A PV system is comprised of two main components; the solar panels themselves and an inverter. The inverter changes DC power from the panels to AC power like what comes out of your plug socket.
A typical PV system will use a ‘central’ inverter which is a large unit that is connected to all your solar panels. Usually this is mounted at eye level in a garage or on the side of a house under cover.
Figure 1: Central Inverter System
In the case of a micro inverter system each panel or pair of panels has its own much smaller inverter mounted underneath the panel on the roof. The outputs of these are then combined together and fed down to the house’s main switchboard, the same as a central inverter system.
This type of configuration has advantages over a central inverter configuration mainly in efficiency because each panel is operated individually rather than as a group but is more expensive for the same size system.
Advantages:
- Shading of small number of panels doesn’t cause whole system to lose performance since all panels are operated individually
- Panels can be placed on different orientations and pitches without compromising efficiency
- Higher efficiencies as each panel/pair of panels is managed individually.
- No single weak link able to affect all the panels
- Reduce losses from longer DC wire runs
Disadvantages:
- More expensive than central inverter systems
- More individual hardware pieces that can fail
- Longevity of systems may be reduced from long term exposure to high temperatures on rooftops
In general homes with large roof faces and no shading issues would be best with a typical central inverter system. However, if your home has multiple roof facings and suffers from shading on parts of the roof area it may be more economical in the long run to look at micro inverter systems.
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