How does your solar system work

Australia has installed more than 3.3. million rooftop solar systems, by far a world leader for a decade or more. Rooftop solar generation has overtaken coal generation and it is the largest clean energy generation in the country, reaching 20GW in 2023. There are numerous brands and types of solar photovoltaic (PV) systems available and new technologies are constantly being developed. 

Solar PV works only when there is sunlight and backup power can be provided by the main electricity grid, a battery, a generator or a combination of them.

The main considerations for installing solar PV include the upfront cost, any rebates and incentives, money saved on energy bills, and money earned through feed-in tariffs. 

A solar PV has 2 main components: the solar panels and the inverter.  

Solar panels contain "cells" made out of silicon which convert sunlight to direct current (DC). Solar cells can be: 

• Monocrystalline cells (high conversion efficiency of 15 - 21%)
• Polycrystalline cells (lower efficiencies of 13 - 17%)
• Thin film cells made from spraying silicon onto surfaces. Efficiencies are much lower and costs are generally higher.

Inverter converts the DC electricity produced by the panels to AC electricity that can be used in the home. There are 4 types of inverters: string inverters, micro inverters, battery-only inverters and hybrid inverters. 

 A solar system can be stand alone, connected to the grid, with or without a battery. the size of the system takes into account: 

• Your expectations regarding electricity usage;
• How much energy you use, when you use it and future electricity consumption needs?;
• How much sunlight can you expect in your region and on the roof of your home?
• How much roof space is available for panels?
• Financial capacity.

In grid-connected systems, the rated output of the inverted influences the power delivered from the solar panels. Often, the distribution network restricts the inverter to 5 kilowatt hour (kW).
In stand alone systems with storage,  the battery should be located as close as possible to the PV array to minimise power loss.  

Panel orientation - panels should be installed so they receive maximum sunlight, thus facing north. Facing panels north-east/east or north-west/west will generate more electricity in the morning or afternoon, when your electricity demand is likely to be higher.

Tilt angle - if you typically use more energy during peak times and want to reduce the impact of time-of-use electricity prices, then facing your array north-north-west and installing it with a greater tilt angle may be best. This is likely to generate more energy during peak times and offset peak energy use, but may reduce your total annual energy production.

Shading and ventilation -  Sometimes shading can reduce the voltage of the entire string of modules if they are arranged in parallel. If shading is an issue, strings should have their own independent inputs. Monocrystalline cells perform better in heat than polycrystalline cells at 25 degrees C, however, the output is decreased by 0.44% for each additional degree.

Mounting array -  Modules can be installed on the ground, on a wall or roof with a frame mount, or integrated into the building fabric. Most roofs have an optimal angle