensed tax adviser. Official GITA Asset window ends 31 December 2026.

From project brief to commissioning: what happens after you apply

The process runs in a fixed sequence, without a promised turnaround time — every step depends on your documentation, site access and, for larger systems, TNB's own processing.

• You send the project brief below with your bill, tariff category and operating pattern.
• Trexon's commercial team reviews the bill and load information remotely and comes back with a scoped proposal.
• You can book a RM100 priority site visit, fully credited when you proceed, so an engineer verifies the roof, switchboard and access constraints on site.
• The system is engineered to your confirmed load and roof survey, and the Solar ATAP application is filed with SEDA on your behalf.
• Equipment is procured and the system is installed to the agreed scope.
• TNB commissions and tests the interconnection before the export credit arrangement goes live.
• You receive the full project handover pack — as-built drawings, warranties and commissioning documentation.