SOLAR POWERED STREET LIGHTING
Solar power converts energy from the sun to produce lighting and electricity. In recent years, it has been used to power street lighting in towns and cities. In 2019, over one and a half million solar street lighting units were sold, with a forecast of a further 9% increase between 2020 and 2030. The COVID-19 pandemic did slow down the production of the streetlights, but solar streetlights are becoming increasing popular worldwide.
What are Solar Powered Street Lights?
So, what are they? They are basically a light raised on a pole just like any other streetlight but they get their energy from sunlight captured by a 'photovoltaic' panel.
These solar panels may be –
- attached to the light at the top of the pole
- built into the pole
- or they could be separate from the pole.
Where panels are housed away from the pole the power generated may be used to supply a number of streetlights. Those with the panel attached to the pole are usually independently operated.
The solar panels may be either monocrystalline or polycrystalline according to the type of silicon used to make them. You can tell monocrystalline panels by their black cells. Polycrystalline ones have a blue colour. The silicon in monocrystalline panels is purer and they generally convert solar energy into usable power much quicker. They also take up less room than polycrystalline panels to generate the same power output. However, the performance of the panels is also determined by the manufacturer. Recent advances have shown that polycrystalline panels can perform similarly to moncrystalline ones in mid to higher end products, so the performance is not as clear cut as many would believe.
The Parts
As well as a solar panel to capture and convert energy and a pole to elevate the light, each solar street light also has:
- Battery - The rechargeable battery stores energy generated during the day and uses it to power the lamps during darkness. These are usually gel deep cycle or lead acid cell batteries, but others include nickel metal hydride.
- Controller - These are needed to turn lighting and charging on and off. Sensors in the controller trigger the light to power up during dusk and darkness. Typically, the sensor detects when there is insufficient sunlight and so it turns on the lamp using some of the power stored in the battery. Controllers can be quite complex and include options for dimming or setting timers, and systems may be activated remotely. They also prevent the battery from being overcharged or discharged.
- Lamp - LED lamps are used because they are capable of emitting higher lumens using less energy than other types of globe. Manufacturers tend to offer a range of different wattage units such as 30, 50, 70 and 100W.
The Advantages and Disadvantages of Solar Street Lighting
Solar Street Lights have their advantages and disadvantages.
Let’s look at the advantages first.
Efficient and Cost Effective
The lightbulb producer, Phillips estimate that just 15 solar streetlights save enough energy to power an electric car for a year. Just imagine if all streetlights were solar? How many cars could that power?
The technology in solar powered products, such as street lighting, is improving daily. This means that the products are generally becoming cheaper.
Solar streetlights are considered to be a cost-effective method of providing light when compared to traditionally-powered street lights.
Once installed, they cost nothing, or very little, to run because the energy is free. They cost little in terms of maintenance.
It should be noted that the cost of lights to the power produced has been gradually declining over time as the technology has become more efficient, and promises to continue falling as advancements are made and more people take up the technology.
LED technology has ensured that solar streetlights can provide the necessary lumens which are required to meet the standards set down for lighting most types of outdoor uses. They currently cannot match the highest lumens of traditional street lighting which is needed in some places, such as petrol stations, but no doubt they will in the future.
Remote satellite operation is coming onboard which allows users to monitor their lighting for efficiency and to control how it works. Also, warnings about maintenance can be included so users can keep on top of any possible problems.
Last Longer
Solar powered lights are able to provide brighter light for longer periods than traditionally powered lighting.
Solar Energy is Renewable
As well as becoming cheaper, using solar energy has a massive potential positive impact upon the environment. Solar energy is an effective form of renewable energy. They are powered by sunlight and rechargeable batteries. This means that they are off the electricity grid, which also makes them immune to blackouts.
Environmentally Friendly
They are also more environmentally friendly as they do not cause pollution.
Flexibility
Solar energy is not just being used on streetlights. It has also been considered on other forms of lighting, parking meters, cars and more.
There really is no limit to where they can use them. As well as the obvious use for street lighting, they can be used to illuminate country roads, highways, promenades, jetties, parks, city playgrounds, walkways, and many other public spaces.
Businesses may use them around loading bays, storage areas, or outdoor dining areas. Universities and schools can adopt them for rest and relaxation spaces. Other users include residents of properties in remote locations where it may be too costly to incorporate traditional lighting. They can be taken to farms, resorts or coastlines.
Because they can quite literally be placed anywhere, they are needed, solar streetlights are ideal when lighting is only needed temporarily. For example, they can be easily and efficiently set up to light agricultural shows, fairgrounds, sporting contests and other outdoor events. Solar streetlights are also ideal where it is not feasible to dig trenches for traditional grid lighting e.g. environmentally sensitive situations.
Portable
They are portable which makes them easy to install since they don't need to be wired into existing power systems. This overcomes the cost and inconvenience of connecting to the grid. Just position them where you want them and off you go.
Remote Control
Remote technology means that they can be controlled remotely from a computer or PC, which gives the operator greater flexibility on how the lights are operated.
What are the disadvantages of solar powered street lighting though?
- The rechargeable batteries do not last forever and will need replace once or twice in a light’s lifetime.
- They are more expensive than traditional streetlights to buy, but as we said earlier, as technology is improving, so the cost of producing the street lights is reducing.
- Their portability means they can get stolen more easily.
- The panels can become less efficient by getting clogged with dust or debris, or through moisture building up inside them. Regular servicing is advisable.
We’ve seen the good and the bad, but is there any ugly?
There really is no ugly - unless you just do not like the appearance of solar panels on lights, but they have been around long enough now for most of us to get accustomed to them. Besides, many of today's sleeker designs more than compensate for the inclusion of panels.
One misconception is that solar lights will not work on a dull or dark day.
Weather Conditions
Although solar lights need sunlight to charge the battery, they do not simply become redundant on days with little sunlight. The batteries are usually capable of storing enough energy to power the light for several nights at a time, with some lasting up to 5 nights. This makes them very reliable. Also, systems can be designed to take into account the prevailing light conditions of an area. As such, more panels can be incorporated if necessary to minimise the risk of lights failing to power up.
Windy sites can also present a problem in some areas, but many lights are engineered in designs to limit wind damage. Wind can also be utilised to generate back up electricity through a turbine when the solar is less effective. The positioning and type of panel can also be adjusted according to local conditions. Movable panels and light heads are also possible so they can deal with wind as force and direction changes.
Snow resting on panels will prevent them from capturing sunlight. Usually because of the angle of panels it falls off as it melts so there is no need to take action. Melting is speeded up because panels emit a small amount of heat at all times plus if the snow is thin then sunlight is reflected onto the snow by the panel. If snow is persistent it may need to be manually removed e.g. by brushing off. Movable panels can be adjusted so that a steeper incline allows the snow to fall off.
Hybrid Lights
In recent years hybrid solar streetlights which incorporate both solar and wind energy have emerged. Such designs can be a better option in areas with sufficient wind but unreliable sunlight. In order to support a small wind turbine these lights necessarily have to have stronger poles. Another focus is to make the turbines as quiet and efficient as possible. Like the solar only street lights a range of designs with different features have found their way onto the market.
Solar street lighting does have disadvantages –
- They can be costly initially
- The panels can take up a lot of space
- Storing solar energy can be expensive
- They can be affected by the weather
But –
- They are a renewable energy source
- They reduce electricity bills
- They have many different applications and potential uses
- They have low maintenance costs
- Technology is also developing all of the time to improve solar powered streetlight and to reduce the cost of producing the lights.
Would you like to learn more about solar energy and alternative forms of energy? Why not have a look at our Alternative Energy online course