TOPCon (Tunnel-Oxide Passivated Contact) adds an ultra-thin oxide + n-type polysilicon layer that cuts electron recombination, pushing module efficiency to 22–23 % vs. 20–21 % for mainstream PERC. The tech is already in mass production—don’t wait; prices crossed PERC in Q2-2025 and bankability is proven.

Only if the installer penetrates or seals incorrectly; use certified “non-penetrating” ballast or flashing kits accepted by shingle/tile manufacturers and register the workmanship certificate with the roof OEM. Most major membrane suppliers (Firestone, Sika, Monier) already list compliant PV mounting partners—demand that documentation.

Yes—plus more. In the EU, CAP “eco-scheme” tops up 30 % on capex, and the U.S. Inflation Reduction Act gives an extra 10 % “domestic-content + energy-community” bonus on top of the 30 % ITC when crop or grazing use is maintained, effectively 40–50 % cashback.

Multiply your evening/overnight kWh use by 1.3 (for 80 % depth-of-discharge and inverter losses), then divide by the battery’s usable kWh rating; round up to the next whole module. Oversizing 20 % covers cloudy-day autonomy without doubling cost, because batteries are now the cheapest part of the system (< $350 kWh installed).

For Tier-1 mono-PERC or TOPCon modules, use 0.45 % yr-1 (not the 0.8 % still seen in old spreadsheets); n-type bifacial datasets show 0.3 % yr-1. Dropping the rate by 0.35 % adds 60–70 bps to unlevered IRR on a 50 MW plant, which can be the difference between a go/no-go PPA bid.

Scan the module barcode with the manufacturer’s WeChat/WhatsApp verifier; Tier-1 brands (Jinko, LONGi, Trina) reply instantly with cell-factory serial, flash-test data and logistics chain. If the response fails or the watt-class differs, refuse delivery—counterfeits typically clone only the outer label, not the database entry.