Submitted by Andrew on Wed, 01/06/2016 - 06:47
solar panels

It’s a question we hear from potential customers all the time: how many solar panels do I need to install?

Whilst this may seem like the obvious question to ask, it’s actually one of the last answers you’ll get when figuring out the type of solar power system you should install.

What you’ll need to know first is how much energy your home is currently using.

To get the answer to this million-dollar question, you’ll need a copy of your last electricity bill. Look out for your daily average usage as this will be key to uncovering the number of solar panels you should install. Your bill will denote your electricity consumption in kWh (or ‘units’ on some bills). If there is no daily average figure, simply divide the monthly or annual average by 30 or 365 respectively to reveal the daily average figure.


What are your savings expectations?

Do you want to offset your electricity costs, neutralise them or aim to earn a credit from your power company every quarter?

Your savings expectations directly impact the number of panels you should install on your home, as well as other factors such as location and installation conditions. Since solar panels thrive on sunlight, locations with more ‘daylight hours’ (for example, Perth) will require less panels to achieve the same result than areas that receive less daylight hours, such as Hobart.

Other influential factors impacting on energy production include solar panel shading, orientation (the way they’re facing), changing seasons and weather conditions. Your solar power retailer may add a small buffer on top of your average daily production to offset these factors.


Finding the right system to meet your need

To work out what size system you should install (e.g. 3 kW, 5 kW, 7 kW etc.), you’ll need to crunch some numbers.

Each kW of solar you install will produce around 4 - 4.5 kWh per day (depending on the aforementioned factors). To ascertain the size of the system you need, just divide your daily consumption by this amount.

E.g.: 14.3 kWh (daily average) / 4.5 kWh = 3.1 (3 kW system)

Your solar retailer can help you calculate these figures as well as tell you the average daily kWh production of your proposed system.


Choosing the right solar panels

There are plenty of solar panels on the market to choose from, but only a handful of them will provide a long, efficient (and painless) experience. If you’re trying to decide between premium and cheap solar panels – don’t miss this blog covering the topic.

We recommend installing solar panels that fall into the top two tiers of quality from manufacturers that have Australian support for customers.


How many solar panels do you need for your home?

Once you’ve decided which solar panel model you’re going to install, you can divide the total kW required by the output of each panel.
This will reveal how many panels you need to install on your home.

Remember that not all panels are the same size – in terms of physical size as well as output. In the case of solar panels in the output range of 250 W - 265 W (which are quite common), you would need 12 panels for a 3 kW system.

E.g.: 3 kW / 250 W x 1000 = 12


Don’t forget

Solar panels will produce electricity whilst the sun is up and what you don’t use, you sell back to your retailer. Your retailer will only give you between 5c and 10c for each kWh (or unit) you send back to them. Factor this into your calculations, because if the majority of your consumption is at night, you’re not going to get the financial benefits you desire, despite producing enough energy to cover your usage.

To increase your savings, you need to use the power you produce and reduce the amount you export.

Clever design can help with this. For example, installing panels on the western aspect to increase afternoon production, suiting families that run an air conditioner or cooking appliances later in the day. Other tricks include load shifting – which is a fancy way of saying ‘using more electricity during the day’ (as opposed to night). This could include pool cleaners, washing machines or dishwashers whilst output from solar PV is at its highest.


For more information about solar panels, our team of experts are here to help!