Question 22N.2.SL.TZ0.2a.i
| Date | November 2022 | Marks available | [Maximum mark: 3] | Reference code | 22N.2.SL.TZ0.2a.i |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Determine | Question number | a.i | Adapted from | N/A |
A solar heating panel is placed on the roof of a house in order to heat water in a storage tank. The rest of the roof is covered with tiles.
On a certain day, the intensity of the solar radiation that is incident perpendicular to the surface of the panel is 680 W m−2.
The following data are available.
Mass of the water in the tank = 250 kg
Initial temperature of the water in the tank = 15 °C
Specific heat capacity of water = 4200 J kg−1 K−1
Overall efficiency of the heating system = 0.30
Albedo of the roof tiles = 0.20
Emissivity of the roof tiles = 0.97
Determine the minimum area of the solar heating panel required to increase the temperature of all the water in the tank to 30°C during a time of 1.0 hour.
[3]
energy required = 250 × 4200 × (30 − 15) ✓
energy available = 0.30 × 680 × t × A ✓
A = «» 21 «m2» OR 22 «m2» ✓
Allow ECF from MP1 and MP2.
Accept the correct use of 0.30 in either MP1 or MP2.
Most candidates had a good attempt at this but there were often slight slips. Some missed the efficiency of the process. Some included the albedo of the roof tiles. Some thought that the temperature rise needed to have 273 added to convert to kelvin. However, sometimes scoring through ECF (error carried forward), the average mark was around 2 marks.
