Australian National University
INDIVIDUAL EXERCISE
COLLEGE OF ENGINEERING AND COMPUTER SCIENCE
TASK: Assessing the Solar Resource
COURSE: ENGN4524/6524 Photovoltaic Technologies
DUE DATE: 11 PM, 2nd Sunday immediately after your exercise section
TASK VALUE: 7.5% total course weighting
CONTEXT:
In this exercise you are asked by your company to write an initial technical report. You will use excel
spreadsheets and databases to assess the solar energy resources available in Canberra and at a site in
Germany. You will use this data, together with the relevant equations and concepts from the lectures, to inform
the company about the suitability of Canberra as a site for a photovoltaic power plant the company is planning
to invest.
ASSESSMENT OUTCOMES:
The course learning outcomes that will be assessed in this task include:
 Identify the potential of the solar resource and photovoltaic systems as a mainstream energy source for the future
 Appraise and design photovoltaic systems
SCOPE:
In this task you will be required to:
 Use simulations of the sun’s apparent motion to estimate the optimum orientation for solar collectors
 Investigate the effect of the angle of a collector on its performance
 Collect and analyse real meteorological data to calculate the irradiance falling on an inclined plane
 Use concise and precise scientific language to describe and report your findings
MARKING CRITERIA:
In this task you will be marked on your ability to:
 Correctly interpret instructions and produce accurate results - define experimental questions, and perform
the appropriate experiments / simulations / calculations. All questions need to be addressed.
 Analyse and interpret results and draw valid conclusions - apply knowledge gained in the course, relate results to
course knowledge, and demonstrate an understanding of the limitations and errors of the experimental processes
or simulations.
 Communicate effectively – As a technical engineer in the company, you need to use concise & precise scientific language
to report your findings. In order to convince the company (the audience is the directors who have good engineering
background but limited knowledge on solar resources) whether a solar plant in Canberra is worth investing in, you need
to provide logical reasoning in your report backed up by appropriate mathematical, graphical and report writing
techniques (i.e. what steps were taken and what the reasons were for doing those steps).

Please note: The Exercise Assessment and Feedback form (which you will find on Wattle, in the ‘Exercises’ section) will be used to provide
you with feedback and the assessment of your report.
INSTRUCTIONS FOR SUBMISSION:
 Max 8 page report, including appendices for additional graphs/data where required. Pages in excess of the
limit will be disregarded. The title page is not included in the 8 page limit.
 The title page of the report must contain your Uni ID, full name, and the date of your scheduled exercise session.
 Text should be no smaller than 12 point size, in a highly legible font
 Submit report, as a pdf file, via Wattle by the due date. The file name should be
__Ex1.pdf, eg u1234567_Smith_Ex1.pdf

Please note: Late submissions will be penalised at a rate of 5% per day that the item is late, unless exceptional circumstances (usually requiring a
medical certificate) can be shown to apply. In such cases, you should i) State on the title page that special circumstances apply, and the modified
submission date; and ii) provide any relevant documentation as an appendix to the document (for example, emails from the lecturer/demonstrator
approving the change of exercise session for that week or approving and extension, and/or relevant medical certificates.

TASK DESCRIPTION (4 PARTS)
BRIEF:

Assuming that the government is announcing a solar auction program, requesting bids from interested
companies to install up to 200MW of solar photovoltaics.

Your solar energy company wants some of this funding. As the leading solar engineer on the project you
have been asked for your assessment of the Canberra region as a potential site for the power station. In the
early stages of planning you are interested in the solar energy resources available in Canberra and the
optimum inclination of a solar collector, so you can start to choose the solar technology most suitable for
the area and estimate the cost of such a system – which will determine the bidding price.

To support your assessment of the Canberra region, you will also do a similar analysis for the 550MWp Topaz Solar
Farm (USA), one of the world’s largest photovoltaic plants. By comparing assessments of the two regions, you will
be able to draw a strong conclusion on whether or not Canberra is a suitable place for a solar power station.

RESOURCES:

In your initial investigation you will use the following web based resources:

SunPosition calculates the position of the sun throughout a particular day and for a given location (latitude).
By definition 12pm is solar noon, which is halfway through the day and the time when the sun is highest in the
sky. Among other things, it can be used to determine the time of sunrise, sunset, and the altitude and azimuthal
angle of the sun.

ModuleSim is an Excel based spreadsheet that simulates the motion of the sun across the sky at any location
on earth and at any time of year. It uses the information to calculate the expected diffuse and direct radiation
incident on a solar module of defined tilt on a clear day for the different months of the year. It may be used, for
example, to roughly optimise the angle of tilt of a PV panel for maximum yearly electrical output.
Note: You will find a link to this spreadsheet on the Wattle course website.

Surface Meteorology and Solar Energy is a database that provides over 200 parameters for meteorology
and the solar resource at locations around the globe. The data is based on 22 years worth of satellite data from
NASA.
https://power.larc.nasa.gov/data-access-viewer/


ACTIVITY:

1) We need to ascertain that Canberra gets a sufficient number of sunlight hours:

Open the SunPosition spreadsheet and enter Canberra’s Latitude (-35.25°)

 What is the minimum and maximum number of sunlight hours for any day throughout the
year? Hint: think about which day of the year is the longest, and which is the shortest.
 How does this compare to the minimum and maximum sunlight hours for Topaz Solar Farm?
(Latitude 35.38°)

We also need to have an idea of how to position our panels in Canberra:

 Which direction should they be facing and what angle of inclination would be best?

To establish a first estimate of the optimum inclination angle, find the minimum and maximum altitude of the sun
in the sky at noon over the year and use them to come up with an estimate. Provide a brief explanation of
your reasoning.


2) The company bosses are pleased with our initial findings so we are asked to do some more in-depth analysis.

Open the ModuleSim spreadsheet. Alter the module parameters as follows: a module size of 1.6 m
2
, an
efficiency of 20%, and for the day of the month to simulate, choose ‘15’.

Determine what inclination angle or tilt (to within one degree) gives the highest annual insolation in
Canberra. Start with your previous estimation

 How does this compare to your previous estimate?
 How does this compare to Canberra’s latitude?
 Why is the optimal inclination angle different to Canberra’s latitude?
 For this angle of tilt, what are the values for the maximum and minimum daily insolation throughout
the year? In what months do they occur?

Maximum annual output is one possible criterion for determining the optimum tilt angle. However, a more
uniform output throughout the year is desirable to maintain a stable energy output for our power station.
This can be achieved by slightly increasing the module angle, giving the system a ‘winter bias.

 By how much (as a percentage) is the minimum daily output increased if you increase the angle by
10 degrees?
 How much has the total annual output reduced by? Calculate the reduced output as a percentage also.

To answer the next question you will need to enter the latitude for Topaz Solar Farm, and do some
more simulations.

 How does the total output for a system situated in Topaz Solar Farm (for an optimally tilted panel)
compare with a system in Canberra? You will need to re-calculate the optimal inclination angle,
and calculate the percentage increase/decrease in annual output as compared to Canberra.
 What are the values for the maximum and minimum daily insolation throughout the year? In
what months do they occur?
 How does the variation in module output throughout the year compare for modules in the two
locations? What do you think are the reasons for this?


3) For the design of the power plant we need to know exactly
how much solar energy would be available throughout the
year.

For this we need to look real data from the NASA Surface
Meteorology and Solar Energy database.
Go to the site and follow the links, click on “Climatology”:

https://power.larc.nasa.gov/data-access-viewer/

Note: Remember these as this is a useful resource for your group project.

Enter the latitude and longitude: -35.25°S, 149.12°E (Canberra), 35.38°N,-120.07°E (Topaz Solar Farm)

You will now be asked which information you would like. Have a look around and see what kind of
information is available. Have a look at the parameter definitions. If you are interested there is information
about the methodology used to create this data. This may come in handy for your group project.

For our calculations we need:
- Insolation on a horizontal surface (Insolation is the same as irradiation)
- Diffuse radiation on a horizontal surface
- Direct normal radiation
- Declination angle
- Sunset hour angle
- Radiation on equator pointed tilted surfaces
- Daylight cloud amount

Choose appropriate data and click “submit”
Use this data to answer the following questions:

 How much annual solar irradiation on a horizontal surface does Canberra receive, and how does
this compare with the value for Topaz Solar Farm?
 How much annual direct normal solar irradiation does Canberra receive, and how does this compare
with the value for Topaz Solar Farm?
 What is the maximum and minimum average monthly irradiation for Canberra and Topaz Solar
Farm (on a horizontal surface)?
 Comment on the annual average cloud cover for Canberra and Topaz Solar Farm. How does the
cloud cover affect both the diffuse and total insolation averages?


4) For our power station we need to know the irradiation that will fall on our collectors tilted at the optimum
inclination angle calculated previously (which gives the highest annual output) and compare these results
with those for a power station situated in Topaz Solar Farm.

We are going to calculate the global irradiation on an inclined plane for a collector situated in Canberra and Topaz
Solar Farm over the months of April and October. Get the monthly averaged global insolation (per day) G and the
monthly averaged diffuse insolation (per day) D for April/October for Canberra/ Topaz Solar Farm.

Do the following calculations: (please include the main steps/equations that are used to derive your answers)
a) Calculate the direct beam irradiation: B = G – D
b) Do the geometrical correction for direct beam (B) and diffuse (D) components for a plane inclined at
an angle of β. Do this calculation for optimum collector angles previously calculated. (You may want
to use a spreadsheet for these calculations)





REPORT:

Now you need to write an initial company report (max 8 pages) to the directors (here the convener/tutors).
Carefully read the marking criteria and make sure you cover all criteria in your report. A clear flow of
reasoning should be obvious to the reader. Your conclusion needs to state your opinion on whether or not your
company should consider locating a power plant in Canberra, based on the available information. As part of the
report, you should identify the assumptions, simplifications and limitations of the work that has been carried
out, and what further work would be required before a final decision could be made.

How you structure the report is up to you. Make sure that your report is logical and easy to follow. Keep in
mind that your directors (here the convener/tutors) have only 10 minutes to read through your report and they
have to read 40-50 reports within a week.