If you are considering installing solar, it is important to understand what the right sized solar system for your needs is. The size of the solar system relates to the amount of electricity it can generate, and the right size depends on a number of factors like the amount of sunlight or the type of roof you have, as well as your household’s energy consumption patterns. We explain how to calculate the right size solar system for your property and factors that affect the solar system size.
What Is Meant By Solar System Size?
Solar system size refers to the total power generating capacity of the solar panels or the amount of electricity a solar system can produce. This energy production is typically measured in watts (W) while multiple panels are determined in kilowatts (kW). The total solar system size is measured by adding the number of solar panels in the system and their individual power ratings in ideal conditions. The size of a solar system that had 10 solar panels each rated at 350 W has a total solar system size of 3500 W or 3.5 kW, for example. A higher efficiency solar panel which can produce more energy per square metre than a low efficiency solar panel, would have fewer panels but still be measured at the same size.
How To Calculate What Size Solar System To Install
To calculate the size of the solar system there are a number of factors to take into account from household electricity consumption all the way to budget. We look at what to consider when calculating the size solar system you need here.
- Electricity consumption: The first step is to understand your electricity consumption. The more energy you use, the bigger the solar system you will need. To do this, look at your electricity bill over the last 12 months. The electricity will be measured in kilowatt hours (kWh) which is the measurement of how much energy is used over a period of time. A kW is the rate of electricity usage. Write down the number of kWh used in a month and multiply it by 12 to get the average yearly consumption. Divide that number by 365 to work out average daily consumption. The average household of 3 people consumes about 18.71kWh per day.
- Consider time of day and seasonal usage: Take into account when the most electricity is used during the day and during what seasons. It is important to understand energy consumption patterns to determine the right sized solar system and if you will need to invest in a battery. If the bulk of your energy usage is during the evening as most people are out during the day, solar panels may not be used as effectively without a battery. If you use most of your energy during the day, then match your solar system size to the amount used during the day, or at different times of the year.
- Consider future usage: Solar panels have a long lifespan of about 25 to 30 years, so consider what might change in that time. Some future needs that will increase or decrease the amount of power you require include having a family, adding a swimming pool, hvac systems, or getting an electric vehicle.
- Consider the environment and amount of sun exposure: The climate and amount of sunlight solar panels will receive needs to be considered when choosing a solar system size. The average amount of sunlight a solar panel needs per day to operate efficiently is 4 to 5 hours. A house that receives a good amount of sun exposure will need fewer panels and thus a smaller solar system to produce the same amount of energy. Similarly, a home that has less sunlight exposure or more cloud cover will need a bigger system to produce the same amount of energy. To find the average daily sunlight hours for your area, you can use the Bureau of Meteorology Climate Data online.
- Consider roof orientation and angle: Solar panels work better on a roof that faces north as they capture more sun exposure. East and west-facing panels can still generate significant energy, though they may experience a slight decrease in efficiency compared to north-facing panels which means the solar system size may need to be larger. The roof angle can also impact solar system size. As a rule a roof that has an angle of between 15 and 35 degrees is ideal for maximum sunlight capture. A flat roof will probably need brackets to create the correct angle.
- Consider available roof space: Roof space is an important practical factor in the size solar system you install. A large sized solar system can generate more power but it also requires more roof space. Most average 6.6kW solar systems require about 30 square metres of roof space if using standard panels. Higher efficiency panels like monocrystalline require less space so may be the best option if roof space is limited.
- Consider battery storage: If you are going to install a battery immediately, you will probably need a larger solar system to meet your energy requirements during the day and evening. If you do have a battery, you will need enough solar panels to directly power your appliances 24 hours a day, rather than just during daylight hours. Without a battery, you may be able to install a smaller solar system.
- Consider budget: When considering the size solar system you need, how much they cost will come into consideration. With any big purchase, it is important to consider your budget as solar panels are a financial investment. Larger sized solar systems will generally cost more than smaller systems due to the increased number of panels, solar installation and inverter size. The average 6.6kW system costs around $6,000 to $10,000. Solar rebates reduce that price significantly, however, with the Small-scale Technology Certificate program offering generous reductions Australia wide. In Tasmania, residents are eligible to receive STCs valued at $2,080 for a 6.6kW solar system. Additionally, if you install a system that is too small, while the initial cost may be less, it can also lead to lower energy production, shorter lifespan, and potentially higher maintenance that will cost you more in the long run.
How Big Should Your Solar System Be?
The average size residential solar system is 6.6kW as this suits a medium sized home with moderate energy consumption. How big a solar system should be depends on a number of factors including energy consumption and sun exposure which all impact the amount of electricity a solar system can generate. It is often a good idea to install a solar system that is slightly bigger than your current needs if your budget allows. A larger system will produce more electricity, leading to lower energy brought from the grid, decreased bills, and a faster payback period. It can also accommodate for future electricity needs like the addition of a swimming pool or an electric vehicle. The size of the solar system directly impacts the amount of energy it will produce. The average 6.6kW system will produce 23.8 to 26.4 kWh of electricity per day depending on weather conditions and other factors. The table below shows approximate energy output per solar system size.
| Average Daily Production in Tasmania | ||||||
| System Size | 3kW | 5kW | 6.6kW | 8kW | 10kW | 13kW |
| Energy Produced (kWh) | 10.5 | 17.5 | 23.1 | 28.0 | 35.0 | 45.5 |
Who Can Help Calculate What Size Solar System To Install
There are two methods to assist with calculating the size of the solar system you need. One is using the expert advice of a solar retailer, and the other is using an online calculator.
- Solar Retailer: Your solar retailer will be able to explain and identify the best sized solar system for your needs. As experts in their field, they can determine the right sized system to ensure it operates at peak efficiency. When discussing the size of the solar system with your retailer, provide them with your electricity usage, future plans for energy needs, and budget. The solar retailer will visit your property and assess the size, condition and orientation of the roof, and any shading issues to determine the best solar system size for your home. With this background information, your solar retailer will design the most optimal solar system for your home. You will receive a detailed quote which will include the right sized solar system for your needs.
- Online Calculator: Online calculators help determine the right sized solar system for your needs by taking into account factors like electricity consumption, sunlight availability and potential savings. To use an online calculator simply look up solar system size online calculator, input your address or postcode, household energy use details, roof space information if you have it, and roof orientation. The calculator will give you an approximate size for your needs. For a more detailed assessment, contact your solar retailer.
When investing in a solar system one of the important considerations is choosing the right size. The size of your solar system will determine how much electricity it generates and how much money you can save on power bills. The aim when installing a solar system is for it to be as energy efficient as possible. To ensure maximum efficiency, our article explains how to work out what size solar system to install. By taking into account your current and future energy consumption, the amount of sunlight exposure and roof type, you can get a greater understanding of the size of the solar system you should consider. For expert advice and a professional assessment of the right solar system size, contact the team at Tasmanian Safer Solar.
 1300 655 808
