What does your camp need?

The prefilled numbers are an example, not measured product results. For a fridge, enter compressor running hours, or measured average watts over 24 hours. Don’t apply a duty cycle twice.

Examples replace the inputs below. Adjust every value for your own trip.

Your devices

Camping fridge (compressor running)Illustrative values; replace with your measurements.WattsHours/day

LaptopIllustrative values; replace with your measurements.WattsHours/day

Camp lightsIllustrative values; replace with your measurements.WattsHours/day

Phone chargingIllustrative values; replace with your measurements.WattsHours/day

Use any row for another device. Enter 0 watts for an unused row. Add extra devices together only when they have the same daily running hours.

Your trip and assumptions

Days without chargingDelivery efficiency (%)Station overhead (Wh/day)Planning margin (%)Peak sun hours/daySolar yield factor (%)

Calculate my setup →

Save your result as a spreadsheet or create a reusable plan link. No email signup required. Shared links include only your numeric settings.

What the assumptions mean

Delivery efficiency: the fraction of battery energy reaching your devices, including conversion losses. The default 85% is a planning assumption, not a tested efficiency for any model. Replace it with appropriate measurements.

Station overhead: energy used by the station itself each day, beyond the conversion losses above. For example, a measured 5 W idle draw for 24 hours adds 120 Wh. The default is zero because your station and operating mode are unknown; this can understate requirements.

Planning margin: adds spare capacity to the estimate. A 20% margin is not a guarantee against bad weather, cold, aging batteries or unexpected use.

Peak sun hours: equivalent hours at full reference sunlight, not hours between sunrise and sunset. The default four hours is only an example. Use a location- and season-appropriate estimate.

Solar yield factor: allows for real-world losses between panel rating and stored energy. The 75% default is an assumption; shade and poor conditions can produce substantially less.

The calculation, without the mystery

Daily device energy = sum of watts × daily hours. Daily battery draw = device energy ÷ delivery efficiency + station overhead. Nominal battery target = daily battery draw × days without charging × planning margin multiplier.

Panel target = daily battery draw × planning margin multiplier ÷ (peak sun hours × solar yield factor). This estimates replacing one day’s use. It does not include rapidly refilling a battery after several cloudy days, input clipping or a forecast of the weather.

The example totals 532 Wh at the devices per day. At 85% delivery efficiency, zero extra overhead, a 20% margin and two days without charging, the target is about 1,503 Wh of nominal storage. Four peak sun hours and a 75% solar factor suggest about 251 W of rated panels to replenish daily use.

Capacity is only one check. Verify simultaneous output and startup demands, low-load shutoff, individual port ratings and panel input limits before choosing equipment.

Energy calculation reference: US Department of Energy PV load-sizing guide. For location-based solar context, PVWatts models grid-connected systems; it does not directly predict portable camping battery charging.