Estimate the battery size you need, how long an appliance will run, or whether your panels can keep up. Choose the question below; each calculator shows its assumptions.
Free to use. No sign-up required.
Sizing
Add the devices you want to run and how long you need them. Estimate usable battery capacity, running output and startup requirements.
CPAP
Set your hours per night, humidifier setting and power connection. Estimate how many nights a station can cover before recharging.
Runtime
Choose your fridge and the outage duration. Compare estimated runtime and the output needed to start its compressor.
Solar
Compare daily device use with estimated solar harvest. See whether the setup can recharge each day or gradually runs down.
Cost
Compare the cost of energy delivered by a generator, a grid-charged station and a solar-charged station using cited national energy prices.
A calculator tells you which station clears the load. A kit lists the cables, adapters, and backups that decide whether the plan survives an outage or campsite. Check the equipment list for your own setup.
Start with the question you need answered. The sizing tool handles several devices together; the CPAP and fridge tools focus on one appliance. Solar recharge compares daily supply with daily use, while the generator comparison estimates running costs. Each page explains the inputs, assumptions and limits behind its result.
A refrigerator may be the main reason for buying backup power, but lights, a router and phone charging also use the battery. Add everything you expect to connect and how long each device runs. The sizing tool checks energy demand and output separately: enough stored energy does not establish that a station can start an appliance. Use the result to narrow your shortlist, then check the exact model review.
CPAP humidification, fridge energy use and the power connection can change an estimate substantially. If you have a measurement for your own appliance, use it in place of a preset where the tool supports that input. Leave room for cold weather, an ageing battery or a heavier load than planned. For essential equipment, check the manufacturer’s backup instructions and arrange another power source rather than relying on a single estimate.
A panel rating describes its output under specified conditions. Shade, placement and available sunlight affect how much energy reaches the station each day. Use the solar calculator to check the daily balance, then read the pairing guide for electrical limits and connectors. The generator tool compares running energy costs using cited national prices and published conversion assumptions. It does not include the purchase price of the station, panels or generator.
We publish the constants and source links beside the calculation so you can check what drives the answer. A result based on an example appliance remains an estimate for that example; it does not certify your equipment or installation. Open a model review to check its sourced specifications, and use a kit checklist to account for cables and adapters. The calculators are free, and you can see their results without creating an account.