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How does our solar-sharing technology, SolShare, compare in terms of cost, against individual solar systems for apartments, units & townhouses?
In this article, we look at upfront cost, lifetime savings and payback periods to determine the ROI of each option.
Australians have some of the highest rates of residential rooftop solar in the world - around 33%!
And around 16% of Australians are now living in apartments but, until recently, there was no feasible way for them to get rooftop solar.
That's why Allume invented SolShare - this world-first, Australian-made solar sharing technology, SolShare, 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 to solar for strata and there are now over 3,000 apartments connected to clean, affordable energy from their rooftops, thanks to SolShare.
The only alternative to SolShare, is to allocate each apartment an equal space on the roof and to install individual solar systems.
But for the vast majority of apartments in Australia, SolShare will have better return on investment - see costing below!
Firstly, let's look at what impacts the lifetime cost of a solar system.
What impacts the cost of solar for apartments?
Total roof space (and therefore solar) available per apartment
Apartment blocks only have so much roof space available and this impacts how many solar panels can fit onto the roof.
Average allocations of 1 – 2kW per apartment are typical. As you increase the amount of solar per tenancy, it has diminishing returns (it’s not a linear increase). For example, increasing allocation from 1.0-1.5kW, will provide a larger benefit than an increase from 1.5-2.0kW.
One of the main benefits of SolShare versus individual systems is that it maximises the amount of solar consumed (more info below). This essentially means higher bill savings (because the energy you feed back into the grid is worth a lot less than the energy you have to buy from your retailer).
Installation costs
Installation costs vary widely depending on the height of the building, roof pitch, roof access, switchboard upgrade requirements and so much more. An installer will always do an in-person site inspection do do a final quote.
Some of these costs are simplified with SolShare, such as wiring & racking; but more importantly SolShare also shares inverters (and batteries if relevant), which add to equipment costs.
Maintenance costs
Additional maintenance costs effect the overall return on investment of the solar system across its lifetime:
- Internet connectivity costs for each and every individual system (generally a sim card plain per inverter ~$100 p/year). Noting that due to Victoria’s backstop mechanism, an internet connection is required to allow any exported solar credits to be obtained by the apartment
- Maintenance of the individual system. Annual or bi-annual checks are recommended. ~$250 p/two years
- Inverter replacement. Assumed an inverter needs to be replaced once out of warranty in a 25 years system. ~$1500-$2500
Building features
Is the building fully electrified or does it use gas too? Fully electrified apartments will see higher bill savings because electric appliances that replace gas, e.g. heating, hot water, stovetops and ovens are high-energy users.
If the building isn't electrified, will it be in the near future? Will electric vehicle charging be added at any stage? If so, it's safe to assume higher energy bills when doing calculations.
The age and efficiency of the appliances within each apartment will also play an impact. Upgrading to smart appliances can huglely improve solar utilisation - see more tips below!
Apartment residents' behaviour and lifestyle
It's important to consider the behaviour of the typical apartment household in question. For example, do people work from home, do they work part-time, are they retired, do they have children?
Behaviour and preferences impact what times we use energy, which is really important in understanding how much solar we'll consume and whether batteries might be improve payback periods.
We’ve found through experience, the average consumption of an apartment in Australia is approximately 14kWh per day, so you can use this if you don't have energy bills from residents.
How will the energy usage of apartments change once they have solar? Will residents be able to move some heavy energy loads to the daytime, timing dishwasher cycles or pre-cooling the space during summer.
Electricity price forecasting
It is common practice to include an increase in electricity prices per annum in calculations. A 4-6% increase in the year-on-year cost of electricity is a safe assumption, as this trends similar to inflation.
Many government solar-for-apartment grants and rebates, required payback periods in years. Ensure this is considered when sizing systems and assessing project feasibility.
SolShare's self-consumption rate is significantly higher
A solar system's 'self-consumption' or 'self-utilisation' rate is instrumental to calculating return on investment, since it impacts bill savings significantly.
Self-consumption relates to the percentage of solar that gets used, versus what is sent back to the grid.
You pay your retailer a lot more to buy energy than they will pay you for selling it back, so the higher the self-consumption rate, the better.
According to Griffith University, a generous estimation of the average annual rate of self-consumption is 36%. That's best case scenario, and typically requires behaviour change from residents.
A SolShare solar system has, on overage, 50% greater self-consumption rate by comparison with indivudal solar systems, including microinverters.
Below is the average self-consumption range for a SolShare solar system by system size:
|
Partially Electrified |
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 using a real-life example, below is a screenshot from our energy monitoring portal, SolCentre, of a SolShare apartment block in New South Wales over a 1 year period (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.
Why is the self-consumptiom rate higher with SolShare?
With traditional solar systems (without a battery), you are only consuming solar when your household is using electrical applicances during daylight hours. The rest gets fed back into the grid, usually for a very low price - around 6c / kWh, compared with ~30c / kWh to buy energy from your retailer.
Apartment buildings with individual solar systems can only access the 2-3 panels of solar that they are connected to, unlike SolShare where 15+ panels can be accessed at any one point in time by a single apartment.
SolShare versus individual solar systems - who's the winner?
For townhouses or blocks of 5 units or less, this may work out better financially when considering the lifetime cost.
But for the vast majority of apartments in Australia, shared solar is going to work out better in terms of the lifetime return on investment for apartments.
Intersted in shared solar for your apartment? Get started below!
Get a shared solar quote for your apartment!
Use our calculator tool below to get a rough idea of the cost of solar for your apartment:
Or enquire below to get a desktop assessment of your apartment block, including upfront cost (with and without rebates applied), monthly savings per apartment and payback period!
