Glossary · Panels · Basic · Pakistan 2026
STC is a laboratory noon that your roof will never be.
Standard Test Conditions: 1000 W/m², 25 °C cell, AM1.5 spectrum. Every watt-peak on a carton is an STC watt.
People also search standard test conditions watt peak stc vs noct
Key takeaways
- The flash report is STC.
- STC irradiance: 1000 W/m² — Lab noon.
- STC cell temp: 25 °C — Not a Karachi roof.
- Flash report: Per-module STC watts — Ask before money.
- Use STC for shopping and string Voc math (then temperature-correct).
What it is
The flash report is STC. The roof is hotter, dirtier, and not 1000 W/m² all day. Designing strings, breakers and yield from STC without a temperature correction is how January Voc surprises happen and how May kWh disappointments happen.
In Pakistan 2026
Importers still advertise only STC. Honest lists also print NOCT watts, which look 75 W smaller and closer to a warm roof. Ask for both. If they only have a WhatsApp photo of the pallet, you do not have STC either.
How we spec it
Use STC for shopping and string Voc math (then temperature-correct). Use derated PSH for kWh. Never mix the two in one sentence on a flyer.
Numbers you can actually use
Street ranges, not a quotation. Confirm the carton the week you book.
| Thing | 2026 number | How to use it |
|---|---|---|
| STC irradiance | 1000 W/m² | Lab noon |
| STC cell temp | 25 °C | Not a Karachi roof |
| Flash report | Per-module STC watts | Ask before money |
Worked example — Multan
Take a 8 kW-class hybrid in Multan (MEPCO, ~5.3 PSH). 13 × 645 W is 8.38 kW DC. Derated yield ≈ 8.38 × 5.3 × 0.78 ≈ 34.6 kWh on a clean day — then dust, heat, and a dawn wash habit. This page (STC (standard test conditions)) is the piece of that plant people skip on WhatsApp. If your quote cannot survive this Multan sentence, it will not survive May. Open the calculator with city set to Multan, and the lookup map for a stocking dealer — not a green-meter SKU.
Keywords this lesson actually answers
People land here asking standard test conditions, watt peak, stc vs noct. The honest 2026 answers still collapse to: N-type plates with flash, IP65 hybrid with GRID vs LOAD, 51.2 V LFP on CAN, 14 SWG, XLPO, derate 0.78, and net-billing at ~Rs 11 export if you file with MEPCO. Everything else on this page is how not to get robbed while buying those things.
Internal links worth clicking before you pay
Size: system sizing · Policy: net-billing · Battery: LFP · Buy: checklist · Shops: near you · City climate: Multan · Numbers: calculators.
How shops fail this
Flyer watts as roof watts
Flyer watts as roof watts
No flash, only STC brochure
No flash, only STC brochure
String math without cold Voc
String math without cold Voc
FAQ — STC (standard test conditions)
Is a 645 W plate 645 W at home?
Only for a moment on a cold clear noon with a clean glass. Plan on less.
What is a flash report?
The factory printout of that module’s STC watts, Voc, Isc. Serial-matched.
STC or NOCT for strings?
Voc/Isc limits: use STC then temperature coefficients. Yield: NOCT/derate.
Read next
NOCT
NOCT is the less-fake wattage on a warm roof.
glossaryVoc (open-circuit voltage)
Voc is the dangerous number on a cold January morning.
glossaryFlash report
No flash, no deal. The sticker is not the module.
glossaryDerating
Nameplate watts are a laboratory. Derate is the roof.
glossaryVmp (voltage at max power)
Vmp is where the MPPT is trying to sit.
glossaryIsc (short-circuit current)
Isc is how you cook an MPPT if you parallel too much.
Open the calculators Shops near you All lessons
Educational page, September 2026. Not a DISCO filing, not a live quotation, not medical or bank advice. SRO 251(I)/2026 net-billing for new files after 9 Feb 2026.