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SOLAR SYSTEM COMPONENTS

 PV Solar systems are quite simple systems. They comprise the following main components;

  • PV panels or modules. The solar industry call these modules, whereas most people in the street call them panels--as that is what they look like.

  • Inverters. These convert the DC power of the modules to AC power that can be used in your house. There are two styles of inverters the traditional string inverter and now micro-inverters. See below for a more detailed explanation of these.

  • Rooftop isolators. In Australia the regulations require a rooftop isolator to be installed for each array. (Australia is probably the only country in the world that requires this and the merit of this is often questioned.)

  • Module Racking: These are the structural components that support the modules and attach them to your roof. Generally they are made from aluminium and there are about 6 main suppliers / manufacturers of this product in Australia.

  • Cabling and switches etc. The balance of system (BOS) is made up of cable, switches, conduit, support cables, screws etc. These must all be suitable for the high UV environment in Australia and also weather proof to a set standard to eliminate water ingress.

INVERTERS

There are two main types of inverters and they are both used extensively in Australia. The traditional inverters are called String Inverters and the latest innovation  Micro-inverters. The attributes of these are outlined below;

STRING INVERTERS

In a system using a string inverter there is only ONE inverter converting the DC power of a "string" of modules, into AC power that can be used in your house or business. The string is likened to a garden hose, whereby if you squeeze a hose the flow of water is reduced. Similarly if one module has low performance, then the whole system has low performance.

The technology for string inverters is very mature and the reputable brands are of high quality and perform very well. There is also a very competitive market for string inverters and they are generally well priced.

The main issue with string inverters is that they have limited ability to monitor systems and usually no ability at all to verify individual module performance. Although a poor module will show up as affecting the entire system, a general system fault, but of course a lot of work then needs to be done to find the faulty module.

 

MICRO-INVERTERS

Quite a number of micro-inverter systems have been developed but only a few have survived in the market place. The leading microinverter is by Enphase.

Micro-inverters work in a distributed manner. Each module will have it's own micro-inverter, tucked in underneath the module and usually attached to the racking system. The micro-inverter manages only module and because of this the performance of the module is optimised and is not affected by any other modules or inverters in the system.

The micro-inverter converts the DC power from the module into AC power actually on the roof which is much safer and cheaper to deal with in regards to isolation and cabling. One of most important features of micro-inverters is that condition monitoring of each module and inverter is always ongoing and the integrity of the system can be determined for all main components at any time. For the Enphase system this is available to the owner and the installer/maintainer of the system via an internet portal.

The down side of micro-inverters is that they are more expensive than string inverters and they do increase the overall system complexity, although they are generally easier to install and simpler to commission than a string system.

 

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