What size solar system should you buy?

There is no ‘one size fits all’ approach when it comes to solar systems. In fact, every household is unique in the way it uses energy, how it can accommodate solar power, and how much it is willing to budget for a new solar panel system.
When you first start investigating various systems, you’ll immediately notice that solar systems have different performance outputs. Look for the PV level, or how much power you can expect your system to produce in ideal conditions on any one day. A 5kW system, for example, will produce 5kW (that’s 5000W) of power in ideal conditions.

The 100% offset model

One way of determining how big your system should be is to determine exactly how much energy you currently use, and then find a system that matches that. You won’t have wasted any money on a bigger system that produces more than you need, and you’ll never be left high and dry. It’s a simple method and a good place to start.

The formula:

By looking at your latest bill, you’ll be able to find the total kWh used in the past year. Divide this by 365 to get your daily usage. Here in Adelaide, we can expect to get 4.2kWh per installed kW os solar panels. Divide your daily usage by 4.2, and this is the size of solar system that will perfectly offset your usage.

Key considerations

Anticipating future usage

This should be considered the bare minimum, if your goal is to offset your usage entirely. In many cases, upgrading to a larger system can be a financially sound move, as it can cost a little more for much more potential gain. As solar continues to rise in popularity, and is adopted on a larger scale, more and more people are opting to ‘future-proof’ their system, going for bigger and better because they know that it won’t be long before they can use it for any number of other things.

Changing weather conditions

One year’s usage is not necessarily the most reliable indicator of future usage. It may be that you had a particularly sunny year, or that you’d just pruned the tree that normally blocks some of the sun from hitting your roof. Remember that the kWh size of the system only indicates how much energy it will produce in ideal conditions.

The best way to give yourself the peace of mind that you’re selecting the right size and output system for your home and family is to discuss your needs with a trained technician.