FlexSolar E 10 W folding panel review

On the maker’s own page

A 10 W 5 V USB foldable solar panel charger, IP67 waterproof.

FlexSolar states a built-in USB-A port at 5 V/2 A maximum for smartphones, tablets, compact power banks under 10,000 mAh, USB fans, flashlights, smartwatches and portable routers, with no energy storage capability; a smart IC chip identifying connected devices with LED indicators and overcurrent, overheating and short-circuit protection; ETFE film lamination over high-efficiency monocrystalline A+ cells at a 24 per cent conversion rate, IP67 rated, with the junction box stated not waterproof; a three-fold design of 7.6 × 8.8 × 0.7 inches folded and 15.5 × 8.8 unfolded at 0.66 lbs (300 g (10.6 oz)), with dual carabiners; and advice to avoid charging through glass, with a maximum 10 W output under direct sunlight.

No test conditions. No kickstand.

Three hundred grams

The lightest panel in this group, by a long way.

The others weigh 671 g (23.7 oz), 771 g (27.2 oz) and 800 g (28.2 oz). This is 300.

Ten watts from a sheet 15.5 by 8.8 inches is only possible at a conversion figure like the 24 per cent published here — which is what this shelf’s introduction means when it says cell type and efficiency tell you how much panel you carry for each watt.

And no test conditions

The axis this shelf asks for, empty on all four.

This shelf’s introduction is explicit: makers publish the peak watt figure under standard test conditions — a defined irradiance, a defined cell temperature and a defined air mass — which the panel meets on a bench, not on a pitch at half past four in October.

Not one of the four panels in this group publishes any of the three. The figure can rank these panels against each other and it cannot promise what reaches a battery.

Twenty-four per cent, and what that number is not

Three listings, one figure, two meanings.

This panel and its stablemate publish 24 per cent as a conversion rate. A rival publishes 25.4 per cent. The fourth publishes “up to a 24% increase in efficiency compared to traditional solar cells” — which is an increase, not an efficiency, and reads like the same number.

The junction box

Not covered by the IP67.

This shelf’s introduction predicts it: an ingress rating usually covers the panel face while the junction pocket is rated separately or not at all.

All three panels in this group that publish a code say the same of their own junction box. The face can be rained on; the socket should be shut, shaded or brought in.

No storage, and no controller

What a bare panel is.

“No energy storage capability”, in the first bullet. A device has to be connected while the sun is on it.

This shelf’s introduction puts the question plainly: ask whether a charge controller is built in or lives in the power station, because a bare panel wired to a battery is not a charging system. None of the four panels here includes one.

FlexSolar’s instructions carry the ports and the ingress rating. Nothing here replaces them, and nothing on this page describes any product as safe.

Availability

The American Amazon store was listing it at about $25 at the time of writing.

Every figure here is what Keepa held on the day this page was last revised. Offers and prices shift without warning.