When you decide to install a solar panel system, you have several panel types to choose from.
But you also have to consider what size of solar panel system is best for your property.
To figure this out, you first need to understand how solar panel systems are sized.
How Solar Systems Are Sized
When you start looking for your solar panel system, you’ll see a range of sizes (i.e.capacities), such as 3kW, 4kW, 5kW, 6.6kW or 10kw
A ‘kW’ is an abbreviation for a kilowatt, which is 1000 Watts (so 3 kilowatts is 3000 Watts).This is the maximum amount of electricity that a system can produce.
But that doesn’t always mean that more panels equals more capacity – it depends on the
individual capacity of the panels.
You can calculate total capacity by finding the capacity of one panel (usually on the panel somewhere) and multiplying it by the number of panels. For example: a 370W panel x 18 panels = 6660 Watts (i.e. a 6.6kW system).
What Do The Sizes Mean?
If you don’t really understand Watts and kiloWatts, this may not mean much to you. It might make more sense when you know how much power you can actually get.
For example, 1 kiloWatt equals around 60 low energy lightbulbs. So a 6.6kW system is equivalent to 396 lightbulbs.
It sounds great, but this power is only generated for a few hours in the hottest part of the day, not all day and night. That’s why the electricity grid absorbs any electricity your home isn’t using for later use.
How Your Usage Affects System Size
To figure out what sized solar panel system you need, you must work out how much electricity you use and when you use it.
A year’s worth of electricity bills will give you an average daily and annual usage for your property.
Your electricity use is measured in kiloWatt hours (kWh). Most households use 18–20kWh in a day, though that varies for single-person households, etc. But, generally, a 5kW solar system works for the average household.
However, it’s also important to know when you use this electricity – specifically how much you use during daylight hours. You might use it more on the weekend, or in summer or winter when you run heating or air conditioning.
You should also consider your future electricity needs, as you will have these panels for many years. Will your family size increase or decrease (as children leave home)? Will you run a business from a home office? Do you intend to buy an electric car?
All this information is useful to figure out what sized solar panel system is best for your household. You don’t need to have all the answers, but it’s important to consider them in your decision.
Other Factors To Consider
Each kiloWatt of your solar panels generates around 4kWh of electricity per day. So a 6.6kW system produces about 26.4kWh per day. This is why knowing your daily use is important so you’re covering your basic need.
But there are other factors to consider too, including:
- environmental factors – where you live, what the seasons are like and the amount of sunshine you get
- the size of your roof – how many panels will fit on the roof and whether you need more powerful panels for a smaller roof
- the system itself – the quality, orientation and age of the panels
- your budget – as more powerful panels are more expensive
- your goals for your system – such as planning for a $0 electricity bill
- whether you’re on the electricity grid or planning to go off-grid.
You also need to decide whether to get battery storage for the system.
Battery Storage For Solar Panels
Most solar panel systems being installed in typical households are 6.6kW in size. However, larger 8–10kW systems are becoming more common, especially systems that include a storage battery. But why would you consider a storage battery?
A storage battery captures the solar power you don’t use during the day, so you can use it at night or when there’s low sunlight. With the recent reduction in the savings you can make from selling excess electricity back to the grid, it might make more sense to store and use the solar yourself rather than export it.
According to the Climate Council, adding a 4kWh battery to a 5kW residential solar system can increase the amount of self-generated solar electricity you use from 30% to 60%.
While this sounds great, it doesn’t make financial sense for everyone. Batteries are still expensive and take longer to pay for themselves than the warranty on them. However, the costs are dropping steadily due to increased use and improving technology.
A battery won’t necessarily stop you losing power if you’re connected to the grid. During a blackout, your system may shut down to protect the grid from ‘anti-islanding’ (pumping electricity into the lines suddenly).
Additionally, the cost of the larger system and installation might outweigh any cost savings from having the battery. As always, it’s essential to run the numbers to determine the best option for you.
However, if you do decide to include a storage battery in your new solar panel system (or believe you probably will in future), you need to include this in your calculations when determining the best sized system for you.
Note: In future, you might be able to replace your original inverter with a hybrid inverter, which houses both the solar and battery inverters in one box.
Getting Professional Advice
As you can see, choosing the right sized solar panel system for your property isn’t simple. There are many factors to consider and new options are coming onto the market all the time. You should definitely get professional advice about this.
At Solar Union, we ask you all the right questions about your power usage, your need for a storage battery, your roof space and more to find the right solar panel system for your needs.
Contact us to chat with our friendly staff and get the best advice!
