How many solar panels do you need to run a house?

How long is a piece of string?

In all seriousness, click here for an explainer on why a simple number of panels is not a good guide for system size.

Speaking in very broad averages:

• Australian houses normally use between 16 and 20 kilowatt hours per day.
• A solar array rated at 1 kilowatt (peak capacity) will generate around 4 kilowatt hours per day.
• Simple maths says the average house will only need 4 or 5 kilowatts of solar however modern systems are seldom less than 6.6kW unless space is constrained.
• When sizing a solar power system, it's worth considering that winter is generally the time of high electricity demand and low solar yield.
• The best system available is generally the biggest one you can install on your roof.
• Excess yield is actually a feature, not a bug. If solar export tariffs become a potential penalty, this is easily solved with battery storage, hot water heating or an export limit.
• Off grid houses normally require significantly lager solar power systems unless they're exceptionally efficient passive solar designs.