Assignment Details You need to decide which energy system is more suitable to power the following household requirement. This system will be installed in Perth, Australia. Since the average annual...

Appliance

Watts

Quantity

Total Watts

Hours/day

Watts/hrs/Day

40W Bulb

40

10

400

4

1600

100W Bulb

100

2

200

3

600

TV

75

2

150

3

450

Heater/air con

2000

2

4000

3

12000

Music system

200

1

200

2

600

Refrigerator

325

1

325

6

1950

Freezer

325

1

325

6

1950

Oven

1200

1

1200

1

1200

Coffee Maker

1000

1

1000

0.5

500

Total

5265

7800

20850

Q1

a)

Calculate the total power requirement (Wh) per day.

b)

Assuming that peak load occurs when the refrigerator, the heater/air con and the TV work simultaneously, calculate the peak load.

c)

Calculate the voltage of your battery bank.

d)

Calculate the amp-hour requirement per day.

e)

The system is required to work even if there are 3 consecutive cloudy days and the batteries must not run down more than 50%. Calculate the Ah you need to store.

f)

Adjust this figure for an inverter efficiency of 93%.

g)

Using the lead-acid batteries listed in the Appendix below, design a battery bank:

-
Battery Model?

-
Number of batteries in series?

-
Number in batteries parallel.

[14 Marks]

A1

Student Answer:

A) 20850 Whr/day

B)

F1

Instructor Feedback

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Q2

a)

Your PV array needs to point true North. Where is true North in Perth, assuming that your compass points to 000 (magnetic North)?

b)

What is the recommended tilt angle for Perth?

c)

Assuming that the total sun hours for Perth is 4 hours in June. What is the amperage required from your PV array?

[6 Marks]

A2

Student Answer

F2

Instructor Feedback

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Q3

a)

What power output should you be able to supply from the 24V D400 at 15.4 m/s?

b)

1.

If the wind drops to 2 m/s, what will the output power be?

2.

According to the performance graph what is the maximum power you can obtain from the 24V D400?

c)

There is a possibility of installing the turbine on top of a 20m high mast instead. Assuming that Z_o=0.012, what would you expect the wind speed to be at that height?

[15 Marks]

A3

Student Answer

F3

Instructor Feedback

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Q4

In this exercise, you are asked to analyse a PV and wind power system for an off-grid house located in the tropic. Your system is composed of a Primary load, PV panels, a wind turbine model
SW AIR (2)
and a battery type Trojan t-105.

Your task is to model the system using the software Homer and comment on its performance.

Base your analysis on the
Optimal system type
graph with the wind speed on the y-axis, the primary load on the x-axis and with the superimposed graph of
Levelized Cost of Energy.

Refer to the instruction sheet for information on how to use the software.

You will need to enter the following data on the following pages in order to complete your modelling exercise:

[25 Marks]

A4

Student Answer

F4

Instructor Feedback

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