Solar Systems is a world leader in electricity production from solar concentrator methods.

Conventional photovoltaic products use unconcentrated sunlight, or "1-sun" strength. This energy is quite diffuse so large panels of photovoltaic (PV) material must be used. This requires large amounts of silicon and expensive photovoltaic materials. As well, the panels are usually mounted in a fixed position as the cost of tracking the sun for optimum output is difficult to justify.

Solar Systems reasoned that while PV is expensive, steel and glass are relatively cheap. Therefore, if the diffuse sunlight were concentrated onto a small area of high efficiency PV then the overall cost per unit of electricity would be lower than unconcentrated methods. With this premise, Solar Systems designed and refined the concept into the CS500 dish concentrator PV unit.

The CS500 has 112 curved reflecting mirrors mounted on a steel frame, which tracks the sun throughout the day. The combination of mirror profile, mounting framework and solar receiver are carefully designed to deliver concentrated sunlight energy to each PV module. The tracking mechanism allows electricity to be produced whenever the sun is more than 5° above the horizon.

The heart of the system is an array of close-packed PV cells that are located in the solar receiver, suspended above the focus of the mirrors. The cells are mounted in a way that allows efficient dissipation of thermal energy as well as extraction of electricity. Since PV performance falls by around 4% for every 10°C rise in cell temperature and the sunlight is concentrated 500x, effective cooling is critical to achieve efficient performance. The module also incorporates electrical connections to deliver DC output as well as current and temperature sensors for real-time monitoring.

The direct current (DC) electricity from the receivers is passed through an electronic inverter that produces grid-quality alternating current (AC) electricity. Transformers step up the voltage to the requirement of the local network at the point of connection.

The control system keeps each dish pointing to the sun, monitors performance and adjusts the DC voltage to maximise electricity output. It also incorporates several failsafe systems to protect the CS500 from damage.

Advantages of this approach are:

• Scalability: other emerging solar technologies (particularly solar-thermal) typically need to be implemented in large power stations, often as high as 30 MW. This compares with the CS500 that can be deployed as small as a few hundred kW, therefore providing a lower entry point to market. Manufacturing scale-up also becomes much easier with the CS500 system as the area of PV material used is 1/1000 that of flat-plate material.
• Modularity: in large scale power stations, the CS500 has the advantage of being very modular, enabling the power station to be distributed over a number of sites. A large power station could be divided into a number of sub stations. This makes access to suitable land easier to achieve and provides additional generation redundancy to the network.
• Upgradeability: unlike traditional PV technology, the CS500 is upgradeable, enabling it to take advantage of future advances in PV technology. The CS500 photovoltaic cells make up around 20% (by value) of the investment in the CS500 and can be easily replaced with newer, higher efficiency modules. This means that the original investment can be enhanced rather than made obsolete by technology improvement in contrast to flat plate technology where the whole installation must be replaced.
• Concentrated Energy: Since the sunlight is concentrated into a single point, it becomes efficient to extract heat at that point and use for other purposes, such as process heating or desalination.
• Longevity: The CS500 has a longer effective operating life than traditional PV. Because the receiver is only a small area of PV (a 35kW CS500 dish has a PV area of 0.23m² where as 35kW of traditional flat plate would use approximately 350m²) maintenance is simple, quick and affordable. The modules include a specially designed filter that removes harmful UV radiation that reduces the operating efficiency and life of traditional PV technology. The modules are also cooled which increases their effective operating life and their efficiency.
• Economy: The CS500 costs significantly less (per installed watt) than traditional PV technology. This is despite the fact that the CS500 is new and still near the top of its cost curve. Advances in technology, maturity and volume production will further increase the gap.
• Power: The CS500 produces more electricity (per installed watt) than fixed flatplate PV technology - by up to 30%. This is because it tracks the sun and operates at lower temperatures.