Tech Specification

  • This page provides guidelines and standards for the solar plant.
  • We recommend each client planning at setting up a solar plant, be it rooftop, ground mount or any other to read through the specs.
  • It will provide the client with basic information about a solar plant and what to take care when installing a solar plant.
  • If you need help in making detailed requirement document for your solar plant please contact us for further discussions.
Panels
  • Panels are the components which convert the solar radiation into electricity (electric output is DC power).
  • In today’s market there are number of players manufacturing and supplying solar panels.
  • Client should keep in mind the following parameters when selecting a solar panel
    • Panel Efficiency :
      • Solar cell efficiency refers to the portion of energy in the form of sunlight that can be converted via photovoltaics into electricity. For example at 16% efficiency 5 KWh of solar energy (per square meter) will be converted into 0.80 KWh of electric energy.
      • Higher the panel efficiency, more the energy the solar plant will generate from the same amount of roof or ground area. Currently Tier 1 panel manufacturers provide 16.5% or more panel efficiency.
    • Temperature coefficient of Power(Pmpp) :
      • A rather unknown fact about PV panels is that they perform the best in a temperature range around 25 °C. But in most cases, during the day the panel temperature exceeds this temperature. Higher the temperature lower is the electricity generated by the panel.
      • This decrease in generation is called Temperature coefficient of Power.
      • Higher the value if this coefficient lower will be the generation from the solar panel.
      • For Tier 1 manufacturers of panels this coefficient is less than or equal to -0.42% /°C.
    • Generation Guarantee :
      • Most Tier 1 panel manufacturers provide a 10-year and 25-year generation Guarantee.
      • Ensure that it is similar to industry standard of 90% generation by end of 10 Years and 80% generation by End of 25 Years.
    • Other parameters :
      • Other parameters like complying to IEC and IS standards (like IEC 61215, IEC62804, EN/IEC61730, IEC 60364-4-41, IEC 61701 etc).
      • Operating range from -10°C to +85 °C etc should also be ensured.

Inverters
  • Inverters are the components which convert the DC power generated by the solar panels into AC power which can be used by the electric machines and appliances everywhere.
  • There are two types of inverters which can be used in a solar plant
    • String Inverters :
      • These inverters take the solar input (DC 1000 V typically) and convert it into 410-415 V AC power. Output from these inverters can be directly connected to the regular 415 V power used by most machines and hence these inverters do not require any transformer.
      • Typically, these inverters range from 1 KW to 60 KW (AC output rating). Some parameters of these inverters to keep in mind are:
        • Output voltage must be 400/415VAC and must allow for either star or delta connection.
        • The inverter must allow for additional DC loading such that DC:AC ratio must be at least 1.22.
        • Each inverter shall have an AC and DC isolator that could shut-down the inverter immediately.
        • The inverter must also have a replaceable AC and DC SPD (IEC Protection Class II) to prevent damage by thunder strikes & surges.
        • Total harmonic distortion (THD) at the AC output of the inverter should not exceed 3%.
        • Night time consumption must be lower than 2W
    • Central Inverters :
      • These are larger inverters with Tier 1 brand starting from 850 KW (AC output power rating) onwards.
      • Their output voltage is in the range of 375-390 V AC and hence always need a Transformer to convert it to usable voltage level (415V).
      • These inverters are suitable in following cases :
        • Larger solar power plants (1 MW and above).
        • When interconnection voltage is HT (11, 22, 66 KV etc).
        • When interconnection point is far away (500 meters or more) from the solar plant, which can result in transmission losses if transmitted at LT voltage (415V).

Electrical components
  • Major electrical components required are :
    • AC Distribution Panel
    • AC & DC Cables
    • Lugs, MCCB, ACB & VCB etc
    • Cable connectors, cable trays and other accessories
  • Ensure that the components used are from good companies and capable of handling the wear and tear (even in open spaces) for 25 years. This means using Hot dipped galvanized trays to carry the cables.
  • Not using Nylon, SS cable ties and instead using cable clips to secure DC cables. Multi contact type of DC connectors and much more.

Mounting Structures
  • The mounting structures are used to secure the solar panels to the roof sheet or to concrete ballasts on RCC roofs and ground columns.
  • In some cases, the solar panels are mounted on elevated structures such as in carports.
  • Life of a solar plant is more than 25 years. Client should ensure mounting structure should be capable of holding the plant till that time.
  • Low quality mounting structure can increase maintenance
  • Some points to ensure in mounting structure are :
    • The structure shall be designed to withstand wind speed as per IS 875 standards and calculations for the same should be provided by the bidder
    • The array structure shall be made of Mild steel or aluminium. In case of MS structures, it shall be finished with hot dip galvanization of sufficient thickness based on the base material. In any case, galvanization thickness shall be not less than 80 microns

Animation of Trapezoidal Bridge roof Installation

Animation of Kliplok-roof Installation

Animation of Standing-seam roof Installation


Monitoring and Data logging
  • The solar plant should have a suitable monitoring system that will constantly monitor all the parameters such as power, energy, voltages, currents as well as all weather data.
  • The system will monitor both the generation as well as the consumption of electrical power in the plant.
  • The datalogger and all necessary controllers must be installed inside the ACDB in a special enclosure earmarked for such a device.
  • Items which could (and if required, should) be installed are:
    • Reverse power protection system.
    • Data Logger and displays (online and display board in plant premises).

Earthing and Lightning Protection
  • The photovoltaic modules, Balance of system (BOS) and other components of power plant require proper grounding for protection against any serious faults as guided by IEC 60364 and IS3043 1987.
  • Lighting arrester/masts should also be provided inside the array field.Provision should be kept for shorting and grounding of the PV array at the time of maintenance work.
  • All metal casing/shielding of the plant should be thoroughly grounded in accordance with Indian Electricity Act / CEA (Measures relating to Safety and Electric Supply) Regulations 2010.
  • Earth resistance should be tested after earthing by calibrated Earth Tester.
  • The following points are to be adhered to :
    • All individual solar panels, array mounting structures, inverters, ACDB and DCDB shall be earthed properly.
    • The number of earth pits shall be based on relevant Indian Standards.
    • The earth pits shall be interconnected to form equipotential bonding. The earthing kits shall be compliant to IS:3043 – 1987.
    • Lightning protection should be provided as per IEC 62305 or NFC 17 (ESE type)
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