Watt Ready

As an Amazon Associate I earn from qualifying purchases. Links to Amazon on this page are affiliate links.

How many solar panels does it take to charge a power station?

Updated

For a 1 kWh power station, plan on about 400W of panels if you want a full refill in one sunny day. With a single 100W panel, the same refill takes about three days. The quick math: watt-hours divided by (panel watts x 0.7) gives hours of strong sun.

Why 0.7

A panel's watt rating is measured under perfect lab light. Outdoors, with the panel lying at a rough angle, some haze, heat and cable loss, a good working guess is 70% of the rating around midday. Most of the US gets roughly 4 to 5 hours a day of sun that strong. Clouds, shade and winter cut it further.

Hours of strong sun for a full refill

Panel watts288Wh unit1,024Wh unit1,152Wh unit
100W4.1 hours14.6 hours (about 3 days)16.5 hours (3 to 4 days)
200WCheck the unit's input limit first7.3 hours (1.5 to 2 days)8.2 hours (about 2 days)
400WMore than a unit this size needs3.7 hours (one day)4.1 hours (one day)

Maker claims are quicker than this because they assume panels running at their full rating. Anker claims 1.8 hours for the C1000 Gen 2 with 600W of solar. BLUETTI claims 2.8 to 3.3 hours for the AC180 with 500W. Treat those as best-case numbers.

Every power station has a solar ceiling

Extra panels past the input limit do nothing. Per the listings we checked:

Match solar to the job, not the battery

What you really need to replace is what you use each day. A full-size fridge uses 1 to 1.5 kWh a day. At 70% output and 4.5 good hours, 400W of panels makes about 1,260Wh a day. That covers most of a fridge in good weather and falls short in bad weather. A CPAP with the humidifier off needs only 150 to 300Wh a night, so one 100W panel keeps up.

Setup tips

  1. Aim the panels square at the sun and move them two or three times a day.
  2. Keep every cell out of shade. A shadow across one corner can cut output by far more than its size.
  3. Keep the power station itself in the shade. Batteries charge slower, or stop, when they get hot.

Put your own numbers into the runtime calculator, or compare all five units on the best picks page.

Portable panels plug into the power station only. Do not connect a power station or panels to your home wiring without a licensed electrician and the proper transfer equipment.