Installing solar on a single house is pretty straightforward, but what happens when you have multiple buildings on the same property?
Whether it’s a granny flat, a big shed, or a detached garage, solar can work across multiple structures, but there are a few challenges to consider.
At PSC Energy, we know how difficult it can be to have a vision for your solar, only to have it dashed by technical considerations. Fortunately, we’ve been installing solar for over a decade. We’ve encountered every technical limitation imaginable and helped customers get their ideal solar system regardless of them.
In this article, you’ll learn about the following:
- Understanding How Electricity Flows: The Path of Least Resistance
- Understanding Electrical Metering for Multi-Dwelling Solar
- Solar on Granny Flats: Shared vs. Separate Systems
- Installing Solar on a Shed: Key Considerations
- Battery Storage for Multi-Dwelling Solar Systems
- Comparing Battery Solutions for Multi-Dwelling Installations
- Technical Considerations: Voltage Rise, Electrical Design, and Trenching
By the end of this article, you’ll know about the big questions that usually revolve around metering, battery storage, and wiring configurations.
Understanding How Electricity Flows: The Path of Least Resistance
Electricity is lazy. It always follows the path of least resistance, meaning it will naturally flow where it encounters the least amount of opposition. It “flows” like water. Understanding this concept is crucial when designing a solar system that powers multiple dwellings.
When we talk about upstream and downstream in an electrical setup, we are referring to how electricity moves through the wiring.
If a solar system or battery is installed at a certain point in the electrical circuit. In that case, it can only supply power to anything downstream from it, anything that is connected after it in the flow of electricity.
However, it won’t send power upstream to wired components before it in the circuit.
This principle is why metering, wiring configurations, and switchboard placement are so important when designing a multi-dwelling solar system.
If you’re interested in learning a bit more about power and energy, you might want to check out the following article titled, Power vs. Energy: kW vs. kWh.
Understanding Electrical Metering for Multi-Dwelling Solar
Before installing solar on multiple buildings, the first thing to check is how your property is metered. If all the buildings share a single meter, it’s much easier.
You can install solar on any roof, and the energy will flow where it’s needed.
But if there are separate meters, things get tricky.
Scenario 1: Separate Meters
Many granny flats and secondary dwellings have their own smart meters, completely separate from the main house. If this is the case, the solar system on the house won’t power the granny flat, and vice versa. Each building’s electricity usage is measured independently by the energy retailer.
One way around this is to remove the separate meter and combine everything under one. The solar system will power both buildings and distribute energy efficiently.
However, removing a separate meter isn’t always simple. It requires approval from your energy retailer and some rewiring by a professional.
Scenario 2: Shared Meter
Integrating solar is much easier if both buildings are already on the same meter. You can install panels on either structure, powering both buildings.
This is the best-case scenario for homeowners who want a shared system without additional complexity.
If you’d like to learn a bit more about smart meters, you might want to check out the following article titled, Smart Meters and Solar.
Ready to go solar? Click here.
Solar on Granny Flats: Shared vs. Separate Systems
A lot of homeowners want their solar system to supply both their house and their granny flat, which makes sense. But the big question is: should you install one system for both or keep them separate?
If your goal is to maximise solar efficiency and self-consumption, then a shared system on a single meter is the way to go.
- This setup ensures that excess solar energy is used wherever it’s needed, whether in the house or the granny flat.
- It allows for better overall energy management because solar power can be used across both buildings without restrictions.
This setup is especially beneficial if both dwellings are occupied by the same household or family members who share energy costs.
However, keeping the solar systems separate makes sense if you want independent billing or metering.
- This is particularly useful for rental properties or situations where the granny flat is occupied by tenants who pay their own electricity bills.
A separate system ensures that each household is responsible for its own energy consumption, making it easier to track usage and costs.
Another factor to consider is future-proofing. If the granny flat is being used for the family now but could be rented out in the future, a separate system might be the better option to avoid complications down the line.
On the other hand, if it will always remain part of the main household, a shared system is likely the most cost-effective and practical approach.
Ultimately, the decision comes down to how the energy will be used and who will pay for it.
If you’re interested in learning a bit more about the importance of monitoring and programming your energy, you might want to check out the following article titled, What is Consumption Monitoring?
Installing Solar on a Shed: Key Considerations
Many homeowners consider installing solar on their shed rather than the main house, because the shed gets better sunlight or simply has more roof space.
While this can work, your property’s electrical setup will determine how effective the system is.
There are three common ways electricity flows between a house and a shed:
- The mains go from the street directly to your house first. If your house is the first point of connection to the grid, installing solar on the shed means running a dedicated cable from the shed back to the house’s switchboard. This allows solar power from the shed to be used in the house, but it does require proper cable sizing and additional electrical work.
- The mains go from the street to the shed first, then feed the house. Solar installation is much simpler if the shed is the first connection point. Solar power generated on the shed will naturally flow to the house because electricity follows the path of least resistance. This is the best-case scenario for installing solar on a shed without extensive rewiring.
- Both the shed and house are connected separately to a private switchboard or pole. This is where things get tricky. If neither building is upstream of the other, the solar system on the shed won’t directly supply the house, and vice versa. In this case, you might need to install separate solar systems or reconfigure the electrical wiring to unify the energy flow.
If you’re installing just solar, any of these scenarios can work with the right wiring adjustments.
However, if you’re adding a battery, the setup becomes much more important because battery power can only back up downstream circuits. It also requires consumption metering to work. That’s the real challenge.
If you’re interested in learning a bit more about the benefits of solar batteries, you might want to start with the following article titled, 7 Benefits of Adding a Battery to Your Solar System.
Power up your savings. Click here.
Battery Storage for Multi-Dwelling Solar Systems
Batteries add another layer of complexity to multi-dwelling solar systems, mainly because of blackout protection. A battery can only back up the circuits that are directly connected to it.
That means if your house and shed are wired separately, a battery installed in one won’t help the other during a power outage.
For example, if your house and shed are both wired back to a private pole, putting a battery on the house won’t necessarily provide backup power to the shed. That’s because the battery is wired only to protect the circuits downstream from it.
If you want battery backup for both, you’ll need to design your system around these electrical constraints carefully.
One option is to make sure the building where the battery is installed is the first point of connection from the mains. That way, the battery can provide power to anything wired downstream.
Another solution is to install multiple batteries, each serving its own building. This can be expensive but might be the best option if rewiring isn’t practical.
Your battery placement is just as important as where you put your solar panels. Understanding how electricity flows and how it behaves during an outage will help you get the most from your investment.
If you’d like to learn a bit more about the cost of SigenStor, we recommend you check out the following article titled, How Much Does the Sigenergy SigenStor Cost?
Comparing Battery Solutions for Multi-Dwelling Installations
Tesla Powerwall 2 vs. Powerwall 3
The Powerwall 2 featured a Neurio meter, which was a useful tool for homeowners who wanted to track solar production and energy consumption across multiple buildings.
This remote metering allowed better integration of solar power between dwellings, making multi-dwelling solar setups easier to manage.
However, Tesla decided to discontinue the Neurio meter with the release of Powerwall 3. Instead, Tesla is developing its own power meter, which is expected to be available in Q2 or Q3 of 2025.
This new meter should restore some of the lost flexibility for multi-dwelling installations, but for now, Powerwall 3 is limited in monitoring energy use across separate buildings.
Sigenergy SigenStor Advantage
If remote monitoring across multiple dwellings is a must, Sigenergy’s SigenStor battery currently has the best solution on the market.
It offers a remote meter with an impressive 400m range, making it a strong choice for homeowners who need seamless energy tracking between buildings.
This feature allows homeowners to monitor and control solar production and consumption across multiple structures, making it one of the most flexible battery solutions for multi-dwelling setups.
Enphase Battery Limitations
Enphase has made a name for itself in the solar industry, particularly with its microinverters, but when it comes to battery storage across multiple dwellings, it has some limitations.
The Enphase Envoy system allows monitoring of solar-only setups across multiple buildings but it does not support battery integration between separate dwellings.
If you choose an Enphase battery, you’ll need to install it on the specific building where the energy is being consumed.
This means if you have solar on both a main house and a granny flat but only one battery, you won’t be able to share stored energy between them. Unlike Sigenergy, which offers a remote metering solution, Enphase currently lacks this capability.
If you’d like to learn more about the price of a Powerwall 3, you might want to check out the following article titled, How Much Does a Tesla Powerwall 3 Cost?
Let’s talk solar savings. Click here.
Technical Considerations: Voltage Rise, Electrical Design, and Trenching
When installing solar across multiple buildings, voltage rise becomes an important factor. Voltage rise occurs when solar energy causes a slight increase in electrical pressure as it travels through wiring. If not managed properly, it can cause the system to throttle its output.
In the Endeavour Energy network, voltage rise is limited to 2% total, with no more than 1% per leg of wiring. This means careful calculations are needed to ensure compliance and system efficiency.
If you need to run solar between buildings, trenching might be required to install the necessary cables. Before trenching, consider:
- Existing underground services – Check for water mains, electricity lines, and irrigation systems.
- Concrete surfaces – If your property has concrete driveways or pathways, you’ll need a concrete cutter before trenching.
- Cable sizing – The longer the run, the larger the cables need to be to prevent voltage drop.
If you’re interested in learning a bit more about voltage rise, you might want to check out the following article titled, Everything You Need to Know About Voltage Rise.
Let’s go solar today. Click here.
We Shingle-handedly Love Installing on Multiple Dwellings
Now you know a bit more about installing solar on sheds, granny flats, and other structures. Installing solar across multiple dwellings is completely doable but requires careful planning.
At PSC Energy, we want you to have a seamless, efficient system designed for your needs and goals. A well-designed system will ensure you get the most out of your solar investment, whether you’re powering a granny flat, a shed, or both! We’re here to take care of it for you. It’s what we do.
If you’re interested in learning a bit more about the solar battery rebate, you might want to check out the following article titled, Everything You Need to Know About the Home Battery Rebate for NSW.
