How Solar Power Works

How Solar Power Works Diagram

Most Australians are connected to the National Electricity Grid, a network of electric cables and transformers that links power generating stations to your home.

A Grid-Connect Solar Photovoltaic (PV) System acts as a mini power station on your roof, feeds power to your home, and surplus power back to the Grid.

Solar systems for domestic homes generally consist of solar panels, an inverter and a metering system.

Most solar power systems use PV modules (panels) installed on a rooftop to create and collect energy from sunlight.  An inverter converts the Direct Current (DC) electricity generated by solar panels into Alternating Current (AC), the form of electricity conventionally used in homes.  The system is connected through a meter to the grid.  Solar systems allow you to use your solar power when it is generating electricity during the day and put any excess back into the grid.  As soon as you need more electricity than your system can generate, your electricity will automatically be supplied from the grid.  At night, your house draws energy from the grid.

Solar panels

Solar cells are produced from thin wafers of silicon.  When light falls on the cells an electric current is produced.  A collection of solar cells connected together forms a module.

Most homes or commercial buildings will need around 10 square metres of unshaded, north-facing roof space to mount the modules for a 1kW solar system.  Ideally the modules should be tilted towards the sun at around 30 degrees to maximise the solar collection.

Inverters

You will need an inverter to convert the direct current (DC) power collected by the solar panels into power for your home, or power to send back to the electricity grid.  It can be placed inside or outside your home and can give you information about the amount of electricity being produced by your system.

Meters and the grid

You still need to be connected to the electricity grid to ensure that you have electricity at night-time when no solar energy is being collected.  A meter will also enable you to sell back excess electricity.  A new digital smart meter will be fitted to your system as part of the solar installation.

For safety reasons, when your electricity supply from the grid is interrupted, your solar PV system must automatically and immediately turn off.

Power and Energy

A quick overview of power and energy

Power is an instantaneous value and is measured in watts (W).

Energy is a measure of the electrical power consumed and is measured in watt-hours (Wh).

 

ie.  Energy (Wh) = Power (W) x time (hrs)

One watt, or for that matter 1 watt-hour, are very small measures.

 

In most cases, power and energy production (and usage) are measured in kW and kWh.

1 kW = 1000W   &   1kWh = 1000Wh

 

For example, a 100W incandescent light globe uses 100W of power.

If the light is left on 24hrs per day the energy consumed is

100W x 24hrs = 2400Wh or 2.4kWh per day

 

If the light is left on 6hrs per day the energy consumed is

100W x 6hrs = 600Wh or 0.6kWh per day

 

 

All about Solar Photovoltaic

Why we need clean energy

Australia's stationary energy sector, which includes electricity derived from coal-fired power, is responsible for around 50 percent of our greenhouse gas emissions.  Australia's environmental, economic and energy security is at risk from climate change unless we can compete in a low carbon world.  Any successful climate change solution must first target the energy sector.

Australia has some of the world's best clean energy sources, many of which are already powering Australian homes and businesses.  Our superior clean energy resources, like solar power, have the capacity to meet Australia's growing energy needs while providing a clean powered, sustainable economy.

Solar photovoltaic - how it works

Solar photovoltaic (PV) panels are usually found on the rooves of homes and businesses.  The panels harness the sun's energy to generate zero emission electricity.  Light energy is converted directly into electricity by transferring photon energy into electrical energy.  The conversion takes place within cells of specially fabricated semiconductor crystals.

While it might be true that solar cannot generate electricity all the time, it does generate electricity when it is needed most - during peak demand hours of the day, such as hot, periods when we all run air-conditioners.

Having solar panels is like having a mini power station on your roof.  PV electricity is generated at the point of demand - where people live and work, which means there is no need to transfer the energy long distances across expensive infrastructure.

Greenhouse gas savings

Solar power is a zero-emission electricity source.  One megawatt hour (MWh) of solar-derived electricity avoids approximately one tonne of CO2.

In Australia

As at the end of July 2009, more than 41,000 homes across Australia have solar PV installed.  At the end of 2008 we have over 100 megawatts (MW) of solar PV capacity installed nation-wide.  This is almost 0.7% of the global installed capacity.

Solar PV has a long history of supplying reliable 'off grid' power to remote and regional Australian communities.  Around 70 percent of all PV installations are currently off-grid.  However, with the introduction of recent government incentives, the number of grid-connected solar PV installations has grown and now accounts for about 30 percent of Australia's total installed capacity.

Potential

Australia is blessed with the highest average solar radiation of any continent in the world,which means our solar industry has the greatest potential to lead the world.

With the right federal policy in place providing incentives for take-up, we can ensure continued growth of Australia's solar PV industry.  Plans for Australia's first large scale solar PV power station are due to become operational in 2013.

Global View

Globally, the annual solar PV market grew to 5,500 MW in 2008.  The total cumulative PV power installed globally at the end of 2008 was almost 15,000 MW 9,000 MW in 2007.  Germany, Spain, Japan and the USA dominate the solar PV industry up from accounting for 80 per cent of global capacity.  The growth in these markets and the emergence of new markets in France,South Korea, Czech Republic and Portugal has driven a sixfold increase in global installed capacity over the last fiveyears.

At the end of 2008, Germany had the highest level of cumulative installed capacity of solar PV with around 5,300 MW installed, followed by Spain with 3,200 MW, Japan with 2,100 MW and the USA with almost 1,200 MW.

Growth of solar PV around the world can be directly attributed to the legislated support provided by various governments.  The development of feed-in tariff (FIT) schemes in countries such as Germany,Spain and Italy sparked rapid take-up of solar PV.

Current Issues

A feed-in tariff is a payment made by your utility for the electricity produced by a solar PV system.  A gross feed-in tariff pays you for all the clean electricity your system produces and a net feed-in tariff only pays you for the excess electricity fed back into the grid.  A number of Australian states have legislated feed-in tariffs but we are yet to see national consistency.

Credits

Written by Robert Arends, Camp Management Committee. 09 April 2012
Large chunks sourced from: http://www.1millionwomen.com.au/blog/read-more-generate-your-own-solar-electricity-at-home/ (19 September 2012) on 09 April 2012
Other sections are my own words.