Solar power in Australia is definitely an idea whose time has come. Both ordinary citizens and government officials have recognised the potential for using more solar power. This interest is being channeled into many beneficial projects. At the municipal scale, one of the most interesting is harnessing solar power to run public amenities like street lights. An integrated solar lighting system is an ambitious project for most cities, but it offers some benefits that are well worth considering.
Photovoltaic modules produce direct current electricity whenever they’re exposed to sunlight. This power can be used immediately or stored in batteries. Hence, battery storage is obviously required for public lighting applications. For effective public lighting, a surprisingly modest solar panel is capable of providing all the necessary power. A 60 watt module (about 2-3 square metres) is more than sufficient to power one street light.
With an effective battery, a light powered with such a module can easily operate for multiple nights off the charge collected in a single sunny day. Besides efficient batteries and PV modules, high-efficiency lights (LED or fluorescent) help to make this possible. Solar lights also require a controller system to switch the light off and on. These can be highly intelligent, further conserving power by matching illumination to current conditions.
Solar street lights can be set up to be independent, with each light operating alone or tied into a larger solar system where several lights draw power from a larger bank of PV modules. There are benefits and drawbacks to each approach. A collective system is more reliable overall, but any failure will affect multiple lights. Setting up a lighting system to use a collective PV power source is more expensive due to the cost of wiring the lights together.
Whether they are powered individually or in a group, the greatest difficulty in installing an integrated solar lighting system is in justifying the increased cost. Despite the advances in every technological component bringing costs down, the overall proposition is still significantly more expensive than traditional grid-powered lighting. A proper solar lighting system requires more than simply adding equipment to traditional lights. Solar set-ups must be carefully designed to optimise solar yield, deal with increased wind load and ensure public safety.
Solar street lighting also requires a shift in attitudes towards a city’s maintenance obligations. While solar lights are reliable and trouble-free in day-to-day operation, they require a different maintenance infrastructure compared to traditional lights.
The city will need solar technicians on staff to handle repair work. Due to the DC nature of solar systems, this is a rare and specialised skill set. Batteries will need to be replaced at regular intervals, and the possibility of damage to the PV modules themselves means that replacements will need to be stocked. Also, equipment theft is a real risk with solar lights. It’s because high-quality solar gear makes a tempting target in isolated areas.
There are considerable positive aspects to installing a solar public lighting system, though. It makes a great choice for rapidly-expanding communities due to the reduced infrastructure requirements of lights that are entirely self-contained. While initial installation costs are high and the proper maintenance issues need to be addressed, the cost of actual operation is much lower. While it may take a great amount of time, it is quite possible for solar lighting to pay for itself in the long run. Removing the strain of lighting the streets from the local power grid can also provide much-needed relief to overloaded electrical services.
The positive publicity generated by a solar lighting system cannot be overlooked either. Solar street lights are a dramatic and highly-visible sign of a forward-thinking community. With intelligent marketing, installing solar street lights can be a significant public relations coup for cities trying to attract new, environmentally-sensitive residents. Marketing experts should be a part of the team for any city trying to install solar lighting. They can maximise the positive impact of the new lights and make them supply much more than just electrical power.
Finally, there is one option that can significantly reduce the cost of solar lighting in public spaces. And this is the direct connection to the utility grid. Thanks to the significant interest in solar power demonstrated by the Australian government over the last few years. Utilities have been heavily encouraged to court solar power. The necessary policies (e.g. FIT schemes) and hardware (smart metres) to connect solar systems to municipal grids is already in place in many parts of the country.
There are numerous advantages to operating solar lighting systems in connection with ordinary utility power. Instead of using expensive batteries, the direct current generated by solar modules is converted to AC power and fed directly into the grid. This production is metred and credited back to the producer in order to offset the cost of power drawn out of the grid. Since public lighting systems are rarely drawing power during solar production hours, grid-tied solar lights pump all of their energy directly into the grid. This can be more than enough to offset the amount of power required to power the lights, resulting in a net energy gain. Depending on the compensation policies governing a particular city, it may even be possible to turn a profit with solar lights.