Transcend Solar systems & Solutions
Transferring to Green
CONTENTS
Executive summary......
Salient features
INTRODUCTION
ELEMENTS INCLUDED IN A SYSTEM OF PHOTOVOLTAIC CONVERSION
EXISTING POWER SUPPLY ARRANGEMENTS:
LV DISTRIBUTION SYSTEM LAYOUT
Solar availability and the details of the irradiances:
PROTECTION AND CONTROLS:
INTEGRATION OF PV POWER WITH GRID:
EXECUTIVE SUMMARY
The proposed Roof Top Solar Photovoltaic Power Plant at the site of 186sq.m^2 would utilize vacant area of about 952 sq. m. available on the roof top. The SPV power plant with proposed capacity of 20 kWp would be connected to grid. No battery storage has been provided. It would meet partial load of the building during working days and feed the surplus power available to the grid during week end and holidays.
The 20 kWp SPV power plant is estimated to afford average annual energy feed of 38.44 (PCU) as 94% and losses as 3% in the DC and AC system. The Plant would
operate at a daily capacity utilization factor of 8.5%. The energy available from
the Plant would vary from a minimum of 2.5 MWh during the month of November to a maximum of 4.092 MWh during the month of March.
The SPV Power Plant is estimated to cost Rs. 20 Lakhs based on the normative
SALIENT FEATURES
1) Location
a) Site Address : The Madras Pharmaceuticals,Karpakkam
b) Latitude : +13.09 (13°05'24"N)
c) Longitude : +80.27 (80°16'12"E)
2) Area of the SPV plant
a) Length
b) Width
c) Location
3) SPV Power Plant
a) Output 20Kwp
b) No.of Modules 80
c) No.of modules in series 40
d) DC bus 1No.
4) Technical details of the SPV module
a) PV module type : Poly crystalline
b) Physical dimensions
i) Length : 1639mm
ii) Width :982mm
iii) Thickness : 35mm
c) Electrical Parameters
5) Maximum power rating
i) Rated current :29.95 V
ii) Rated voltage : 8.35 A
iii) Short circuit current : 8.95A
iv) Open circuit voltage : 37.25V
6) Mounting Arrangement
i) Mounting : Ms structure with coating
ii) Tilt angle(slope) of PV module: 13 deg
7) Inverter/Power Conditioning Unit(PCU)
i. No.of units : 1 Nos.
ii. Rated capacity : 20kW
iii. Input voltage range : 350 – 1000V
iv. Output voltage : 415V
v. Frequency : 50Hz
vi. Efficiency : 98.7%
8) Grid connection details
i) Electrical parameters for interconnection
9) Annual Energy Generation
Cost Estimate :
Construction time
INTRODUCTION
In one minute, the sun provides enough energy to supply the world‟s energy needs for one year. In one day, it provides more energy than the world‟s population could consume in 27years. The energy is free and the supply is unlimited. All we need to do is find a way to use it. The largest solar electric generating plant in the world produces a maximum of354 megawatts (MW) of electricity and is located at Kramer Junction, California. Since India has abundant sources of RE especially sunlight, it can cater to all the energy needs of the country. The country receives an average radiation of 5 KWh per square meter (m) per day and with 2300 to 3200 sunshine hours per year. The potential of solar photovoltaic has therefore been estimated at 20 MW per square km.
Conversion from Solar energy into Electrical energy
There are 2 ways to convert the solar energy into electrical energy
1) Solar thermal
2) Solar photovoltaic system
Solar photovoltaic systems are superior when compared to the solar thermal system where the solar thermal system can only use the direct irradiance of the power generation whereas the solar photovoltaic system can convert the diffuse irradiance as well. That means that, they can produce electricity even with cloud –covered skies.
So the Solar photovoltaic solutions are preferred one when compare to solar thermal systems.
ELEMENTS INCLUDED IN A SYSTEM OF PHOTOVOLTAIC CONVERSION
The main elements that can be included in a system of photovoltaic systems are
Ø Solar Panels
The solar panel is the power source of all photovoltaic Installation. It is the result of a set of photovoltaic cells in series and parallel. Solar panel gives power to battery or inverter through charge controller (Regulator).
Ø Solar charge controllers:
It is the element to protect the battery against to risking situations as overloads and over discharges. The theoretical formulation of the model can be simple, although it is necessary to consider the peculiar discontinuities of the model and the inter-performance with the rest of the analyzed models.
Ø Inverter:
The inverter allows transforming the DC current to AC. A photovoltaic installation that incorporates an inverter can belong to two different situations, based on the characteristics of the alternating network. In first an isolated system, where the inverter is the element of the network and has to feed the set of loads and in second situation the inverter is connected to the public network, to which it sends the energy generated by the system.
Ø Batteries
Normally they have been considered as a simple element of storage of
Electrical energy. Batteries are often sold with a PV system. The primary purpose is to store the electricity not immediately used, which could be used at some later time. With net metering, the value of batteries is less because the utility grid basically acts as a storage facility. For a reliable generation system that can function independent of the utility grid, however, batteries may be a viable component to the total system. Backup generators may be included in a system to provide power when the PV system is not operating, and are generally included when systems are not grid connected.
Types of Photovoltaic systems
There are two types of photovoltaic system generally used in the houses, Industries and power plant generation.
Ø Grid Connected PV Systems
These systems are connected to a broader electricity network. The PV system is connected to the utility grid using a high quality inverter, which converts DC power from the solar array into AC power that conforms to the grid‟s electrical requirements. During the day, the solar electricity generated by the system is either used immediately or sold off to electricity supply companies. In the evening, when the system is unable to supply immediate power, electricity can be bought back from the network.
Ø Standalone Systems:
PV systems not connected to the electric utility grid are known as Off Grid PV Systems and also called „stand-alone systems.‟ direct systems use the PV Power immediately as it is produced, while battery storage systems can store energy to be used at a later time, either at night or during cloudy weather. These systems are used in isolation of electricity grids, and may be lighting and general loads. PV systems also provide invaluable and affordable electricity in developing countries like India, where conventional electricity grids are unreliable or non-existent.
SITE DESCRIPTION:
The roof top is having an area of close to 952.8 sq.m of area where it is proposed to utilize the vacant area on the roof top for installation of 20 kWp which could serve as a grid connected system and could be used for collection of data for analysis on the of availability of solar power.
Plant is having around sq.ft of rooftop which will be used to for installing ON grid solar solutions to the industry.
The data are collected from the recent metrological data, the details as follows.
Chennai,India- Solar energy and surface meteorology
From the above figure of the data the average solar irradiance is 5.273kWh/m^2/day, and the maximum wind speed is 5.52m/sec. The sun path direction of the solar system is
The basic information at the site is:
Latitude: +13.09 (13°05'24"N)
Longitude: +80.27 (80°16'12"E)
FUNCTIONAL DESCRIPTION OF SPV POWER SYSTEM
The solar PV system shall be designed with either mono/ poly crystalline silicon modules or using thin film photovoltaic cells or any other superior technology having higher efficiency.
Three key elements in a solar cell form the basis of their manufacturing technology. The first is the semiconductor, which absorbs light and converts sit into electron-hole pairs. The second is the semiconductor junction, which separates the photo-generated carriers (electrons and holes), and the third is the contacts on the front and back of the cell that allow the current to flow to the external circuit. The two main categories of technology are defined by the choice of the semiconductor: either crystalline silicon in a wafer form
or thin films of other materials.
The grid interactive roof top solar PV system generally comprises the
following equipment.
i) SPV Power Source
ii) Inverter (PCU)
iii) Mounting Structure
iv) AC and DC Cables
v) Earthing equipment /material
vi) Junction Boxes or combiners
vii) Instruments and protection equipments
Photovoltaic solar system use the light available from the sun to generate
electricity and feed this into the main electricity grid or load as the case may
be. The PV panels convert the light reaching them into DC power. The amount of power they produce is roughly proportional to the intensity and the angle of the light reaching them. They are therefore positioned to take maximum advantage of available sunlight within site constraints. Maximum power is obtained when the panels are able to 'track' the sun's movements during the day and the various seasons. However, these tracking mechanisms tend to add a fair bit to the cost of the system, so a most of installations either have fixed panels or compromise by
Incorporating some limited manual adjustments, which take into account the
different 'elevations' of the sun at various times of the year. The best elevations vary with the latitude of the load location.
The power generating capacity of a photovoltaic system is denoted in Kilowatt peak (measured at standard test conditions of solar radiation of 1000 W per m2). A common rule of thumb is that average power is equal to 20% of peak power, so that each peak kilowatt of solar array output power corresponds to energy production of 4.8 kWh per day (24 hours x 1 kW x20% = 4.8 kWh)
Solar photovoltaic modules can be developed in various combinations depending upon the requirements of the voltage and power output to be taken from the solar plant. No. of cells and modules may vary depending upon the manufacturer prudent practice
Inverter
i) The DC power produced is fed to inverter for conversion into AC.
ii) The output of the inverter must synchronize automatically to the grid system based on the voltage and the frequency.
iii) Inverter efficiency of min.94% is considered in the PV system
PROTECTION AND CONTROLS:
i) Inverter shall be provided with islanding protection to isolate it from the grid in case of no supply, under voltage and over voltage conditions so that in no case there is any chance of accident.
ii.) In addition to above, PV systems shall be provided with adequate rating fuses, fuses on inverter input side (DC) as well as output side (AC) side for overload and short circuit protection and disconnecting switches to isolate the DC and AC system for maintenances are needed.
ii) Fuses of adequate rating shall also be provided in each solar array module to protect them against short circuit.
ANNUAL ENERGY GENERATION:
The annual energy generation from the SPV power plant has been worked out
based on the data on mean global solar radiant exposure over puducherry at
The mean global solar radiant exposure for a complete year is 5.27kWh/m^2/day. Considering the efficiency of PV module at 16% and temperature coefficient of 4.4 % per deg C, the annual energy generation feed into the grid is estimated as 38.44 MWh. This takes into consideration an efficiency of the Power Conditioning
Unit (PCU) as 97% and losses in the DC and AC system as 3% each up to the
point of interconnection. The month wise energy generation during the year is
given below.
INTEGRATION OF PV POWER WITH GRID:
The output power from SPV would be fed to the inverter which converts DC
Produced by SPV array to AC and feeds it into the main electricity grid after
Synchronization. In case of grid failure, or low or high voltage, solar PV system shall be out of synchronization and shall be disconnected from the grid. Once the DG set comes into service PV system shall again be synchronized with DG supply and load requirement would be met to the extent of availability of power.
Inverter shall have the software and controls capable of operating the complete system for safe and efficient operation and includes the Islanding protection, Over voltage/ under voltage protection, Ground fault /short circuit protection system, communication equipment such as modems, web box etc, DC reverse polarity protection, Grid monitoring of all the phases & pole sensitive residual current monitoring unit, protection against voltage fluctuations in the grid & protection against internal faults in the power conditioner, operational errors and switching transients etc.
The output power from inverter would be fed to the panel of common AC bus system where both the Grid and DG sets are connected. The solar power would be used locally in on working days to the extent of load in the building and the generation over and above the requirement of the building would be fed into the grid. On the week end and other holidays, almost the entire energy from the SPV module would be fed into the grid. The connection of the grid connected SPV power plant with the existing power supply system is shown
in the diagram below.