Are all solar lights terrible, or just mine?

September 19, 2016 4:33 PM

I bought some cheap solar pathway lights and some decorative solar lanterns. They provide next to zero light, for about three hours. Then they really provide zero light. Also, about 80% of them turn on at all on a given day, though they all turn on *sometimes*. It's a shady area, so I know they aren't charging as much as they might if I lived elsewhere, but might higher quality solar lights be better and brighter, or is this just how they work?
posted by OrangeVelour to Home & Garden (11 answers total)

Best answer: If you describe the area as shady, even the "good" ones aren't going to get a whole lot of power during the day. Solar panels really like bright, direct sunlight, and the surface area for the panel that such lights have isn't really enough to gather a lot of power in anything less than ideal cases.

If you have AC available in nearby, you're better off with the ones that plug in and just have a wire between the different lights to carry the power.
posted by Candleman at 4:45 PM on September 19, 2016 [3 favorites]

Best answer: Yeah, it's this weird intersection of price point, durability, battery storage, a bunch of other production stuff (I used to work in the Solar Lighting industry), and you will get some better performance/storage for spending more money, but the big issue is actually solar collection.

You are right that any shade at all dramatically alters performance (on top of the cheapest products not performing well in the first place). For path lighting, it can be impractical to use the kind of solar devices that have a remote panel you can put some feet away, but those can sometimes offer a workaround for a few spots in a larger area and they often have larger panels which means you can run brighter lights.
posted by Lyn Never at 4:59 PM on September 19, 2016 [3 favorites]

They are WAY better if you can put the collector in the direct sun at all. Ambient light from the shade really doesn't cut it and I'm a bit surprised that you're even getting 3 hours out of them (and I bet you won't over the winter).

Look around a bit; there are some where the lamp portion is connected by a cable to the solar cell / battery portion, which can be placed like 6 feet away. For example a search for "solar led with extension" turned up these on Amazon.
posted by Joey Buttafoucault at 5:10 PM on September 19, 2016

For sure it's the shade.

We have a 10+ kW system of solar panels on our roof, in full sun. We have a realtime chart of its output, and when a cloud rolls over it immediately dies down to almost zero power generation. (It's actually very fun to watch!). Your little shaded cells don't stand a chance, unfortunately.
posted by Drosera at 5:12 PM on September 19, 2016 [5 favorites]

It's the shade factor, as others have said. A couple of thoughts in addition. There are two major forms of panels for solar lights; I'm familiar with them being called crystalline and amorphous, though those may not be true for the most recent solar technologies. The difference is crystalline really needs full, direct sunlight to charge, while amorphous panels can still charge in bright light. Also, there are solar path lights with independent panels that can be placed 25-35 feet away, and that sort of solution seems to be what you need.
posted by vers at 5:29 PM on September 19, 2016 [1 favorite]

There's no improving if your solar lights aren't really getting sun.

General note for when you do put some in sun: I had some inexpensive ones that stopped working after a while. I don't remember if they got dimmer over time, or if they just went from normal brightness to completely dark. Anyway, I replaced the batteries inside, which turned out to be not-so-good ones, with batteries intended for solar lights. The new batteries were much better than the originals.

I'm not advocating recycling still-working batteries, just saying that your lights have a bright second life ahead of them.
posted by amtho at 6:06 PM on September 19, 2016

At a given point on Earth's surface, you'll get some light directly from the sun, and some diffuse sky radiation which is responsible for most of the light that illuminates things that are in the shade. However, the solar power from diffuse sky radiation is only about 7% of what you get directly from the Sun. You might get a bit more or a bit less than this hitting your solar cells, depending on how much of the sky your cells can see and what other objects the solar radiation might be reflecting off of. But I would expect that these lights are getting at most 10% of the power that they would if they were in direct sun.
posted by Johnny Assay at 7:23 PM on September 19, 2016 [1 favorite]

I also recently replaced the batteries inside solar lights (only fairy lights, but still). I didn't even know that was possible, but it turns out there was a panel that was accessible by screw, and they just had normal AA batteries inside. They were ridiculously crappy, and I put in much better quality ones and now have brighter, longer lasting lights. Previously a shaded panel would mean no lights at night at all. Now, I still do get lights - just not for as long. And in the sun they are great.
posted by lollusc at 8:03 PM on September 19, 2016 [1 favorite]

How cheap is "cheap"? Like the ones at Target for $3/ea? Those are woefully underpowered (single thin photocell, one white LED) and just won't do the job.
posted by JoeZydeco at 5:59 AM on September 20, 2016

Why not move a couple into full sun and test them? If they still only give three hours weak light it's likely they're just cheaply made, but you may find they're good given enough sunlight.
posted by Jilder at 6:55 AM on September 20, 2016 [1 favorite]

I guess the design concept is that, with full sun to charge them during the day, they will give light up to the time the guests leave (maybe). I bought one (about $3) as an experiment. It didn't work well for that purpose, and after about 3 months, wouldn't work at all.

I looked into a wired light. For my very modest purposes, a transformer (whatever they call it) to produce low voltage current would have be about $75. Very light wire run from there to the fixture. These get buried, but it would not take much more than opening a slot with a spade to get them 6" deep, safe from the lawn mower. More difficult if you have to cross a paved driveway or sidewalk.
posted by SemiSalt at 7:55 AM on September 20, 2016