A school wants evidence for the fixed tilt of a small roof-mounted solar panel. (a) Formulate a research question linking tilt angle to electrical power under stated conditions. [2] (b) Give a reasoned hypothesis based on radiation incident on a surface. [3] (c) Design a method using a panel, adjustable stand, resistive load, voltmeter, ammeter and irradiance meter. Include range, controls, repeats, normalisation, graph and safety. [7] (d) Explain why one clear-day investigation cannot determine annual energy yield. [2] Do not invent results.

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Vary tilt, calculate P = VI at a controlled load, and normalise power by measured irradiance and panel area. Predict the largest normalised power when the panel is closest to perpendicular to the incoming sunlight. (a) Ask: At a stated date and time range, how does panel tilt from 0° to 80° affect electrical power per unit incident irradiance for the same panel and load? (b) Predict a maximum when the panel normal points closest to the Sun because the same beam power is spread over the smallest panel-plane area. Electrical conversion and temperature may prevent a perfect cosine response. (c) Test 0°–80° in 10° steps in randomised order. At each angle record irradiance in the panel plane, panel temperature, load voltage and current after a fixed settling time; calculate P = VI and P divided by irradiance and area. (c) Control panel, load, cable, orientation around the vertical axis, location, shading and measurement timing. Repeat complete angle sequences and include a reference-panel reading to identify cloud drift. (c) Plot normalised power against tilt with repeat spread. Secure the panel and stand against wind, keep electrical connections dry and insulated, avoid roof work by performing the study at ground level, and manage glare. (d) Sun elevation and direction vary with time, season, weather and latitude; temperature, dirt and shading also change yield. Combine longer monitoring with a validated solar-path model before choosing an annual optimum.

Design a solar-panel angle field study

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