What size solar panel do you need for your power station?

By the Ferncharge team · Figures last checked 21 October 2026

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The short answer: it depends far more on the month than on anything else. To replace 500 Wh a day with a panel tilted to face south in London, our arithmetic on EU PVGIS sunshine data gives about 140 W of panels in June, about 260 W in October and over 500 W in December (PVGIS). Then check the power station's maximum solar input: watts above it are wasted.

Based on published data and manufacturers' specs. Ferncharge has not tested these products. Estimates only.

Work it out for your month in the solar charging time calculator: pick your location, month and panel angle.

Step 1: how much energy do you need back each day?

Start with what you use in a day, in watt-hours. The sizing calculator adds it up from your appliances. The examples below use 500 Wh a day.

Step 2: how much sun is there?

Solar data is often given as peak sun hours: the day's sunshine squeezed into hours of full sun. These are the averages for 2014–2023 from the European Commission's PVGIS tool, which our solar calculator uses (PVGIS). "Flat" is a panel lying flat, as on a van roof; "tilted" faces south at PVGIS's best angle for the location.

Long-run averages, not a forecast: a dull week can be far lower.

Step 3: allow for real-world losses

Panels rarely deliver their rated watts. Jackery lists light intensity, angle, temperature, cables and charge-controller conversion as causes (Jackery). Our calculator assumes a panel delivers 70% of its rated watts at peak-sun equivalent: a planning estimate, not a published figure.

Panel watts needed = daily Wh ÷ (peak sun hours × 0.7)

Worked examples: 500 Wh a day

Our arithmetic, rounded.

Two things stand out:

• Winter needs several times more panel than summer. In December a 500 Wh day can need more panel than a power station accepts (see Step 4), so plan on mains or car charging too.
• Angle matters most in winter. In London in December, a tilted panel needs about half the watts of a flat one (514 W against 1,099 W). In June there's little difference.

Step 4: check the power station's limit

A power station only takes up to its maximum solar input, so panel watts above it are wasted.

Alphabetical. Stated figures only.

For example, the 262 W needed in October in London (tilted) is within the C1000's, AC180's and Explorer 1000 v2's limits, but above the RIVER 3's 110 W. Voltage and current limits matter too: see is a solar panel compatible with your power station?

FAQs

What size solar panel do I need to charge my power station?

Divide the energy you need back each day by your month's peak sun hours, then by about 0.7 for losses. For 500 Wh a day in London, that's about 140 W in June and over 500 W in December with a tilted panel.

Will a bigger solar panel charge faster?

Only up to the power station's maximum solar input. Above that, the extra watts are wasted.

Can solar keep a power station charged in a UK winter?

Often not on its own. December averages in the table above are between 0.38 and 1.39 peak sun hours, so plan on mains or car charging as well.

Related: Solar charging time calculator · Solar panel compatibility · Power station for a campervan · Spec table