What Size Solar System Do I Need?

Don't waste money with a system that is too big or too small for your needs find the perfect size for you!

Working out what size solar system you need can be tricky, overwhelming and complicated with different sources saying different things. This article is set out to remove the complexities from this whole scenario. We will go through the steps you should take when deciding on what solar system size is best for you and will provide some good resources to help in your solar installation journey.

1. What Is your current power usage?

   Firstly and probably the most important step is to work out what your current power usage needs are. Your current power usage will greatly affect the size of the system you get and your decision-making further on in this list. the best way to do this is to get a copy of your last few power bills and calculate the average power usage of your home.

2. What is your future power usage?

   Once you have worked out what your current power usage is, it’s time to forecast your future power usage. This doesn't have to be an exact science this step is just trying to future-proof your solar system. On average a solar system can last up to 20 years so to get the most out of your investment it's a good idea to plan for it now. Some things to keep in mind when making this decision are:

   • Are you looking to grow your family or start a family?
   • Are your kids still young? As they grow up their power usage may increase.
   • Are your kids going to move out soon and your power usage going to decrease?
   • Are you looking to start working from home or are you going back to the office?
   • Are you going to get an electric car in the future?
   • Do you want to have a pool at home?
   • Will you need to upgrade to electric appliances (stoves, water heater, etc.)?
   • Are you looking at expanding the house in future?

   These are just a few of the things worth keeping in mind when deciding on your future power needs. Once you have settled on either a ballpark figure or a rough estimate of whether it's going up or down. one thing to note is that if you are looking to sell your home when the kids do move out a bigger system that works for a family can improve the sale value of your home compared to a system that is too small for a family.

3. Are you going to get solar batteries?

   Solar battery storage is an important part of costing your solar system as it will increase the price but will mean you won't have to worry about how much power you can feed back into the grid. It will also mean you can go for a bigger solar system as you will use all the power generated. But not to fret solar batteries can be installed down the track.

4. How much power can you feed into the grid?

   This will depend on your electricity distributor and what hardware you have at your home. The Australian Energy Regulator has a page to help locate your energy distributor, each distributor will have their own caps on solar energy. Your home's connection to the grid will also put a cap on how much you can feed into the grid. Your feedback will depend on whether you have a 3-phase or single-phase power connection. To check which you have you will need to check the main switch in your switchboard if it is a single switch you have a single phase if it's three switches you have 3 phases. A 3-phase connection in most cases will let you feed three times the amount of power into the grid, and then a single phase would let you. This is important to know as there is no point in getting a bigger solar system than what you can use at home or put back into the grid.

5. How much roof space do you have to work with?

   This is probably the biggest limiting factor so far as you can only install as many solar panels as you have space for. A single solar panel is typically 170x100cm or 1.7m² and when measuring your roof space it is important to note that you are only going to be working with the sunny side of your house (typically the north, east, and western sides of your home) a there is no point putting your panels in the shade. once you have worked out how much space you are working with it is time to work out what all the numbers mean.

6. What do all the numbers mean?

   There are a few different units we work with when it comes to solar systems there are as follows:

   1. kW: or kilowatt is 1000 watts and is a measure of power.
   2. W: or watt is a measure of power
   3. kWh: or kilowatt hours is the measure of how much energy is produced or used in an hour. For example, a solar system that outputs 5kW produces that for 1 hour it will be equal to 5kWh. this means that in a day you use 24kWh then you don't need a 24kW solar system you would need a 2-4kW solar system as on average you are using 1kWh each hour of the day.

   These are probably some of the most common units you will come across when deciding on what size solar system is best for you.

7. How many panels do you need?

   So, now the all-important question how many solar panels do you need? Well, this is where it gets tricky. As we said in step 6 you will only need to cover your power a good rule of thumb to work is 1kW of solar panel equals 4kWh of electricity a day. So a 10kW solar system will produce 40kWh per day. Using this rule use your power bills to work out how big of a solar system you need to make to meet your home's needs. Once you have worked out what size you need now to calculate how many panels you need. This is where you get a bit of flexibility as to what you can pick as solar panels come in a myriad of sizes 400-700 watts the wattage of a solar panel doesn't affect the total output of the system it just affects how many you can have. For example, to have a 10kW solar system you will need 20x500W panels or 25x400W panels so if you are tight on roof space it is worth going for higher wattage solar panels or if you want to have room to upgrade in future it might still be worth going for the higher watt panels.

8. What size inverter do you need?

   Choosing an inverter size can depend on your budget and the size of your solar system. A good rule of thumb is if you have a 10kW solar system you will need a 10kW inverter however just because your solar system is rated to 10kW doesn't mean it will always be outputting 10kW. In this case, you can get away with a slightly smaller solar inverter however it is best to ask a solar installer about this as if you get an inverter that is too cheap you will end up losing most of the power you generate.

If you are still confused or you know what you want and want it installed look no further than Powerix. Our team are Clean Energy Council and Solar Accredited Australia accredited solar installers and designers and are here to help you decide what system is best for your needs and install it correctly. Don't wait contact our team today and cut down on your next power bill.

References:

Size your solar system | Energy.gov.au

Solar Panel Calculator | SunSpot

Sizing your solar panel system | Choice