Rooftop solar on a commercial building is a roof project, an electrical project and a utility application at the same time. Here is how the three fit together in the Klang Valley — and what your tender has to itemise before you can compare two bids.
Commercial figures are deliberately absent from this page: a business system is priced after a roof survey, a load study and a grid check. The only RM figures below are the home range published in our home solar cost guide, quoted to show the contrast. Ask for a survey on WhatsApp.
Three projects run at once and any one of them can sink the other two.
It is a roof project: several hundred to several thousand square metres of existing roof has to carry new load, keep water out around every new fixing, and stay accessible for maintenance afterwards. It is an electrical project: an installation of a size that has to be designed, protected, earthed and connected properly, by people the law recognises. And it is a utility project: an application, an approval and a meter change that happen on somebody else’s timetable, not yours.
The commercial logic is different from a home too. A factory or an office consumes most of its electricity in daylight hours, which is exactly when a roof array generates — so the business case usually rests on self-consumption, offsetting units you would otherwise buy, rather than on exporting. That is why the first thing a serious installer asks for is not your roof plan but twelve months of bills and, ideally, your interval consumption data.
Business owners often arrive having read a residential guide — ours included — and the numbers do not transfer. Here is where the two jobs actually part company:
| Home rooftop system | Commercial rooftop system | |
|---|---|---|
| Typical published cost | Our home solar guide publishes RM14,000 – RM55,000 installed for a 3–13 kWp domestic system | Not published — quoted after a roof survey, a load study and a grid check. Anyone quoting a commercial roof sight-unseen is guessing |
| Sizing driver | Household annual consumption | The daytime load profile of the operation, shift pattern included |
| Roof | Tiles, small metal roof or a flat slab; structure rarely the binding constraint | Large metal deck or concrete; structural capacity, sheet condition and remaining roof life are all binding constraints |
| Electrical installation | Connects at the consumer unit | Connects into a switchboard, often three-phase, with protection, isolation and labelling to match the rest of the installation |
| Who signs it off | A registered wireman | Larger and higher-capacity installations fall under the supervision of a registered chargeman |
| Procurement | Two or three quotes, one decision-maker | A tender, a scope document, a board or committee, and a landlord or management body who may also have to agree |
| What kills the project | Shading and an oversized system | A roof that needed replacing first, or a lease with too few years left to reach payback |
Send us a photo of the job on WhatsApp — we reply with an instant quote.
💬 Get Your Instant QuoteThe last row is the one we see most. Solar has a working life measured in decades; a tenancy or a tired metal roof may not. Sort out which of the three is shortest before you tender.
The panels are the cheap part of the risk. The expensive part is what happens to a large roof once you have fixed thousands of components to it and made it difficult to reach:
The mounting method follows the roof, and each type brings its own thing to check before design starts:
| Roof type | Usual mounting approach | Check first |
|---|---|---|
| Metal longspan / standing seam | Clamped to the seam or fixed to the rib with sealed fasteners | Sheet gauge and condition, purlin spacing, coating age, existing leak history |
| IBR / corrugated metal sheet | Clamp-on or through-fixed rail system with sealing washers | Sheet condition — older IBR may need replacing before anything is fixed to it |
| Flat concrete roof / deck | Ballasted or bolted tilt frames | Existing waterproofing membrane, drainage falls, and whether ballast load is acceptable |
| Concrete or clay tile (shoplot, office block) | Roof hooks under the tiles onto the battens or rafters | Tile brittleness, timber condition, and access for the installers |
| Car park / covered yard structure | Purpose-built canopy structure rather than an existing roof | This is a new build, with its own structural design and approvals — price it as one |
Whatever the roof, insist the mounting system, the fixing detail and the sealing method appear in the quotation by name and manufacturer. “Standard mounting” is not a specification.
How your system talks to the grid is a scheme question, and the schemes change. Here is what we can state, and where you must go for the current position:
Where the building is not yours, or the roof is common property, the application is not the only permission you need — see commercial property tenancy → for the landlord side and JMB responsibilities & duties → where a management body controls the roof.
This is the part of a commercial solar project where cutting corners is both illegal and expensive, so we will state only what is settled and already on our electrical pages.
In Malaysia, wiring and electrical installation work must be carried out by a wireman registered with Suruhanjaya Tenaga (the Energy Commission) under the Electricity Supply Act 1990, and larger or higher-capacity installations fall under the supervision of a registered chargeman. A commercial rooftop array is not a plug-in appliance; it is an installation that connects into your switchboard and must be designed, protected and certified accordingly. Only a registered contractor can issue the electrical certification the utility needs.
Unregistered electrical work is illegal, will not pass the utility, and can void your insurance if a fault causes a fire. Ask your solar bidder, in writing, who holds the registration for the electrical scope — the solar company itself, or a subcontractor — and get the name. A competent-person load assessment is also how the connection point and protection are properly sized; our three-phase power upgrade guide → explains what that assessment involves, and electrician services → covers the wider electrical picture.
Alongside the electrical registration, ask for the contractor’s current CIDB registration and grade, and check where the works sit in your building’s wider approval picture — our commercial renovation permit guide → sets out the council, Bomba, DOSH and DOE sequence for commercial premises.
No number, but no mystery either. These are the items that make one quotation differ from another:
Two quotations that differ by a wide margin usually differ because one of them has priced the roof remedial work and the other has assumed you will do it.
| Line item | What the quotation must state | Why it matters |
|---|---|---|
| Yield basis | The assumptions behind the generation estimate and the consumption data it was modelled against | A yield figure with no stated basis cannot be compared or held to |
| Structural assessment | Who performs it, what they sign, and whether it is in the price | Decides whether the roof can take the array at all |
| Roof remedial works | Included, excluded, or provisional — stated explicitly | The commonest cause of a large variation later |
| Mounting system | Manufacturer, model, fixing detail and sealing method | This is what keeps water out for twenty years |
| Panels and inverters | Make, model, quantity, and the exact warranty terms for each | Substitution after award is a real risk without this |
| Electrical scope | Who holds the registration, the connection point, protection, earthing, and who does any switchboard work | The most commonly disowned scope on site |
| Utility application | Which scheme, who submits, what happens if approval or quota does not come | Your programme depends on somebody else’s timetable |
| Access provisions | Walkways, anchor points, safe routes to inverters | Determines whether the system can actually be maintained |
| Commissioning & handover pack | Test results, as-built drawings, O&M manual, monitoring credentials | Without it you cannot prove the system ever performed |
| O&M offer | Scope, frequency and term, priced separately from the install | Lets you compare bids on capital cost and running cost independently |
Three separate warranties matter and they are usually confused with each other:
Then insist on monitoring you can actually see. A commercial array that silently loses a string can run for months at a fraction of its yield, and nobody notices because the bill is still lower than it used to be. Agree who watches the monitoring, how often, and what they do when output falls — that is a maintenance arrangement, not a hope, and it belongs in a planned preventive maintenance schedule → alongside the rest of your building services.
Tell us what you need — we reply within the hour.