Switching to solar is one of the smartest investments for homeowners looking to cut energy costs. But installing the right number of solar panels is important. Too few won’t generate enough power, while too many could cost more than necessary.
The best setup depends on your energy use, location, and the type of panels you choose. This guide will make it easy to figure out the right number of solar panels for your home.
What Affects the Number of Solar Panels You Need?
Many homeowners expect a simple answer when figuring out how many solar panels they need. But getting it wrong could mean higher electricity bills or spending too much on panels you don’t actually need.
A few key factors influence how much power your system can generate and how efficiently it runs. Understanding these details will help you make the best decision.
Solar panel systems come in different sizes and configurations, depending on energy needs and roof space. Exploring solar system installations can give you a better idea of what setup works best for your home.
Your Home’s Energy Consumption
Your home’s electricity consumption is the biggest factor in determining how many solar panels you need. In Australia, the average household uses about 18.71 kWh per day, or approximately 561 kWh per month. However, this can vary depending on several factors.
- Household Size: Larger families typically use more electricity. A four-person household averages around 21.36 kWh per day (about 641 kWh per month).
- Climate and Location: Homes in colder areas, like Hobart, consume more power due to heating needs, averaging 25.96 kWh per day (779 kWh per month)
- Appliances and Lifestyle: Energy-intensive appliances like air conditioners, electric water heaters, and pool pumps can significantly increase energy consumption.
Checking your electricity bill will give you a clear idea of your monthly energy usage. Once you know your average kWh consumption, you can move on to calculating how many solar panels you need.
Solar Panel Wattage and Efficiency
Not all solar panels produce the same amount of power. The wattage and efficiency of a panel determine how much electricity it can generate, directly affecting how many panels you need for your home.
Solar panel wattage refers to the amount of power a panel can produce under ideal conditions. Most residential panels range between 300W and 400W, but higher-wattage panels can generate more electricity, meaning you need fewer panels to meet your energy needs.
Efficiency measures how well a panel converts sunlight into electricity. Standard solar panels have an efficiency of 15% to 22%, with higher-efficiency panels generating more power in the same amount of space. If your roof has limited space or your home gets less sunlight, choosing high-efficiency panels can help you maximize energy production.
The combination of wattage, efficiency, and sunlight hours determines how many solar panels your home needs. Higher-wattage and more efficient panels reduce the number of panels required, while lower-efficiency options may require more panels to generate the same amount of power.
Sunlight Hours in Your Location
The amount of sunlight your home receives is crucial in determining the number of solar panels you’ll need. According to Australian Bureau of Meteorology, Brisbane receives an average of approximately 5.2 peak sun hours per day.
This means that, on average, each square meter of solar panel in Brisbane receives about 5.2 hours of full-strength sunlight daily. This high level of solar exposure makes Brisbane an excellent location for solar energy generation.
Homes in areas with higher peak sun hours, like Brisbane, can generate more electricity with fewer panels compared to regions with less sunlight. By considering Brisbane’s specific solar exposure, you can design a solar panel system that efficiently meets your household’s energy requirements.
Roof Space and Solar Panel Placement
Your roof size and layout affect how many solar panels you can install. Key factors to consider include:
- Orientation: North-facing panels in Brisbane receive the most sunlight, while east- and west-facing panels may require more to generate the same power.
- Tilt Angle: The ideal tilt is 26 to 28 degrees for maximum efficiency.
- Shading: Trees, chimneys, or nearby buildings can reduce energy production. Microinverters or power optimizers help minimize losses.
- Limited Roof Space: High-efficiency panels generate more power in less space, making them a great option for small roofs.
A solar installer will assess these factors to design the best system for your home.
How to Calculate How Many Solar Panels Do You Need
A simple calculation can help you determine the right number of solar panels for your home. By considering your energy usage, sunlight hours, and panel efficiency, you can estimate how many panels you need for an efficient system.
Basic Formula to Calculate How Many Solar Panels Are Needed
To estimate how many solar panels you need, use this simple formula:
Daily Energy Use (kWh) ÷ Peak Sun Hours ÷ Panel Wattage (kW) = Number of Panels
Example Calculation for a Brisbane Home:
- Daily energy use: 18.7 kWh (based on 561 kWh monthly consumption)
- Peak sun hours: 5.2 hours per day
- Panel wattage: 400W (0.4 kW)
18.7÷5.2÷0.4=9 panels
This estimate may vary based on factors like shading, panel efficiency, and future energy needs. A professional assessment can provide a more precise calculation.
Adjusting Based on System Type (Grid-Tied vs. Off-Grid)
The number of solar panels you need depends on whether your system is grid-tied or off-grid. The grid refers to the main electricity network that supplies power to homes and businesses. Grid-connected solar systems can draw electricity from the network when solar production is low, while off-grid systems must generate and store all the power they need.
- Grid-Tied Systems
- Connected to the electricity grid, allowing access to backup power.
- Require fewer panels since the grid supplies extra energy when needed.
- Excess energy can be exported for feed-in tariff credits, lowering electricity costs.
- Off-Grid Systems
- Operate independently without access to the electricity grid.
- Require more panels and battery storage to maintain power supply at night or on cloudy days.
- Need careful planning to ensure enough energy is generated and stored.
Grid-tied systems are the most common and cost-effective option, while off-grid setups are ideal for remote locations without grid access. Choosing the right system ensures your solar panels generate enough power to meet your needs.
Choosing the Right Solar Panel System for Your Home
Selecting the right solar panel system goes beyond just choosing the right number of panels. The type of panels you install affects efficiency, space requirements, and overall cost. Incentives and installation costs also play a major role in making solar more affordable. Understanding these factors will help you make the best choice for your home.
Monocrystalline vs. Polycrystalline vs. Thin-Film Panels
The type of solar panel you choose determines its efficiency, durability, and price.
- Monocrystalline Panels
- Highest efficiency (18-22%), requiring fewer panels.
- Work well in limited roof space.
- More expensive but long-lasting.
- Polycrystalline Panels
- Mid-range efficiency (15-18%).
- More affordable but require more space.
- Suitable for homes with larger roofs.
- Thin-Film Panels
- Lightweight and flexible.
- Lower efficiency (10-12%), requiring more panels.
- Ideal for non-traditional roofs or portable solar setups.
For most homeowners, monocrystalline panels offer the best balance of performance and longevity, especially if roof space is limited.
Incentives and Installation Costs
Solar panel systems can be a big investment, but government incentives and rebates help reduce costs.
- Small-Scale Renewable Energy Scheme (SRES) – Offers Small-Scale Technology Certificates (STCs) that lower upfront solar costs.
- Feed-in Tariffs (FiTs) – Earn credits for excess solar power sent back to the grid, reducing electricity bills.
- State and Local Rebates – Additional programs may be available depending on your location.
Installation costs vary based on system size, panel type, and installation complexity. On average, a 6.6kW system in Brisbane costs between $5,000 and $9,000 after incentives.
Getting multiple quotes from accredited installers can help you find the best deal while ensuring a quality installation.
Get a Custom Solar Panel Estimate
Every home has unique energy needs, and the best way to determine how many solar panels you need is with a custom assessment. While general calculations provide a good estimate, factors like roof size, shading, and panel efficiency can impact your system’s performance.
A professional solar installer can analyze your electricity usage, location, and budget to design a system that maximizes savings and efficiency. Getting multiple quotes ensures you find the best deal while taking advantage of available incentives. With the right setup, you can reduce electricity costs and enjoy the long-term benefits of solar energy.