Panels, inverter and mounting from either the roof area you have or the energy you need.
Electrical and plumbing. 5 questions answered below, each with the arithmetic behind it and the limits of what the tool decides. Open the Solar PV Estimator tool.
A solar estimate is a list of components at the quantities a design calls for. Panels, an inverter, mounting, cable, isolators and a battery if one is specified, each with its own count, and each with a price that comes from a price book or from you. The tool does not decide the array, because the array follows from the load and the roof. What it refuses to do is invent the sunny hours. Yield depends on the location, the tilt, the shading and the losses, and those are site facts rather than constants. Where a figure is not supplied, the page asks, so a yield number in the estimate can be traced to an assumption someone made deliberately rather than one the tool made quietly.
A five kilowatt array in four hundred and fifty watt panels is twelve panels, not eleven and a bit, therefore twelve. Mounting at two rails of two and a half metres per panel gives sixty metres of rail with the clamps the system needs. A five kilowatt inverter with a DC isolator, an AC isolator and a generation meter completes the component list. Cable from the measured DC run of eighteen metres and the AC run of nine metres, and prices from the book or from your supplier. The yield figure, if you enter one, is yours, and it is the only number on the page that depends on the weather.
As a component takeoff. You describe the array size and the equipment, and it returns panels, inverters, isolators, mounting, cable and protection at the quantities that configuration needs, priced from the market book or from figures you supply. It does not decide the size of the system, because that follows from the load and the roof, and it does not forecast production, because that follows from the site.
Panel and inverter counts follow from the array size and the equipment you specify, mounting follows the panel count and the rail system, and cable follows the measured runs. Every one of those is arithmetic once the design is fixed. Where a component's coverage is a property of the product, such as how many clamps a rail system needs per panel, that comes from the product record rather than from a guess.
It is reported as a gap. A component carried at zero would make the quote look complete and would produce a total that cannot be delivered, and on a solar job the unpriced item is often the battery or the mounting system, which is not a rounding error. The page shows the gap so it can be closed with a real figure before the quote goes out.
No. Array size, string length, inverter matching, protection and earthing are design decisions that follow from the load profile, the roof and the regulations where you are building. What the tool does is take a decided design and return the components and their quantities, which is the part that can be counted and priced before anything is ordered.
No. Sun hours, tilt, azimuth, shading and system losses are all site specific, and a default figure would produce a yield estimate that looks precise and is wrong for most locations. Where you supply a figure, the page uses it and the assumption is visible. Where you do not, the estimate covers materials and leaves production to a proper yield calculation.