• Cooling India
  • Feb 15, 2018

Cooling Mechanism
in Solar Inverter

Inverter modules generate heat and usually require a cooling mechanism. For low power solar inverters, providing a cooling air flow around heat-producing elements of the inverter module is sufficient. Higher power solar inverters require more sophisticated cooling. One known solution is liquid cooling…

- Preeti


 Inverters are the devices usually solid state, which change the array DC output to AC of suitable voltage, frequency, and phase to feed photovoltaically generated power into the power grid or local load. These functional blocks are sometimes referred to as power conditioning. The current can be used in two modes: (1) as an inverter changing DC to AC or (2) as a rectifier changing AC to DC, thus, charging the battery. Solar power inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti-islanding protection.

Solar inverters may be classified into three broad types:

1. Stand-alone inverters: These are used in isolated systems, where the inverter draws its DC energy from batteries charged by photovoltaic arrays.
2. Grid-tie inverters: These are designed to shut down automatically upon loss of utility supply, for safety reasons.
3. Battery backup inverter: These are special inverters which are designed to draw energy from a battery, manage the battery charge via an onboard charger, and export excess energy to the utility grid.

  Solar micro-inverter is an inverter designed to operate with a single PV module. Its design allows parallel connection of multiple, independent units in a modular way. Micro-inverter advantages include single panel power optimization, independent operation of each panel, plug-and play installation, improved installation and fire safety, minimized costs with system design and stock minimization.

  Few industries has introduced central solar inverters in sizes 1MW, 1.5MW and 2.0 MW with advanced water-cooled technology and high performance even with temperatures exceeding 50 plus degrees. This product is especially designed to suit harsh, humid and dusty conditions that prevail in the Indian subcontinent.

Water Cooled System is Better

• The IGBT stacks can operate up to 50+°C ambient temperature without de-rating at full power.
• A very unique mechanism i.e. the water part and electrical part are physically separated, which keeps the area neat and tidy.
• The water cooled system requires zero maintenance and the water doesn’t need replacing, therefore, a supply of water at site is not required.
• The water cooled system creates uniform cooling of the IGBTs, which improves the life of the IGBTs and in turn the life of the solar inverter.
• No addition air conditioning required.

  The standard elements are: a DC (input) module, an inverter module and an AC (output) module. The DC module includes a number of photovoltaic cells that provide a direct current (DC) input to the inverter. The inverter module uses a number of electronic switches, typically, insulated gate bipolar transistors (IGBTs), to convert the DC input into an alternating current (AC) output. For inverters, providing electric power to an electricity grid, the AC module provides the AC output in a format suitable for the electricity grid. Inverter modules generate heat and usually require a cooling mechanism. For low power solar inverters, providing a cooling air flow around heat-producing elements of the inverter module is sufficient. Higher power solar inverters require more sophisticated cooling. One known solution is liquid cooling.

  Liquid cooled solar inverters provide a cooling liquid to a liquid inlet of the solar inverter. The cooling liquid is directed around heat producing parts of the inverter and the liquid is heated, thereby, extracting heat from the inverter circuitry. A liquid outlet of the solar inverter is used to remove the heated liquid from the solar inverter. Typically, the cooling liquid provided to solar inverters is part of a larger cooling system used for many purposes. For high power solar inverters, such a mechanism is inadequate to remove the heat generated. Moreover, the integration of such a solar inverter into a cooling system on-site is a skilled task and makes the installation and maintenance of such solar inverters expensive.

Recently Developed Inverters

  The recently introduced PVS980 1500 VDC outdoor central inverter by ABB is optimized for large multi-megawatt solar power plants. With the simplicity of air cooling and with the power density of a liquid cooled inverter, ABB’s inverter has very high total efficiency and low maintenance. There are no fillable liquids, pumps, valves, inhibitors and thus, no leaks. All this makes the PVS980 suitable for any outdoor utility-scale PV plant.

  GE Power Conversion is introducing Silicon Carbide (SiC) technology into its next-generation 1500V PV inverter product line, bringing increased power conversion efficiency to the PV industry. The LV5+ Solar Inverter is the first multi-MW, utility scale inverter based completely on SiC technology and has an efficiency rating of 99% weighted EU and is being showcased at Solar Power International 2016.

  Floating solar systems are gaining rapid interest across the globe and recent projects that have been in the 20MW and 40MW range are moving to the 150MW size in China, according to major PV inverter manufacturer, Sungrow in 2017. The new Samsung S-Inverter Air Conditioner series is engineered to consume less power and produce exceptional cooling comfort in 2017. The digital inverter compressor optimizes usage by minimal wear-and- tear and extends the life of a refrigerator by over ten years. With low noise level, the smart direct cool refrigerator can withstand voltage fluctuations ranging from 100 volts to 300 volts. 


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