Solar power is awesome.

It helps us reduce our footprint on the planet, saves us money, and generally is just a great thing all around.

But there are times when the clouds come out and the sun says “adios!”

It’s not so great then because, well, we can’t power our lights and batteries when the sun’s down, the clouds are getting cozy with the planet, or we realized we forgot to set our travel solar panel in the sun yesterday before the lights went out.

So, the big question is, can you charge a solar panel with a light bulb or some other way that doesn’t fully rely on direct sunlight?

The answer is, yes.

Let’s see out how.

Decorative lighting inside tropical bamboo garden at night web

How Does Solar Power Work?

First, let’s start with a short overview of how solar power works.

Solar power systems involve photovoltaic cells that make up the solar panel. The panel collects energy from the sun – thus “solar power” – and converts it into useable power for the batteries or lights to turn on and run for a few to several hours.

Of course, solar power is far more complicated than this simplified view, but the basics are what most of us need to understand about solar power and how it affects our use of it.

What Kinds of Things Can You Run by Solar Power?

You can run basically everything off solar power. Lights, disk lights, solar flashlights, fridges, laptops, air conditioners – literally anything.

The key is, however, that you have the right solar power system in place. You need solar panels with enough wattage, and the proper connectors paired together to create the full system.

How To Charge Solar Lights Without Sun

There are definitely ways to charge your solar-powered appliances and electronics without the use of direct sunlight.

Some are more effective than others, and some are faster than others.

We’ll take a look at the two basic realms in which we can charge solar-powered objects, though, and review the best ways for both indoor and outdoor charging for solar-powered pieces without the sun.

How to Charge Solar Lights Indoors

There are several ways that solar lights can be charged indoors.

Let’s take a look at a few of the most common questions, like:

  • Can a light bulb power a solar panel?
  • Which kinds of bulbs can you use to power a solar panel – or charge another light?
  • Can solar lights charge through windows?

Charging Your Solar Batteries with Regular Lightbulbs

It is possible to charge solar batteries with regular – i.e. incandescent – lightbulbs.

I’ve done it many times myself when I realized that my solar-powered flashlight was needed the next day, and it was, well, midnight.

I wouldn’t exactly have much sun available before four a.m. when I was headed out for my spelunking trip.

Because the only flashlight I had working at the time was my solar-powered flashlight, I had to find a way to charge overnight/before I took off for the dark morning. On a whim, I put my flashlight, with the photovoltaic cells facing the light, beneath a lamp and left the light on for a while and worked on my other preparations.

When I returned two hours later, the battery was partially charged.

Solar cells respond to incandescent light much the way they do to solar power because solar and incandescent bulbs both put off light waves that the solar cells can collect and convert into energy.

Incandescent lights need to be bright enough, but if they are, the light wavelengths are similar enough to the sun’s Ultraviolet waves that the solar cells can convert the energy into useable power.

Incandescent bulbs aren’t as efficient at charging solar cells, mainly because they require power to create power when solar charging requires only the renewable energy of the sun.

To charge the battery or other solar-powered objects with an incandescent bulb, you want to position the object about 20 inches away from the light source for as many hours as possible.

Incandescent bulbs are not as powerful as direct sunlight, so it will probably take longer to charge than it would outdoors.

My solar-powered flashlight took about 6 hours to fully charge with incandescent light when normally it takes 4 in direct sunlight.

Note: Most incandescent bulbs produce between 40 and 100 watts of light. The higher the wattage, the faster the charge the incandescent bulbs will produce.

Tent with solar light on inside with starry sky how to charge solar without sun

The Kinds of Light Bulbs You Can Use to Charge Solar Panels

You can use any kind of lightbulb that creates light within the correct light wave spectrum.

LED lights, for example, create light with visible light, long infrared waves, and ultraviolet waves, which the sun creates.

However, most light sources – including LED and incandescent, halogen, and most household lights – do not create much in the way of ultraviolet light waves.

This applies the same concept to the incandescent light. As you want to use another source of electric energy to produce solar light, LED light is a good option.

Like the Sun, LED is designed to produce a spread of light wavelengths, which consist of visible light, long infrared waves, and ultraviolet waves.

However, each source of light has a distinctive spectrum. While the Sun produces abundant amounts of ultraviolet, an incandescent light releases just a little of it.

Note: If you wish to use an ultraviolet lamp to charge solar panels or items, you should be aware that UV lamps put out significantly more heat and energy than the average indoor light and maybe a safety hazard. For this reason, we recommend using some alternative source of indoor light instead.

How to Charge Solar Without Sunlight Outdoors

Generally speaking, when you charge solar-powered objects outdoors, this will be with the sun. However, there are circumstances when your charging outside may need a bit of help with proper equipment.

Charging Your Solar Batteries on Cloudy Days

First off, I want to reiterate that even on cloudy days, solar panels do collect some charge.

It won’t be as strong as on bright, sunny days, but there’s still solar energy being sent down to earth from the sun.

That being said, the best way to charge solar batteries or lights on cloudy days is with the use of an amorphous solar panel rather than the more popular polycrystalline or monocrystalline panels.

Amorphous panels aren’t as efficient as poly and monocrystalline panels, but they gather more light energy from cloudy skies because of their nature.

Silicon panels of solar batteries against the cloudy sky in the middle of the day

How to Charge Solar Lights in Winter

It’s important to remember that solar lights will still charge in winter, though it will not be as quickly or as efficiently as during the summer months when the hot sun sends out all those intense light waves for more hours.

Ultraviolet light from the sun will penetrate the clouds and still hit those solar panels in the yard on just about any day, even in wintery, cloud-covered months.

If you get snow in your region during the winter months, you’ll need to do a few things to keep the light powering up the panels.

First, you’ll need to regularly clear the snow from your solar panels and light faces. This simply requires a gentle removal of the snow with a brush that has soft bristles or a soft cloth that won’t damage the solar cells.

Second, during winter months, you may want to relocate your solar panels to avoid shadows. Winter days have shorter daylight hours, which means longer, more frequent shadows.

Position the solar panels to the south to collect the most light.

If you have panels that swivel or tilt, you can reposition them throughout the day (generally at noontime as the sun shifts toward a descent) to ensure the panel gets as much sunlight as possible.

solar panels covered in snow in winter
It’s not just that the sun is out for less time in the winter…it’s the fact that snow can cover the panels, rendering them useless! Make sure to clear yours of snow as often as possible. (And be safe!)

Alternative Ways to Charge Solar-Powered Items

You’ll be glad to learn that a number of solar-powered objects have alternative power sources, including standard electricity through the grid.

Some Solar-Powered Appliances and Electronics Can Be Charged with Standard Electricity

Many of the best solar-powered products I’ve recommended in the past have options for charging by directly being plugged into a wall socket, DC charger in the car, or other “standard” means of charging.

The reason I recommend these products when I’m all about off-the-grid living?

Mainly because there are times when you simply need to start out with a full charge right away.

This is generally for when you may find yourself in unusual circumstances or emergency situations – think hiking, camping, backpacking, lengthy travel through remote areas, and other outdoor activities where you won’t be near to standard electric and communication options.

Plus, if you’re loading up a bug out bag or something for emergencies, solar is a great idea…but you want everything to be fully charged so it’s ready to be used ASAP.

Many of these products have USB charging options or use standard electrical outlet style plugs for charging up ahead of time. I prefer those with USB charging options as these give the most versatility for any situation.

Charging Solar-Powered Items Through Windows

Technically, charging your solar panel through a window qualifies as with-sun charging, but it is indoor charging and therefore indirect sunlight charging…which is why I’ve included it here.

And, yes, you can charge solar panels through windows.

I’ve used many small solar-powered electronics and appliances over the years and often charged them through my windows.

Place the solar cell portion of the object directly in the window sill for the fastest, most effective charging.

FAQs About Solar Charging Without the Sun

Can artificial light power a solar panel?

The short answer is yes, artificial light can power a solar panel.

Depending on the wattage, the number of bulbs, and distance the solar panel is from the light source will determine how strong a charge the solar panel receives, and how much wattage the solar panel will then be able to produce for powering other objects.

Can LED lights power solar panels?

Yes, you can charge solar panels with LED lights.

However, the light waves are not as similar to sunlight waves as incandescent bulbs produce.

This means that it will take longer to charge and you will need more LED lights to charge the solar panel than you would with incandescent bulbs.

Shoot for wattage closer to 100 than 40 for LED light charging of solar panels.

Can solar lights be charged indoors?


If you read in-depth in the sections above, you will see the various ways that you can charge your solar-powered objects indoors via artificial light, standard electricity sources, and through windows.

Do solar lights need direct sunlight?

No, solar lights do not need direct sunlight to charge. They do require light in some form to power them on, however.

This may be produced through indirect sunlight – think cloudy days – or via artificial light sources like incandescent bulbs or LED lamps.

Can you charge solar objects through a tinted window?

If you have tinted windows on your car or home, you can still charge solar-powered objects. The tint on the windows only blocks a portion of the light and energy that comes through the glass as it strikes the surface.

Some forms of tint vary the amount of light getting through, however.

Limousines with privacy tint, for example, will block significantly more of the light from getting in to the solar cells that draw in the power.

This happens because the tint is darker, yes, but also because the tint is designed specifically to reflect back the light, which allows the folks riding inside to see but prevents those on the outside from seeing in.

Do solar panels need direct sunlight to work?

Solar panels use the energy from daylight, not necessarily direct sunlight, to produce the energy that they then convert into useable electricity.

That means that, just like on a cloudy day at the beach when you get a worse sunburn, daylight is the source of solar energy.

The photons in natural daylight are what are converted, not the heat, which is generally what we associate with sunlight versus daylight.

This means that while, yes, direct sunlight will produce a stronger charge for a solar-powered device, direct sunlight is not absolutely necessary for power to be created. Solar panels are about 40% as effective on cloudy days as sunny days. The more sunlight, the more electricity is created.

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