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Most people start with the brand. The brand matters less than you'd think: what decides how much electricity you get, and for how long, is printed on the panel's datasheet. Two panels with the same wattage can behave quite differently on a hot terrace in May, and wear out at different speeds over 25 years.
Here is what to read on that datasheet, how Indian summers change the picture, and what to ask so the panels keep working and the subsidy still comes through.
- Panels on a summer roof
- 60 to 70°C
- Output lost per °C above 25°C
- about 0.30% N-type, 0.35% P-type
- For the subsidy, panels must be
- made in India, with Indian cells
- Performance warranty
- 25 to 30 years
Start with the rule that sets your shortlist
If you plan to claim the PM Surya Ghar subsidy, the choice is narrower than any brochure suggests. A subsidised home system must use DCR panels: panels made in India, using solar cells that are also made in India. Panels with imported cells don't qualify, however good they are, and the only fix after installation is replacing them.
Since 1 June 2026 this has tightened further. Panel models on the government's approved list (ALMM List-I) must now use cells from manufacturers on a second approved list, for cells (ALMM List-II). A model that can't show that drops off the approved list and can't be used for a subsidised or net-metered system.
So the first question for any quote is simple: is this exact model on the current approved list, and is it a DCR panel? Everything below helps you choose between panels that pass that test. For the scheme itself, see our PM Surya Ghar guide.
Output: watts and efficiency
Wattage is the size of each panel, not the system
Every panel has a rating in watts-peak (Wp), measured in a lab at 25°C. Most home systems now use large panels of roughly 540 to 600 Wp each, about 2.3 metres by 1.1 metres. A 3 kW system might be five or six of them.
What you actually buy is the total: 3 kW of panels makes about the same electricity whether that's five big panels or six smaller ones. A higher-wattage panel helps when the roof is small or partly shaded, not because it's better in itself.
Efficiency matters when roof space is tight
Efficiency is how much of the sunlight hitting the panel becomes electricity. Typical figures today are about 20 to 21.5% for P-type PERC panels and 22 to 23% for N-type TOPCon panels. A more efficient panel fits more kilowatts on the same roof. If you have plenty of space, a percentage point of efficiency changes little.
Check the power tolerance
Look for a positive tolerance, usually written as 0 to +5 W. It means a 550 W panel is guaranteed to test at 550 W or slightly more, never less. A tolerance that allows minus figures is a reason to look elsewhere.
Heat: the number most people skip
Panels are rated at 25°C, but on an Indian terrace in summer they often reach 60 to 70°C, well above the air temperature. As they heat up, their output drops. The temperature coefficient on the datasheet tells you by how much: the percentage lost for every degree above 25°C. The lower that number, the better the panel copes.
Here is what it means for a 550 W panel at 65°C, which is 40 degrees above its rating:
- N-type TOPCon, about −0.30% per °C
- Loses about 12%, so it gives about 484 W.
- P-type mono PERC, about −0.35% per °C
- Loses about 14%, so it gives about 473 W.
Two percentage points sounds small, but it applies on every hot afternoon for months a year, for 25 years. In Hyderabad, Delhi or anywhere with long, hot summers, it adds up to a noticeable amount of extra electricity.
Whatever panel you choose, leave a gap under it. A structure that lets air flow beneath the panels keeps them cooler than panels laid close to a hot slab.
What lasts: wear and warranties
All panels lose a little output each year. This is normal, and the datasheet tells you how fast. There are two numbers to read:
- First-year loss. Panels drop a little more in their first year as they settle: around 1% for N-type, and 1 to 2% for P-type.
- Yearly loss after that. Roughly 0.4% a year for N-type panels, and 0.5 to 0.55% a year for P-type.
Two warranties, and they mean different things
- Product warranty
- Covers defects in the panel itself: the frame, the glass, the junction box, the build. Usually 12 to 15 years, and longer on some N-type models.
- Performance warranty
- Guarantees how much output the panel still gives after a set number of years. Many P-type panels guarantee around 80 to 85% after 25 years; many N-type panels guarantee around 87% after 30.
A warranty is only as good as the company behind it and your ability to claim it. Get the warranty papers with the serial numbers of your panels written on them, and keep them with your installation documents.
N-type or P-type?
This is the choice most home buyers end up making. P-type mono PERC panels have been the standard for years and are well proven. N-type TOPCon panels are newer, and most manufacturers are now moving their production to them.
- Efficiency
- N-type about 22 to 23%. P-type about 20 to 21.5%.
- Loss in heat
- N-type about −0.29 to −0.32% per °C. P-type about −0.34 to −0.37% per °C.
- Yearly wear
- N-type about 0.4% a year. P-type about 0.5 to 0.55% a year.
- Typical performance warranty
- N-type around 87% after 30 years. P-type around 80 to 85% after 25 years.
- Price
- N-type costs a little more, roughly ₹2 per watt. P-type is the lower-cost option.
Choose N-type if
Your summers are long and hot, your roof space is limited, or you want the most electricity over 25 years for a small extra cost upfront.
P-type still makes sense if
The budget is tight, the roof has room to spare, and you'd rather keep the upfront price as low as possible.
On a 3 kW system, the price difference is usually a few thousand rupees. For most homes in hot cities, we think N-type is worth it. You can see the two side by side on our N-type and P-type pages, or compare them here.
Signs of a well-made panel
Beyond the headline numbers, a few lines on the datasheet tell you the panel was built and tested properly:
- BIS and IEC certification: the BIS registration (IS 14286) and the IEC 61215 and 61730 durability and safety tests. Any panel on the approved list should have these.
- PID resistance. Potential-induced degradation is a slow loss of output in hot, humid conditions, and good panels are tested to resist it.
- Salt mist and ammonia tests. Near the sea, look for the salt mist test (IEC 61701); near cattle sheds or farms, the ammonia test (IEC 62716).
- A mechanical load rating, which shows how much wind and weight the panel can take. Around 5,400 Pa on the front and 2,400 Pa on the back is common for good panels.
- Half-cut cells. Most panels now use cells cut in half, which cope better when part of the panel is shaded by a water tank or a parapet.
Before you sign: a checklist
Ask your installer to show you each of these for the exact model in your quote, not the brand in general.
- The model is on the current ALMM list, and it's a DCR panel if you're claiming the subsidy.
- The datasheet for that model, with its wattage, efficiency and power tolerance.
- The temperature coefficient, ideally around −0.30% per °C or better.
- Both warranties in writing, with the years and the guaranteed percentage.
- The serial numbers of your panels on the warranty papers once they're installed.
- How the panels will be mounted, with enough height for air to flow underneath.
For the other things that go wrong before installation, from undersized systems to roofs that were never surveyed, see common mistakes to avoid before installing solar. For the paperwork, see how to get a government subsidy for solar panels.
How we help
We fit both N-type and P-type panels, so we'll tell you honestly which one suits your roof and your budget.
- A free site survey, including shade, roof space and how the panels can be mounted
- Approved DCR panels for subsidised systems, with the datasheet and warranty for the exact model we quote
- A system sized to your bills and your sanctioned load
- Installation by our own team, help with the subsidy paperwork, then after-sales service and panel cleaning
Comparing two quotes?
Send us both. We'll check the panel models, the datasheets and the warranties, and tell you plainly how they compare.
Questions people ask
Are Indian-made panels as good as imported ones?
It depends on the model, not the country. Panels sold in India go through the same IEC and BIS tests, so compare the datasheet: the temperature coefficient, the yearly degradation and the warranty terms. Several Indian manufacturers now make N-type TOPCon panels with figures in line with imported ones.
Should I pick the highest-wattage panel I can find?
Not for its own sake. A 3 kW system makes about the same electricity whether it uses five big panels or six smaller ones. Higher-wattage panels help when roof space is tight, but they are larger and heavier, so the structure and the roof layout have to suit them.
Do I need bifacial panels?
Only if the back of the panel will see light. On a raised structure over a light-coloured terrace, bifacial panels can add a few percent. Mounted low over a dark roof, the extra is small. Many N-type panels are bifacial anyway, so it often comes at no extra cost.
Are DCR panels more expensive?
Yes, usually more per watt than panels with imported cells. For a home claiming PM Surya Ghar, the subsidy of up to ₹78,000 is far larger than that difference, and without DCR panels there is no subsidy at all.
Can I mix two kinds of panel on one roof?
Not on the same string. Panels wired together should be the same model, or the weakest one holds back the rest. If you add panels later, either match the model or put them on a separate inverter input.
What happens if a panel fails under warranty?
The manufacturer repairs or replaces it, usually through your installer. Keep the warranty papers with the serial numbers of your panels, because the claim is made against those serial numbers.
