It’s not that many years ago that powering lighting properly through the renewable energy of the sun was simply out of reach, but nowadays solar has become common place as the technology has improved and become affordable.
It may be familiar now, but it’s no less incredible to think every night the lights come on for free! So we ask, how do solar lights work?
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Solar lights work through the conversion of energy from sunlight into electricity through the photovoltaic effect. Solar lighting will have built into each product or within the system a solar cell or photovoltaic cell (PV Cell), this cell harvests daylight and sunlight and turns that solar energy into a direct electrical current.
These PV Cells are the dark panels commonly seen on street lighting or within people’s gardens always facing up towards the sky. However, these solar panels can turn any light into a DC current, even artificial lighting. This means that you do not need sunlight to charge the battery and even if you keep it close to household lights, it will work. However, in such a case, the solar panels might take up to 12 hours to fully charge the battery.
It’s all about electrons. The structure of a cell contains negatively charged electrons in layers of crystalline silicone and chemicals, which between them are positively charged spaces. The light excites the electrons to move into the surrounding positively charged spaces between those layers.
This passage of electrons is harvested through embedded small wires in the solar cell, transferring the direct electrical current into rechargeable batteries. The battery charges throughout the day at a rate dependant on how much direct sunlight enters the cell.
At night this electron flow stops and a diode between the cell and battery prevents the flow of current back to the cell and wasting the energy. It remains stored until called for.
Most solar powered dawn to dusk lights incorporate a lux sensing photoresistor (dawn to dusk sensor) which acts as a switch signalling to a controller board to allow the stored current out to the LEDs to create light when it is dark enough. The board in turn switches the power off if the photoresistor senses an adequate amount of light when dawn breaks.
If you ever want your solar lights to work but have not charged them, most solar lighting come with a standard AA battery. A fully charged standard AA battery can run LED lights throughout the night depending on the load.
There are certain ways through which you can make the solar lights work at their best.
There is no cover used for solar panels and therefore it often becomes dirty. As a result, the receptors do not get an adequate amount of sunlight, and eventually, the battery gets less power. This is why you will need to clean the solar panels. Solar panels are waterproof and so, you can clean them with clean water and then, scrub all the dirt using a clean cloth. Well, you should not use detergent water to clean the panels because it can lead to solar panels streaking. It can hamper the functionalities of the solar panels.
Did you know that you can charge solar lights without the sun? If you are living in an area where you are not getting minimal sunlight, you will not have to worry. You can still get a good result indoors as the pv panel can even convert artificial lighting into the required DC current and charge the batteries.
Well, if you are getting bright sunlight, it will take 7 to 8 hours to fully charge the battery installed inside the solar light system. However, if you are charging the battery using artificial lights or household LED lights, it will take up to 123 hours to fully charge the battery. So, depending upon the ambiance, you will have to keep the solar lights on charging mode. If the batteries are not properly charged, you will not get a satisfactory result.
You will face situations when your solar lights will not work properly, but help is at hand with these handy check points:
Sounds obvious but there is usually an off and on switch on the back of the solar panel that will need to be in the ON position during the day for the switch to remain open for the power to reach the LEDs when the lux sensor senses it is dark enough.
Pressing this switch in the day is confusing as it will not turn on the lights to test them unless you place your hand over the front of the panel to simulate darkness by covering the photoresistor.
A new product can be shipped with the battery isolated from it’s terminals with a plastic pull tab. Make sure that has been removed.
Dirt will build up quickly on the front of the cell, hindering the efficiency of the charging process – follow our guide on How to Clean Solar Lights
A panel facing north or near another object that will cast a shadow over it for some of the day will drastically reduce the charge rate and even stop the lights working as not enough power is being created and stored. Make sure the panel can see the sun even if for just half the day.
Many products take a AA battery and use a rechargeable one to store the current. Test the system with a new standard battery to see if the battery is damaged.
A standard battery can last for three years. But, after this, you will have to change the battery to keep the solar light in working condition.
A rechargeable battery could need a number of days to reach full charge if it’s charge rate is slow, so let the power be built up over a number of days by leaving the lights off at night. Then test to see how long the lights stay on for.
If the light sensor (photoresistor) is damaged, the LED light will not automatically be turned on. It’s unlikely the design of the panel will allow you to easily swap for a new one so a new panel will be required.
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