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I purchased an Osram Ledvance DoorLED Solar product which charges its own batteries and turns on automatically at nighttime to provide light. It requires a 7 hour minimum charge time. When there is no motion, it dispenses light at 20% of its maximum luminance.

I installed the product to receive daylight (not direct sunlight) and had it charge for 12 hours. However, at night, I realized the product had stopped providing light after about 5 hours of use at 20% intensity. It is placed at a location where I am positive there is no motion to trigger full luminance.

Web research I have done indicates that direct sunlight is not required for solar panels and nowhere on the product packaging does it say that direct placement in sunlight is required.

Is direct sunlight a requirement for such solar-powered products?

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  • Welcome to Sustainable Living! I don't think direct sunlight is a necessity, but it will help charge the battery faster. Of course there is a minimal amount of light required during the day to fully charge and it is possible that on cloudy days you don't get enough. Doesn't the manual or the manufacturer say anything about this?
    – THelper
    Commented Sep 13, 2019 at 10:43
  • @THelper The manual is poorly worded. I contacted the manufacturer (Germany), but they have directed me to the local rep., whom I have already talked to and don't trust that much. I am really upset with the whole venture and am going to return the product.
    – Sabuncu
    Commented Sep 13, 2019 at 13:17
  • By the way, the local rep's response to me was "It is a solar panel after all, what'd you expect? It obviously needs to be placed in direct sunlight" implying that the product's packaging does not really need to state this fact.
    – Sabuncu
    Commented Sep 13, 2019 at 13:41
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    US $14.35 37%OFF | LED Solar Light 36 leds PIR Motion Sensor night light Outdoor Waterproof Garden Street light Security Wall Lamp with mounted rod s.click.aliexpress.com/e/L0zr5WKU
    – Graham Chiu
    Commented Sep 13, 2019 at 18:01
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    It looks like this from AliExpress, and you are using it in mode 1. Try pushing the mode button next to the pir sensor to switch to mode 2 to save power. But realistically without direct sunlight you're not going to get a light on all night.
    – Graham Chiu
    Commented Sep 13, 2019 at 18:03

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Solar panels receiving indirect sunlight Indirect sunlight produce around 10% to 25% of their optimal output. A solar panel of the size illustrated could optimally churn out around 4W with direct sunlight or 0.4W with indirect sunlight.

The website for that light suggests it has a nominal wattage of 3W.

So. If you had 12 hours of direct sunlight, you would easily get 12 hours of full luminance LED light. It might even get 16 hours of full luminance if the battery is up to it.

But if you are only getting 10% power because of the indirect sunlight, then you'll only get a tenth of that, so 1.6 hours of full luminance. If it runs at 20% luminance then you'll only get 1.6 / 20% hours, which is still a good eight hours.

But I've ignored the battery, the various other power draws and efficiencies.

That seven hours minimum charge time with indirect sunlight isn't going to give you 12 hours of 20% lighting. Its going to give you about five hours, maybe four hours.

In answer to the headline question:- Yes, light fixtures with small solar panels require direct sunlight. They'll still work a bit with indirect sunlight, but they won't do everything you expect of them.

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  • Thank you! I really think the packaging for the product should have stated what you've described. Thanks for the invaluable information you've shared.
    – Sabuncu
    Commented Sep 13, 2019 at 13:15
  • This would be better for your purpose. aliexpress.com/item/32985318187.html 18 hours of light after fully charged. On continuously. 4400mAh batteries which are replaceable. 9.8ft cable so you can place the solar panel in direct sunlight.
    – Graham Chiu
    Commented Sep 15, 2019 at 2:09

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