N-type vs P-type solar panels explained

What the letters mean

Silicon by itself is a poor conductor. Manufacturers dope it with tiny amounts of another element to give it a useful electrical character. Dope with boron and you get positive charge carriers, which is P-type. Dope with phosphorus and you get an excess of electrons, which is N-type.

Almost every panel sold in Pakistan before 2023 was P-type, usually with the PERC rear-surface treatment that squeezed efficiency up to around 21 percent. Since 2024 the big Chinese lines have converted to N-type, and by 2026 N-type modules are common on Lahore rooftops rather than exotic.

The reason the doping choice matters is boron. In a P-type wafer, boron pairs with residual oxygen from the manufacturing process, and sunlight triggers a reaction that permanently drops output in the first weeks of life. That is light induced degradation. N-type wafers have no boron, so they do not suffer it in the same way.

TOPCon, HJT and what you can actually buy here

N-type is a family, not a single product.

• TOPCon adds an ultra-thin tunnel oxide layer plus doped polysilicon on the rear of the cell. Efficiency runs 22 to 23.5 percent. This is the mainstream N-type product and covers virtually all N-type stock in the Lahore market.
• HJT sandwiches a crystalline wafer between thin amorphous silicon layers. Efficiency reaches 23 to 25 percent with the best temperature coefficient of any commercial cell, around minus 0.24 percent per degree. Rare and expensive in Pakistan. Available on special order at a premium most homeowners cannot justify.
• ABC and IBC designs move all contacts to the rear for maximum efficiency and a very clean look. Effectively unavailable at reasonable prices here.

So in practice the choice in Lahore is P-type PERC at PKR 19,500 for a 585W module against N-type TOPCon such as the Astronergy 585W at PKR 25,450. That gap of PKR 5,950 per panel is the entire commercial question.

Heat, the argument that carries the most weight in Lahore

Panels are rated at a cell temperature of 25 degrees. Nothing on a Lahore roof in June is ever at 25 degrees. On a flat concrete roof in Johar Town with 44 degree ambient, still air and no gap under the array, we have measured module backsheet temperatures of 68 to 74 degrees at 2 pm. That is 43 to 49 degrees above rating.

Cell type	Temp coefficient (per degree)	Loss at 70C cell temp	Real output from a 585W panel
Old poly	-0.42%	18.9%	474 W
P-type PERC	-0.35%	15.8%	493 W
N-type TOPCon	-0.29%	13.1%	508 W
HJT	-0.24%	10.8%	522 W

Fifteen watts per panel does not sound like much. On a ten panel array it is 150 W, or roughly 3 percent more generation during the exact hours when your ACs are drawing hardest and your summer AC load is deciding whether the battery gets charged. Over a full Lahore year, with about five hot months and the rest mild, the real annual advantage from temperature alone lands near 1.5 to 2.5 percent.

You can close half that gap for free

Mounting matters more than most buyers realise. A panel clamped flat to a concrete roof with a 4 inch gap runs 8 to 12 degrees hotter than the same panel on a raised structure with 18 inches of clearance and airflow underneath. Raised mounting costs PKR 12,000 per kW against PKR 7,000 per kW for a standard frame. On a 5 kW build that is PKR 25,000 extra, and it buys you a cooling benefit comparable to what PKR 53,000 of N-type upgrade would deliver. Do the mounting properly first.

Degradation over 25 years

The second real advantage of N-type is that it fades more slowly.

Year	P-type PERC output	N-type TOPCon output	Gap
1	98.0%	99.0%	1.0%
5	95.8%	97.4%	1.6%
10	93.1%	95.4%	2.3%
15	90.3%	93.4%	3.1%
25	84.8%	89.4%	4.6%

Typical warranties reflect this. P-type PERC usually carries an 80 to 84 percent guarantee at year 25. N-type usually carries 87 to 89 percent at year 30. Whether a warranty written in Chinese and administered through a Pakistani importer is worth much in year 22 is a separate question, and one worth being sceptical about.

Does the price gap pay back?

Run it on a 5.85 kW build, ten panels.

• P-type route: 10 x 585W at PKR 19,500 = PKR 195,000
• N-type route: 10 x 585W Astronergy at PKR 25,450 = PKR 254,500
• Extra cost: PKR 59,500

Assume a P-type array in Lahore produces 8,200 units a year. N-type gains roughly 2 percent from heat and starts about 1 percent higher after first-year degradation, so call it 3 percent, which is 246 extra units a year. At a blended value of PKR 45 per unit, mixing self-consumption at retail rates with a little export at the low buyback rate, that is about PKR 11,000 a year.

Payback on the upgrade is roughly five and a half years, improving slightly each year as the degradation gap widens. That is decent but not spectacular. Compare it against spending the same PKR 59,500 on two extra P-type panels, which would add about 12 percent more output immediately. If you have the roof space, more panels beats better panels. Every time.

When N-type is clearly the right call

Four cases where we specify N-type without hesitating.

Tight roof

A 5 marla house in Model Town or a portion in Garden Town where the usable area is 22 square metres. You cannot add panels. The only way to get more kilowatts is denser panels. N-type at 235 watts per square metre against PERC at 226 gives you an extra 200 to 300 W on that roof, which matters when you are trying to run an inverter AC.

The array will run hot no matter what

Flat mounting on a low parapet roof with no airflow, common in older Gulberg houses where the parapet is high and the array is boxed in. If you cannot fix the cooling, buy the cell chemistry that suffers less.

You plan to keep the house for decades

The degradation gap compounds. Someone who will still own the property in 2050 gets real value. Someone who will sell in 2031 does not.

Commercial installs with a demand charge

Where peak-hour generation directly offsets the most expensive tariff block, the summer afternoon advantage is worth more per unit than a home would see.

The honest caveats

Three things nobody selling N-type will tell you.

The market is full of panels labelled N-type that are not. TOPCon carries a price premium, which means it attracts relabelling. We have tested modules sold as N-type whose open circuit voltage and temperature behaviour clearly matched PERC. Ask for the flash test report for the specific pallet, check the serial with the manufacturer's portal, and buy through an importer with a physical presence in Lahore rather than a WhatsApp-only trader.

Second, N-type is more sensitive to poor system design. Higher current per string means undersized DC cable and cheap connectors run hotter. The wiring budget of PKR 25,000 for a 90 metre DC run and 20 metres of AC is not the place to economise on an N-type array. Bad connectors are the single most common cause of the roof-level faults our repair team attends, covered in solar repair costs in Lahore.

Third, none of this rescues a shaded roof. A neighbour's newly built third floor casting shade across your array from 3 pm onwards will cost you 20 to 30 percent of afternoon output, which dwarfs every cell-chemistry advantage discussed above. Survey the shade first. That is the whole reason we charge PKR 3,000 to come and look properly.

Practical recommendation

Your situation	Buy
Plenty of roof, standard budget	P-type PERC 585W at PKR 19,500, spend the savings on more panels or a bigger battery
Limited roof area	N-type TOPCon 585W at PKR 25,450
Raised structure over a light-coloured terrace	645W bifacial at PKR 21,000, see the bifacial article
Long-term hold, 20 years plus	N-type, the degradation gap earns its keep

Related reading: mono versus poly, whether bifacial is worth it in Lahore, the 585W panel guide and today's panel prices. For system-level decisions see 5 kW pricing or 15 kW pricing, and our hybrid and battery page for the storage side. Estimate a build on the calculator, or contact us to book a survey. We cover DHA, Wapda Town and the rest of the city.