How to Charge Solar Batteries Without Sun

This site contains affiliate links to products. We may receive a commission for purchases made through these links.

Sunlight is the best form of energy to use when charging a solar panel. You should strive to charge your solar panel for at least 8 to 10 hours per day in direct sunlight which can ultimately produce 15 hours of light. 

However, in the sun’s absence, you have to find other alternatives that are equally effective. Let’s take a look at why solar lights are so important and alternatives on how to charge solar batteries without sun.

Importance of Solar Light

  • Solar light uses clean energy which is conservative, with the sun being the main source of power. This helps reduce bad electricity production practices
  • They require little or no maintenance, but a few cleanups and washing here and there. Solar lights do last for long
  • They are cost-effective; once you buy one, be assured that it will serve you for long, unlike having to pay electricity bills
  • They are safer to use than other kinds of lighting. Your children will also be safe from electric shock when playing around or when there is a fault
  • They come in different sizes and shapes and suit one’s preference easily

Incandescent Light Bulb

Most people believe that solar cells can only be charged using natural sunlight, but they can also be charged from an incandescent light bulb. However, the light needs to be bright enough for the charging to occur because the solar cell normally converts the wavelengths of the sun into electrical energy. 

Both the incandescent bulb and the sun produce a spectrum which is a spread of light wavelengths. This includes long infrared waves, visible light, ultraviolet waves waves, and x rays. The spectrum of the incandescent light tends to be similar to the sun rays making it easy for the cells to convert it.

A typical incandescent light bulb tends to produce between 40 and 100 watts and has the longest infrared wavelength. This makes it as effective as the sun’s rays because although the sun produces a lot of light, only a small amount reaches the solar panel.

The energy received by a cell from incandescent light tends to reduce rapidly because of the distance. The lesser the light that falls on the cells the weaker the output, making it take longer to charge. When using an incandescent bulb, place the solar lights as close as possible to the light bulb; if it is further away it will take longer to charge. For maximum results charge the solar panel for 12 consecutive hours.

1 e1565271169214

Charge from LED Light

Just like the sun, an LED light is designed to produce a spread of light waves which consist of visible light, ultraviolet waves, and long infrared waves. However, both the sun and LED light have a distinctive spectrum that is useful in charging.

When far from home, you can use LED lights to charge the solar lights. This is important when you don’t have indoor lighting like when you are camping.

Avoid placing solar lights near street lights. When exposed to high-intensity light in the evening, their sensitivity may decrease over time; therefore, keep them away from artificial light as much as possible during the night.

Use of Limited Sunlight 

There are certain solar panels that are customized to charge even in low-sunlight conditions, like when it is cloudy. However, this leads to a low charge and the solar panel will not light for too long. They are mainly found in areas that experience winter longer than the summer.

However, when cloudy days persist and only a low charge is obtained, it may affect the life and efficiency of the battery. The light receptors in solar panels tend to convert the slightest light to electric energy. 

However, when the sunlight is too much, ensure you have a charge controller to prevent it from affecting the batteries or solar components.

When charging in indirect sunlight, you need to clean the solar panels to ensure maximum light penetration. Cleaning any dust or dirt off the surface of the panel will help charge the solar panel more efficiently and make better use of the limited sunlight.

When cleaning use clean water and don’t use detergents that can make it hard for the solar batteries to charge. You can use a microfiber cloth to clean the dirt off.

You should also move the solar light to a position in which it can easily receive the limited sunlight. Put it at an angle where it can directly face the sun as it moves, move the solar panel too. Ensure you do not place the solar panel in the shade when the sunlight is limited.

If need be, you can try to use a mirror to redirect the sunlight to your lights; reposition your solar panels in the direction of the reflected light. However as tiresome it is, it produces good results. 


The next time there is limited sunlight, you should use these alternatives to ensure you will have light during the dark hours. These methods are equally effective, but be careful that they do not destroy your solar panel batteries. Ensure you use the alternative tactics well and maintain your solar panel for it to last long.

Special offer for our visitors

Get your Solar Lights Free Guide

We will never send you spam. By signing up for this you agree with our privacy policy and to receive regular updates via email in regards to industry news and promotions