Solar Stain - Model 12-Part Series - Components
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In this issue, Quality Components, we examine the ...
In this issue, Quality Components, we examine the details of what goes into a solar powered LED lighting system. How and where the components are manufactured, the various regulatory bodies who govern quality assurance, and what makes one system different from the next. As with any system, different components have different life expectancies. Understanding the tolerances and expectations of solar lighting systems will help Agencies better determine what system is best suited for their needs. Above all we hope to provide Agencies with key questions to ask regarding system components and what other factors they may want to consider to ensure they acquire the “best fit” solar system.
Components Overview
A solar powered bus stop or bus shelter lighting system consists of several primary components: Batteries, Controllers, Solar Modules; LEDs; Wiring/Fuse; and a system Enclosure or (Metal Work). From system to system and company to company there are a wide range of variations when it comes to the specific components used. With so many variables at play, one key element for Agencies to utilize to better evaluate quality components is to consider UL certification. Companies offering a solar lighting system with UL certification can ensure quality components; as a result customers see higher performance standards and have the comfort knowing their solar lighting system is certified by a world leader in safety compliance.
Obtaining quality components for your solar lighting system is paramount. Below is a brief summary on the primary components that make up a solar powered LED lighting solution and crucial questions to ask solar lighting companies when evaluating components.
Batteries
Batteries allow for power storage overnight and over long periods of time so that solar powered lighting systems may produce light when there is no solar power from the sun. All solar powered lighting systems have batteries. This is why it is important that the vendor you work with has a strong understanding of the variations in quality and scaling for systems installed in a wide range of locations. Batteries vary in size, composite materials, temperature tolerances, and expected lifespan. An inexperienced vendor, who may not provide solar lighting systems as their core competency, will choose a battery solely on price so that they are able to provide the lowest cost solution. It is important that agencies and customers understand the difference between the different levels of quality, as pertains to their application.
Questions to ask when looking for quality Batteries:
- What is the temperature rating? Is this battery suited for the intended environmental conditions?
- If the battery isn’t UL listed or certified for safety by itself, is the battery part of a UL certified system?
- How many reserve days (autonomy) are being provided?
- Has an ALR calculation (Array to Load Ratio) been provided to demonstrate the battery is appropriate for the proposed load (LED light)?
As the brains of any quality solar powered lighting system, controllers play a vital role for system performance and maintenance. As an example, some vendors will assert that controllers with Bluetooth or wireless connectivity are superior and allow the end user to change settings monthly. However on closer inspection, this functionality will have a significant impact and drain the available system power, not to mention the requirement of adjusting the system monthly.
In contrast, reactive controllers allow for transitions between a changing dusk and dawn. They consume significantly less power than a controller that tries to do too much. While certainly an improvement with respect to adjusting the program every month, it can cause issues with false transitions if there is any overhead street lighting or lighting from nearby buildings.
Therefore, a pre-programed automatically adjusting timer based configuration is ideal for the public transit industry. This allows for a low power consumption, no overhead lighting issues, and no need for manual adjustments. Having a solar company that understands this highly sophisticated process and the impact of specific geographical areas/zones is paramount. No ‘off the shelf’ mass produced controller can do this.
- Questions to ask when looking for a quality Controller:
- Is the controller proactive for changing seasons and weather conditions, requires manual adjustments, or is reactive?
- Does the controller offer a self-test feature for maintenance staff to easily test system state of health status during the day? And are there any special tools required to conduct this test?
- If the controller isn’t UL listed or certified for safety by itself, is the controller part of a UL certified system?
- Where applicable, does the controller automatically adjust on / off light transitions for daylight savings?
- Can the controller automatically adjust LED light levels based on local weather conditions?
- Is the solar controller one unit, built and tested as one package or a collection of smaller components thrown together?
LEDs
LEDs are great low power high light output electronic components. In terms of solar powered lighting for bus stops and shelters, LEDs are an excellent choice, creating strong lighting with the highest levels of efficiency. If LEDs are so perfect, why even bother talking about them? As with all components, not all LEDs are created equal. Some key LED metrics to consider for use in solar powered lighting system are: number of lumen/watt; number of LEDs per fixture; size and mounting of fixture; dimming options; lenses/optics; and color temperature.
The number of lumens per watt will determine the efficiency of the LEDs that you are using. This number is constantly increasing as LED technology increases, with industry standards sitting around 100-125 lumen/watt. This means if you are using a 10W fixture you should expect to see an output of 1000 lumens.
While more bulbs usually sounds better and mean more light, with LEDs, it’s not so simple. Over time, the color temperature of an LED will change and become inconsistent with neighboring LEDs, which gives you a light fixture that looks strange and less appealing to observers. Quality LEDs which have been carefully selected will retain their color longer but still have eventual degradation. Therefore if you have a fixture with a lot of small inexpensive LEDs, there is greater likelihood of discoloration. Then why not go with a single high power LED? First of all, LEDs run hot, and while using lots of small LEDs are great at spreading heat over a larger area, one big high power LED focuses all that heat into one small space, requiring much larger heat distribution measures. It is important to meet somewhere in the middle with a few medium power LEDs per fixture.
- Questions to ask when looking for a quality LED fixture:
- Is the LED fixture certified for safety by UL or an equal independent third party safety organization?
- What is the power output in Watts; output in lumens; and how many LEDs are contained in the fixture?
- Does the fixture offer vandal resistant qualities and should it be required? Can the LED fixture be serviced in the field with minimal time and effort?
Enclosure: Metal Work and Painting
How does someone compare one metal enclosure to another? First of all the system you choose should be the one you like aesthetically. Obtrusive or ugly systems will stand out. Attractive systems with proper colors will naturally blend in making them less prone to vandalism. Proper low profile solar mounting brackets will also reduce visibility and vandalism. All of these you can visually see with examples from previous installations.
Secondly, the manufacturer should be ISO9001 certified. This guarantees the proper measures are carried out to produce quality products. This carries over to the powder coating finish for the metal products. Proper powder coating of metal components are critical because if done improperly, chipping or peeling may occur. Asking other agencies their experience with a specific vendor’s products will help determine if there have ever been issues of poor metal work, painting or assembly and how well they were able to respond to the failure.
- Questions to ask when looking for a quality Enclosure:
- How is the enclosure secured to the shelter? Does the metal work integrate with the shelter architecture?
- Does the solar lighting system include the enclosure in its UL certification or how is the enclosure certified for safety?
- What are the quality metrics used for the materials, including the powder coat?
- How does the weight and size of the system impact the wind loading of the shelter?
Solar Modules/Panels
Typically there are 3 different types of solar panel used with solar powered bus shelter lighting systems. Rigid, flexible, and building integrated photovoltaics (BIPV). While this is highly simplified more information is available from our “Solar Maintenance 101” section – Coming soon. Rigid solar panels provide the most efficiency per square inch of solar absorption thus allowing for more compact systems. Flexible and BIPV require a significantly larger amount of space to achieve the same levels of solar absorption. It is critically important to vandalism reduction that systems are low profile and limit visibility. Upon impact with a projectile rigid panels fair the best as they are equipped with tempered glass and continue to function even if the glass is cracked.
Wiring and Over Current Protection
This is often an overlooked component of a system, but certainly a critical factor. Improper sizing of wiring or low quality connectors can result in unreliable systems. Loose connections will eventually come apart, requiring ongoing repairs and maintenance. A wire gauge that is too small and or improperly fused will cause the wires to overheat and become a fire hazard. Excess wiring can also be an issue resulting in inductive fields if spooled further exacerbating the overheating issue (safety hazard). This can also create additional resistance resulting in performance issues. All of this amounts to unnecessary replacement of parts and maintenance.
In Conclusion
Quality components are proven to provide safer, higher performing, and longer lasting solar lighting systems. Requesting certification and proper documentation for your preferred solar lighting system, ensures that you can feel safe in the fact the vendor is doing their due diligence to serve your best interests. The result will be reduced maintenance costs; increased value for the public and transit users; increasing the agencies public image; and overall better return on investment (ROI).
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