Assessing the Viability of Solar Street Lighting: Considerations for Government, Municipal, Industrial, and Construction Projects
Solar street lighting has established itself as an extremely credible, and in some situations, providing significant cost advantages to mains powered lighting. This is being demonstrated again and again as we see more solar street lights being deployed for significant government, municipal, industrial resource and construction projects.
Solar lighting systems comprise the solar panel (photovoltaic = PV), that captures the UV (from sunlight), to create electricity, and then stores it in the battery. The ‘brains’ of the system is the solar controller, that initiates the light to turn on at dusk, and turn off at dawn, with options for variations of power throughout the night, or the use of sensors for dimming and boosting, if adaptive lighting is preferred. To comply with Australian and New Zealand standards (AS/NZS 4509 and AS/NZS 3000) any stand-alone power system with a battery capacity that exceeds 76AH 12v, requires clearly marked circuit breakers. Solar lights can be permanent (typically using cage/pier footings), and temporary utilising a relocatable concrete block or trailer system. These arrangements are popular on road work projects, as the project progresses, the lights can be easily moved.
Assessing when solar street lights should be deployed instead of mains power fed street lights, the following points should be considered. Please note, we are defining solar street lights as completely stand-alone solar lights with their own solar panel and energy storage (battery). Therefore completely free from the electrical grid, therefore not requiring any trenching or cabling. Every project and location is unique, so these considerations should be looked at on a case by case scenario.
- How much shade is at the location of the light poles? If heavy shading is across much of the site, solar lighting may well not be an option. If there is only part day shading, or heavy shading on one or two, out of many light poles, solar may still be a very effective solution. With part shading, solar lighting can work if the correct de-rates are applied. Power in = power out, therefore the light in the part shade may need to be run at a lower wattage to ensure the constant and reliable all night light. Light poles in heavy shade can have a ‘slave pole’ running them, this is a pole with the solar panel in a shade free location, with an extra low voltage cable running to the light pole.
- A cost comparison needs to be conducted. This has to compare the hardware, the electrical design, trenching and cabling, and ongoing power costs for the AC powered lights, the solar lights need to factor in the hardware cost, installation and a battery change every 5 to 10 years depending on the battery type. For lighting projects where there is a long distance from existing mains power to the site, and/or the trenching and cabling costs are high due to long distances, rocky ground that is cost prohibitive to trench, or perhaps foreshore lighting where the water can disrupt underground electrical infrastructure, solar lighting can provide a significantly lower upfront and total life-cycle cost.
- Solar lighting projects can often be designed, supplied and installed faster than 240v AC lighting due to the completely stand-alone and easy to assemble nature of the systems. As no electrical design, connection point to the grid, trenching and cabling works are required, this can reduce project delivery times significantly.
In conclusion, solar street lighting systems have proven to be a reliable and cost-effective alternative to mains powered lighting in various situations. Before deciding to deploy solar street lights, it’s essential to assess the location’s shading, conduct a cost comparison, and consider the project delivery time. By doing so, governments, municipalities, industrial, and construction projects can make informed decisions to choose the most appropriate lighting system for their needs. As the demand for sustainable and energy-efficient solutions grows, solar street lighting is expected to become even more popular, contributing to a cleaner and more sustainable future.