The benefits of solar lights are obvious. Mainly, that you can reduce your electricity costs, and place the the lights wherever you want without having to worry about outlets and wiring. But maybe you’re wondering, are solar lights bright enough?
Solar technology, you’ve come a long way
In the 1950s Bell was producing solar cells that were only 6% efficient, meaning that only 6% of the sunlight energy falling on the cell was converted into electrical output. Sad.
Efficiency climbed to about 15% by 1992, and in 2015 Panasonic broke through the 20% efficiency barrier. Cutting edge solar panels are now about 45% efficient – tremendously exciting news for societies working towards a break with fossil fuels.
Now, to be clear, the typical home installation or garden light is not yet making use of 45% efficient solar cells – consumer solar panels are still working in the range of 15 to 20% efficiency. But the promise is there. Exciting times!
Battery technology is another area where the science is supporting better and better solar products. The 2019 Nobel prize for chemistry was awarded to the researchers who developed the lithium-ion battery, and these batteries are now commonly in found in solar lights, particularly the brighter lights, i.e. those that emit 400 or more lumens.
How much light do solar lights give off?
Some of the brightest models available will provide 2000 or 3000 lumens. That’s about what you’d get from a 150 or 200 watt incandescent light bulb.
So yes, solar lights are bright. It’s really just a question of understanding how much light you need and then choosing lights that match those needs.
Know what your goals are
You’ll need to be clear about your purpose for the light and make sure that you choose something suitable.
We’ll be describing brightness using lumens, which are the best metric for describing the brightness of LED lights. (Virtually all solar lights use LED, rather than incandescent or CFL.) Some people are more comfortable with the idea of watts, so we’ll try to give a sense of equivalent lumen and watt ratings as we go.
Solar lights for landscaping
Recommended brightness for landscape spotlights – whether wired or solar – varies between 50 lumens at the low end and 600 lumens at the high. (Incandescent equivalent: roughly 5 to 45 watts.) This is easily within the capabilities of modern solar lights.
Lighting up a tree or shrub or other feature of your garden
For this you’ll want to look into landscape spotlights. 50 lumens is enough to throw gentle light from below on a shrub. Many landscape spotlights are considerably brighter. Urpower sells a set of 4 lights at 200 lumens each. Litom sells sets of two or four at 600 lumens each. This is easily enough for this sort of application, and the nice thing about these sets is that you can experiment with different locations and configurations of the lights. Need more light on one particular spot? Put two lights on it. Not happy with the shadows? Place the lights so that they fall on the object from different angles.
Lighting up the front of a house
Again, landscape spotlights are a great option for this. A set of four or eight 600 lumen lights (incandescent 45W) placed at intervals will do a great job of casting light evenly across the front of your home. (Picture: landscape spotlight). And the wonderful thing about solar lights is that there are no wires to worry about, giving you perfect freedom to place the lights where you want and change or experiment as needed.
Solar lights for garden paths
Path lights don’t need to be very bright. Too much brightness can be bothersome and interfere with creating a gentle, welcoming ambience, if that’s what you’re after. Individual path lights typically have a brightness of 5 to 15 lumens, easily achievable with solar lights. The idea is to have a set of lights that you will spread out along the path. Each individual light will illuminate the ground within a radium determined by its brightness, and the lights are positioned so that there are no gaps in the lighting or dark spots on the path.
Solar lights for security
Obviously you want something bright in a security application. A 100W incandescent bulb is roughly 1600 lumens, and there are many solar models on the market that provide this much brightness and more. And again, because there is no need for wiring, you can easily arrange one or more lights in the exact spot where light is needed.
Solar lights for ambience
How much light do you need for a patio? That’s going to depend on the size of the space. For 250 square feet, 600 to 700 lumens will provide ambience without being overpowering. That’s the roughly the equivalent of a 50 watt incandescent bulb and is well within the capabilities of solar lights.
For ambient lighting, consider string lights. Similar to path lights, the brightness of each individual light will be on the low side – it’s the cumulative effect of the lights, spread across a space, that gives the gentle relaxed lighting that you want when enjoying an evening outdoors.
Lumens vs Watts
As technology progresses, lumens are replacing watts as the most useful metric for discussing the brightness lights. What’s the difference? Lumens are a measure of the total amount of visible light emitting from a light source, and that’s what we’re interested in. Watts, on the other hand, are not a measure of brightness at all. Watts measure the amount of energy consumed by the light. That would tell us something about brightness if all lights used the same technology, but they don’t. With LEDs, CFLs and incandescent lights all in widespread use, and with huge differences in energy efficiency, lumens let us compare apples with apples.
As an aside, candlepower is also a useful number for comparing brightness, but is used when comparing flashlights and headlights – applications where we are interested in the maximum brightness at the center of a beam. For outdoor lights around the home, lumens – total visible light – are the way to go.
Incandescent bulb brightness, in lumens
|25 W||230 – 375 lumens|
|40 W||440 – 460 lumens|
|60 W||800 – 850 lumens|
|100 W||1300 – 1600 lumens|
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