The Secrets of a Successful Solar Lighting System
There are a number of variables which must be taken into account by the designers and selectors of a solar lighting system. Understanding the way in which these variables are managed by Orion and our product designers, reveals the reasons why our solution is superior to anything else on the lighting market. At every stage shown in the energy conversion diagram, the Orion solution maximises the efficiency, performance and reliability of the lighting solution.
Where in the world your light is to be located determines how much solar energy is available for collection. This requires the precise latitude and longitude be programmed into the light, from which can be determined the available solar energy at that location by referencing the weather data from agencies like NASA. The location will also determine what autonomy the light can achieve. Autonomy is defined as the number of days the light can operate from full charge to a light failure in the event that there is no sun to charge the batteries. Again, the weather data will provide the designer with the information required to determine the likely number of days without sun for a given location, taking into account the effects of extreme weather patterns and solar panel shading.
Solar panel efficiency and tilt angle are the next variables to influence the amount of energy the system can collect. Mono-crystalline solar panels typically convert 15-19% of absorbed light to electrical energy and our lighting engineers are achieving the maximum efficiency of 19%.
The battery type chosen by our lighting designers and the way in which the energy is managed within the battery are key factors which make our products stand out from the competition. We select batteries from those which have the longest life cycle, where the life cycle is defined by the number of charge/discharge cycles that can be delivered. Some of our competitors select batteries with the largest initial capacity in Amp hours, batteries which generally have a shorter cycle life. The lifespan of all batteries depends upon the way they are charged, the depth of discharge and the temperature. The energy management system built into our lights, controls the charge and depth of discharge of the battery for varying ambient temperatures and controls the energy output to the LEDs.
The application will generally determine the amount of energy output required of the lighting system. For example, an obstruction beacon which is required to maintain a set light output during all hours of darkness will have a fixed requirement for energy out. On the other hand, many lights are not required to be on at all hours or of a fixed luminance. This means that the lighting system can be supplied with a variable operating profile. If the operating profile allows you to dim or turn off the light when it is not needed, then the lighting system can be down sized, cost reduced and/or the autonomy can be increased.
Operating profiles can be programmed for the light to be dimmed at certain hours or turned off altogether when the facility is not being used. Optionally the lights can be activated by occupancy sensors, providing light as and when required.
Notice in the energy flow diagram that the whole system is DC from end to end. Some of our competitors use off-the-shelf AC fixtures which are designed for hard wired lighting. This means that they have to add an inverter between the battery and the luminaire and they use the LED driver built into the AC luminaire. This adds to the cost of the system and creates an additional point for energy loss and system failure. Solar panels, batteries and LEDs all operate with DC power. It is redundant to convert to AC and then back to DC in the same system.
Even if the systems use off-the-shelf DC fixtures, they will typically use the manufacturer’s drivers, which have been designed with a constant hard wired supply in mind. Orion Solar lighting systems incorporate our own drivers which include technology like pulse width modulation, increasing efficiency and providing better control of the fixture to match the variability of solar energy supply. Balancing energy out with energy in.