Start with daily watt-hours
Add each device’s watts multiplied by actual hours of use. A battery rated 12.8 V and 100 Ah has 1,280 nominal Wh: 12.8 × 100. Delivered energy can be lower because of discharge limits, temperature and conversion losses. Measure cycling loads such as a portable fridge over a full day instead of multiplying its peak wattage by 24.
Use the WilderWatt calculator to make your assumptions explicit.
LiFePO4 battery or portable power station?
A 12 V LiFePO4 battery can suit an installed RV system, but AC appliances need additional equipment and appropriate wiring. A power station bundles the battery, charger, inverter and outlets; it is easier to move, while expansion and repair options depend on the model.
Read our solution comparison before narrowing down brands.
Account for the missing parts
Check continuous output power, accepted solar input, weight, warranty, manufacturer-stated low-temperature charging behavior and connectors. If an inverter or charge controller is not included, add it to the full system cost. Match the specifications of every part rather than trusting a bundle name.
Frequently asked questions
How many Wh does a portable fridge need?
Use its measured energy use across a representative day, the backup time you need and your system losses. A nameplate watt figure alone does not capture cycling behavior.
Are 100 Ah and 1,000 Wh the same?
No. Amp-hours measure electrical charge; estimate energy by multiplying nominal voltage and amp-hours. Delivered energy may be lower.