For homeowners who are already convinced of the benefits of solar – the challenge isn’t deciding whether to go solar — it’s optimising your solar setup for peak performance. Whether you’re upgrading an existing system or designing a new one from scratch, this guide aims to provide actionable insights for maximising your solar investment.
This article dives deep into the intricacies of determining the ideal type and number of solar panels for your home.
Our follow on article then looks at if you can actually fit the panels your energy usage needs and determines where to place the panels which you can read here.
A precise solar panel system is tailored to your home’s energy requirements, and the first step toward that precision is having an in-depth understanding of your annual energy consumption. This forms the basis for determining how many solar panels you’ll need and where they should be placed for maximum efficiency.
Many energy retailers provide detailed yearly consumption data via their online customer portals. Logging into this portal will give you a more accurate reading of your energy needs, typically presented in kilowatt-hours (kWh). This data is invaluable for configuring your solar panel system with precision. If you’ve been diligent about keeping past energy bills, you can also calculate your annual kWh usage manually. This gives you a robust dataset to work from and complements the information available from your retailer’s portal.
If you haven’t kept past bills and your online portal only gives you daily kWh usage, you can still get a reasonable estimate of your annual consumption. Simply multiply the daily kWh number by 365 days to get an approximate yearly figure. However, this doesn’t account for seasonal usage changes—such as increased air conditioning in the summer or heating in the winter—so you’ll need to adjust this estimate accordingly.
Energy consumption is not uniform throughout the year. It’s essential to consider the impact of climate on your energy needs. Summer might demand more air conditioning, while winter requires heating. These fluctuations in usage should be taken into account when calculating your annual kWh figure. A buffer for these seasonal variations is advisable for a more accurate solar system sizing.
Once you have reliable data on your annual energy consumption, you’re well-placed to make educated decisions about your solar panel system. This includes not only how many panels you will need but also the most effective orientation and placement to maximise their efficiency. By basing your solar panel decisions on sound data, you’re ensuring a more effective and cost-efficient solar setup tailored precisely to your needs.
When selecting solar panels, it’s not just about quantity but also quality. Consider factors like brands, the colour of panels, and their sizes to find a panel that suits your specific requirements.
Some considerations to take when determining which solar panels to use:
To calculate the number of panels you’ll need, first look at the kilowatt-peak (kWp) rating of a single panel. This rating is a measure of how much power the panel can produce under ideal conditions. Multiply this by the average daily sunlight hours your location receives. Then, take that result and multiply it by 365 days to get an annual figure.
Don’t forget to factor in the efficiency of your solar system, as real-world conditions like shade, dirt, and cloud cover will reduce the panel’s output. Multiply your annual figure by the system’s efficiency, usually given as a decimal (e.g., 90% efficiency is 0.9).
Finally, take your annual kWh needs, which you’ve calculated from your energy bills or your energy retailer’s online portal, and divide this by the figure you’ve calculated. This will give you the number of panels you’ll likely need to meet your energy needs for the year.
Plug in your own figures to tailor this to your needs. Keep in mind that these calculations provide a yearly average and don’t account for seasonal variations or peak energy requirements. You may need additional panels or a battery storage system to ensure sufficient energy during less sunny months or times of high energy use.
Determining which solar panels and the number you require to offset your energy usage is a multifaceted process which involves understanding your energy needs and other elements such as how you want the panels to look. Once you know how many panels you want/need on your roof – the next step is to actually see if you can fit them and work out the perfect panel placement to maximise your return on investment. You can read our follow on article about how to decide where to place solar panels on your roof here.