Rooftop solar – the future of domestic electricity?

Electricity prices and consumer demand for renewable energy has spurred an increase in rooftop solar around the world. This popularity can be seen in countries that typically have many sun soaked days and high levels of solar energy potential such as Australia through to countries in Europe which have a comparatively lower number of warm sunny days and daylight hours.

In Australia over 2 million households have rooftop solar, which is about one in five households.  Over 1 million households in Germany have rooftop solar and demand for battery storage units is increasing.  Each of these countries have very different levels of solar energy potential, but are both reaping the benefits of rooftop solar. 

Solar energy potential is measured as solar irradiation. Solar irradiation is the amount of the sun’s energy that falls on different parts of Earth. Hotter climates nearer to the equator have higher levels of solar irradiance than areas closer to the north or south poles.

It is now the norm to see solar panels on rooftops soaking up the sunshine all around the world, and it is easy to see why. Our rooftops are a large expanse of unused real estate.  It makes good economic sense to use that space to capture the power of the sun and reduce our electricity bills.

On average, households in Australia with rooftop solar save $540 a year on their power bill. And rooftop solar systems pay for themselves in approximately 4 years. While this will vary depending where you live, the long term environmental and economic benefits are substantial.     

How do rooftop solar panels work?

Solar panels work by converting light from the sun into electricity. The solar panels on your roof generate DC (Direct Current) electricity. This is then sent to a solar inverter which converts the DC electricity from your solar panels into AC (Alternating Current) electricity that can be used in your home. 

If the solar system produces more electricity than your household needs, the surplus can be exported back into the electricity grid. In some places electricity fed back into the grid attracts a tariff which means money back in your pocket. 

Alternatively, excess electricity can be stored in a home battery storage unit. If stored in a home battery storage unit, households are able to draw on this stored energy at times when there is little or no solar input, such as at night.  Due to advancements in the electric car sector, home battery storage technology is improving all the time and becoming more affordable.

A number of factors will influence how much energy your solar panels will generate. These include:

  • The amount and intensity of the sunlight
  • The number of daylight hours
  • The position of the panels (known as the orientation and tilt)
  • Shadow or shade that may obscure the solar panels.

Many people are unclear about how much electricity a rooftop solar system will generate or the size system that would be right for them. 

Household electricity consumption varies around the world due to a range of factors such as infrastructure, the size of houses, and the cost of electricity.  The highest electricity consumption per household is in North America and parts of the Middle East, followed by counties like Australia and New Zealand. Most European countries are also above the global household electricity consumption average. Areas below the global average include parts of Asia, Africa and South America, though there are exceptions and pockets of higher household electricity usage in these areas too.

As an example (and subject to a wide range of factors) a 5kw rooftop solar system can generate approximately 20kWh of electricity per day.  This would meet the average daily electricity requirements in most countries, except Canada and the United States. Also if you were a particularly high energy user because, for example, you have a large house that requires heating or cooling, have a pool, or a larger than average number of appliances, you would likely need a larger system to meet your electricity needs.  Please be aware this is an example only and you should talk with your rooftop solar supplier to determine the appropriate system for your needs.    

As countries move away from fossil fuels, and toward renewable energy sources, rooftop solar will continue to be a major contributor in supplying homes with electricity.  Already there are places where networks allow excess energy generated by households to be shared and sold within their communities. In the future this may be the norm, and would substantially reduce our reliance on fossil fuels. 

Why we take action

By turning to rooftop solar and battery storage units we let industry and governments know we want our energy from renewable sources and that these solutions are more cost effective for consumers than electricity from fossil fuels.

How we can take action

  • Get a rooftop solar system and a battery storage unit for your house. 
  • If you can’t afford a rooftop solar system right now, start a savings account so you can install one in the near future.

Clean Energy Council, Clean Energy Australia Report 2019

Choice, 2019, Solar Panel payback time. Retrieved from URL

Enerdata, World Energy Statistics