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How Many Solar Panels Do I Need?

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How Many Solar Panels Do I Need? Don't end up too short.

How many solar panels are too many solar panels? Or is there no such thing as too many solar panels? One of the most common questions I get is, ‘how many solar panels do I need?’

Knowing how many solar panels are suitable for you and your home is determined by your needs. For example, if you have a larger family with an EV, you will need more power than a house for only 2 people. So, not one size fits all. 

I will help you figure out how many solar panels you need by guiding you through a few questions. Such as, do you want to minimise your carbon footprint? 

How much money do you expect to save from solar? Questions like this should hopefully give you a clearer picture of how many are best for you. 

Of course, if you plan on moving homes at a later date this may factor into the number of solar panels you require for a short term payback period. Differently, for homeowners looking to stay in their home long term, may want to fill their roof with solar panels to “future proof” themselves.

So, let’s dive in and find out how many solar panels you need. As always, if you have any questions get in touch

If you want to skip to the cold hard accurate facts, please request a design proposal from our solar engineers who will be able to work out the exact number of panels to suit your requirements (this is the most accurate way).

Table Of Contents

how many solar panels do i need?

How To Work Out How Many Solar Panels You Will Need For Your Home

Put simply, the size of your solar panel system should be decided by how much electricity you use as well as how much energy you expect to use in the future. Remember that your system will be on your roof for at least 25 years, if not 40 years minimum with Sunpower. 

To put it into context, the size of a solar system is measured in the total kilowatt capacity of the solar panels. However it’s important to know that solar systems never operate at 100% efficiency due to the sun hitting the panels at different angles or bad weather conditions. This is similar to saying a car has 200kW of power, it doesn’t necessarily mean you’ll be using or generating that much constantly.

How Much Energy Do You Use Per Day?

This is not as complicated as it may first seem. You can determine how much energy you use by looking at your energy bills. You must ensure you account for all the energy you have used, not cutting corners. 

Once you assess your current energy usage patterns, it gives you a clearer picture of how many solar panels you need to meet this energy usage. For example, if you are consuming 900kWh per month you will need to be producing around 30kWh or more per day to see the best returns. 

(Now this doesn’t always mean you have to get a system that is going to totally wipe the cost of your energy bills as some days you may use more and other less. It’s important to remember to get a system that will make a dent in your energy usage though).

I suggest you collect the last year of energy bills. This is because there will be some months higher than others, so you need to account for the times you use the most energy. Then take an average from all these numbers, which should leave you with how much energy you use daily.

What Time Of The Day Do You Use The Most Energy?

So, it is no secret that Australia has a large amount of sunlight all year. Which is why solar panel systems are so popular in Australia. However, it is important to consider that some times of the day will produce more energy than others. 

Therefore when working out how many solar panels you need, start by understanding how much sunlight your roof gets. This can have a direct impact on how many panels you need. Why? Because the amount of sunlight you get changes based on the time of year and location. 

For example, if you live in Perth, you will have more sunshine hours than in Melbourne. So if you live in Melbourne, you will need a bigger solar system than those in Perth. Align the placement of your panels with the time of the day you need the energy the most. Therefore you can get optimal use out of your energy and your sunlight.

In the morning and late afternoon the sunlight is at its weakest meaning your energy generation will be lower than midday. If you use most of your energy during these hours (before work/school and after work/school) which most people do then consider getting a system that captures sunlight during these hours.

the time of day that you use the most energy in your home

How Big Is Your Available Roof Space?

One factor that will impact how many solar panels you can have is the size of your roof. The smaller the roof, the less room you have for a large solar panel system. 

This is where you need to consider the type of solar panels you want. If you read my blog about how many solar panels you need for a 10kW system, you’ll know there are ways around fitting a larger system on a smaller roof. 

For example, a smaller roof space means you need a smaller or more powerful system. Panels such as 425 w Sunpower Maxeon 6, Trina 415w Vertex S+panel or Jinko 415w N Type Panels are great for smaller roofs. All in the 415w size so your system can produce more power. 

Additionally, Enphase and Solaredge are some of our best sellers and offer flexible designs for different houses. Assessing the size of your roof and how much room you have for solar panels will help you determine how many you need. 

Either way, your roof space will determine how many solar panels you need. The smaller the roof space the less panels you need but they will have to be bigger in power (Wattage). 

If you have a bigger roof space then you may get more solar panels but they might only be in 370-390w size. However, I want homeowners to consider the future of their system and allow for room to expand in 25 years in case their energy consumption has increased.

The Amount Of Time Your Roof Gets Sunlight

Another factor that you need to consider is how much sunlight your roof gets. Now, you could live in Perth and have a lot of sunshine, but your solar panel system will be less efficient if your roof is under a tree or covered by shade. 

If you work out that your roof doesn’t get that much sunlight, then you need to opt for a bigger system that can harvest more energy. This way, with a larger solar system, you are optimising the energy you can self consume when you need it most. 

Of course, let’s not forget time differences. Let’s say Queensland for example begins to get light at around 4-5am. The sun will then set at around 6pm allowing a good 12 hours of continual sunlight. 

This is different with Melbourne Summer when it gets light around 5-6am and doesn’t get dark until 9-10pm. This is a strong 15 or so hours of sunlight which is considerably more than Queensland.

how many hours your roof gets sunlight during the day

Your Predicted Energy Consumption Increase Over The Next 10 Years

If you think about it, you probably have twice as many electrical appliances and devices as you did 5 years ago. With the electrical age forever increasing, households are gaining more devices and appliances to power.

Additionally, the increased demand for EVs in Australia has led to many households using their solar panel system to power their EVs. Therefore you need to remember that your energy usage will increase in 10 years. 

10 years ago, 3-4kW was normal for a household, whereas now 6.6-8kW is the norm. In 10 years, your whole roof may be made out of solar tiles with a capacity upwards of 20kW. So, when calculating how much energy you use daily, you need to account for how much that could rise. 

You either need to build a bigger solar panel system now or ensure you have room to expand in the future when you need to increase. You can only expand on flexible systems like Enphase or risk ripping your old system off to replace it with a new, bigger one.

Goals For Deciding To Install Solar

You also need to ask yourself why you decided to install solar panels in the first place? Was it purely to save money on energy? Or was it to increase your property value? Perhaps you want to help the environment by doing your bit. 

Everyone has their own personal motivations for installing a solar panel system. If you want to save more money on your energy bills, the larger your system, the more you will save. 

You need to have a clear goal of your energy requirements and how much you want to be generated by your solar panels. Your goals will heavily impact how many solar panels you need and the sort of panels you need. 

Additionally, some homeowners want to completely offset their energy bills with solar power. Therefore, you will naturally need a more extensive solar system to become completely energy-independent. Whereas those who want to contribute to the energy bills with solar panels won’t need as many.

It's Important To Invest In a System That Produces More Energy Than You Are Using To See Maximum Savings

A key takeaway from this blog is that you need to install a system that is realistic. You may outgrow it very quickly if you base how many solar panels you need on the energy you consumed in the past.

If you try to cut corners by installing a system that is too small, it will only cost you more in the long run. If your solar panel system is only taking a small dent out of your energy bill in the next 6 years, it might not make a difference in your bills. It will only lead you to need a bigger system to be installed. 

Therefore, when you work out how much energy you use on average, I suggest going a ⅓ bigger. Of course, this accounts for any electrical devices or appliances you use in the future. 

Similarly, you want to invest in a solar battery which helps to store your excess solar energy. This can be used at any time of the day as it is stored for use. If you choose to have one in the future, then you will benefit from a larger solar system to maximise the amount of energy you can store.  

important to future proof your home by getting a system that will outlast an increase in energy consumption.

Make Sure You Account For Future Energy Increases And Other Factors

At the end of the day, every home will have different needs. Also, every solar system owner will have different motivations for wanting a solar system. Therefore, you are going to know exactly what your household needs.

As the demand for energy increases and the forecast of the future of digital technology increases, the number of solar panels you will need will increase. Therefore, consider this when deciding on how many solar panels you need. Ensure you install a system that can be expanded on as your needs change over time.

If you have any further questions on solar panels and how many solar panels you need, get in touch; I’d be happy to discuss 😁

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Written By:

Luke Cove
Managing Director
Lightning Solar & Electrical

1 thought on “How Many Solar Panels Do I Need?”

  1. I have a Tesla Model S, two kids, and my partner and I both work from home so as a family we use a fair bit of power. I think we need about 2000KW. does this sound right. Also what inverter do i need, i’ve heard really bad things about the huawei inverter.

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