Rooftop solar for strata (off-grid)
Rooftop solar for strata requires a far different approach from residential rooftop solar. For starters, every strata member must agree to it, and the roof is strata property.
Strata means you own the title to a flat, unit, apartment, townhouse, or duplex (called a lot). It starts from two lots sharing the same property to thousands of units. You own the ‘interior’ of your lot, although strata can determine policies (by-laws) that may restrict what you can do inside that.
Strata owns the ‘exterior’ common property, including the land, driveway, foyers, gardens, walls, and roofs. It is managed by a Body Corporate, Owners Corporation or an elected management committee that makes decisions affecting all lot owners.
So, it is important to know that you can’t just wack solar on the roof without going through numerous steps. If you do, it may be torn down, and you must pay for restoration.
Before you read on you may be interested in our Rooftop Solar series
- Rooftop Solar Part 1 – where do I begin?
- Rooftop Solar Part 2 – All you need to know before you start
- Rooftop Solar Part 3 – working as it should
Rooftop solar for strata options
Solar takes many forms
- Common areas such as security lighting, pool motor, gates, lifts, etc., reduce Administrative levies.
- Sole use by individual lots (townhouses/duplexes) where it is more likely to be approved to use the roof overhead.
- Shared use between common areas and participating apartments depends on building design and access to sub-boards. Allocating available and productive roof areas fairly between units and having all owners agree may not be easy.
- Solar for shared use for apartments operating as an embedded network. Here, rooftop solar and batteries power the entire complex. Any complex with individual lot meters can use this.

There are some steps that you must take
Please note that CyberShack’s advice is general in nature and may not cover your circumstances.
Why rooftop solar for strata?
The focus must be on the greater good, not just reducing your energy bill. Strata must be unanimous in its wish to pursue environmentally friendly, zero-carbon emission solar power from the sun. Let’s overlook the massive amounts of carbon used to make the panels, batteries, controllers, and sea freight, as 97% of systems are Chinese-made. Or the end-of-life disposal issues for solar panels, batteries, etc., and recycling, which hopefully will be 20-30 years away.
Other prime reasons include that you may live in an area that experiences
- Blackouts (loss of power)
- Brownouts (Undervoltage or flickering lights)
- Transient spikes (Overvoltage),
- Bad voltage harmonics (polluted power resulting in a square wave instead of a sine wave).
These usually happen in older areas where the electricity wires and poles are old and overtaxed by unit developments. However, it can occur in new areas where the trend to all-electric homes can overtax the wires and poles.
Another reason is to provide energy for EV charging. Many unit blocks lack the power infrastructure (cables, local transformers and switchboards) to add hundreds of kilowatts for EV charging. For example, we were quoted $60,000 to upgrade the cabling, local transformer, and switchboard simply to install 3-phase power for a semi-fast community EV charger.
Put a motion to the AGM to investigate solar
Whether your strata comprises a few lots or a major one put a motion to the AGM (or any suitable EGM) to form a sub-committee to investigate installing solar. Make sure you are on it and any other ‘drivers’.
Poll all lot owners
Send a questionnaire to all lot owners to gauge support. Questions to ask include:
- Are you in favour of installing building solar if it is viable? Yes/No/Caveats
- There may be an upfront shared capital cost, offset mainly over time by ‘free’ electricity. Are you able to provide, say, up to $10,0000 capital via a special levy? $10,000 is about the cost of a 5kW system and battery.
- If no, do you agree with Strata obtaining system financing?
- Do you consider somewhere between 5-10 years a reasonable return on investment?
- Are you in favour of the Body Corporate being the grid manager and charging each lot for electricity if it is below energy provider costs?
- Please provide a copy of your past four quarters’ electricity bills. This helps to size the system.
- Will you need EV charging in the next five years? Yes/No/Maybe
As a guide, you a) won’t get a 100% response, and b) those who respond will either be passionately for it or strongly against it. You need about ‘50% in favour. Adding solar is an ordinary motion in NSW, requiring a 50% vote against it to fail. Check your state Strata Laws.
Can’t afford it, or ROI is too long
Some lot owners cannot afford an extra $10000, so consider the Strata getting a loan to pay for all lots and recouping it over 5-10 years. Remember, power from the sun is free, and as long as the strata charges less than energy providers, it may get the project over the line.
Some installers offer a Power Purchase Agreement (PPA) that provides a solar system at $0 upfront cost. Then, lots pay a fixed, indexed rate for power (less than buying from the grid) for a specified term, e.g., 10 years. The PPA provider is responsible for maintaining the system for the term. Remember that the PPA makes the profit that the Strata could.
What size do you need?
The four quarters of electricity bills are a good start. They will show annual usage over four seasons. By analysing the power used for the various tariffs (peak, shoulder, off-peak), you get an idea of when power is used. The majority will be at peak rates from 2 -8 PM and shoulder rates from 7 AM to 2 PM (shoulder). The cheap power is from 10 PM to 7 AM, and that is when you should top up batteries.
If that sounds difficult, put the data (even if you don’t have all the power bills) into a spreadsheet and calculate an average based on bedrooms.
As a guide, 5kW is enough for 1-3 bedrooms but it does depend on air conditioning and water heating costs. Battery backup depends on nighttime and peak period use.
For example:
Let’s say you have 10 units, and they need 15kWh AC per day/night (that is not a lot over 24 hours, especially with AC and all-electric apartments).
Assuming a 20% loss from DC to AC conversion, that is 190kWh or 65 x 400W panels (each panel produces about 3kWh DC on a good sunny summer day) and an area of 130m2 – MINIMUM. The caveat is that the roof direction is largely east/west facing at around 30% pitch (depending on the city). Now, 10 units will have a lower economy-of-scale than 100 units, where that 15kWh AC average may come down to 10kW across all units. It is not disastrous if you are slightly under as you can make that up with battery and electricity grid.
Where are you going to put the panels?
Remember that a typical panel is about 2 x 1m—2 m2. Depending on your building, you could consider a mix of locations: car park shade, building facades, balcony shades, a solar farm, etc. If you use microinverters (on each panel), you can mix and match with different BAPV, BIPV, solar tiles, and even solar glass.

Next, look at battery capacity
There is no case where Strata does not need batteries! Forget Lithium-ion and look at larger-capacity LFP commercial batteries. Beware of new technologies using salt water, zinc bromide, etc.
In our example, let’s say half the use is day and half night. You will need about 8 x 10kWh batteries (half 190kWh). It may be more economical to use larger capacity battery banks, charge them with solar energy, and top up with grid power off-peak.
Don’t forget the other issues
- Flat and concrete roofs will mean additional equipment is required to ballast and tilt the solar panels
- Tall buildings might require crane hire and traffic control from the local council
- If there isn’t space in existing electrical risers (cable conduit that travels vertically up a building), then there could be an extra-long cable run or some costs to drill a core hole through the floors.
Now that you have done your homework, it is time to call estimates based on a written brief
Too many Strata solar committees put the cart before the horse and get an installer involved from the beginning. Sure, they can do a lot of the work, but the outcome is limited to what they know, sell, and will profit most from. One Strata took this step too early and was only given the $100,000 option. By calling quotes later, armed with the knowledge gained, a far better system was closer to $70,000.
It may be fine for a 2-10 lot strata to use a local installer, but larger ones need specialist installers.
System management and billing
System management involves little. Most parameters, like battery off-peak top-up and automatic blackout, are part of a good app. Individual lot consumption is also measured. The main issue is having someone issue and collect quarterly energy bills. Talk to your strata manager as they already issue levy notices for admin and capital works.
Is it ethical for a strata to profit from Solar? – YES
Legally, a lot can choose whatever energy supplier they want (as they have a lot meter) under the Power of Choice legislation.
Strata is generally run as a not-for-profit, but that is more of a philosophy to ensure owners have the lowest running and capital costs. Becoming an embedded network manager means strata can bill less than energy providers and help reduce the ROI on capital costs. Strata must pay for insurance and maintenance unless the installation is exclusively for the benefit of a lot holder. In that case, the lot holder pays for all costs except insurance.
If a lot is tenanted, the owner can re-bill the tenant or agree on a fixed rental increase. It is not wise for an owner to try to try to profit from a tenant.
Advice: Do not rely on Feed-in tariffs for revenue, as these may be curtailed soon.
Do you need a Council Development Application (DA)?
All strata buildings are class 2 (including townhouses and duplexes) and have special requirements for alterations and additions. Cheap installers offering BAPV (Building fixed photovoltaics) that bolt onto a roof will tell you no, but that is very risky. You don’t know if the existing trusses can take the extra weight (20kg per panel), if water drainage will be affected (causing roof leaks), or if the roof pitch and aspect will produce maximum kW output.
If construction is involved, however minor, or you need to change waterproofing, you will likely need a DA. Many Councils have no-fee DAs for solar, so talk to their planning department first.
Our sage advice is to seek advice from a Class 2 Architect or Class 2 Engineer because if a DA is needed, their plans and certifications will assist in getting the required Construction Certificate Commencement and Occupancy certificate.
By-law
A suitable by-law must be added based on the group solar exclusive use schemes. Most Strata solicitors will have a proforma, which should cost <$1000.
CyberShack’s view: Rooftop solar in strata makes sense, but it requires a lot of hard work and determination to achieve.
If you want to drive this—and someone has to champion it—be prepared to spend perhaps hundreds of hours over a couple of years getting the Strata Committees’ final approval.
If there are too many ‘dogs in the manger,’ advise them that the Body Corporate Act encourages sustainable housing. It takes 50% of the lot holders to vote against it, but only a simple majority of those present at the meeting to approve it. Such a vote cannot be based on preserving the appearance of a building.
Or give up and look for a strata with solar!
We don’t have any financial statistics for strata, but we can say from the examples we have seen that ROI is well under 10 years and even shorter for larger installations where greater economies of scale apply.
With the growing demand for all-electric and EVs, it just makes good sense.
rooftop solar for strata, rooftop strata for solar
Brought to you by CyberShack.com.au