PERC, TOPCon or HJT: Which Cell Technology Suits Malaysian Heat?

Published by Quinn Lai | By InverPower Technical Team

Published 22 August 2026 · Last updated 22 August 2026

Module selection conversations tend to run on one number, the efficiency printed on the front of the datasheet. On a Malaysian roof that number is measured at a cell temperature nobody here ever sees. What the cell is made of decides how much of it survives the middle of the day.

The three architectures, briefly

PERC — passivated emitter and rear cell — added a rear passivation layer to the conventional p-type cell and dominated the market for a decade. It is mature, it is cheap per watt, and its efficiency ceiling is lower than what came after. It also carries the light-induced and light-and-elevated-temperature degradation behaviours that manufacturers have spent years mitigating.

TOPCon — tunnel oxide passivated contact — is an n-type design that adds a thin oxide layer and a doped polysilicon layer at the rear contact, cutting the recombination losses that limit PERC. It delivers higher efficiency, a better temperature coefficient, higher bifaciality and lower degradation, and it has become the default in most of the market rather than a premium option.

HJT — heterojunction — puts thin amorphous silicon layers either side of a crystalline n-type wafer. It has the highest efficiency of the three in production, the best temperature behaviour, very low degradation and strong bifacial gain, at a higher price and with a more demanding manufacturing process.

All three are crystalline silicon, and none of them is a different kind of solar. The differences are in how the cell's surfaces are passivated and how the contacts are made, which is to say in how much of the light-generated charge escapes as electricity rather than being lost inside the cell. That is why the comparison comes down to a handful of measurable numbers rather than to a claim about the technology.

The temperature coefficient decides it here

Every module datasheet is rated at a cell temperature of 25 °C. On a Malaysian rooftop, cells run far above that for most of the generating day — ambient plus the solar gain of a dark laminate in still air. Every degree above the rating costs output at the rate given by the module's temperature coefficient of power.

That is where the three technologies genuinely separate. PERC coefficients typically sit around a third of a percent lost per degree; TOPCon is meaningfully better; HJT is better again. Take the exact figures from the datasheets you are comparing rather than from a rule of thumb, then multiply the difference by the temperature rise your roof actually sees. Across a full year in this climate, a better coefficient can outweigh a difference in nameplate efficiency that looked decisive on paper.

Side by side

On a real project

For most Malaysian C&I rooftops the answer is TOPCon, and it is not a close call any more: it is available, the price gap against PERC has narrowed, and the temperature and degradation advantages are exactly the ones that matter in this climate. PERC remains defensible where budget dominates and the roof is large enough that a slightly lower efficiency costs nothing but area.

HJT earns its premium where area is constrained — a small roof that has to produce a fixed output — or where the ground conditions give a bifacial array real rear-side gain, or where the operating temperature is unusually high. Lead time is the practical constraint, so it belongs in a design conversation early rather than as a late substitution.

Whichever way it goes, compare like with like: efficiency at the same module size, temperature coefficient of power, the first-year and annual degradation figures in the warranty, the bifaciality factor if the array is bifacial, and the PID test result. Those five lines say more about twenty-five years of output than the technology's name does.

Watch the module dimensions while you do it. Manufacturers change wafer and module sizes between generations, and a comparison that holds efficiency constant but not area is comparing two different roofs. Rail spacing, clamp positions and the number of modules per row all follow from the physical size, so a late substitution can quietly change the mounting bill of materials.

Sourcing it

InverPower distributes Trinasolar modules in Malaysia and holds stock locally, with the datasheets and certification behind them. Send the roof area, the target output and the constraints you are working to, and we will tell you which technology fits, what is on the shelf and what the lead time looks like on the rest.

Frequently Asked Questions

Is HJT worth the premium for a Malaysian rooftop?

Where area is the binding constraint, or where the array is bifacial with genuinely reflective ground, it can be. On an unconstrained roof the same money usually buys more TOPCon capacity, which produces more energy overall. Lead time is the other consideration — HJT is less widely stocked here.

Which technology ages best in high heat?

The n-type designs. TOPCon and HJT both have lower degradation profiles than PERC and better temperature coefficients, and they are not subject to the same light-and-elevated-temperature degradation behaviour. The warranty's annual degradation figure is where a manufacturer commits to that in writing.

Does a higher efficiency module always produce more in Malaysia?

Not necessarily. Efficiency is rated at 25 °C cell temperature, which a Malaysian roof exceeds for most of the generating day. A module with slightly lower rated efficiency but a better temperature coefficient can produce more energy across a year on the same roof.

Is PERC obsolete?

No, but it is no longer the default. It remains a reasonable choice where cost per watt dominates and roof area is not limited. The gap that used to justify it has narrowed as TOPCon production scaled.

Sources

• IEC — IEC 61215 series, Terrestrial photovoltaic modules: design qualification and type approval, including performance at NMOT and temperature coefficients — https://webstore.iec.ch
• IEC — IEC 60904 series, Photovoltaic devices: measurement principles and reference conditions — https://webstore.iec.ch
• IEC — IEC TS 62804-1, Test methods for the detection of potential-induced degradation — https://webstore.iec.ch
• Trinasolar — module datasheets and technology documentation for current n-type and p-type ranges — https://www.trinasolar.com
• Department of Standards Malaysia — MS 1837:2018, Installation of grid-connected photovoltaic (PV) system — https://www.jsm.gov.my

Related InverPower posts:

• Why Do Solar Panels Lose Power in Malaysia's Heat?
• How Do You Size a Solar String for a Malaysian Rooftop?
• Where Do EPCCs Source Solar PV Components in Malaysia?