How much solar do I need?
A good solar system makes about as much power in a year as your home uses, with extra if you plan a battery or an electric car. Answer four quick questions and we will suggest a system size and the number of panels, using the output we measure on our own Geelong systems.
It takes about a minute, and you do not need to give us your details.
Solar size calculator
Solar size questions
What size solar system do I need?
Size it to make about as much power in a year as you use. We suggest a system that makes about 85% of what you use in a year, because power sent to the grid earns only a few cents. In Geelong a north-facing system makes about 1,100 kWh per kW of panels a year, which matches what our monitored systems make. A home using 20 kWh a day (7,300 kWh a year) needs about 5.7 kW, or thirteen 440 W panels. Plan more if you want a battery or an electric car.
How many solar panels is a 6.6 kW system?
Fifteen 440 W panels make 6.6 kW. With 475 W panels, fourteen panels make 6.65 kW. Each panel needs about 2 square metres of roof.
Does the direction of my roof matter?
Yes. North-facing roofs make the most power over a year. East and west roofs make roughly 10 to 15% less, but spread the power across the morning and afternoon, which suits many households. South-facing and shaded roofs make a lot less, so we check your roof before we quote.
Should I get more solar if I want a battery or an electric car?
Yes. A battery needs spare solar to fill it, so we suggest about 30% more panels than you would need without one. An electric car driving about 30 km a day needs roughly 5 kWh a day, which adds about 1.5 kW of panels.
Is there a limit on how big my solar system can be?
Your electricity network sets the rules. Most single-phase homes in the Geelong area are limited in inverter size and in how much they can send to the grid, which usually caps panels at about 13 kW. Bigger systems often need three-phase power. We check your connection rules before we quote.
How much does solar cost in Geelong?
Across our 26 recent solar-only installs, the typical price was about $1,440 per kW after the federal rebate, including GST. A 6.6 kW system on its own came in at about $9,400. See every size in our Geelong solar and battery price guide.
Want a system designed for your roof?
Related pages: Battery size calculator · Battery rebate calculator · Solar in Geelong · Geelong price guide · Case studies
