All lighting projects are basically built using the same formula, and by putting that formula to the next project, you can quickly determine what you need and how to best put that into play. This will cover some of the best practices to learn how to design a solar lighting project from the ground up.
Step 1 – Determine Light Level Requirements
Understanding light level requirements is the best starting point for any lighting project. IESNA provides a great deal of information on light level requirements. This, along with local building requirements, can help you get on track to understanding the exact light level requirements of your next project.
For example, most parking lots have a .2-.5 foot candle minimum; however, some larger cities, like Miami, FL have a 1 foot candle minimum. Find out what your area requires and what the IESNA recommends and you will know exactly the amount of light that is required.
Step 2 – Determine the Area of Illumination
The next step is to determine the area of illumination. This differs between projects and different optics and distribution patterns can be used to illuminate the areas required. Knowing the area of illumination helps lighting designers and engineers understand the area that needs to meet the lighting level qualifications.
This can include small applications such as a sign to large applications such as roadways and parking lots. It is not always necessary to have a lighting plan completed by an engineer; however, to ensure you are meeting light level requirements and know the quantities of lights required, a good rule is to get this done. Most professional companies will provide this without hesitation.
Step 3 – Determine the Operation Requirements
Standard operation is dusk to dawn; however, with adaptive lighting techniques and more advanced forms of controls, dimming and split time operation are gaining traction. Ensure that the solar lighting system is sized properly to operate the required operation profile needed for each project. Controls, such as battery saver mode and smart electronics that take over for times of inclement weather, should not be allowed in all circumstances and will not allow the lights to operate as required.
For example, Miami has a 1 foot candle requirement as mentioned above. Utilization of a smart control that takes over when battery has not been able to fully charge due to inclement weather will not allow for maintaining this 1 foot candle requirement. Instead, the solar power system should be sized for worst case to ensure the project meets minimum requirements year round.
Step 4 – Speak to Engineers and Lighting Professionals
The next step is to speak to the engineer or lighting professional. Working together with them to determine what wattage fixtures are required with what optics and other design parameters required for the project will ensure that the systems are not oversized and wasting energy.
Most people will arbitrarily pick a wattage that sounds good; however, this is not always what is required. For example, mounting a 100 Watt LED fixture 10-15 feet high will provide a lot of light directly under the fixture; however, a 50 Watt LED fixture may provide the same amount of light spread using the same optics and be 50% lower in cost to operate, all while not reducing visibility. Lighting engineers understand this and can show this through the use of lighting plans.
Step 5 – Design the Solar Requirements
Once the lighting plan is completed, and all the variables are understood such as mounting height, fixture count, distributions, etc., the next and final step is to design the solar requirement. Using the geographic location of the installation, a solar lighting engineer can put together a system that will operate the required light as laid out by the original design (Step 3).
Following the above steps provides a good design for a commercial solar lighting system. Working directly with a lighting engineer will guarantee that the lights provided will meet the requirements of the project and meet IESNA as well as local lighting requirements.
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