Question

Cold water flows to the solar panels at 15°C. During the day, the panels supply 3.8 kg of hot water

at 65°C every hour.
(a) Calculate the average energy that the solar panels deliver to the water in one hour.
Specific heat capacity of water = 4200 J/(kg°C). ​

Answer 1

The average energy that the solar panel delivers to the water in one hour is 798,000 Joules

Step-by-step explanation:

The given parameters are;

The temperature of the water that flows to the solar panels, T₁ = 15°

The mass of the hot water the panel supplies during the day, m = 3.5 kg

The temperature of the hot water supplied by the panel, T₂ = 65 °C

The heat capacity of the water, c = 4,200 J/(kg·°C)

The heat delivered to the solar panels in one hour, ΔQ, is given by the following formula

ΔQ = m·c·ΔT

m = 3.8 kg, c = 4,200 J/(kg·°C), and ΔT = T₂ - T₁ = 65 °C - 15 °C = 50 °C

∴ ΔQ = 3.8 kg × 4,200 J/(kg·°C) × 50°C = 798,000 joules

∴ΔQ = 798,000 joules

The average energy that the solar panel delivers to the water in one hour, ΔQ = 798,000 joules.