A photovoltaic panel has an efficiency of 30% and an output power of 50W. Calculate the power input and the surface area needed if the solar intensity reaching the surface is 560 Wm⁻².

Efficiency (η) = (Power output) / (Power input)

Power input (P_in) = (Power output) / Efficiency (η)

Given: Power output (P_out) = 50.0 W, Efficiency (η) = 30% = 0.30
P_in = 50.0 W / 0.30

P_in = 166.666... W

The power input into the photovoltaic plate is approximately 167 W.

ii) Above the earth's atmosphere, the solar constant is 1.4 kWm⁻². However, only 40% of this power per unit area reaches the earth. Estimate the surface area of the panel in figure 10.

Solar constant (S) = 1.4 kWm⁻² = 1400 Wm⁻²
Intensity at Earth's surface (I_earth) = 40% of S
I_earth = 0.40 × 1400 Wm⁻²
I_earth = 560 Wm⁻²

Power input (P_in) = Intensity (I_earth) × Surface area (A)

Surface area (A) = (Power input (P_in)) / (Intensity (I_earth))

P_in = 166.67 W (from part i)
A = 166.67 W / 560 Wm⁻²

A = 0.2976 m²

The estimated surface area of the panel is approximately 0.298 m².

iii) Explain why solar energy is referred to as renewable source energy.

Solar energy is considered a renewable energy source because it originates from the sun, which provides a virtually inexhaustible supply of energy on a human timescale. The sun continuously emits vast amounts of energy, and its supply is not depleted by human use, unlike fossil fuels which are finite and take millions of years to form.

i) What is the ozone layer?

The ozone layer is a region within the Earth's stratosphere that contains a relatively high concentration of ozone (O₃) molecules. Its crucial function is to absorb most of the Sun's harmful ultraviolet (UV) radiation, preventing it from reaching the Earth's surface and protecting living organisms from its damaging effects.