10 Easy Ways to Charge Solar Lights Without the Sun

By Kami Turky

Last Updated:

Solar lights are perfect for lighting up your garden from sunset to sunrise using just the sun’s energy. 

But what if the sun’s playing hide and seek or your favorite spot is too shady? 

No worries, there are plenty of ways to keep those lights glowing. 

You can use indoor LED or fluorescent lights, pop some mirrors around to catch and reflect sunlight, or even hook them up to a battery charger. 

In this guide, I’ll walk you through the 10 easy ways to charge solar lights without the sun regardless of weather conditions or natural light availability.

Key Takeaways

  • To charge solar lights without sun, you can use indirect sunlight or artificial lights like LEDs.
  • Solar lights can also capture energy on cloudy days by maximizing exposure through optimal placement.
  • Mirrors can reflect additional light onto solar panels, or batteries can be charged using a standard battery charger when sunlight is insufficient.
  • Options like yellow LED lights, fluorescent bulbs, and incandescent bulbs can charge solar panels, though they can be a bit inefficient.
  • In urgent situations, charging with moonlight or fire is possible but offers minimal energy and comes with risks to the solar panels.

How Do Solar Lights Charge?

Before we dive into how to charge solar lights without any sun, let’s first break down how these lights charge up. 

It’s simpler than it sounds, I promise!

Electrical energy is just a bunch of electrons moving around. 

These electrons need to flow through a material, and if we can get them moving in the right direction, voilà, we’ve got electricity. 

Solar panels, which are often made from a semiconductor material called silicon, come into play here. 

Silicon has 4 electrons that are not too clingy to their nucleus, making it easier for them to break free and get moving.

Now, for these electrons to start their journey, they need a little kick of energy. 

Silicon has 4 valence electrons
How silicon atoms are connected to each other

This is where light comes in, but not just any light—the light is made up of particles called photons. 

When these photons, which carry energy, hit the electrons, they push them, freeing them from their atomic ties. 

Imagine photons as tiny balls thrown at a row of plastic bottles (the electrons). 

If you throw the ball hard enough, you’ll knock a bottle off its base, getting it to roll around freely.

This process, where the photons energize the electrons, happens in something called photovoltaic cells. 

Photon hitting an electron and knocking it loose from the atom
Photon hitting an electron and knocking it loose from the atom

More photons hitting the panel means more electrons get freed, and we can harness this flow of electrons to generate an electric current. 

This current is what charges up the solar batteries.

How solar panels generate electricity
How solar panels generate electricity

Pretty straightforward, right? 

We just need enough photons with the right amount of energy, and we’re set to power up our solar lights.

And guess what? 

When I say light, I don’t just mean sunlight. 

Any light source that has photons with enough energy can do the trick. So, no sun? 

No problem! There are plenty of other ways to get those photons to our solar panels.

In the next section, I’ll show you some of the best ways to charge your solar lights, even when the sun decides to play hide and seek.

How to Charge Solar Lights Without Sun Or With Indirect Sunlight?

1. Indirect Sunlight

You might think that only direct sunlight can power your solar lights, but that’s not the whole story. 

Even on those gloomy, overcast days, the sun is still up there doing its thing, sending light our way. 

It’s just that clouds scatter the sunlight, spreading the light out instead of letting it beam straight down to us.

So, what can you do when it’s more gray than bright outside? 

First, grab a damp cloth and gently wipe off any dirt or leaves blocking the light. 

Next, position your solar lights to catch as much light as possible. 

You want them to be facing up, straight at the sky

This way, even the scattered light from a cloudy day hits them right on the nose, or in this case, right on the panel.

And a quick winter tip: if it starts to snow, you should bring those lights inside

Snow can pile up and squash your solar lights, which could be better. 

Also, if your lights aren’t made for winter weather (like if they have an IP rating below 65), keep them cozy indoors until spring rolls around again.

2. Mirrors

How to reflect sunlight to a solar panel with a mirror
How to reflect sunlight to a solar panel with a mirror by Geodome

Even when your solar lights are in the shade, they can still pick up a little bit of charge, though it’ll be slower than if they were soaking up direct sunlight. 

But here’s a neat trick to speed things up: use mirrors.

If you place mirrors around your solar lights, you can bounce some extra sunlight directly onto the panels. 

This boosts the light intensity hitting them, helping them charge up faster.

Keep in mind, though, that using mirrors is easy.

Since the sun moves across the sky during the day, you’ll need to adjust the mirrors now and then to keep the light focused on your solar panels. 

It can be some extra work, but it can make a difference on those less sunny days. 

3. Battery Charger

Solar light battery charger
Solar light battery charger by Powerowl

Normally, solar lights have solar panels on top that capture sunlight and use it to charge batteries inside the lights

This works great on sunny days, but what about when the sun isn’t shining much?

Here’s a simple alternative: you can charge these batteries using a regular battery charger, just like the ones you use for gadgets at home. 

Just plug the batteries out of the solar lights into the charger. 

It’s not the greenest method since it uses household electricity, but it’s quick and gets the job done when you’re in a pinch.

Also, if you find that your solar lights are running out of juice too quickly, you can try using a bigger battery

However, make sure the new battery has the same voltage as the original to ensure everything works smoothly. 

This way, you’re not overloading your solar lights with too much power, which could damage them.

4. Dual Charge Option

Some solar lights are flexible—they can charge up using sunlight or even from a regular wall outlet. 

If you’re ever in a situation where there isn’t much sun, you can simply plug them into an outlet at home for a quick charge. 

Plus, a neat little trick: if you make sure the battery is fully charged, your lights will shine brighter

Pretty useful, right? 

This can be especially helpful when you need that extra bit of light during the night!

5. LED Lights

LED lights wavelength
LED lights wavelength by Toshiba

Remember how we said photons—the little energy packets in light—can knock electrons loose? 

Well, a study in 2015 found that solar panels work best with yellow light or any light that falls between 600 to 700 nm in wavelength—that’s the light in yellow, orange, and red colors.

Best color to charge solar lights
Best color to charge solar lights by Bobby Garces

So, if you have yellow LED lights hanging around, those are your best bet for charging your solar lights when there’s no sun. 

The brighter and more intense these LED lights are, the quicker your solar lights will charge. 

So, it helps to use strong, high-powered LED lights or even set up several LEDs to beam right at your solar panel. 

This way, you’ll get the fastest charge possible.

6. Fluorescent Lights

fluorescent lamp light spectrum
fluorescent lamp light spectrum by Webb

Fluorescent lights give off light in the 400 nm to 700 nm range, which is perfect for charging up your solar lights when the sun isn’t shining. 

They’re not quite as effective as yellow LED lights for this job, but they still do a pretty good job. 

So, if you’re out of yellow LEDs, no stress—just flip on some fluorescent lights.

7. Incandescent Bulb

Incandescent bulbs wavelength
Incandescent bulbs wavelength by MLB

Incandescent light bulbs are like a rainbow—they emit all sorts of colors, including yellow. 

But, they also throw out a bunch of infrared light, which isn’t great for charging your solar lights. 

This kind of light doesn’t just slack off on the charging front; it also heats your solar panels. 

When it gets too hot, the electrons in your panel start bouncing around more, which makes the panel less efficient.

That said, if you’re in a pinch and don’t have any yellow LED lights around, incandescent bulbs can still give your solar lights a bit of a boost. 

8. Heat Lamps

Heat lamps wavelength
Heat lamps wavelength by Joovv

Heat lamps can technically charge your solar lights, but they’re pretty much the last resort. 


Well, almost 99% of the light they emit is above 660-670 nm

That means only about 1% of their light is good for charging your solar lights, which isn’t much. 

Plus, they’re called heat lamps for a reason—they crank out a ton of heat. 

This isn’t just a minor issue; all that heat can seriously damage your solar panels. 

So, while they can give your lights a bit of a boost, it’s better to consider other options first to avoid any harm to your setup.

9. Moonlight

Moonlight wavelength
Moonlight wavelength

Believe it or not, moonlight can give your solar panels a little boost

Most of the light from the moon hovers around 400 nm

Now, this isn’t the strongest for charging up your solar lights, but on a really clear night, it does offer a bit of charge.

10. Fire

Fire wavelength
Fire wavelength by CFBT

Yes, you read that right.

You can use fire to charge your solar light. 

Sounds wild, doesn’t it?

But as you might guess, it’s not the most efficient or safest method. 

The light from things like campfires and candle flames mostly falls in the infrared and red spectrum, and these wavelengths aren’t great for charging solar panels. 

Less than 1% of this light is in the yellow range, which is what helps generate electricity.

So, while you can technically get a tiny bit of power this way, it’s not going to do much. 

And remember, safety first.

Keep your solar panels a safe distance from the fire to avoid any risk of melting or damage. 

If you’re really out of options and need to try this, just be super careful.


How Do Solar Lights Work When There Is No Sun?

Solar lights store energy in batteries during sunny days, which they then use to provide light when there is no sunlight.

Do Solar Panels Charge When There Is No Sun?

Solar panels can still charge on cloudy days or with artificial light, though less efficiently than under direct sunlight.

Do Solar Lights Need to Be On to Charge With the Sun?

Solar lights do not need to be turned on to charge; they can collect and store solar energy while turned off.

What Is the Best Way to Charge Solar Lights?

The best way to charge solar lights is under direct sunlight, but alternative light sources like LEDs or indirect sunlight can also be used effectively.


Just like I promised, you can charge your solar lights even without direct sunlight, and it’s not as tricky as it sounds. 

You can use mirrors to catch and focus sunlight, or you can go for artificial lights like LEDs or fluorescents to keep your solar lights glowing. 

Sure, each method works a bit differently, but if you mix and match them, you can keep your lights bright even on the gloomiest days.

Here’s a pro tip: Keep checking and adjusting the angle of your solar panels to make sure they’re catching as much light as possible. 

Also, keep them clean and free from any dust or leaves. 

This bit of extra care not only helps them soak up more light but also makes them work better and last longer. 

Kami Turky

Kami is a solar engineer with nearly a decade of experience in researching, testing, and reviewing various solar products.He has also provided technical consultation to several organizations on the best ways to incorporate solar energy into their operations.When he’s not busy helping others find the best solar solutions, Kami enjoys spending time outdoors, hiking, camping, and exploring the natural wonders of his home state.

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