Here’s a very common question that comes in to SQ HQ.
“My roofline is North/South, so my roof areas face either East or West. I know North Facing is ideal, but I don’t have a North facing roof! Should I put my solar panels on the East or West Facing roof (or both) ?”
Short Answer: Probably West
Longer Answer: In terms of the amount of power produced, facing your panels East will produce exactly the same amount of power as facing them West. In either case you’ll generally take a 10-15% power hit compared to having them facing the ideal direction (North).
So why do I say “probably West” as the short answer to the question?
Well, the reason I err on the West facing roof is because that part of your roof will get the sun later in the day. An East Facing solar array will generally produce its peak power at 10-11am. A West Facing array will produce its peak at closer to 2pm.
Most people use more energy later in the day. And most people want to use as much of their solar energy as possible, without exporting it. Why? Because at the time of writing most Feed In Tariffs give you less per kWh if you export the electricity than you pay for imported electricity. So most people will pay off their solar system quicker if they minimise exports.
Here’s a much more detailed explanation of how solar energy is exported depending on the time of day.
So if you face the panels West, and you are a typical family (in terms of electricity usage patterns anyway!), and your FiT is less than your retail electricity price, then West facing Solar Panels makes more sense than east facing.
In fact, if you live in a State with a really miserly FiT (hello NSW & WA !) then it may actually make more financial sense to face your solar panels West rather than North! To work out if this is the case you’ll have to get a good feel for when in the day you use electricity, then estimate how that will affect what % of solar power you export. Then you can use my solar power payback calculator to see which configuration pays back quicker.
Or if that sounds like too much trouble – you could always engage a good solar power sales person / installer to do the analysis for you. And asking them to do this is a great way to filter out the not-so-hot sales people out there!
Time of Use Electricity Pricing is Coming!
One more reason to consider West facing panels is that many people (me included) believe that in the near future everyone will be forced on to Time of use (TOU) electricity pricing where you pay differing amounts per unit of electricity depending on when you use that electricity.
For example Energy Australia‘s weekday TOU tariff costs 18c per kWh from 8am to 2pm, and a whopping 44.7c per kWh from 2pm to 8pm.
If you were on a similar tariff, it could make a lot of sense to push your solar power generation to later in the day, where every kWh of solar power you use is worth 2.5 times more!
The key is to find a solar installer or salesman that understands this stuff.
All this talk of Feed In Tariffs, TOU tariffs, and solar panel orientation can start to overload your brain when you combine it with trying to choose an installer and solar panel and inverter hardware. I feel your pain! The answer, as I mentioned above is to find a solar company that asks the right questions:
1) What times of day do you use your electricity?
2) How much do you use?
3) What kind of electricity tariff are you currently on?
So that they decide which panel orientation is right for you based on numbers (not a Wild Assed Guess!) and also so they can provide accurate payback calculations that take into account the ridiculously varied Feed In Tariffs in every state.