Solar System Performance Guide
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Performance Variations and Income Generation
Comparison of solar brands and technologies
As a basic introduction, you can assume that a single kW of Solar Power (facing North at your Latitude with no shading all year) will pay you around $1000 per annum under the NSW Solar Bonus Feed in Tariff (regional NSW).
With the support of Desert Knowledge Australia and the Federal and NT Governments, companies with confidence in their own product have installed panels at an independent test site in Alice Springs. This site has been collecting data for over a year now, and both historic and live system performance can now be viewed at www.dkasolarcentre.com.au
Variances in these popular systems demonstrate that performance is critical when considering what panel you choose and what you pay for you system.
The basic price of a system is only one aspect to consider in a quote, and a common sales trap is that the system performance is not considered.
For example: the information below shows the best performing system's output is just under 6kWh per day (average) in the near perfect location of Alice Springs. In regional NSW the figure is more like 4.5kWh, and even less on the coast. If you are being quoted figures higher than this verbally, ask for them to be guaranteed in writing. Please also note that variations in performance of only 5-10% (as demonstrated by major brands below) will quickly add up to variances in returns of hundreds of dollars, or for 10kW systems, tens of thousands of dollars.
To demonstrate, this video is an introduction to the variances in performance between different products. The graphs below also demonstrate the variances in performances per site that system designers will consider when quoting your solar power system options.
Making sense of performance comparisons
The more detailed section below may help you understand the information presented to you by your Clean Energy Council accredited installer during the quoting process.
The information has been 'normalised' to 1kW of capacity which levels the playing field between technologies and brands. This data can be multiplied to suit the size of system you are considering.
Orientation and Angle of Solar Panels
During quoting, your system designer will take your panel choice and location and then consider;
- The orientation (from North)
- The tilt angle (from horizontal)
- Shading effects
When locating Solar Panels for residential sites there is often a trade off between aesthetics and performance. The variations on performance at different angles and orientations (E, W, N, NW, EW etc) are graphed below.
System power output comparison with variation from optimum orientation of North
Demonstrating $ returns with variations from Optimum tilt angle of 30°
Most roofs are generally set an angle of between 0° and 30° and this graph shows the effect on output of the tilt angle of the panels (from horizontal). This is designed to help you assess whether tilt legs are a worthy investment or even necessary. The best angle to have your panels set at is generally the latitude of your site (NSW is 30° to 35°).
Some more extreme tilt angles for comparison
East and West facing roofs are ok!
If you have ample space on your east or West orientations and no suitable Northern facing roof, the information below shows that putting your panels on Eastern or Western faces can be considered. Graphs below show that East and West arrays perform well during Summer but not so well during Winter - giving an estimated total loss in performance over the year of around only 17%.
Note: The Estimated graphs are generated using local average weather data from a sample site, being Armidale Airport in NSW. Using some standard panel system assumptions. Please note that actual outputs and return will vary for each location and do not consider shading. Assessment of shading effects will require a site visit by your installer.
