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

Depends on the size of the house and the average number of sunny days in your location, and how careful you are with your usage. Many houses too have solar panels that only provide part of the electricity needed.

A medium sized house in a sunny climate might need a

• 4.0 kW system, which could mean
• 16 x 250W solar panels,
• a roof area of 27 sq metres.
• This will provide a daily output of between 16 and 20kWh, depending on daily sunshine hours.

The average energy use in a sunny country like Australia is 20 kW of electricity a day. To catch that much electricity on your roof you need a 4.0 kW system. In Australia you can buy reasonable quality systems for about $2 a watt (factoring in federal government rebates). This means a 4.0 kW system might cost $8,500. This is not cheap, so it makes sense to cut down your energy use first.