Australians have some of the highest rates of residential rooftop solar in the world at about 33% — around 16% of us now live in apartments, but until recently, rooftop solar wasn't feasible.
With the cost of solar panels decreasing, various government grants and solar-sharing technology such as SolShare, the adoption of solar for multi-dwelling buildings is scaling rapidly.
SolShare is a world-first, Australian-made technology that divides the electricity from a single rooftop solar system and shares it fairly between apartments each month.
This overcomes many of the technical, legal, and financial barriers of solar energy for strata.
SolShare is the dominant technology for apartment residents, having connected over 5,000 apartments (as of December 2024) to clean and affordable energy - SolShare had over 85% market share in Victoria's Solar for Apartments grant, which closed in February 2025.
Individual solar systems are like those you find on standalone homes. If an owners' corporation wanted to connect individual systems, they would need to allocate a roof area for each apartment, and each solar system would require its own inverter.
It's important to specify both upfront and ongoing costs to determine the ROI.
SolShare delivers a better return on investment for most apartment buildings in Australia —the only exception is townhouses or blocks of five units or fewer.
We've modelled a 12-unit apartment block in the table below to illustrate this.
| With SolShare | Individual Systems | |
| Upfront cost | $65,000 | $65,000 |
| Annual ongoing costs | $240 | $2,480 |
| Annual net savings of 12 apartments | $8,928 | $5,760 |
As you can see, SolShare provides a much more favourable return on investment for most apartments in Australia due to the higher monthly bill savings and lower maintenance costs.
SolShare pays itself off in under 10 years, whereas individual systems would take closer to 20 years.
The upfront cost varies depending on the number of apartments, but it is usually similar. What you pay for the solar-sharing technology is normally offset to some extent by simplified wiring and fewer inverters required.
Net savings breakdown:
A SolShare system allows residents to consume more energy than individual systems connected to each apartment, which translates into more bill savings —we explain how below!
A solar system's 'self-consumption' or 'self-utilisation' rate is instrumental in calculating return on investment because it significantly impacts bill savings.
It's nearly impossible to use all the electricity your solar system generates without a battery. You'd be lucky to utilise 30%, even if you attempt to use high-energy appliances during the day.
You want to use as much of your system's solar power as possible because you pay your retailer much more to buy energy from them than they pay you to sell solar energy back.
On average, a SolShare solar system has a 55-75% greater self-consumption rate than individual solar systems, including microinverters.
Below is the average self-consumption range for a SolShare solar system by system size:
|
|
1-1.25kW |
1.25-1.5KW |
1.5kW-1.75kW |
1.75-2.0kW |
|---|---|---|---|---|
|
Partially Electrified |
40 - 70% |
30 - 65% |
25 - 60% |
25 - 60% |
|
Fully Electrified |
45 - 75% |
40 - 70% |
35 - 65% |
35 - 65% |
To illustrate this with a real-life example, below is a screenshot from our energy monitoring portal, SolCentre. It shows stats of a SolShare apartment block in New South Wales over the course of one year (from November 2023 to October 2024 inclusive):
As you can see, the utilisation rate (solar consumed divided by solar delivered) is roughly 56%, much higher than it would have been with individual systems.
With traditional solar systems (without a battery), you only use solar energy when your household operates electrical appliances during daylight hours. The surplus is fed back into the grid, usually at a very low price—around 6c/kWh—compared to >30c/kWh to purchase energy from your retailer.
Apartment buildings with individual solar systems can only access the 2-3 solar panels they are connected to, unlike with SolShare, where a single apartment can access 15+ panels at any time.
SolShare has more households to supply energy to at any one time, allowing much more of the energy it produces to be utilised compared to individual systems. Its algorithm ensures that everyone receives their allocated share throughout the month.
Apartment buildings have limited roof space, which affects the number of solar panels that can be installed on the roof.
Typical allocations of 1 to 2 kW per apartment are standard. As you increase the solar capacity per tenancy, the returns diminish (it’s not a linear increase). For instance, boosting the allocation from 1 to 1.5 kW will yield a greater benefit than increasing it from 1.5 to 2.0 kW.
One of the main benefits of SolShare compared to individual systems is that it maximises the amount of solar energy consumed, asmentioned above. This essentially translates to greater bill savings because the energy you feed back into the grid is valued significantly less than the energy you purchase from your retailer.
Installation costs can vary significantly based on factors like the building's height, roof pitch, access, need for a switchboard upgrade and others. An installer will always carry out an in-person site inspection prior to providing a final quote to ascertain these factors.
SolShare simplifies some of these costs, such as wiring and racking, and more importantly, it enables each unit to share the inverters (and batteries, if relevant), which adds to equipment costs.
Additional maintenance costs influence the overall return on investment for the solar system throughout its lifespan:
The costs outlined above must be covered by each apartment for individual solar systems, rather than being paid just once with SolShare.
Additionally, multiple individually owned systems on a commonly owned roof create complexities in ownership. For instance, if one owner has their system serviced by an installer and damage occurs to the roof, where does the liability rest? With SolShare, the responsibility lies with the owners' corporation as a whole.
*Note that, due to Victoria’s backstop mechanism, an internet connection is required for the apartment to obtain any exported solar credits.
Is the building fully electrified, or does it also utilise gas? Fully electrified apartments will experience greater savings on bills because electric appliances that replace gas heating, hot water systems, cooktops, and ovens are high-energy consumers.
If the building isn't fully electric, will it be soon? Will electric vehicle charging be implemented at any point? If that’s the case, it's reasonable to expect higher energy bills when making calculations.
The age and efficiency of the appliances in each apartment will also affect solar utilisation. Upgrading to smart appliances can significantly enhance solar utilisation—see more tips below!
It's important to consider the behaviour of the typical apartment household in question. For instance, do people work from home or part-time? Are they retired, or do they have children?
Behaviour and preferences influence the times of day we consume energy, which is crucial for understanding how much solar we'll use and whether batteries could enhance payback periods.
Based on our experience, we’ve discovered that the average electricity consumption of an apartment in Australia is about 14kWh per day, so you can use this figure in your calculations if you don't have energy bills from residents.
Once solar is installed, residents might be able to shift some heavy energy loads to the daytime, timing dishwasher cycles or pre-cooling the space during summer.
It is common practice to include an annual rise in electricity prices in calculations. A 4-6% increase in the year-on-year cost of electricity is a reasonable assumption, as this reflects expected inflation.
Many government grants and rebates for solar in apartments require specific payback periods, so ensure this is taken into account when sizing systems and assessing project feasibility.