Water, Solar and Backup

Water heaters, solar, batteries and generators.

Compare the running cost of two water heatersTank vs tankless water heater costSee what two water heaters cost to run in a year for your hot water use, and how long a higher price takes to pay back.Open calculator
Find how many home batteries you need for backupHome battery sizeWork out how many home batteries cover your home for the number of days you choose, and check that they can carry the load.Open calculator
Find the generator size you need in an outageGenerator sizeList what you want to power during an outage and see the running and starting watts a generator must deliver.Open calculator

Planning water heating, backup power and storage

These calculators help you compare options before you ask for quotes. They work from the numbers you can find on a label or a spec sheet, such as the efficiency of a water heater, the usable energy of a battery or the watts of an appliance.

They give a first estimate, not a design. Installation, wiring, local code and safety rules decide what can be installed in your home, so check them with a licensed professional.

See how we handle data and formulas on the methodology and sources page.