How Is Solar Energy Used In Lighting? Using the sun’s daytime energy to light the darkness has the potential to offer zero carbon lighting. The underpinning science and technology rely upon basic principles, but the quality of design and choice of materials have a significant influence on the efficiency, efficacy, and cost-effectiveness of the installation. This week, we look at four key components of solar lighting and explain their importance.
1. The Photovoltaic Effect
The photovoltaic effect is a physical and chemical reaction caused when light touches a semiconducting material. The light stimulates the atoms, causing a flow of electrons that become electricity. The more easily that the electrons can move, the greater the conductivity and therefore the higher the voltage. As such, achieving the ideal photovoltaic surface requires creating the perfect chemical compound. Generally, the more impurities that are added to the crystal – a process that chemists call ‘doping’ - the more the electrons will be able to move.
Why does the photovoltaic effect matter?
Lots of materials are good enough semi-conductors that they can turn light into electricity. However, the amount of electricity produced always depends on how well the crystals are designed and manufactured. Photovoltaic surfaces can also be doped with different types of impurity to achieve different properties, such as the speed at which energy is generated. As such, when working with solar power, the chemical design is highly influential in the quality of the outcome
2. The Diode
A diode is a physical component that controls the direction of the electrical flow. Like a cut-off valve, diodes create a one-way pathway to prevent stored electricity from flowing backwards through the system. Complex solar set-ups usually have several diodes to ensure that power is in the right place at the right time.
Why does the diode matter?
Solar power provides intermittent energy, so channelling and storing it is important for when systems need to be used on cloudy days or after dark. The quality of the diode is therefore central to the functionality of the system. Diodes that are vulnerable to corrosion will allow energy to leak, leading to sluggish performance or a reduced battery life. The choice of materials, design, and casing are all factors that need to be considered.
3. Rechargeable batteries
Rechargeable batteries are electrical components that collect and store electrical charge. In the case of solar lighting, this means collecting the energy generated by the photovoltaic effect so that it can be accessed after dark. When a bulb is connected to the battery, it draws upon the electrical charge to make it glow
Why do rechargeable batteries matter?
Rechargeable batteries are prone to a phenomenon called ‘battery discharge’. This is where the battery holds its charge reasonably well until it reaches around 30%, at which point it starts to drain rapidly even when not in use. Various factors influence the risk of battery discharge, including:
* the operating temperature
* the load the battery is being asked to provide
* the manufacturing materials
* the quality of maintenance
* the charging and discharging cycle
As such, the quality and cost-effectiveness of the solar installation depends firstly on how the batteries are made, and secondly upon how they are maintained.
4. Light Emitting Diodes (LEDs)
LEDs are a form of solid-state lighting (SSL) technology. Like solar panels, they use a semiconducting material. In the case of LEDs, the purpose of the semiconductor is to transform electromagnetic energy into light. The technology is known for its energy efficiency, with a small charge being capable of producing very intense illumination of between 46 and 75 lumens per watt. In comparison, incandescent lighting produces around 17 to 19 lumens.
Why do LEDs matter?
Their low energy consumption is often cited as the main reason for choosing LEDs. However, there are a few more benefits. For instance, their low brightness output makes LEDs very reliable in poor lighting conditions, and they have a lifespan of up to 50,000 hours – roughly 50 times longer than traditional bulbs. LED technology is also very versatile, with an extensive range of colours, tones, and lumens to achieve the desired aesthetic. As such, the manufacturing quality is the main determiner of solar powered LED performance.
What are the problems with the solar lighting installations?
The main challenge with solar lighting is efficiency. Many people will have encountered solar lighting that gradually loses its brightness, or which gives a tepid output after a cloudy day. These issues tend to result from design problems with the photovoltaic surface, the diode, or the batteries. As such, very few commercial settings currently rely entirely on a solar installation, leading to the adoption of less environmentally friendly but considerably more reliable hybrid approaches. The challenge for engineers is to improve both the amount of sunlight that can be harvested and the ways in which it is stored and used. Crucially, this must be achieved in a way that is commercially viable in terms of cost, and practical issues such as space.
Head back for part 3 next week to find out how Alternative Energy is changing the face of Events Lighting
To find out more about the advantages of our sustainable event lighting and how we can help, please contact us.
