With the development of photovoltaic technology, the conversion efficiency of solar panels has improved significantly: from 5% in 1945 (the solar panel’s inception) to 20% in 2015.
Solar panels also stirred a big commercial change all over the world, especially in the Middle East, where Dubai Awards $3.9 Billion Solar Energy Contract couple of months ago.
Indeed, more and more municipal projects choose to use solar street lights to replace traditional streetlights.
But what are the benefits of replacing traditional halogen streetlights with solar streetlights?
And what are the differences between them?
Let’s dive into the useful information!
Types of solar streetlights
Typically, there are two types of solar streetlights: off-grid and grid-tied.
Off-grid solar streetlights are disconnected from the electric utility company and stand alone like a small solar lighting system unit. They convert solar energy into battery storage during the day, then illuminate the road at night.
Commonly, they are designed to sustain 3 cloudy days, when there is little solar power to convert.
So, if your location has seasonal rainy days that last more than 3 days, you may consider going with grid-tied solar panel streetlights.
Vice versa, grid-tied solar panel streetlights are connected to an electric utility company, and will only use electricity as a backup in case there is a period of prolonged cloudy weather.
Design and installation of streetlights
When it comes to a solar streetlight design and installation,
in order to get optimal results, both off-grid and grid-tied types should consider several engineering parameters: local weather conditions, panel size, light source watts, battery bank size, days of autonomy, lux level on the ground, beam angle and light posts distance.
Traditional halogen streetlights consider little about these parameters.
LED technology dramatically benefits solar streetlights
Nowadays, with the development of LED lighting technology, all types of streetlights are switching their light sources to LED, because LED provides great lighting efficiency: >150lumen per watt and a long lifespan (>35000 hours), which means there is no maintenance cost for over 7 years.
Meanwhile, rather than traditional halogen bulb lights, which emit diffused light and require a reflector cup on its upper side to reflect light downwards, LED lights emit directional lights, so a reflector cup may not be essential.
Furthermore, it is more feasible to apply a lens on an LED light source to meet different street lighting distribution requirements;
for instance, the Type III distribution is meant for roadway lighting, general parking areas and other areas where a larger area of lighting is required.
Additionally, LED lights provide the same brightness as bulb lights, while using less battery energy (commonly, LED lights only need 1/5 to 1/2 watts compared to halogen lights).
This is important information for solar street lights.
When designed, a solar street system requires a smaller solar panel and a smaller solar battery than before in halogen age. This means that people can integrate solar panel, light source, battery and charge controller into one structure when designing a compact structure for solar street lights.
Finally, new compact solar streetlights, also called all-in-one solar streetlights, have become popular in recent years.
We have another article that provides more information about the advantage of these kinds of streetlights:
But what do we get in comparison?
If your projects relate to grid-tied types, switching to LED is the most viable solution to reduce your power consumption. Furthermore, grid-tied projects can use solar panels to harness solar energy to reduce, even more, the electricity bill every month.
If your projects are new, or are in a rural area where it is impossible to bring in municipal electricity, then off-grid solar streetlights are the best option.
Impact on the Environment
Suffice it to say, solar panel streetlights, which harness green and free energy from the sun, have less or no impact on the environment, while traditional streetlights use the electricity, which is produced from non-renewable energy. Moreover, the use of non-renewable energy also results in the production of greenhouse gas – carbon dioxide.
Initial investment and future cost
The initial investment of solar streetlights is higher than conventional halogen streetlights because of the higher cost of solar panels and batteries. But since it harnesses free solar energy, future savings will offset the upfront investment. In the long term, solar streetlights are more cost-effective, for sure.
The kind of streetlights one should select is based on the concrete requirements of projects and one’s budgets. Switching to LED fixtures will lower the power consumption and system loads. We should also expect the technology of the graphene battery, which could be the revolutionary energy storage technology in the future. Also, we think the graphene battery technology will benefit solar lighting dramatically as LED technology since a powerful battery will ensure longer days of autonomy at the same battery size level.
Let’s expect the new battery technology.
What do you think? I hope to hear your comments :)