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Educational October 2019

7 Questions you need to ask before you start your Solar Commercial Lighting Project


When you install a traditional commercial light, you don’t often need to be concerned with whether it will be “bright” enough or will operate continuously because there is an expectation that it will work as specified. You trench, lay cables, connect to the utility, and bam—you have light!


However, if avoiding those trenching and utility costs is your goal, rest assured that a properly-sized solar lighting system is a suitable option. While a solar-powered commercial light can achieve the same lighting results as a traditional light, there are a few specific things you will need to evaluate to ensure you get the right results.


This article will help you get started on how to evaluate the best solar lighting option for your project. In this first step, we will cover what information will need to be collected in order to eventually compare solar lighting specifications from different manufacturers.


To explore the next steps, get a copy of our free Ultimate Solar Lighting Guide.


Download our free Ultimate Solar Lighting Guide

Gathering the Project Specifics: 7 Things You Need to Ask and Why


Asking the right questions upfront will ensure any comparison between manufacturers is equal, and that each manufacturer sizes or customizes their solar lighting solutions to your exact project requirements.

Why should you ask these seven questions?

  • Avoid overspending: ensure the lighting system will use properly-sized components for your project needs vs. having an unnecessarily large and expensive system to compensate for poor design.
  • Avoid battery replacements or auto shut-off: install an efficient system that will be able to sustain your light requirements over the long term vs. one that dims the lights, leads to premature failure of the battery, or shuts the lights off completely.

Here are the top 7 things you need to ask.

1. Ask about the Project Location


What is the exact location of the project? Try to get an accurate street address and site description whenever possible.

Why? This allows the manufacturers to factor solar insolation data into their system design.


Different areas receive different amounts of sunlight each day. For example, a solar light specified for sunny, southern Los Angeles would be smaller and therefore wouldn’t be able to generate enough power to provide continuous light for Anchorage, Alaska. And a solar light specified for Anchorage would be unnecessarily large for Los Angeles.


Knowing the project location allows the manufacturers to build and specify their systems for your exact location and to avoid proposing a system that’s too small or too large for your area.


Also, a street address can allow for the assessment of potential shading hazards—like trees, buildings, or other obstructions—which could block the solar panel from the sun and decrease your system’s performance.

2. Ask about the Project Application


What kind of area are you trying to illuminate? Knowing the basic type of street vs. pathway will change the lighting output requirement.


Why? The application may affect pole height, pole spacing, and light levels requirements. A street, for example, will probably require higher light levels than a trail or park. Here are some possible applications:


  • Collector street
  • Residential street
  • Park/pathway
  • Parking lot
  • Boat dock
  • Entryway to a building

3. Ask about the Project Dimensions


What is the length of the street/pathway or size of the general area (for a parking lot, etc.)?


Why? The size or length of the area will affect the number of lighting systems required, and uniformity of the light hitting the ground, which all factors into the overall project cost. Here are some measurements you might use:


  • 2,000-foot residential street
  • 1,000-meter pathway
  • 150 feet x 300 feet parking lot

4. Ask about the Pole Details


Is there a specified pole height? What type of pole is required?


Why? Pole height may affect the number of lighting systems required for the project. Pole type may affect the installation costs. Some examples:


  • Common streetlight height: 25-30 feet
  • Common pathway light height: 12-20 feet

Common pole installations:

  • Bolt-down
  • Direct burial/embedded

5. Ask about the Required Light Levels and Uniformity


Is there is a state/municipal standard for light levels for the project, what are they? What light levels need to be met on the ground (measured by foot candles or lux)? What uniformity requirements are there, if known?


Why? Different applications will require different light levels, which plays a large role in determining the overall project cost. Here is an example:

  • 5 fc min. average with 0.2 fc minimum and a uniformity of 4.0 min. average

6. Ask about the Operating Profile


How long does the light need to be on each night? When the light is on, do the light levels need to be met throughout the night or just at certain times? If you’re unsure, a good manufacturer should be able to help.


Why? The operating profile is a key aspect of a solar lighting project. Manufacturers will “tune” their systems differently for power management, based on these profiles.


Here are some examples of operating profiles:

  • Dusk to dawn (all-night operation): the light will run at the same light output level all night.
  • Dim in off-peak hours: for example, the light will run at the required light output level for 5 hours after dusk, then dim to 30% of the required light level. 2 hours before dawn, the light levels will return to 100% until sunrise.
  • Off or dimmed at an exact time: for example, the light will run at the required light output level until 11 p.m., then will turn off.

Important note about Dark-Sky Friendly lights: An operating profile with a schedule to dim during low activity periods (middle of the night) can reduce overall system costs and make the project more dark-sky friendly.Read more about the benefits of dark-sky compliant lighting: https://solarlighting.com/dark-sky-controls/

7. Ask about the Color Temperature


What color of light is required—warmer (3000K) or cooler (6000K)?


Why? Color temperature affects the fixture power output, and can factor into the project cost. While light color temperature may be more of a preference than a requirement, cities are leaning more towards lights with warmer color temperatures as they seem to be better for our health and the environment.

Read more Sol articles

The Future of Solar is Bright: The Top Three Things We Learned at SALC 2023

Sunna Design Lights the Way: Achieving New Milestones in 2023

Sol exhibited at Light Fair 2023

man installing light fixture

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