How do solar photovoltaic systems generate electricity, and what is one advantage and one limitation?

• A. They convert energy stored in PV materials to electricity via solar chemical reactions
• B. They convert sunlight directly into electricity via the photovoltaic effect; advantage: modular and low operating costs; limitation: intermittency and sun dependence
• C. They rely on wind to generate electricity
• D. They require fossil fuels to generate electricity

Answer: (B)

Solar photovoltaic systems generate electricity by converting sunlight directly into electrical energy through the photovoltaic effect in semiconductor materials. When sunlight hits a PV cell, photons excite electrons and create electron-hole pairs. The built‑in electric field at the cell’s p-n junction pushes these charge carriers in opposite directions, creating an electric current that flows if the circuit is closed. This current is direct current, usually then converted to alternating current with an inverter for use in homes and on the grid, and PV panels are often connected in series or parallel to build up the desired voltage and current.

One clear advantage is that these systems are modular and have very low operating costs. You can add more panels to increase capacity, and after installation there’s no fuel to burn and minimal moving parts, so maintenance costs stay relatively low.

A key limitation is intermittency and sun dependence. The output varies with time of day, weather, and season, so power isn’t constant unless paired with storage or other power sources or a strong grid.