3, 5 or 10 kW Solar: Which Size Suits Your Home?

The right solar system size for each home depends on 3 main factors: how much electricity you use during the day, your home’s power supply, and the roof area that gets sun. This article is a basic guide to comparing 3, 5 and 10 kW systems before an engineer surveys your site.

Start with your daytime electricity use

Solar reduces the part of your bill used while the sun is out, so choose a size close to your home’s daytime use. If you are not sure, read how to estimate it in Is Home Solar Worth It? Check Your Electricity Bill.

Basic sizing guide

• 3 kW suits small to medium homes, or homes where few people are in during the day and air conditioning and appliances are used moderately in the daytime.
• 5 kW suits family homes where someone is home during the day, several rooms run air conditioning, or someone works from home.
• 10 kW suits large homes with high daytime use, such as several air conditioners, a swimming pool, or a small home business. A system this size usually requires three-phase power.

These figures are only a guide. Homes with the same number of people can use very different amounts of electricity. An engineer will recalculate from your actual bills.

Single-phase or three-phase power

Homes with single-phase power can install up to the size set by the local electricity authority. An engineer will check your meter and consumer unit, then recommend the size you can install, or recommend switching to three-phase power if necessary.

Roof area and orientation

A larger system needs more panels and more roof area. A roof that faces the sun and is not shaded by trees or neighbouring buildings generates well. Tile, metal sheet and concrete rooftop decks can all be fitted, but use different mounting methods. See examples in our home solar installation projects.

Should you install a bigger system to start with?

A system larger than your daytime use produces surplus power, which is worth less than power you use yourself. If you expect to use more electricity in future, such as buying an electric car or adding air conditioners, tell the engineer from the start so they can choose an inverter that allows the system to be expanded or a battery to be added later.

See our home solar packages or fill in the form below for an engineer to recommend the right size for your home.