How do I ensure we receive quality components?
A solar powered bus stop or bus shelter lighting system consists of several primary components including batteries, controllers, solar modules, LEDs, wiring/fuse, and a system enclosure or metal work.
From system to system and company to company, there is 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.
See Batteries 101 for full technical details
All solar powered lighting systems have batteries. They allow the lighting systems to produce light when there is no power from the sun. This is why it is important that vendors you work with have 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, which may not provide solar lighting systems as its core competency, may choose a battery solely on price so it is able to provide the lowest cost solution.
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)?
See Controller 101 for full technical details
Controllers are the brains of any quality solar powered lighting system and 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, 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 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 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 put together?
LEDs are great low power high light output electronic components. In terms of solar powered lighting, LEDs are an excellent choice and create 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 systems are number of lumen/watt, number of LEDs per fixture, size and mounting of fixtures, 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 sound 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 that 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. So 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: Metalwork and painting
How does someone compare one metal enclosure to another? First off, 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, which can help make 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 metalwork, 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 and panels
Typically there are three different types of solar panels used with solar powered bus shelter lighting systems, which are rigid, flexible, and building integrated photovoltaics (BIPV).
Rigid solar panels provide the most efficiency per square inch of solar absorption, which allows for more compact systems. Flexible and BIPV require a significantly larger amount of space to achieve the same levels of solar absorption.
Rigid panels fair the best against rocks or other hard objects tossed at it, as they are equipped with tempered glass and continue to function even if the glass is cracked.
Wiring and overcurrent protection
This is often an overlooked component of a system, but it is 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, which further exacerbates the overheating issue and becomes a safety hazard. This can also create additional resistance resulting in performance issues. All of this amounts to unnecessary replacement of parts and maintenance.
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 its due diligence to serve your best interests. The result will be reduced maintenance costs, increased value for the public and transit users, increased public image for the agency, and a better return on investment.