The answer depends on your personal circumstances aside (e.g. available roof space), however, we can answer this in a general sense.
Conventional wisdom says that in the Southern Hemisphere you should install North-facing solar panels because they are more exposed to sunlight and will generate more electricity as a result.
Contrary to this advice, iO Energy recommends that you install solar panels in the following order of preference:
- West-facing,
- East-facing,
- North-facing, and finally
- South-facing.
This will both future-proof your system and reduce Australia's carbon emissions.
Why does iO Energy's advice differ from conventional wisdom?
The reasons are economic and environmental.
Economically speaking, electricity generated in the evening and morning is more valuable than electricity generated during the middle of the day because of supply and demand. Demand tends to peak during the evening and morning, so electricity generated by West and East-facing panels tends to be more valuable than alternatives. Conversely, North-facing panels are now common enough that there is often an oversupply of energy during the middle of the day.
Environmentally speaking, West and East-facing solar panels will reduce the amount of fossil fuels that are needed by widening Australia's solar envelope. To illustrate, at 1pm in South Australia renewables generate an average 85% of the energy consumed, but only 42% of the energy consumed at 7pm.
In short, North-facing solar panels generate electricity at and around midday when electricity generation is less valuable economically and less needed environmentally. Whereas West-facing solar panels can generate energy as late as ~8:30pm when electricity is more in demand and will help to reduce the amount of fossil fuels being burned to make energy.
Why do other companies still recommend North-facing solar systems?
In the early days of solar adoption, feed-in tariffs were high(ly subsidised). Buyers maximised their return on investment by exporting electricity to offset energy costs, rather than self-consuming the electricity produced. North-facing systems earned more at this time because they generated more electricity overall.
Today, feed-in tariffs are no longer subsidised and the oversupply of solar power