2kW Solar System

The 2kW solar system is a fairly sensible size for a typical aussie home which is empty between 9am and 4pm weekdays and is in a state with a not-very-generous Feed In Tariff. Which at the time of writing is everwhere except the lucky folks of NT.

The reason smaller systems make sense in working households with tight-fisted state governments is that you want to minimize your exported electricity. This is because you only get 8c per kWh when you export compared to saving approximately 30c per kwh when you use the electricity in your home and avoid buying it from the grid.

How many solar panels will you need?

To make up a 2kW Solar System you need 8 solar panels, assuming that you use 250W panels.

Each panel will be about 1.6m x 1m, so you’ll need at least 13m2 of roof space.

To give you a feel for how big 13m2 is this picture may help

A scale diagram of a 2kW solar system

And here’s a picture of a 2kW solar system on a roof (made up of 12 x 165W solar panels). The panel on the lower level is an evacuated tube solar hot water system in case you were wondering.

A 2kw solar system on a roof

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.

Most states in Australia pay about 8c per kWh for exported electricity. And most people pay about 30c per kWh to buy electricity from the grid. So 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, or work from home. You would save approximately $1000 in the first year. And about $25,000 over 20 years assuming electricity inflation of 5%.

2) You export half the electricity: You would save about $650 in the first year.

3) You export all the electricity: You would save about $250 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?

About $5,000 before STCs. You should get about $1400 in STCs (AKA the solar rebate). So expect to pay about $3,600 out of pocket.

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 less than 4 years assuming you pay 30c for your electricity from the grid and electricity prices rise at 5% per year. 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. 

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