Solar powered flashlights or solar powered torches are

flashlight A flashlight ( US, Canada) or torch ( UK, Australia) is a portable hand-held electric lamp. Formerly, the light source typically was a miniature incandescent light bulb, but these have been displaced by light-emitting diodes (LEDs) since the ...

s powered by

solar energy Solar energy is radiant light and heat from the Sun that is harnessed using a range of technologies such as solar power to generate electricity, solar thermal energy (including solar water heating), and solar architecture. It is an essenti ...

stored in rechargeable

batteries Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...

. Most of these flashlights use

light-emitting diodes A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (cor ...

lamps since they have lower energy consumption compared to

incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxida ...

Features

Solar powered flashlights vary in features and capabilities. A typical solar flashlight can give useful levels of illumination on objects up to 50 metres away, and beam may be visible for much longer distances. The solar cells used for battery charging have an indefinite life expectancy. A solar powered flashlight may give several hours of light after being charged during the day. These flashlights may be designed to be impact resistant, weatherproof, and to float. Other models include features such as a

solar cell phone charger Solar cell phone chargers use solar panels to charge cell phone batteries. They can be used when no electricity supply is available—either mains or, for example, a vehicle battery—and are sometimes suggested as a way to charge phones without ...

, an AM/FM radio, or a siren to call for help in an emergency. Some models include a hand crank dynamo for charging at night. An experimental solar flashlight the size of a credit card features a white LED powered by 16 solar cells.

Comparison with primary battery flashlights

Solar powered lights need not be manually recharged as in the case of conventional battery operated flashlights. Pollution from discarded batteries used in normal flashlights is eliminated. Solar powered flashlights can be used in remote locations where it is impossible to find any source of electricity except for solar power. A built-in solar cell array in a hand-held product has a very small capacity. The light output and run time of the solar flashlight are limited by the amount of energy that can be absorbed in a day. Flashlights are usually stored indoors or otherwise out of direct sunlight; consumers may find it inconvenient to remember to place the flashlight in full sunlight for several hours before use. Rechargeable cells self-discharge, so unless the flashlight is stored in a sunny location, the light may not function in an emergency. Rechargeable cells have a finite charge/discharge cycle life, and when the cells wear out it may be difficult for the consumer to replace them. Some of these disadvantages can be mitigated by separating the solar cell array from the flashlight, but then the simplicity of automatic charging is lost.

Significance

Solar powered flashlights have been distributed to countries where there is either no or erratic power supply, helping people feel safer leaving their homes at night, and giving children the opportunity to study after sunset. A dual purpose solar flashlight, which also functions as a lamp has helped families in such countries spend more time together, surgeries to be performed during power outages and people to travel in the dark under a halo of light.

References

{{DEFAULTSORT:Solar Powered Flashlight Applications of photovoltaics Flashlights

Features

Comparison with primary battery flashlights

Significance

See also

References