Photovoltaics and energy conversion: A solar cell in a photovoltaic module converts incident sunlight directly into which form of usable energy (without any intermediate thermal or mechanical stage)?

Introduction / Context:
Solar cells are semiconductor devices that transform solar radiation into electricity by means of the photovoltaic effect. Unlike solar-thermal systems, they do not first heat a working fluid; rather, they produce electric power directly at the junction of specially doped materials.

Given Data / Assumptions:

• Device is a solid-state photovoltaic (PV) cell.
• Illumination is by sunlight within the device's spectral response.
• No moving parts or heat engines are involved.

Concept / Approach:
In a PN junction under illumination, photons with energy greater than the bandgap create electron–hole pairs. The built-in electric field separates these charge carriers, generating a photovoltage and photocurrent. The net result is direct conversion of radiant energy into electrical energy at the terminals of the cell.

Step-by-Step Solution:
Recognize that PV cells rely on the photovoltaic effect, not on heating a fluid.Identify the output form of energy: electron flow (current) at a measurable voltage.Conclude that the direct product is electrical power (P = V * I).Therefore select the option describing electrical energy.

Verification / Alternative check:
Current–voltage (I–V) curves under standard test conditions (STC) quantify electrical output without any mechanical stage, confirming direct conversion to electricity.

Why Other Options Are Wrong:
Thermal: solar-thermal collectors convert sunlight to heat, not PV cells.

Mechanical: requires turbines or engines, which PV systems do not employ.

Chemical: while solar energy can drive electrochemical storage (batteries), the cell itself outputs electricity.

Common Pitfalls:

• Confusing PV panels with solar water heaters.
• Assuming energy storage is inherent to PV; storage is external.

Final Answer:
Electrical