Asking someone how many solar panels you need for your home is equivalent to asking “how long is a piece of string?” The simple fact is that it’s different for everyone. Fortunately, it’s possible to calculate how many solar panels you need, viding you know the variables.
The key, before you start, is to get the contact details of a reputable specialist in solar panels and solar repairs. This will ensure you have the expert help you need when installing or maintaining the panels.
It’s worth noting you’re not alone, an estimated 2 million houses in Australia have solar panels. You’re on the right track!
Your Power Usage
An average solar panel delivers between 150 and 370 watts of power. The exact amount depends on the pane you choose. The lower the wattage the cheaper the panel.
While your budget is going to play a part in choosing panels, you need to know how much power your house actually uses.
It’s possible to go around your house and record the wattage of every appliance. However, as you don’t know how often you have each item on and how much power they actually use this will only tell you the maximum power consumption possible in your home.
Instead, check your meter reading daily for at least a week. You’ll be able to tell how many watts of electricity you use every day and even what days you use more.
This will give you your power requirement. However, it’s a good idea to produce a little more, just to be sure.
For example, if you find that you use 3,000 watts per day you’re going to want one panel at 370 watts to cover this level of consumption. Within 12 hours the panel will have collected 3,700 watts. Equally, three150 watt panels will create roughly the same amount of power in the same amount of time.
Unfortunately, the equation is not quite as simple as that! The above illustration assumes you have sunlight all day and can produce the power as and when you need it. The reality is that power can only be produced in sunlight. The greater the level of sun exposure the more power you’ll be able to create.
You need to look at how many hours of sunlight your house gets per day. This will help you to decide the number of panels you need. With the above 3,000 daily consumption example, if you get 10 hours of sunlight a day you need to produce at least 3,000 watts during that time.
If every panel produces 150 watts then you can produce 3,000 watts for two panels in ten hours. You’ll need a third panel to give you a cushion.
The Usage Factor
However, to complicate things further, you also need to consider the power draw of individual appliances. While the electricity created by the solar panels can be stored in batteries, you need to ensure you have enough to cover needs.
For example, a kettle is usually rated at 3,000 watts. This means if it is allowed to run for an hour it will use 3,000 watts. During the five minutes, it takes to boil it will likely use 250 watts of power. If you have a water heater on at the same time and a stove, you can easily be pulling 750 watts of power. Add in some lights and television and you’ll hit 1,000 watts.
In the above example, you may only need three panels to produce the power you need for the day. But in any given hour the three panels will only create 450 watts, you’ll need seven panels to cover your usage.
The bottom line is that it’s complicated. You should speak to your solar panel supplier and installer before you decide how many you need.