Photovoltaic System Design
Even if you have a great system if it is installed in the wrong location or designed incorrectly you will not get the maximum benefit of having solar power and at worst it will be a complete waste of money.
Panel Location
Shading
If your solar panels are shaded during peak power generation times (9am to 3pm) your system will only generate a fraction of the power it could if the panels were unshaded. Shading hampers electricity generation on a bigger area than the solar cells that are shaded because of the way the electricity current flows through the panel.
North Facing
The best place to locate panels is on a north facing roof at a 30 degree angle. Any change from this will reduce your system's performance. The rule of thumb is north than west than east then south but we would never install on a south facing roof. A flat roof has 88% efficiency but then the panels are more likely to get covered in dirt, in turn hampering their performance. Panels can be mounted on a rack to achieve the ideal 30 degree pitch.
The sales person should determine if you have enough roof space to install the panels on a north (or west) facing roof. As a rule of thumb allow 2m x 4m per kilowatt of solar panels on the roof. The installers can install the panels in one row or several rows, landscape or portrait without reducing the output of your panels.
If panels are put on roofs facing different directions it will generally reduce the output of your panels to the poorer performer at any point in time, see Inverter sizing below for the exception.
Your retailer should advise you where they intend to locate the panels and what impact that placement should have on power generation.
Inverter Sizing
If the inverter is sized incorrectly it could reduce your power generation up to 30% and even damage your inverter. Check that the inverter offered will operate at the wattage range you require. You can use a transformerless inverter if you want to add more panels to your system at a later stage.
Some of the larger and more expensive inverters can cope with panels on different roof orientations without reducing power generation. The inverter needs two independent "Maximum Power Point Trackers". These will allow for the inverter to optimise for each array at the different times of day that energy is being generated at different rates. This technology is more expensive and tends only to be available for larger (4kW) models and quality brands.
