How Much Solar Do I Actually Need? (Adelaide Guide)

The most common mistake Adelaide homeowners make when buying solar is choosing a system size based on what the salesperson recommended, rather than what their home actually needs. Here's how to think about it properly.

Start with your bills, not a system size

Your quarterly electricity bills tell you exactly how much power you consume. The goal of a solar system is to offset as much of that consumption as possible during daylight hours, and, if you add a battery, extend that offset through the evening.

A typical Adelaide household uses between 15–25 kWh per day. A 10kW system in Adelaide produces roughly 40–42 kWh per day on average across the year. That sounds like more than enough, but the timing matters.

The export problem

Without a battery, you only benefit from solar when you're actually using power at home. Every kilowatt-hour you export to the grid earns you a feed-in tariff, currently around 5–8 cents per kWh in SA, but you pay 30–35 cents per kWh for power you import at night. The maths only works in your favour if you maximise self-consumption.

If you're out of the house from 8am–6pm, a 13kW system isn't going to give you a $0 bill. It's going to give you a large export credit and a still-significant evening import cost.

What actually determines the right size

Your daily consumption and usage timing, when are you home? When do appliances run? Does anyone work from home?

Your roof space and orientation, north-facing is ideal, but east/west can work well with the right design. Shading from trees or neighbouring rooflines reduces output.

Your budget and battery plans, a smaller system with a battery often outperforms a larger system without one for households with evening-heavy usage.

The Adelaide climate advantage

Adelaide receives more solar irradiation than almost anywhere else in Australia. A well-sized and oriented system here will outperform the same system in Melbourne or Sydney. This means you don't need to oversize, you need to optimise.

How we approach it

At Next Generation Solar, we don't size your system until we've reviewed your last 12 months of electricity bills, mapped your roof, and modelled your self-consumption profile. The result is a system that's sized for your actual life, not a round number that looks good on a brochure.