The Amonix High Concentration PV system, recognized as the world’s largest commercial PV array is a unique patented technology that converts sunlight to electricity in a pollution free and highly efficient manner.
Amonix developed a highly efficient silicon solar cell which has established world records for performance which forms the basis of the high concentration photovoltaic (HCPV) system. This integrated HCPV system uses a Fresnel lens to concentrate the sun’s energy onto the high-efficiency, silicon solar cell. Solar cells are mounted onto assembly plates and a rectangular steel structure is sandwiched by Fresnel lens parquets on one-side and cell assembly plates on the other to form what is referred to as a MegaModuleTM. The MegaModule™ provides all electrical connections of the cell string and is capable of multiple configurations to match a variety of inverter designs. ™. Designed to offer superior performance, reliability, and ease of installation and maintenance, the MegaModule™ also incorporates ease of manufacturing design considerations, allowing significant cost savings. The MegaModule™ system provides significant advantages over older approaches to tracking concentrator system designs by using a novel concept that "integrates" the lens, solar cell and solar receiver plate into a single unit, eliminating over 75% of the parts and costs associated with earlier designs
Each Amonix system has its own custom power conditioning unit and patented hydraulic two axis tracker, these systems utilize a dual-axis tracker to stay focused at the sun. The tracker is the only moving component on the system and has been designed for reliability and minimum maintenance. Parasitic power requirements of the hydraulic tracker are minimal (<1% overall power output). Other system components are made up of steady state, non-moving parts that are inherently reliable and long-lived. A 45 x 11’ MegaModule™ contains 48 receiver plates. Each one having its own matching 24 fresnel lens parquet and producing 5 kW DC. Multiple 5kW MegaModule™’s are attached to a single torque tube to make up a multi kW array.
The MegaModule™ building block can be combined into single system sizes ranging from 5 to 35 kilowatts; however, Amonix is currently focusing on the market for systems sized 25 kilowatts and higher. Smaller-sized systems are not currently available but could be readily introduced if justified by a large enough demand.
MegaModule subsystem – Concentrates the sun’s energy on a solar cell that converts it into electrical energy. It consists of Fresnel lenses, solar cells, and structure. Each system consists of five to seven MegaModules.
Drive subsystem – Rotates the MegaModules in azimuth and elevation to track the sun. The drive system consists of a foundation, pedestal, rotating bearing head, hydraulic actuators, and torque tube.
Hydraulic subsystem – Applies hydraulic pressure to one side of the hydraulic actuators to move the torque tube and MegaModules in elevation and azimuth in order to keep the system pointing at the sun. The hydraulic system consists of hydraulic valves, accumulator, pump, reservoir, and pressure sensors.
Tracking control subsystem – Monitors sensors on the system, calculates the required movement for the commanded operation, and applies signals to the hydraulic valves to move the system to the commanded position. The commanded position could be to track the sun, move to a night stow position, move to a wind stow position, or move to a maintenance position.
AC/DC control subsystem – Combines the DC power, converts it to AC power, and interfaces with the AC grid. It consists of DC fuses, circuit breakers, and inverter.
System Operation:
The system is designed for unattended operation for either grid- connected or off-grid applications. As has been described previously (Ref-6), the system moves automatically from a night stow position to tracking the sun in the early morning. It tracks the sun throughout the day, typically generating electrical power whenever the Direct Normal Irradiance (DNI) is above 400 W/m2, until the sun sets in the evening. An example of the generated power profile is shown in Figure 7. The controller monitors the sun position with respect to the centerline of the unit and adjusts the tracking position if required to maintain the required pointing accuracy. If clouds occur during the day, sun-position mathematical algorithms are used to keep the unit pointing at the expected sun position until the clouds dissipate.
An unattended and/or remote system not only needs to be very reliable, but also needs to have good diagnostic information available that can be retrieved from a central or distant location. This system was designed with this in mind, and the diagnostic capability has been improved over the years of operation. The currents, voltages, and power data over the day are stored in memory. This data can then be used to determine if there is an inverter problem, fuse problem, PV string problem, tracking problem, or poor environmental conditions, etc. It can also be used to determine when the lenses have become soiled and need to be washed. Control system and hydraulic drive system data are also stored. The controller continuously checks a number of its operating parameters. If any of these parameters, such as fluid level, pump cycling frequency, etc., deviates from its normal operating range, it is noted, and the system can then be halted if necessary. This data is retrievable from a central operating facility and can be used to diagnose a current problem or to detect a potential future problem. Based on this data, it can then be decided not only when to send a maintenance person to the site, but also what equipment and parts that are needed for the repair.
