Parity manufactures certain key PV solar components such as classical silicon wafer type modules, thin film modules, inverters and mounting hardware including fixed and tracking systems.
Photovoltaic (PV) Solar Modules
Silicon wafer type:
This type of module is constructed using varying numbers of silicon wafers, usually between 48 and 96, that have been process into solar cells. The wafers are sliced from a single crystal of high purity silicon and this process and supply chain is a derivative of semiconductor raw materials processing. This type of module is very high efficiency and well suited in space constrained situations such as roof top systems, in order to get the maximum power output possible within a limited space.
This type of module is similar to monocrystalline although slightly lower in power output. The difference is the wafering process which uses a multi crystalline ingot casting process designed specifically for the solar industry to reduce cost. There is a dramatic difference in visual appearance compared to mono-crystalline wafers because the different crystals and a more brilliant blue color is seen in the multi crystalline cells.
a-Si (amorphous silicon)
This is a “Thin Film” PV module technology which is a process whereby thin semiconductor films are deposited on glass or other mediums, to create a PV module. This technology is evolving and currently the efficiency is much lower than the traditional modules. But the cost is also lower on a per Watt basis. It is generally used in larger scale projects where the ROI is the key consideration and there are no space constraints.
This device is a key component of the system as it represents the system intelligence and monitoring capability. But the primary function of the inverter is to take the DC power from the PV modules and “invert” it to AC so that it is compatible with the grid power. There are many brands of inverters on the market, with different features, intelligence, different levels of reliability and performance. Inverters are sold at many capacity points which allow the system designers to match the capacity of the inverters and modules quite closely. Parity recommends certain inverter brands based mainly on reliability and performance. At 50kW or above, Parity inverters from Satcon (www.satcon.com). One key feature of Satcon inverters is the robustness of the design, which allows the units to be installed outside, without any facilities support such as shade, air conditioning or chilled water. This reduces upfront and long term operating costs. But there are other brands that may be specified by customers and Parity will work with those suppliers to integrate the inverter into the overall design.
Below 50kW there a number of world class suppliers recommended by Parity, depending upon location and design.
Parity offers mounting systems in four main categories:
- Low-profile, roof top: This is mainly for sloped roof, residential applications to improve aesthetic effect and conform to the basic architecture of the house.
- Tilt rack: A fixed mount rack system so that the modules are tilted toward the equator at the ideal angle, according to the latitude of the installation. This type is generally for commercial roof top or small ground mount applications.
- Cable suspension: This innovative and proprietary design allows easy installation on large scale with minimal land usage and on uneven terrain. It is also good for prevention of tampering and is safer than other schemes because of the elevated mounting position of the modules and wiring. The application is generally large scale power stations but there are also variations for smaller parking and shade structures.
- Tracking: Parity offers a simple 1-axis tracking system for large scale applications. The tracker is a fixed but adjustable angle array which rotates on a circular track. This method is low cost to install and simple to maintain, which boosting power yield by 15 to 20%.