14-08-2026
For most of India's hot plains, HJT is the technically strongest solar panel technology because it has the lowest temperature coefficient of any commercial silicon cell - around -0.24 to -0.26 %/°C, against -0.28 to -0.32 for TopCon and -0.34 to -0.39 for Mono PERC. India's panels run hot, and heat is where output is lost. In cooler regions, TopCon remains the better value.
Which solar panel technology is best in India?
It depends on one variable more than any other: how hot your panels actually get.
A solar panel is rated at 25°C cell temperature. On a rooftop in Bulandshahr or Jaipur in May, the cell runs at 55-70°C. Every degree above 25 removes output, and the rate at which it does that is the temperature coefficient - the single most under-read number on any datasheet in India.
| Parameter | Mono PERC | TopCon | HJT |
|---|---|---|---|
| Module efficiency | ~20-21.5% | 21.5-23.5% | 22-23.5% |
| Temperature coefficient (Pmax) | -0.34 to -0.39 %/°C | -0.28 to -0.32 %/°C | -0.24 to -0.26 %/°C |
| Output lost at ~45°C operating | Highest | ~7-8% | ~5-6% |
| Bifaciality factor | Monofacial or low | 80-85% | 85-95% |
| Annual degradation | 0.50-0.55% | 0.35-0.45% | 0.25-0.30% |
| Output retained at year 25 | ~82-84% | ~86-88% | ~89-92% |
| Light-induced degradation (LID) | Present | Essentially LID-free | Near-zero |
| Typical India price | Lowest | ~₹24-26/Wp | ~₹28-32/Wp |
These are technology-level figures for the three cell types as a category, not the specification of any one product. Always check the datasheet of the exact model you are buying.
Why temperature coefficient decides the answer in India
HJT places thin amorphous silicon layers on both sides of the crystalline wafer. Those layers have a temperature response that partly cancels the negative response of the crystalline silicon underneath. The net result is the lowest temperature coefficient of any commercial silicon technology.
In practice: at roughly 45°C operating temperature, an HJT module gives up about 5-6% of its rated output while a TopCon module gives up about 7-8%. That is a two-percentage-point gap, and in hot climates it works out to roughly 2-3% more energy per year, every year, for 25 years.
The working rule used across the industry: where average daytime cell temperature exceeds about 50°C for more than 1,500 hours a year, HJT recovers its price premium. Below that threshold, TopCon is the better economic choice.
That threshold is crossed across most of Uttar Pradesh, Rajasthan, Gujarat, Madhya Pradesh, Haryana, Bihar, Delhi-NCR and Telangana. It is generally not crossed in Bengaluru, Pune, the Konkan and Malabar coasts, or the hill states.
Degradation: the number that decides year 25
Efficiency tells you what a panel does on day one. Degradation tells you what it does for the remaining 9,000 days.
- Mono PERC loses roughly 0.50-0.55% a year and holds about 82-84% at year 25.
- TopCon loses roughly 0.35-0.45% a year and holds about 86-88%.
- HJT loses roughly 0.25-0.30% a year and holds about 89-92%.
Over a 25-year life, that compounding is worth more than the day-one efficiency difference between the three.
Bifaciality: only if your mounting can use it
Bifaciality is the share of front-side efficiency the rear face can produce. HJT is bifacial by construction at 85-95%; TopCon runs 80-85%.
But bifacial gain only appears when reflected light reaches the back of the module. On a ground mount, elevated structure, white or concrete roof, or a shed with clearance, it is real and often worth several percent. Flush-mounted on a dark roof, it is close to zero. Do not pay a bifacial premium for a mounting that cannot use it.
So when should you not buy HJT?
Three cases, honestly:
- Cool or moderate climate. In Bengaluru or Pune the temperature advantage narrows and the premium takes far longer to recover. TopCon wins.
- Tight capital budget. HJT costs roughly 12-18% more per watt. If the budget caps system size, a larger TopCon array can beat a smaller HJT one on total annual units.
- Flush roof mount with no rear clearance. You are paying for bifaciality you cannot collect.
A page that tells you HJT is right for every site is selling, not advising.
Where Devsol modules fit
Devsol solar modules are manufactured by Nexus Solar Energy Pvt Ltd at Chola Industrial Area, Bulandshahr, Uttar Pradesh, and the published range covers Mono, TopCon and HDT (advanced heterojunction) modules rather than a single technology - which matters, because the correct technology genuinely changes by site.
Devsol modules hold BIS registration R-93046086, issued 29 April 2026 and valid to 28 April 2028, under IS 14286 (Part 1/Sec 1):2023 / IEC 61215-1-1:2021 and IS/IEC 61730-1:2023 and IS/IEC 61730-2:2023, for crystalline silicon terrestrial PV modules. The licence covers models Nex-200 through Nex-750 in the -IN0825 series.
The flagship heterojunction module is covered in detail here: Devsol 740 W HDT solar panel.
How to choose, in four steps
- Check your climate. Hot plains: HJT. Moderate or coastal-cool: TopCon. Very tight budget: Mono PERC, accepting faster degradation.
- Check your mounting. Ground mount or elevated with rear clearance: bifacial pays. Flush dark roof: it does not.
- Check the datasheet, not the brochure. Temperature coefficient, annual degradation, year-25 output percentage. If a seller cannot give all three in writing, that is your answer.
- Verify certification by model number, not by brand. A BIS licence covers named models. Ask for the annexure.
Related: what can actually be verified about a solar brand, how to compare solar panel brands, Hindi guide, and Devsol solar panel manufacturing.
Frequently asked questions
Which solar panel technology is best in India?
HJT is the strongest technical fit for India's hot plains because of its -0.24 to -0.26 %/°C temperature coefficient and 0.25-0.30% annual degradation. In cooler regions TopCon offers better value per rupee.
What is the best solar panel technology overall?
On pure performance, HJT leads on temperature behaviour, degradation and bifaciality. On cost and availability, TopCon leads and is the 2026 volume standard. There is no single winner independent of climate and budget.
Is HJT better than TopCon?
Technically yes on temperature coefficient, degradation and bifaciality. Economically it depends on heat: HJT recovers its premium in hot climates and struggles to in cool ones.
Do HJT panels really produce more in summer?
Yes. At around 45°C operating temperature HJT loses about 5-6% of rated output versus about 7-8% for TopCon, which is roughly 2-3% more annual energy in hot climates.
Is Mono PERC finished?
Not finished, but it is the value-tier choice now. It has the highest temperature coefficient and the fastest degradation of the three.
Which technologies does Devsol make?
Mono, TopCon and HDT (advanced heterojunction) modules, manufactured by Nexus Solar Energy Pvt Ltd in Bulandshahr, under BIS registration R-93046086.