Solar LEDs - The BASICS
A solar light requires no in-depth knowledge to use it - that's wonderful thing about them. A consumer can elect to purchase the light, install it and enjoy it without the slightest understanding of how it works. Kind of like a kitchen appliance. For those out there that demand to know, we've assembled the following summary of Solar LED Basics.
A solar light is an assembly of 4 primary components; Solar Cell, Storage Device, LED light and Circuit Controller. While there are an unlimited variety of component variations and system design, all Solar LED lights will incorporate these fundamental elements.
Solar Cell or Photovoltaic Cell
Einstein developed a theory that the sun's energy could be converted in electricity and he was right (something called the Photoelectric Effect). Today we use solar cells comprised largely of silicon to perform this function. The two primary types of solar cells are called monocrystalline and polycrystalline. A polycrystalline solar cell is created from a large block of molten silicon. Evidence of this type of cell is often demonstrated with what appears visually as a random assortment of crystals.
In contrast, monocrystalline solar cells are created from a single silicon crystal. They tend to be more expensive but are more efficient than polycrystalline solar cells.
Storage Device - The Battery
The amount of energy derived from a small solar cell is quite small and would struggle to power anything directly. Think of a leaking garden hose dripping water into a bucket all day long. Finally, at the end of the day that that slow trickle of water has filled the bucket completely. For a Solar LED system, that bucket is a battery storing not water but energy all day long. It collects the electricity from the solar cell and stores it until it is needed.
There are many different types of batteries but again for our Solar LED market it essentially comes down to two different types; Ni-Mh and Ni-Cd. There is no perfect battery and these two batteries both have their strengths and weaknesses. The Ni-Cd is great for high current draws such as power tools but suffers from something called "battery memory". This effect is caused when the battery is not charged and discharged properly. Worse, this battery contains Cadmium - a toxic material.
For solar LED lights, the best battery solution is Ni-Mh. These batteries support hundreds of repeated charge discharge cycles, work well in extreme weather conditions. Ni-Mh batteries contain no toxic material and can be disposed of without harming the environment.
Control Circuit - The Brains
This sounds more complicated than it really is and truthfully some designs do incorporate very technical design considerations. However the primary function of the control circuit is to control the overall operation of the Solar LED system. Fundamental actions such as when the unit stops storing energy and starts discharging to power the LED is controlled by this circuit. Some designs incorporate additional design aspects such as light oscillation to help prolong the amount of light or run time for the unit. A properly designed control circuit is critical for a world class Solar LED light.
Unfortunately, this critical component is largely hidden from sight and quality cannot be readily observed from a consumer's perspective. As a result, overall product quality cannot be assessed until it has been purchased and performance can be evaluated.
LED - The Light!
An LED is a light emitting diode and it is what the entire Solar LED system is there to support. From a quantum physics perspective an electroluminescence effect is created when a diode is forward biased and electrons are forced to drop an "energy level" - whew. The best explanation is that they are a light component available in red, green, blue, yellow and white. When compared to that old humble incandescent light they are superior in almost every aspect.
The LED light requires very little power, lasts over 25,000 hours, works in almost any environmental condition and is extremely shock resistant.
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