As battery storage becomes more affordable and popular, many early adopters of solar are asking the question:
“Can my existing solar system charge a battery?”
If your solar array is on the smaller side—especially systems installed around 2010–2015—this is an important question to ask before investing in a battery.
Let’s unpack the key factors and take a look at how solar system sizes have changed in Australia over the years.
🔙 A Look at Solar System Sizes Over the Years
Australia has been a global leader in residential solar adoption—but the average system size has grown significantly over time:
| Year | Average Residential System Size |
| 2010 | ~1.5 kW |
| 2015 | ~3.0–4.0 kW |
| 2020 | ~6.5 kW |
| 2024 | ~8.0 kW and rising |
In the early days, 1.5kW systems were extremely popular—especially when generous feed-in tariffs were on offer. They made sense at the time because electricity prices were lower, and panels were more expensive.
But those same 1.5kW systems are now too small for most modern battery setups—particularly if your household electricity usage has increased over the years.
🔋 How Much Solar Do You Need to Charge a Battery?
A few rules of thumb:
- A typical home battery (e.g. 6.5kWh to 13kWh usable capacity) will need significantly more than 1.5kW of solar to charge reliably each day—especially in winter.
- To fully charge a 10kWh battery in a day, you typically need at least 5–6kW of PV, depending on your location and how much energy your home uses during the day.
- Systems under 3kW are usually only able to trickle charge a battery—if at all—after meeting your daytime consumption.
That means a 1.5kW system likely won’t generate enough excess to meaningfully charge a battery unless your energy use is extremely low, and you live in a region with consistently high solar irradiance.
☀️ What About Location?
Solar output varies across Australia, but here’s a rough idea of how much a 1.5kW system might produce annually in different cities:
| Location | Avg. Daily Output (1.5kW system) |
| Darwin | ~7.0 kWh/day |
| Brisbane | ~6.0 kWh/day |
| Sydney | ~5.5 kWh/day |
| Melbourne | ~4.5 kWh/day |
| Hobart | ~4.0 kWh/day |
| Perth | ~6.0 kWh/day |
| Adelaide | ~5.5 kWh/day |
Now subtract your daytime usage (fridge, appliances, etc.), and what’s left? Usually—not much. Which means very little excess energy for battery charging.
🔄 What Are Your Options?
If you have a 1.5kW system and want to add a battery, consider:
- Upgrading or expanding your solar system
Most modern batteries are designed to work with larger arrays, and adding panels will improve your battery’s usefulness and ROI. - Installing a battery-ready inverter with a new system
Many homeowners opt for a full system upgrade—higher capacity panels, modern inverter, and battery integration all in one go. - Start with a load diverter (e.g. hot water)
If you’re not ready for a battery, a solar diverter (like Catch Power) can help you use excess solar in a cost-effective way.
💡 Final Thoughts
While a 1.5kW solar system was a smart choice in 2010 or 2015, it’s unlikely to be able to support a battery effectively today.
If you’re serious about battery storage, it may be time to reassess your energy needs and consider a system upgrade. With panel prices at all-time lows and battery technology maturing fast, now is a great time to build a solar setup that works for the next decade—not just the last one.
Still unsure if your solar system is battery-ready?
We’re happy to assess your setup and help you design a future-proof energy solution.
