Thinking about going solar? It’s a great way to save on your energy bills and reduce your carbon footprint. But before you jump in, there’s one big decision to make: What size solar system do you need?
Getting the right size solar system for your home or business is key. If you go too small, you won’t generate enough power, and you’ll still rely on the grid to meet your energy needs. If you go too big, you might spend more than necessary, producing more energy than you can use.
Here in Ballarat, the amount of sunlight we get changes with the seasons. That’s why it’s so important to size your system properly, based on how much energy you use now, and what you might need in the future.
In this blog, we’ll walk you through five simple steps to help you figure out the right system size for your energy needs.
By the end, you’ll have a clear idea of how to get the most out of your solar investment.
Let’s begin.
Step 1: Assess Your Energy Consumption
Before choosing a solar system, it’s important to know how much energy you use. A simple way to do this is by looking at your past electricity bills. Your energy usage is usually listed in kilowatt-hours (kWh). This measures how much electricity your home or business uses.
Review Past Energy Bills
Start by checking your electricity bills from the last year. This will give you a good idea of your average energy usage, both monthly and annually.
- Monthly Usage: Check how many kWh you used each month. Add these up and divide by 12 to get your average monthly usage.
- Yearly Usage: Add up the total kWh from the whole year to see your overall energy consumption.
Knowing how much energy you typically use will help you figure out what size solar system you’ll need to cover your electricity needs.
Identify Peak Usage Times
Think about when you use the most electricity. Do you use more power in summer to run the air conditioner? Or do your bills spike in winter when you’re heating your home? Figuring out when your energy usage is highest is important so that your solar system can keep up during those peak times.
For example, if you use more electricity in summer when the sun is shining, your solar system will generate plenty of energy. But if your usage is higher in winter, you’ll need to plan for shorter days and less sunshine.
By understanding both your average energy use and peak times, you can choose a solar system that’s the perfect size for your home or business.
Step 2: Consider Your Future Energy Needs
When choosing a solar system, it’s important to think ahead. Your energy needs today might not be the same in a few years, so it’s a good idea to plan for any changes that could affect how much electricity you use.
Account for Lifestyle Changes
Think about any changes that could increase your energy use in the future. For example:
- New Appliances: Are you planning to buy new appliances like a bigger fridge, air conditioner, or maybe even a pool heater? These can all add to your energy consumption.
- Home Expansion: If you’re thinking of expanding your home or adding new rooms, you’ll likely use more electricity to heat, cool, and power the extra space.
- Electric Vehicles (EVs): Planning to get an electric car? Don’t forget that you’ll need extra electricity to charge it. EVs can significantly increase your energy use.
By considering these potential changes, you can make sure your solar system is big enough to handle future energy needs.
Energy Efficiency Upgrades
On the flip side, if you’re planning to make your home more energy-efficient, you might need a smaller solar system. Some upgrades that can help lower your energy use include:
- Better Insulation: Improving your home’s insulation can reduce the energy needed for heating and cooling.
- LED Lighting: Switching to energy-saving LED bulbs can cut down on electricity compared to older lighting.
- Efficient Appliances: Upgrading to energy-efficient appliances can help lower your electricity bills.
By thinking about both future changes and energy-saving upgrades, you can choose the right-sized solar system that works for now and the future.
Step 3: Understand Solar Panel Output
Now that you know your energy needs, it’s time to understand how much electricity solar panels can produce. This depends on two main factors: the efficiency of the panels and the amount of sunlight they receive.
Panel Efficiency
Solar panels come in different levels of efficiency, which means how well they convert sunlight into electricity. The more efficient a panel is, the more electricity it can produce with the same amount of sunlight. If you have limited roof space, more efficient panels might be the best choice because they generate more energy from a smaller area.
Keep in mind that higher-efficiency panels often come with a higher price tag, so it’s important to balance efficiency with your budget.
Peak Sun-Hours
The amount of sunlight your panels receive matters too. We call the best sunlight peak sun hours. These are the hours each day when the sun is at its strongest and your panels produce the most energy. In Ballarat, we typically get about 4 to 5 peak sun hours per day, on average.
Peak sun hours change with the seasons, so you’ll get more in summer and fewer in winter. The more peak sun-hours you get, the more electricity your solar system can generate.
System Size Examples
Here are a few common solar system sizes and how much electricity they can produce per year:
- 3kW System: A smaller system that can generate around 4,380 kWh per year. This might be enough for a small home with lower energy use.
- 5kW System: A popular choice for most homes, producing about 7,300 kWh per year, enough for an average household.
- 10kW System: A larger system that generates around 14,600 kWh per year. This size works well for bigger homes or businesses with higher energy needs.
Step 4: Calculate the Size of Your Solar System
Now that you know your energy needs and how much solar panels can produce, it’s time to figure out the right-sized solar system for your home or business. Don’t worry. It’s easier than it sounds!
Simple Formula for Sizing
Here’s a simple formula to help you calculate the size of your solar system:
System Size (kW) = Annual Energy Usage (kWh) ÷ (Peak Sun Hours per Day × 365)
This formula tells you how many kilowatts (kW) of solar panels you need to generate enough energy for your yearly electricity use, based on the peak sun hours in your area.
Example Calculation
Let’s walk through an example. Imagine your home uses 6,000 kWh of electricity per year, and you live in Ballarat, where we get about 4.5 peak sun hours per day. Here’s how you would calculate the system size:
System Size (kW) = 6,000 ÷ (4.5 × 365) = 6,000 ÷ 1,642.5 ≈ 3.65 kW
So, you’d need a system of around 3.65 kW to cover your annual energy usage.
Consider System Losses
In real life, things like shading from trees, dust on your panels, and the efficiency of your inverter (which turns solar energy into usable electricity) can reduce how much energy your system produces. These losses are usually about 10–20%.
To account for this, it’s a good idea to add a little extra to your system size. For example, if you calculate that you need 3.65 kW, rounding up to a 4 kW system will help ensure you generate enough power, even with a few losses.
By using this simple calculation and adding a buffer, you can confidently size your solar system to meet your energy needs.
Step 5: Consult with a Solar Expert
While it’s great to estimate the size of your solar system on your own, talking to a solar expert is a smart final step. They can help fine-tune your system to make sure it’s perfect for your specific needs and situation.
Professional Assessment
Solar experts have the experience to get all the details right. They’ll consider your energy usage and future needs, but they’ll also factor in local conditions like weather, shading, and other things that might affect your system’s performance.
By consulting with a professional, you’ll ensure your system isn’t too big or too small, helping you get the best value and the right amount of energy to cover your needs.
Site Assessment
One of the biggest perks of working with an expert is getting a site assessment. A professional will visit your home or business to figure out the best spot to install your solar panels.
They’ll look at:
- Roof angle and direction: Making sure your panels are positioned to get the most sunlight.
- Shading: They’ll check for any trees or buildings that might cast shadows on your panels, which could reduce their efficiency.
- Space: They’ll measure how much roof space you have and recommend the best layout for your system.
A site assessment ensures your solar panels are set up in the best way possible to maximise energy production.
By working with a solar expert, you can feel confident that your system is sized and installed just right for your home or business.
Factors to Consider Beyond System Size
When picking the right solar system, there are a few other things to think about besides just how much energy you need.
Budget
Your budget will play a big part in deciding the size of your solar system. Bigger systems generate more electricity, but they also cost more upfront. It’s all about finding the right balance between what you need and what you can afford. The good news is, you can start small and expand your system later if needed.
Roof Space
How much roof space you have can also affect the size of your solar system. If your roof is small, you might need to choose more efficient (but possibly pricier) panels to maximise the space. If you have plenty of roof space, you can install a larger system and spread out the panels for the best performance.
Grid Connection
Are you staying grid-tied or going off-grid?
- If you’re grid-tied, you can rely on the grid for backup when your solar system isn’t producing enough power, like at night or on cloudy days. This means you might not need as large a system.
- If you’re going off-grid, you’ll need a larger system (and batteries) to make sure you have enough power stored for when the sun isn’t shining.
Over to You
Ready to go solar? Contact Ballarat Solar and Electrical for a personalised consultation to estimate the perfect size of a solar system for your home or business. We’re here to help every step of the way, from planning to installation.
