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Install solar for common areas


Energy from solar panels can be used to power equipment and appliances in common areas.

Installing a solar system can reduce energy bills and provide your building with emissions-free electricity. Appropriately sized systems can pay back your up-front investment within five to nine years.

A solar system can power common property appliances in apartment buildings like foyer lighting, air-conditioning, pool pumps and lifts. Typically there is just one energy bill for common areas; which is paid for collectively by the owners corporation and may be passed on through strata management fees or levies.

A small 2kW system could offset some of the energy consumed by the common property in your building, and might cost around $4,500. A large 10kW system might cost around $18,000.


  • Owners corporation: approves expenditure and authorizes the project
  • Technical expert – recommends design and size of your solar system
  • Solar installer – installs the system and provides warranty and arranges grid connection
  • Electricity retailer – sets the feed-in tariff and bill structure
  • Electricity distributor – connects the system to the grid
  • Local council: provides planning approval if required and general assistance


It’s a good idea to start with a small solar project first. Designed correctly, you will be able to show other apartment owners that the investment has lowered energy bills whilst reducing your impact on the planet. Over time, you can build up larger solar projects, potentially even delivering power to individual apartments.


Check your apartment building for places where solar panels could be mounted: the roof, external walls, facades, or even above windows. Solar panels need as much sun a possible so ensure surrounding buildings or trees will not overshadow them. Consider where the shadows of buildings and trees fall at different times of the year, and watch out for smaller objects such as TV antennas. If even one panel is shaded, the performance of other panels can be severely impacted.

Your panels perform best when they face the sun. North-facing panels generate the most energy but it’s okay for groups of panels to face in different directions.

The average solar panel is about 1.6 metres long and 0.8 metres wide. A 1kW solar panel system will require around 8-10 square metres of space, a 1.5kW system requires around 12 square metres of space and a 10kW system requires around 60-64 square metres of space.


One of the first questions you’ll need to answer is: Who owns the roof, wall or façade where the solar panels will be installed? Generally the roof and external walls on strata buildings are collectively owned by the owners corporation. This is good for common-area projects, as the owners corporation can fund the installation and benefit from the reduction in electricity bills.

Building structure

Solar panels must be mounted securely to resist high winds. Most roofs and external walls are strong enough, but the installer will check this. If you or your installer have any doubts, it is best to obtain advice from a structural engineer. Some roofs, walls and facades require specialised equipment to install or maintain solar systems, for example, a high-rise apartment block or steeply pitched roof can mean a more expensive installation.

Where panels are easily accessible to residents, they should be fenced off for safety purposes.

Waterproofing membranes

Some roofs and walls have a waterproofing membrane. Penetrating the membrane when installing solar panel should be avoided wherever possible. There are less invasive solar panel mounting systems designed specifically for flat roofs.

Where membrane penetration cannot be avoided, they should be kept to a minimum. Consideration should also be given as to how a membrane would be repaired or replaced in future. It is best to discuss waterproofing with your solar installer and determine who is responsible if leaks occur.


In strata buildings, shared walls between apartments are often rated for fire-proofing. You should check with the installer about whether solar cabling would compromise this. It may be possible to lay the cabling externally. Any penetrations holes that might impact on fire safety separation between apartments, or between apartments and common areas, should be discussed with the building’s fire services company.

Planning permits

Check with your council to ensure the local planning requirements allow for solar. A planning permit is not usually required unless your building has heritage significance and is covered by a Heritage Overlay in your local council area planning scheme.

Understand energy use

You may need to consult an expert to determine the right size solar system for your building. Alternatively, an installer may also offer advice. You will first need to understand how much energy is being used by common property in your building.

  • It’s a good idea to complete the ‘Understand energy bills’ project in Smart Blocks at this point
  • Or you could enter the details of your Strata energy bills into your ‘Building Profile’ by clicking on the 'My building' button Smart Blocks website

The quickest way to estimate energy use is to look at your common area electricity bills for the past year. Divide the total annual number of kWh used by 365 to get an average daily consumption.

To get a more accurate understanding of electricity usage, contact your building’s energy retailer or distributor to ask for the interval data recorded by your electricity meter. To do this, you will need to quote the National Meter Identifier (NMI) number from your common area electricity bill or the meter itself. Interval data will show you how much electricity is being used at a paricular time on a particular day and can be used to build a usage profile for your building. Employing an energy consultant to help analyse energy use in your building can reduce the workload on the owners corporation and ensure the best financial outcomes.

Choose the right solar system

You’ll want the size of your new solar system to match the daytime energy usage of your building’s common areas.

When you obtain a quote from an installer they should estimate how much energy your solar system will generate and recommend a size that matches your building’s average daily energy use. This will ensure you get the best value from your investment within a short payback period. You will need to supply energy bills for the past year, or better yet, data from your electricity meter.

Energy generated by your new solar panels will either used immediately within your building, or fed into the mains grid if it is not required by your building immediately. Solar energy generation varies by season – with greater output in summer than winter. Larger systems and locations with greater sunshine and higher temperatures also generate more energy.

A typical solar panel has a rating of 250 watts and is 1m x 1.7m. If your building has limited space you might consider using high-efficiency panels, which cost more than standard panels but generate more electricity per square metre.

Choose a trusted supplier

  • Ensure your solar supplier is accredited by the Clean Energy Council
  • Ask lots of questions, the Clean Energy Council has some tips and a list of questions to help when choosing a supplier
  • Choose a supplier with experience in designing and installing similar systems for apartment buildings, and seek references from those buildings
  • Obtain at least three detailed quotes and ensure your quotes are for the same size system
  • Seek independent advice on panel quality from your local sustainability organisation (eg Alternative Technology Association)
  • Ask for detailed contracts and agreements
  • Insist on seeing the warranty details (products and service) before signing
  • Ensure local suppliers are available to fulfil any warranty claims that may arise in the future

Visit the Smart Blocks ‘Contractors and quotes’ page for more information and templates you can use for requesting a quote.

Insurance and maintenance

Check with your building’s insurance company to understand if the installation will impact insurance premiums. After installation, notify the insurance company to ensure the solar system is covered.

It’s useful to know that the responsibility for the solar panel and inverter warranty ultimately resides with the manufacturer, but that the workmanship and installation warranty resides with the supplier. 

One of the great things about solar systems is that they need minimal maintenance. For small systems an annual visual check is recommended, looking for panels that are damaged or loose, with a thorough inspection by a solar installer every five years is also advisable. For larger systems your facility manager should be briefed by the solar installer about maintenance. An outline of maintaining larger solar systems can be found on the Facility Management Magazine blog.

Replacing inverters

Generation will decline slightly as your solar panels age, but should still be above 80 per cent of their original rated capacity after 20 years. Check the warranties provided on both the panels and inverters to ensure they have adequate guarantees.

Taxation and depreciation

The installation of solar systems can generate income or credits on an owners corporation’s electricity accounts. Your owners corporation may also be able to claim depreciation on the new system, which could have a positive impact on any cost-benefit analysis. Owners corporations should clarify the income tax and depreciation implications of any new system with their accountant with a view to the Australian Taxation Office Ruling No. IT 2505.