Need to deliver a successful outdoor solar lighting project? Orca Solar Lighting’s John Warren runs through seven steps to get the job done.

When planned, selected and installed correctly, solar lighting is an extremely reliable solution that can provide quality lighting outcomes wherever it is. In some instances, solar lighting will provide a lower total lifecycle cost than 240v mains lighting alternatives as well.

You can see why some of Australia’s who’s who of government, municipal, industrial and property development companies have incorporated solar into the lighting aspect of their very large infrastructure projects.

The improvement of technology and methodologies over the past ten years has been significant, however there is the full spectrum of products and suppliers, from great to inadequate, therefore it is critical that the customer is discerning in their selection and planning process.

Addressing the following points may well avoid unreliable lighting, non-compliant product and constant repair and servicing costs.

1. Qualify the manufacturer/supplier

Establish how long the manufacturer or supplier has been in the business of supplying solar lighting. Is this their core business or a side business alongside other non-related business? Request referees to verify their back up service. Ensure they provide numerous references on relevant jobs. If necessary, go out and inspect their lights at night.

2. Is the product proven?

Has the product a proven track record? Ensure numerous relevant projects are available for reference. If necessary, inspect their lights at night.

Are spare parts readily available and what are the terms and conditions of the warranty?

3. Quality lighting outcome

For compliant and mission-critical lighting, a lighting design should be undertaken, to determine the optimum mount height, wattage and optic is used to ensure the minimum number of lights to perform the task well. This will ensure the light is safe and compliant to relevant Australian Standards as well as caters for the following points:

• In most instances, natural and warm white colour temperatures are the most desirable (4500k or less), research shows that cool and blue, white colour temperatures are detrimental for humans and animals, affecting our natural circadian rhythms. Warmer colours including amber are often used for marine environments where turtles hatch, as research shows these colour temperatures are less likely to disorientate the hatchlings.
• Minimal or no glare for the user of the facility.
• Dark sky compliant and no light pollution (into neighbouring properties or up-light).
• Adaptive lighting note: To comply with Australian pathway and car park lighting standards (AS/NZS 1158 3.1 2020 PP and PC subcategories), the light levels must be based on the LOWEST level the light runs on for the entire duration of the night. (This pertains particularly to lights that use sensors to dim and boost the lights). If the lowest/dimmest light level throughout the night is less that required by the particular sub-category, it does not comply to Australian lighting standards. For more information on this important topic, please read the ‘Adaptive Solar Lighting and Public Lighting Standards’ article on the Orca Solar Lighting website.

4. Solar engine sizing (sufficient solar panel and battery)

This is one of the most common of problems, some manufacturers/suppliers do not understand solar engine system sizing and supply a battery and/or solar panel that is too small.

This ends up being a big cost to the end customer as this causes the light to be unreliable, and depending on the shortfall of the battery capacity, the life of the battery plummets due to frequent deep discharges.

A quality and properly sized battery (with a correctly sized solar panel) should last five-to-ten years. Batteries are the largest and most expensive consumable in a solar lighting system, so it is important to get this sizing correct.

Here is a general rule of thumb. For most of mainland Australia, a solar lighting system requires four full nights of battery back-up, allowing for the longest winter nights.

For example, Sydney has 14.39-hour long nights, therefore the battery should run the light at 100% illumination for 57.56 hours with no input from the solar panel. This example is used only to give an indication of battery back-up requirements, for example in the tropics such as Darwin or Cairns, the monsoon season requires over five nights battery back-up, however being the summer season, the night times are a lot shorter.

It is important that your solar lighting supplier understands the night time lengths and climatic affects for different regions, so that the solar engine sizing is sized accordingly, or the light is run at an appropriate wattage to suit the solar engine sizing.

To calculate this amount of battery back-up, a lead acid cannot discharge more than 70% and the average daily depth of discharge should not exceed 50%. A lithium phosphate Ion (LiFePO4) should not be discharged more than 80%. It is important to note that solar panel ratio is CRITICAL, a LiFePO4 battery at 80% of discharge is going to take a lot more solar panel to recharge than an acid battery at 50% discharge.

The battery size calculation then needs further derating applied to allow for performance drop in extreme temperatures, degradation over time and voltage drop.

The solar panel needs a de-rate to allow for high temperatures (solar panels are more efficient in cooler temperatures), dirt and dust, voltage drop and degradation over time. AS/NZS 4509.2 Stand-alone power systems – system design states a minimum of 30% extra solar panel redundancy needs to be allowed for the de-rates.

5. Planning for shading

Many proposed lighting locations will have shading from neighbouring buildings and trees. Solar lights perform properly with the solar panels unobstructed from shade all day, all year around.

Performance plummets with shade and most solar lights are designed to perform with no shade ever on the solar panel.

For most of mainland Australia, the most challenging time of year for solar lighting is winter, when the night times are longest, the days are shortest and the sun is tracking very low to the North, therefore the shadows are the longest. The exception to this is tropical northern locations, summer monsoon months are the most challenging times for solar lighting.

The supplier/installer of the solar lighting project needs to carefully assess the shade and if necessary, allow for buffers or lower power settings on the solar lights to allow for any shade at site.

Alternatively, the light pole can be powered by a solar ‘slave’ pole, which has the solar panel and battery, located in a shade free location, with a low voltage cable trenched and cabled to the light pole in the shade.

We recommend a highly experienced solar lighting company conduct the shade assessment and any slave pole planning.

6. Compliance

This pertains to larger solar slighting systems that have a battery larger than 76AH 12volt (or equivalent).

Ensure the proposed solar lighting system conforms to the relevant Australian standards such as AS/NZS 3000 electrical safety standards, AS/NZS 4509.1 battery enclosure signage, AS/NZS 4509.2 Standalone power systems – system design which refers to and requires compliance to AS/NZS 3000 electrical safety standards.

7. The limitations of integrated (all in one) style solar lights

Integrated (all in one) style solar lights have a place, however the fundamental nature of their design severely limits their performance in the Southern Hemisphere, where the sun tracks very low to the north in the winter months, causing the direct sunlight to hit the solar panel on a very shallow angle (Integrated solar lights tend to have a very shallow solar panel angle to the horizontal). This shallow panel angle is more suitable in equatorial latitudes where the sun does not stray far off straight overhead, therefore the solar panel operates effectively.

The Lighting Council of Australia has a Solar Lighting Guide on their website that runs through the limitations of integrated/all in one solar lights. Additionally, on the Orca Solar Lighting website, we have a technical paper for a deeper scientific explanation.

Note: This shallow solar panel angle issue does not necessarily apply to solar lighting bollards, which tend to run at low wattage output and generally installed closer together, where-as overhead integrated solar lights are generally run at high wattage output to compete with proper solar lighting systems that have a completely independent swivelling and angle adjustable solar panel.

Solar lighting can be a very reliable, compliant, low maintenance and cost-effective solution, however it requires a bit of up-front planning, including product and supplier due diligence and shading assessment.

If these points are addressed, maximum safety, product life and minimal maintenance amounts to considerable long-term savings.

To find out more, visit the Orca Solar Lighting website here.