Quick answer
Panel count is determined by target array size and individual panel wattage, but roof layout decides what can actually be installed.
What matters most
- A 10 kW target with 475 W panels requires about 22 panels because the count must be a whole number.
- Module dimensions matter as much as wattage on constrained roofs.
- Roof orientation and shading can make two layouts with the same panel count perform differently.
Solar decision framework
Separate production from value. System size and location drive generation; your daytime load drives self-consumption; tariff structure determines what each kilowatt-hour is worth.
How to calculate it with SunnyWatly
Use the relevant calculator with your own bill, quote or vehicle information. Defaults are examples only and can become stale as tariffs, rebates and hardware change.
Do not rely on a headline figure alone. Ask what assumptions sit behind the estimate and whether they match your property, tariff and usage pattern.
What can change the result
- Electricity usage and time of day.
- Retail import and feed-in tariffs.
- Roof, shading, inverter or charger constraints.
- Hardware efficiency and usable capacity.
- Network limits and future tariff changes.
Primary public sources used by SunnyWatly