In Australia, solar panels will produce the most energy over the course of a year if facing north. This is especially important in winter when the sun is lower in the northern sky.
Technically, the panels should be tilted north for maximum performance. However, by tilting the panels, the performance is basically only shifted from summer to winter. So if you have a flat roof and are using more electricity in the summer, it makes more sense to leave the panels nearly flat with just a slight slope to ensure rain flows off the panels and does not collect on the surface. If you have a pitched roof, we will always install the panels in line with the roof.
If your house has a north-south roof line with the option to install the panels east or west, we can install panels on both sections of the roof depending on what time of the day you are using the most electricity. For many families, they will use more electricity in the afternoon when the kids come home from school and the air conditioning and pool pump are on. In that case we would install your solar panels on the west roof, or we could do a split system with most of the modules facing west and some facing east.
We can split up your array using Enphase microinverters. This can also help avoid shade later in the afternoon, as pictured below. You can see in this picture that we are using 3 sections of roof with each row of panels giving off power at different times throughout the day. By dividing the modules in this way, the output of solar energy is distributed over the day, which makes it easier to use more solar energy as there is not such a large peak in the middle of the day:
The other point that can affect the decision to install panels is that your energy trader will sometimes charge tariffs based on usage time (ask us for help if you are not sure). This usually only applies to households in the Ausgrid range (roughly in the eastern half of Sydney):
A solar system will peak when the sun shines directly on the panels. For a north-facing array, this will take approximately 4 hours during mid-day.
The graphic below shows a system installed on a north-west facing roof with some shade in the early morning. This is a good guide to a Sydney solar system, especially if you have a billing time when electricity is most expensive after 2pm on weekdays in summer. You can see in the graphic how the system continues to work until 7 p.m. in the fall, if you've installed the panels on a roof that catches the late afternoon sun:
The other important point to take away from this picture is that a 5kW system almost never reaches its peak performance. This system achieved a maximum output of 3.84 kW and still produced 29.1 kWh of output over the day:
For a 5 kW system to produce almost 5 kW at the same time, it has to be the right time of day and the right season, which is very rare. In this example the system is installed on a tile roof with a normal slope of about 20 degrees. There are 19 panels, all of which face northwest. This helps to extend the output into the late afternoon as shown in the graphic above. In Sydney, panels installed flat work closer to their peak efficiency in summer because the sun is so high in the sky.
The peak power of this system on a sunny March day is only 3.84 kW. Even in March, this 5 kW system will typically produce around 30 kWh per day, which is well above the Clean Energy Council's guideline of 19.5 kWh.
Contact the Solaray team today for more information. We can help you develop a system that makes the most of your roof and energy usage patterns: