2kW Solar System
The 2kW solar system used to be a fairly sensible size for a typical Australian home empty between 9am and 4pm weekdays and is in a state with a not-very-generous feed-in tariff.
The reason smaller systems used to make sense in working households is because solar was still quite pricey and feed-in tariffs – what you received for surplus energy exported to the grid, started to reduce
But these days with solar systems so cheap, it really is time to be aiming bigger – much bigger; such as 6.6kW, or better yet, 10kW or more.
How many solar panels will you need?
When this page was originally published, 250W solar panels were the size (capacity) most commonly installed. These days (2024), 415W panels are the most popular.
To make up a 2kW solar system you need 8 solar panels, assuming that you use 250W panels (415W panels are a little larger, but of course you don’t need as many of them).
Each 250W panel was around about 1.6m x 1m, so you needed at least 13 square metres of roof space.
To give you a feel for how big 13 square metres is this picture may help:
And here’s a picture of a 2kW solar system on a roof made up of 12 x 165W solar panels – but bear in mind these days solar panels are more than double the capacity, but not double the physical size thanks to techonology improvements.
The panel on the lower level is an evacuated tube solar hot water system in case you were wondering.
How much electricity will a 2kW solar system generate?
A 2kW solar system will generate approximately 8kWh per day. This is about half the electricity usage of a modest aussie home.
How much cash will a 2kW solar system earn?
The amount of cash you make from a 2kW system will depend on when you use electricity in your home.
Having read, above, that a 2kW system will generate the equivalent of half the energy of a typical home – you may be thinking that your bill would simply be halved. Unfortunately it is more complicated than that. It depends on how much solar energy is used in your home and how much of the stuff you export.
Solar feed-in tariffs in Australia range from 0-15 cents depending on location and electricity plan. And most people pay about 30c per kWh to buy electricity from the grid. Assuming you receive 8 cents for exported electricity, lets consider 3 scenarios to see how the payback works:
1) You use all the solar electricity in your home. This is likely if you have a family at home during the day, work from home, or set appliances to switch on during the day. You would save approximately $875 in the first year. And about $17,500 over 20 years.
2) You export half the electricity: You would save about $550 in the first year.
3) You export all the electricity: You would save about $230 in the first year.
If you think that this sounds very counterintuitive, then you can read about the relationship between exports and payback here.
You can see the numbers for yourself with my solar payback calculator.
How much will a 2kW solar power system cost?
Expect to pay about $3,000 – $4,500 for a 2kW system after the solar rebate. Now, compare that to a 6.6kW system that currently (2024) costs around $5,500 as a starting point – offering more than three times the capacity for less than double the cost.
How long before a 2kW solar power system pays for itself?
If you are using all the electricity in your home then it will pay back in around 4 years assuming you pay 30c for your electricity from the grid. Although I would argue that if you can get cashflow positive with a solar system from day one (which is usually perfectly possible) then who gives a toss how long it takes to pay back? If it is cash flow positive then you are saving real money from the get go. To see if you can achieve this in your situation have a play with my solar calculator.