Walk into any solar market in Lahore or Karachi and the first thing you’ll hear is “N-type hai, latest technology.” Two years ago the same shops were selling Mono PERC with the same confidence. So what changed, and does it matter for your house?
- N-type TOPCon loses less power in heat and ages slower.
- PERC is older tech but still works well and costs a bit less.
- On a hot Pakistani roof, the N-type advantage is real but modest, around a few percent a year.
- Check the datasheet, not the sticker. Look at temperature coefficient and yearly degradation.
What the two names mean
Both are monocrystalline silicon panels. The difference is in how the cell is built. PERC (Passivated Emitter and Rear Cell) adds a reflective layer at the back of a P-type cell so it catches a little more light. TOPCon uses an N-type wafer with a very thin oxide layer that cuts down energy losses inside the cell.
You don’t need to remember any of that. What you need to know is how each behaves on a roof in June.
Heat: where N-type earns its money
Panels are tested at 25°C. On a Pakistani roof in summer, the cells easily run at 60 to 65°C. Every degree above 25 costs some output, and the datasheet tells you how much through the temperature coefficient of Pmax.
- Typical Mono PERC: around -0.34% to -0.36% per °C
- Typical N-type TOPCon: around -0.29% to -0.32% per °C
At 40°C above test temperature, that gap works out to roughly 1.5 to 2.5% more output from N-type during the hottest hours. Not dramatic, but it adds up over 25 years.
Ageing: the bigger difference
N-type cells don’t suffer much from light-induced degradation, the small drop that happens in the first year. Most N-type panels promise a first-year loss of about 1% and around 0.4% a year after that. PERC panels usually promise 2% in year one and about 0.55% a year after.
After 25 years, that’s the difference between a panel giving you roughly 87% of its original power and one giving you about 84%. Again, real but not life-changing.
So is PERC a bad buy now?
No. A good PERC panel from a known brand will still work for decades. If you find a solid PERC deal from a reputable seller and the price gap is big, it’s a reasonable choice. What you should avoid is a cheap “N-type” panel with no traceable datasheet. A good PERC beats a fake TOPCon every time.
How to check before you pay
- Ask for the datasheet with the exact model number printed on the panel’s back label.
- Look at the temperature coefficient and the linear power warranty (years and percentage).
- Confirm the wattage on the label matches what’s on the bill.
- Ask who handles a warranty claim in Pakistan. A foreign brand with no local partner is a headache later.
Panels are half the system
Whichever panel you pick, the inverter decides how much of that power actually reaches your appliances. A good MPPT inverter that matches your string voltage makes more difference than the PERC vs N-type debate. If you’re unsure what size you need, run your appliances through our solar load calculator first.
Not sure which panels pair with your inverter?
Send us the panel model and your load. We’ll tell you if the string voltage fits.