What Size Solar System Do I Need? How to Find Your Solar Fit

Roughly sizing up a solar system is easy; solar power can save you around $400 per kW per year, and a solar system will output around 4 times its size as a daily average.

For example, a 5kW system will output around 20 kWh a day and may save you up to around $500 every quarterly power bill. For many households, this rule of thumb is good enough to answer the question of ‘how much solar do I need?’

As solar power prices continue to fall and battery storage is now a realistic option for most households, we are now starting to size up nearly all of our solar systems to match your 24-hour usage rather than guessing how much solar you could use during the daytime.

Once you know how much solar power you will need across an average day, you can then work out how many panels you will need to generate that amount of power. Most solar good panels are now rated 400W per panel, with highly-efficient panels being around 400W-420W. The solar panel size is around 1.7m by 1m.

Generally, high-efficiency modules are more expensive per panel, however, because you need fewer panels for the same output it is often recommended to choose a panel such.

As an example, if you decide to go with a 10kW solar system for your home, you could then choose to install 24 x 415W panels, rather than 29 x 350W panels.

It is recommended that you spend a bit of time on the phone so that we can discuss the various options and help you understand the value of the different technology (and price points). Click here to request a callback.

We understand there is a lot of misinformation out there when it comes to sizing up a system, and this isn’t helped by salesmen trying to up-sell customers to large solar systems that they don’t need. So let’s have a look at sizing up a solar system in detail.

Perhaps this is an obvious statement, but solar power only works during the day. Without battery storage (which is now available), solar power needs to be used in the home as it is generated, otherwise, it automatically feeds out to the grid.

The other option if you have time-of-use billing is to add the usage during the peak billing period with the shoulder billing period. This will give you your usage from 7 am until 10 pm, which you can then multiply by 0.7 (or so) to give you your daytime usage.

On top of the baseload, you then have the ability to use appliances during the day. Have a look at the average daily usage figure that is on your power bill – how much of this can you move to the daytime to run on solar power? Without solar power, you may be running appliances at night during the off-peak billing period, or you may be paying little attention to when you use your power as you pay a flat rate for your power. How much power can you use during the day without too much hassle?

The biggest users of power in a typical home include:

Generally, we advise not to worry too much about lights when considering solar power. They use very little power compared to the items on the list above and are typically on at night.

Also, keep in mind that your power consumption will often change on the weekend, during the weeks of holidays you have each year and the odd day off from work here and there.

One final point – keep an eye on the future. A surprisingly large number of people we speak to are getting solar now while they are employed, in preparation for retirement or in expectation of a baby, when the mum (or dad!) will be home all day using power.

The output of a solar system depends on which way your roof is orientated, and now we are getting into the specifics of maximising the benefit of a solar power installation. The 1KOMMA5° Team will often advise people to go for a split array. Yes, having the panels facing north is best, however, this creates a rough bell curve of output where you get a peak generation period during the middle of the day. Are you going to be able to use most of the solar power most of the time if you have an output curve like in the image below?

Look at google maps (or get out a compass) to see what roof sections you can install solar panels on. Anything north of west or east is usable.

Panels facing east will output more power in the morning and panels facing west will output power in the afternoon. Compared to North, panels facing east or west will not output quite as much over the course of a year, however, losses are not that great, being more significant in winter when the sun is lower in the sky to the north. The 1KOMMA5° Team have access to detailed aerial photos, and we can accurately measure your roof and provide advice based on that. For more information give us a call today on 1800 052 749. We can help you size up a system in less than 10 minutes.

In most cases, it can be a good idea to have two strings of panels giving you two smaller peaks of output. This makes it easier to use most of the solar power most of the time, and this is how you can maximise the benefit of your system and hence reduce your return on investment.

According to Renewable Energy World, shading of as little as 9% of a solar system connected to a central inverter, can lead to a system-wide decline in power output by as much as 54%.

The below image is a great example of how micro inverters can significantly increase output. In this image, the system will be working at near maximum output, despite the patchy shade. With a string inverter, the system will be outputting almost no power because of the panels in the bottom right. I have heard a bit of talk about bypass diodes lately. It is important to state that bypass diodes are designed to help stop hot spots on panels from bird droppings and the like. They do not work in the same way as microinverters and will not help maximise output in shaded conditions like microinverters do.

If you have patchy shade, please call the 1KOMMA5° Team for more information. We have shade analysis tools that can help us provide professional advice on whether you need micro inverters or not, and to what extent shade will impact the predicted output of your system.

We hope this information helps you cut through the sales talk. If it all gets too much, just keep it simple; solar can save you around $100 per kW per quarterly power bill and will output around 4 times its size, doing more in summer and less in winter.

In terms of how many panels you will need, compare the different price points and consider whether it is worth looking at a premium panel. There are some real tangible benefits such as a 25-year product warranty, higher efficiency and increased performance to premium panels such as the 1KOMMA5° Full Black Module.

Given this knowledge, you can get a good idea of how much solar power you might need. But remember, this is just a starting point! For a truly customised system designed to maximise your energy savings, there's more to consider.

Check out everything you need to know before investing in solar for your home. This in-depth guide walks you through all the nitty-gritty details to ensure your solar system perfectly fits your home and energy usage pattern.

If you are ready for personalised advice, we are here to help. If you have a few power bills ready, and you have read this article we should be able to help you find the right solution in a matter of minutes.

We work a little differently here at 1KOMMA5°; we help you find the right solution – without any pressure. We want you to make an informed decision and we want you to buy the system that fits your requirements.