6.6 kW, 10 kW or 13.3 kW Solar: Compare the Design Behind the Size

Choose solar capacity from a design comparison, not from the number that sounds safest. A 6.6 kW, 10 kW or 13.3 kW array describes panel capacity; it does not tell the whole story of the installation.

The useful question is what each option adds for your household. Ask for a roof layout, expected seasonal generation and an explanation of where that electricity would go.

Start with a property-specific solar assessment, especially if your plans include electric heating, hot water or a car within a realistic timeframe.

Read three ratings separately

Array capacity is the total rated power of the panels. The inverter has its own conversion rating, while the connection approval can place separate conditions on exports.

The Australian Government sizing guide distinguishes these quantities. A familiar panel-and-inverter pairing is an example, not a requirement that every installation must follow.

Government guidance on system sizing.

Ask the designer to label all three figures on each option. A larger panel array does not establish that you can export more, and its nameplate rating is not an annual energy estimate.

Measure the home you have

Gather electricity use across different seasons, including when it occurs. A daily total cannot show whether the household uses most electricity during sunlight hours or after dinner.

For a home that already has panels, grid imports exclude electricity supplied directly by solar. Consumption monitoring can help fill that gap rather than treating the bill as total household use.

Government monitoring guidance.

Consider an illustrative household choosing between two layouts. Their workday demand is modest, but they plan a heat pump next year. Model current use first, then add that specific change as a separate scenario.

A possible appliance five years away deserves a different confidence level from equipment already ordered. Keep those assumptions visible instead of making future demand look certain.

Compare roof layouts fairly

Request the actual panel dimensions and the number proposed on each roof face. Shade, obstructions and practical access can change the result even when the total roof looks generous.

Our shade-assessment guide explains the information to request before accepting a layout.

If the larger option uses another roof face, ask for the contribution of those extra panels separately. The average performance of the original array does not automatically describe the extension.

Value the additional capacity

Compare the extra installed cost with the extra electricity used at home and exported under your plan. Count electricity only once, including any proposed battery charging.

Ask for a less favourable case as well: lower daytime use, a delayed appliance purchase or a different export rate. A convincing design should make the consequences understandable.

Keep network export conditions in the model. They can affect the usable result without turning one standard array size into the universal answer.

When the smaller option deserves a hearing

A smaller design can be reasonable if useful roof area is limited or the additional panels add little value under your actual use. A larger design may suit documented future demand and a workable roof.

Neither conclusion follows from the number of people living in the house. Two families with the same headcount can have very different appliance schedules and energy needs.

Talk to Lightning Energy with your bills and plans. Ask for two supported designs and the incremental difference between them, rather than three package sizes with identical savings promises.