What Size Solar Panel Do You Need for a Power Station?

For most power stations, plan on panel watts of about 20 to 40% of the battery's watt-hours: 200 to 400 W for a 1,000 Wh unit refills it in anywhere from under a day to about two days of decent sun. Panels deliver about 70% of their label in real conditions, the station caps how much solar it accepts, and the season and region decide how many good hours of sun you get. The table below does the math for common sizes.

How do you calculate solar recharge time?

Three numbers decide it: the energy to put back, the watts that actually reach the battery, and the peak sun hours where you are.

• Effective watts = the smaller of (panel watts × 0.7) and the station's maximum solar input. The 0.7 factor covers heat, angle, dust, wiring and charging losses. A well-tilted rigid panel on a cool clear day can reach about 0.80; a panel flat on the ground in the heat can fall to 0.55.
• Hours of full sun = watt-hours to refill ÷ effective watts.
• Days = watt-hours to refill ÷ (effective watts × peak sun hours).

A peak sun hour is one hour of sunlight at the 1,000 W per square meter used to rate panels. A place with 5 peak sun hours gets as much solar energy in a day as five hours of that full rated sun, spread across the whole day.

How do you stay under the voltage limit?

Every solar input has an operating voltage window and a maximum open-circuit voltage (Voc). Going over the maximum can permanently damage the input, and manufacturers usually don't cover that under warranty. Panels wired in series add their voltages, so the limit decides how many you can chain.

Voltage also rises as panels get colder. Using a typical coefficient of −0.30% per °C, a four-panel string of 21.6 V panels (86.4 V at the 25°C rating) reaches about 98 V at −20°C (−4°F). The safe rule: keep the string's rated Voc at or below 85% of the station's maximum input voltage.

Series or parallel?

• Series: voltages add, current stays the same. Better on long cable runs and in low light. Must stay under the maximum voltage, including the cold-weather rise.
• Parallel: currents add, voltage stays the same. More tolerant of shade on one panel. Must stay under the maximum input current and needs Y-branch connectors.

Panels use MC4 connectors; stations use their own inputs, such as XT60 on EcoFlow and many others, or DC8020 on Jackery. Adapter cables are common; match polarity and current ratings. Mixing brands works if voltage and current stay within limits, though it can affect warranty terms.

Folding or rigid panels?

Folding panels set up in a minute and pack into a car, which suits camping, renters and occasional outages. They cost more per watt, wear faster and often deliver less because they sit flat or get hot. Rigid glass panels cost the least per watt, last decades and produce more when tilted, but need a mount; they suit a semi-permanent outage or off-grid setup. Either way, keep the whole panel in full sun: shading even part of it cuts output far more than the shaded area suggests.

So what should you buy?

• 300 Wh station: one 100 W panel tops it up in a day of good sun. Not enough for daily fridge use.
• 1,000 Wh station: 200 to 400 W of panels, checked against the station's solar cap.
• 2,000 Wh station and up: 400 to 800 W or more, with the series string checked against the voltage limit.

To see whether solar can keep up with your devices, compare what the panels put back per day (effective watts × peak sun hours) with what your devices use; the runtime calculator gives the daily figure. For outage planning, see the hurricane outage plan.