Solar power system sizes

What solar power system size is best for you?

With a grid-connected system, you are free to install any solar power system size you may want. To figure out which system size you may wish to install, here are three key factors you might consider first.

  • Do you want a solar power system that will eliminate or reduce your power bill;
  • Would you like a solar power system that has the maximum amount of solar panels that will fit on your roof or;
  • A system size that comes within your budget.

To give you an idea about the range of sizes available for solar power systems, the smallest system a solar power installation company will generally offer is a 1.5kW system. Home solar power systems rarely don't get systems over the 8kW size.

Solar Power System Sizes on Roofs

A 5kW to 6kW system produces enough electricity to match the electricity the average New Zealand home uses in a year (7,000kWh/year), but...

Export Rate for Solar Power in New ZealandMatching a system size to your power demands doesn't eliminate your power bill, even when you export a lot of power to the grid. You do get paid for power that you export, you just don't get as much as what they charge you for power. See buy back rates here>

If the aim is to eliminate your electricity bill, think of ways to use solar power when it is created i.e. during the middle of the day.  This is known as solar power self-consumption, click here to read more about it.

A 3kW solar power system size has proved to be a popular system size in New Zealand. This is due to the fact that it will make a significant change to your power bill, and it is also relatively affordable (around $10,000).

A 3kW system in Auckland will generate around 3740kWh/year. For the average New Zealand home, you won't be eliminating your power bill with a 3kW system. However, a slightly smaller system (3kW size) will ensure that the majority of the power from the system is used by your household and less will be exported back to the grid.

When figuring out what system size to go for, best to find out how much power you use or how much money you spend on power in a year by referring to past power bills. When you have a figure, request three quotes here and enter the figure amount into the comments field on page two of the quote request form. Likewise, if you know how much roof space you want to maximise, or if you have a budget in mind, please write that in the comments field as well.

3kW solar power system on a home in nz

Above: A 3kW solar power system in Tauranga

What does it mean to have a 1.5kW system?

Try not to get too caught up in the title of your system size, all these different system sizes can be confusing - 1.6kW, 2.3kW, 4.5kW. What is important is to find out how much power the system will actually provide for you in a year and what your return on investment will be. 

Simply stated: having a 1.5kW system means that at any given time on a clear, sunny day, the system will produce up to 1.5 kilowatts.

1.5kW solar power system maximum output

This graph is provided only to help reinforce the point above; the data is not precise.

A 1.5kW system in Auckland will produce an estimated 2,000 kWh annually.

Scalable system sizes

If you would like to start with a smaller system, it is possible to scale the system size up after a year or two. If you were to install a solar power system with micro-inverters, then you can easily add more panels onto your roof in the future. 

If you install a string inverter there are some considerations you need to think about;

  1. You will need to install a larger inverter size initially. For example, you could have a 3kW system with a 5kW inverter. In the future, you could add extra panels to build up to a 5kW system. However, not all large inverters are compatible with smaller system sizes. You will need to ask the solar power company which large inverters will be compatible with a smaller system size.
  2. Secondly, you will need to make sure you can get the same size and type of panels in a few years' time. If you initially go for the standard 190W panels, then you will likely be able to get these panels again in the future. This is important, because if you get panels that are a different size then you may experience some power loss.
  3. You will need to be sure you have enough roof space to add extra solar panels to the system later down the track.

Scaling up with a micro-inverter system

Being modular, a micro-inverter system can have one panel added at a time. That said, you would need to consider the cost of getting an installer out to your house every time a panel needed to be installed. Additional panels wont need to match previous panels already installed on your roof.