10kW Solar System

If you are thinking of buying a 10kW solar system then you probably have a big roof and an even bigger electricity bill!

A 10kW solar system is about as big as residential solar systems get, practically speaking. Here's a picture of a 10kW system so you can get a feel for how it may look on your home (no space left to waste on this one!):

10kw Solar System on a roof

How many solar panels will you need?

To make up a 10kW solar system you need 40 solar panels, assuming that you use 250W panels (higher capacity panels are often used these days, meaning fewer panels are required).

Each panel will be about 1.6m x 1m, so you'll need at least 64m2 of roof space.

To give you a feel for how big 64m2 is this picture may help

scale drawing of 10kW solar system

How much electricity will a 10kW solar system generate?

A 10kW solar system will generate approximately 40kWh per day. This is enough to run 2-3 average aussie households or one really inefficient household!

To put it in perspective 40kWh per day will power:

Approx 2x ducted aircon systems on a hot (or cold) day.

OR

4 small pool pumps for 10 hours per day.

OR

40 x 5 star energy rated fridges with the freezer on top or below (not side-by-side; those suckers use a lot more energy).

How much revenue will a 10kW solar system generate?

The amount of cash you make from a 10kW system will depend on how much you get paid for exported electricity (solar feed in tariffs) and how much you self consume.

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 let's consider 3 scenarios to see how the payback works:

1) Use all the solar electricicty in your (huge) home or business: You would save approximately $4500 in the first year. And about $150,000 over 20 years assuming electricity price rises of 5% per year.

2) Export half the electricity: You would save about $2700 in the first year.

3) Export all the electricity: You would save about $1000 in the first year.

Moral of the story: The more solar you self consume, the faster your payback.

If you think that this sounds very counterintuitive, then you can read about the relationship between exports and payback here.

How much will a 10kW solar power system cost?

About $21,000 before STCs. You should get about $8,000 in STCs (AKA the solar rebate). So expect to pay about $13,000 out of pocket for a good quality 10kW system, well installed by a reputable installer.

How long before a 10kW solar power system pays for itself?

If you are using all the electricity on-site then it will have paid for itself in under 5 years, assuming you pay 30c for your electricity from the grid and electricity prices rise at 5% per year. After that the electricity is free apart from a small maintenance cost (expect to pay $500-$700 every 5 years) and a replacement inverter every 15-20 years.

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