Where do the calculations happen?

Entirely in your browser. The tools require no email or sign-up. Nothing is sent to Wattbench unless you sign in and deliberately save a result.

Are the results a formal quote?

No. Every tool gives an estimate to help you reason about a system, not a quote or an engineering specification. Each calculator shows the formula it uses so you can check the working.

Do the tools cost anything?

No. Every tool is free to use with no sign-up. Saving a result to an account is optional. Where a formula or worksheet has been reviewed, its page carries that specific review date.

Run the numbers

Field Calculators

Fast field calculators that work in your browser. Formulae and assumptions are shown, with AS/NZS context where a standard applies. No sign-up required; saving is optional.

Calculators: 18; free field tools
Work areas: 3; design, grid and storage
Data: local; runs in your browser

System design

Size the array, record roof direction and check the inverter relationship.

Sizing Tool

Solar System Size Calculator

Turn your daily energy use, location-specific sun hours and entered system losses into an indicative array size and panel count.

Array kW · panel count · effective sun input

Strings, cables and grid

Work through string limits, conductor sizing, voltage and supply identification.

Engineering Tool

Solar Cable Voltage Drop Calculator

Work out voltage drop on a DC string or single-phase AC run from the entered length, current, conductor size, voltage and material.

Voltage drop (V) · drop % · disclosed inputs

Batteries, rebates and financials

Explore storage capacity, backup runtime, incentives and project economics.

Battery Tool

Battery Backup Runtime Calculator

Estimate how long a battery can support a nominated essential load from usable capacity, backup reserve and conversion efficiency.

Available kWh · estimated runtime · supported load check

About the tools

Using the calculators

Where do the calculations happen?: Entirely in your browser. The tools require no email or sign-up. Nothing is sent to Wattbench unless you sign in and deliberately save a result.
Are the results a formal quote?: No. Every tool gives an estimate to help you reason about a system, not a quote or an engineering specification. Each calculator shows the formula it uses so you can check the working.
Do the tools cost anything?: No. Every tool is free to use with no sign-up. Saving a result to an account is optional. Where a formula or worksheet has been reviewed, its page carries that specific review date.