Some Links To Useful Resources
Here’s some links to information that may save you some time in your renewable energy investigation.
Australian Bureau Of Meteorology
THE WIND ACROSS AUSTRALIA
Energy Saver NSW
Energy Rebates Queensland
Energy Policy WA
SCIENTIFIC EDUCATION ON PV SOLAR
Calculation of Solar Insolation – Adjustable Charts to measure Power and SunHours relative to your location
Adjustable Charts to measure Power and SunHours relative to your location
The Issue With Reliance On Solar Alone
As light passes through the atmosphere it’s absorbed and also scattered as direct and diffuse radiation, due to molecules of dust particles, pollutants and aerosols. The light becomes undirected, incident solar radiation. Therefore, the incident power from solar panels is severely reduced – say around 10% already on a clear day. Depending on your location, pollution levels and cloudiness, direct sunlight on a PV array can drop substantially more, depleting your needed energy output.
The Sun’s Position
The azimuth angle and the elevation angle at solar noon are the two key angles which are used to orient photovoltaic modules. To calculate the sun’s position throughout the day, both the elevation angle and the azimuth angle must also be calculated throughout the day. These angles are calculated using “solar time”. In conventional time keeping, regions of the Earth are divided into certain time zones. However, in these time zones, noon does not necessarily correspond to the time when the sun is highest in the sky.
Sun Position Calculator
The position of the sun in the sky can be determined from the observer’s location and the time of day. An alternate calculator for the sun’s path is also available here: PV Lighthouse Solar Path Calculator
Time and Date
The time is given as 24-hour time and the minutes are entered separately. Thus for 5:15 pm, enter 17 in the hour box and 15 in the minute box.
Longitude, Latitude and Time Zone (GMT)
Longitude, latitude and time zone of locations throughout the world are available at www.timeanddate.com. Minutes of longitude and latitude are entered as fractions, so 17° 30′ becomes 17.5. Enter locations with a west longitude as negative. For daylight saving (summer time), subtract 1 hour from the given values. Generally speaking, locations east of Greenwich (UK) are positive and locations west of Greenwich are negative.
There are other services that will determine your approximate latitude and longitude from your IP address. Here: ip2location.com. For a given latitude and longitude http://timezonedb.com/ to calculate the GMT offset.
Sun’s Position to High Accuracy
For flat plate modules the siting is only accurate to a few degrees and errors introduced by simple algorithms are negligible when compared to the unknown factors at the location such as atmosphere effects. For concentrator modules, where the modules track the sun and focus the light, simple equations introduce an unacceptable degree of error. As the concentration increases so does the need for sun tracking accuracy.
For systems with concentration ratios of 1000:1 the sun must be tracked to within 3.5 minutes (0.06°) of arc. One possibility for tracking the sun is to use a look up table based on the Astronomical Almanac or the computer implementation, the Multiyear Interactive Computer Almanac (MICA) available from the United States Naval Observatory. However, such a system would be unwieldy for the micro-controllers used in tracking systems. There are numerous algorithms developed for sun tracking with a trade-off between accuracy and complexity.
Now even small micro-controllers can handle quite complex mathematical formula.The PSA algorithm has been specially optimised in C++ code for micro-controllers and is available at http://www.psa.es/sdg/sunpos.htm. The code has been converted to work with the PVCDROM and is presented below. The PSA algorithm is also implemented the PV Lighthouse Solar Path Calculator.
A further refinement is available at: http://www.nrel.gov/midc/solpos/spa.html
Making Use of TMY Data (Typical Meteorological Year)
The amount of insolation acquired by the module during a certain time interval is one of the main preconditions for designing a PV system. It can be estimated by calculating the position of the Sun in the sky as well as the Air Mass value as shown on the page Calculation of Solar Insolation.
Conductive heat losses are due to thermal gradients between the PV module and other materials (including the surrounding air) with which the PV module is in contact. The ability of the PV module to transfer heat to its surroundings is characterized by the thermal resistance and configuration of the materials used to encapsulate the solar cells – discussed in Heat Generation in PV Modules;