Solar. How much power do I need?

13 November 2015
Solar. How much power do I need?

I’m thinking about installing solar – how much power do I need?

This is a question I get asked a lot, and tough to provide a quick answer.

But I will. 

You would install a 5 kilowatt system.

Of course, there are a lot of options. You could throw one panel on the roof and generate 1 kilowatt hour per day, you could also get off the grid completely and never pay a power bill again - if you have a spare $15,000 - $20,000.

It’s really about how much roof space do you have and how many kilowatts do you want to make.

I could get technical (don’t tempt me) about your energy needs, how to make the most of your power and avoid selling it back to the energy companies for chump change, but generally a 5 kilowatt system will do it.

Let me explain.

Your house probably uses around 16-20 kilowatt hours each day. If you have a look at your smart meter you’ll see that your demand changes every day depending on who’s at home and what they’re doing.

My average energy consumption is around 20 kilowatt hours at the moment, as my family is at home through the day.

If you live in Victoria your solar panels will generally get around 3.6 kilowatt hours of sunshine each day (5 kilowatt hours if you live in Alice Springs).

While the sunrise and sunset times change, and there may be some cloud coverage, for around four hours you’ll get the good stuff shining on your roof.

That means for each solar panel you install, you’ll generate nearly four hours of power each day.

If you put five panels up (a 5 kilowatt system) you’ll get that power, five times over. That’s nearly 15 kilowatt hours, which is actually a fair bit of power.

There’s a good chance you’ll be able to fit it on your roof too.

How you can store and use this power is a topic for another day, but assuming you have proper battery storage in place then this is enough to power your home for the most part.

Even if there hasn’t been much sun, your system will work in with mains power so there’s never a risk of running out. 

A 5 kilowatt system (which includes roof panels, an inverter and battery storage) will cost you around $6000 - $10,000 and take two days to be installed.


Nerd Notes

  • The way we ‘size’ a solar system is to work out how many kilowatts are used during daylight hours.
  • Solar works better if you’re facing North. If your house is south facing you’ll receive 70% less sun.
  • I’ll be uploading a new blog each month. If you have a question or suggested topic you can tweet me at: @FusionPowerSys


Go Back