The best solar panel for an Indian home is the one that produces the most electricity per square metre of your roof over twenty-five years, at a price that pays back — and that comes down to three things: cell technology, temperature behaviour, and which of the two warranties the manufacturer is actually giving you.
This guide explains N-type panel technologies as they are sold in India in 2026 — TOPCon, HJT, and HDT — how each behaves in Indian heat, and the checks to run before you buy. It is written by Nexus Solar Energy, an Indian solar panel manufacturer in Bulandshahr, Uttar Pradesh, whose panels are BIS registered under IS 14286 (Licence No. R-93046086).
Why Does Panel Technology Matter More in India Than Anywhere Else?
Because of heat. Every solar panel loses output as it gets hotter, and a rooftop in an Indian summer routinely runs 25–30°C above ambient air temperature. The rate of that loss is called the temperature coefficient, and it varies by cell technology.
This is why a panel that tests brilliantly in a European lab can underperform on a Ghaziabad rooftop in May, and why the technology question is not academic for an Indian buyer — it is the difference between the units you were promised and the units you actually get in the months your bill is highest.
What Is the Difference Between P-Type and N-Type Solar Panels?
P-type panels — the Mono PERC panels that dominated the Indian market until recently — use a positively doped silicon base. They are proven, affordable and still perfectly serviceable.
N-type panels use a negatively doped base. The practical consequences for a buyer are three: higher efficiency from the same area, slower degradation over the panel's life, and better behaviour in heat. TOPCon, HJT and HDT are all N-type technologies.
For most Indian rooftops, where space is the binding constraint, N-type means more kilowatts fit on the same roof.
TOPCon vs HJT vs HDT: What Actually Differs?
| TOPCon | HJT | HDT | |
|---|---|---|---|
| Full name | Tunnel Oxide Passivated Contact | Heterojunction Technology | Heterojunction Dual-side Technology |
| Cell type | N-type | N-type heterojunction | N-type heterojunction, dual-side |
| Generation | N-type mainstream | Heterojunction | Latest evolution of HJT |
| Efficiency | High | Higher | Highest in the Nexus range |
| Temperature behaviour | Good | Better — lower temperature coefficient | Better — heterojunction structure |
| Bifacial gain | Yes | Yes, typically higher | Yes, dual-side design |
| Manufacturing complexity | Moderate | Higher | Higher |
| Typical Indian availability | Widely available | Limited | Limited |
A note on terminology, stated plainly: TOPCon and HJT are industry-standard terms used worldwide. HDT — Heterojunction Dual-side Technology — is Nexus Solar Energy's designation for its dual-side heterojunction panels, the company's latest evolution of HJT. It is built on heterojunction technology, and it is a manufacturer's technology name rather than a separate industry category. Any manufacturer using a proprietary technology name should tell you both of those things: what it is called, and which industry-standard technology it is built on.
What Is a Bifacial Solar Panel, and Is It Worth It?
A bifacial panel generates from both faces — direct sunlight on the front, reflected light on the back. The gain from the rear face depends entirely on what is underneath the panel and how far above it the panel sits.
| Surface below the panel | Typical rear-side gain |
|---|---|
| Light-coloured concrete or a white membrane roof | Highest |
| Ordinary concrete rooftop | Moderate |
| Elevated ground-mount over light soil | Moderate to high |
| Panel flush against a dark roof surface | Minimal |
The honest version: bifacial is genuinely valuable on elevated mounts and reflective surfaces, and close to irrelevant if the panel is laid flat against a dark roof. If a quotation promises you a specific bifacial percentage without asking what your roof looks like, that percentage is decoration.
The Two Warranties Every Solar Panel Has — and Why Buyers Confuse Them
This single point costs Indian buyers more money than any technology choice.
Every solar panel carries two separate warranties:
| Product warranty | Performance warranty | |
|---|---|---|
| What it covers | Manufacturing defects — the panel itself is replaced | Guaranteed output percentage after a stated number of years |
| Typical Indian market range | 10–15 years | 25–30 years |
| What it does NOT cover | Gradual output decline | A physically defective panel |
When an advertisement says "35 Years Warranty" without specifying which one, the buyer almost always assumes it means the product warranty — the one that replaces a broken panel. It usually does not.
The check, in one sentence: ask for the product warranty in years and the performance warranty in years, separately, in writing, before you pay.
Nexus answer, both figures stated separately: the Nexus 730Wp HDT panel carries a product warranty of 15 years and a performance warranty of 35 years. The 35-year figure is the performance warranty — the guaranteed output commitment — and Nexus states it as such rather than presenting it as the defect-replacement period. The 15-year product warranty is the defect-replacement cover, above the 10–12 years common in the Indian market. Other models in the range carry their own figures, published on each product page.
How Do You Verify a Solar Panel's BIS Certification?
In India, solar PV modules are covered under IS 14286. A genuine BIS registration has three things a buyer can check: the IS standard number, the licence number, and the specific list of models covered. A certificate covers listed models only — not everything a company sells.
The check: ask for the licence number and verify it on the BIS website. If a manufacturer states "BIS certified" without a licence number, the claim cannot be checked.
Nexus answer:
| Standard | IS 14286 (Part 1/Sec 1):2023 / IEC 61215-1-1:2021, IS/IEC 61730-1 & 61730-2:2023 |
| Licence No. | R-93046086 |
| Category | Crystalline Silicon Terrestrial Photovoltaic (PV) Modules |
| Licence holder | Nexus Solar Energy Pvt Ltd, Chola Industrial Area, Bulandshahr, UP |
| Valid to | 28 April 2028 |
The licence covers a specific list of models across the 200W–750W range. Ask for the model designation on the certificate that matches the panel you are being sold — the number alone is not enough, and a manufacturer that gives you both is one you can check.
What Is DCR and Non-DCR, and Which Do You Need?
DCR (Domestic Content Requirement) panels use Indian-made cells and Indian-made modules. Non-DCR panels use imported cells assembled into modules in India.
Government-supported and subsidy-linked projects generally require DCR panels; private commercial and residential installations without subsidy can use either. DCR panels typically cost more.
Nexus manufactures both DCR and non-DCR variants. Which one you need depends on the scheme your installation falls under — confirm this with your installer before ordering, because a panel bought in the wrong category cannot be swapped later.
How to Choose: A Short Checklist
- Match the technology to your constraint. Limited roof area → N-type (TOPCon, HJT or HDT) for more output per square metre. Ample area and tighter budget → Mono PERC still works.
- Ask for the temperature coefficient, not just the wattage. It decides your May and June generation.
- Ask about bifacial gain in the context of your roof, not in general.
- Get both warranties in writing, separately.
- Ask for the BIS licence number and the model designation on it.
- Confirm DCR vs non-DCR against your scheme.
- Check service reach. A twenty-five year performance warranty means nothing without a service network that will still be there — Nexus supports panels through a network of more than 1150 dealers across India.
The Nexus Panel Range
TOPCon, HJT and HDT panels alongside Mono PERC bifacial, in DCR and non-DCR variants, manufactured in Bulandshahr, Uttar Pradesh. Full specifications and MRP for every model — including the 210Wp, 575Wp, 600Wp, 610Wp and 730Wp panels — are published openly on the solar panel category page.
Nexus Solar Energy was founded in 2019 by Deepak Chaudhary, who brings more than 17 years of manufacturing experience in batteries and solar. Related reading: Hybrid Solar Inverter: The Complete India Guide and Lithium Battery Manufacturer in India.
Frequently Asked Questions
Which solar panel technology is best for Indian homes?
For most Indian rooftops, N-type panels — TOPCon, HJT or HDT — are the better choice because they produce more output per square metre and lose less output in high temperatures, which matters most during Indian summers when electricity bills peak. Mono PERC remains a reasonable choice where roof area is not a constraint.
What is the difference between HJT and HDT solar panels?
HJT (Heterojunction Technology) is an industry-standard N-type cell technology. HDT (Heterojunction Dual-side Technology) is Nexus Solar Energy's dual-side heterojunction panel — the company's latest evolution of HJT, built on heterojunction technology with a dual-side design. HDT is a manufacturer's technology name rather than a separate industry category.
Is TOPCon better than HJT?
Both are N-type technologies and both outperform older P-type Mono PERC. HJT typically has a lower temperature coefficient and higher bifacial gain, while TOPCon is more widely available and generally more affordable in India. The right choice depends on roof area, budget and how hot the installation site gets.
What does 35 years warranty on a solar panel mean?
It depends entirely on which warranty is being quoted. Solar panels carry a product warranty (defect replacement, typically 10–15 years in India) and a performance warranty (guaranteed output percentage, typically 25–30 years). The Nexus 730Wp HDT panel carries a 15-year product warranty and a 35-year performance warranty, stated separately. Always ask any manufacturer for both figures in writing — a single large number without that split does not tell you what is actually covered.
Are Nexus solar panels BIS certified?
Yes. Nexus solar panels are BIS registered under IS 14286 (Part 1/Sec 1):2023, Licence No. R-93046086, held by Nexus Solar Energy Pvt Ltd, Bulandshahr, valid to 28 April 2028. The licence covers a specific list of models in the 200W–750W range; ask for the model designation matching the panel you are buying.
Is a bifacial solar panel worth the extra cost?
On elevated mounts or light-coloured reflective surfaces, yes — the rear face adds real generation. On a panel lying flush against a dark rooftop, the additional gain is minimal. Bifacial value depends on the mounting and the surface underneath, so evaluate it for your specific roof rather than in general.
What is the difference between DCR and non-DCR solar panels?
DCR (Domestic Content Requirement) panels use Indian-made cells and modules and are generally required for government-supported and subsidy-linked projects. Non-DCR panels use imported cells assembled in India and are typically less expensive, suitable for private installations without subsidy requirements.
How much roof area does a solar panel need?
As a working figure, a high-efficiency N-type panel in the 600–730Wp range occupies roughly 2.5–3 square metres. Higher-efficiency N-type panels deliver more watts from the same area, which is why they suit Indian rooftops where space, not budget alone, is often the limiting factor.
See also: How to Choose a Solar Company in India: 9 Checks Before You Buy