Comparing Solar PV Systems

There seems to be a lot of confusion over solar PV; do they ever pay for themselves, is getting more kWs better and are they the best way to offset? Our clients regularly ask us these questions, so we came up with a simple way to help you find the answers.

We’ve put together a short LCA comparing an average Australian 3X2 house (benchmark), one with a 1.5kW solar PV system and one with a 5kW solar PV systems to show you how they perform on cost, embodied and operational carbon and design life.

There will be quite a few numbers coming up on your screen, but don’t worry we’ll be summarising them afterwards…

So what did you think, still confused?

As you can see from the video choosing the right solar PV system for your home has the potential to save you money and carbon both in the long and short term. In this LCA we haven’t included any government rebates at all and have worked with an average of ‘one for one’ unit of grid electricity. This gives you an average indication of savings across the design life of your house, whether it’s 15, 35 or 40+ years.

Here are some of the final figures…


Total design life cost over 15 yearsTotal design life cost over 35 years
Benchmark Home – $168,393*Benchmark Home – $208,144*
Home with 1.5kW – $167,982*Home with 1.5kW – $197,285*
Home with 5kW     – $167,023*Home with 5kW     – $171, 948*



Embodied and operational carbon used over 15 yearsEmbodied and operational carbon used over 40 years**
Benchmark Home – 193,795 tBenchmark Home – 414,123 t
Home with 1.5kW – 160,922 tHome with 1.5kW – 321,386 t
Home with 5kW     – 80,107Home with 5kW    – 104,474 t


As you can see, both 1.5kW and 5kW solar PV systems are paid back within 15 years. Further into the design life of your house, they will start to save or earn you money depending on how much electricity you are using, generating and exporting.

Eventhough 5kW looks like the best solution, the initial cost outlay is considerable and there are other factors to consider. If you are looking to build a carbon neutral house, (in terms of embodied energy) using a smaller 1.5kW system and changing elements of the construction method can help you acheive this.

Have a look at some of our case studies to see what size systems other people have used.

* These costs are approximate and based on the costings in the LCA at the time of assessment.

**This takes into account the replacement of the solar systems every 20-25 years.


Written by Siobhán McGurrin.

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