Lesson 1.1 — How Sunlight Becomes Electricity
A PV cell is a silicon sandwich: photons knock electrons loose, and the cell's junction pushes them one way — direct current. Cells make ~0.6 V each; 60 in series make a panel of ~36 V open-circuit. Panel ratings you must read from the nameplate: Voc (open-circuit voltage), Isc (short-circuit current), Vmp/Imp (max-power point) and Pmax in watt-peak. Cambodia's insolation averages 5 kWh/m²/day — a 400 Wp panel yields roughly 1.6–2 kWh daily.
Key points
- PV output is DC — batteries store DC — inverters make AC
- Nameplate: Voc, Isc, Vmp, Imp, Pmax (Wp)
- Heat reduces panel voltage: hot roofs yield less than cool ones
- Shade on one cell can drag down the whole string