Sunday, 21 February 2016

SOLAR PV MODULE

Photo Voltaic:

A photovoltaic (PV) module is a packaged, connected assembly of solar cells. Each module is rated by its DC output power under standard test conditions (STC), and typically ranges from 100 to 365 watts. A single solar module can produce only a limited amount of power; most installations contain multiple modules. A photovoltaic system typically includes a panel or an array of solar modules, a solar inverter, and sometimes a battery and/or solar tracker and interconnection wiring.

Most solar modules are mostly produced from crystalline silicon (c-Si). Solar cells made of Poly crystalline and Mono crystalline silicon. However, emerging solar technologies use advanced Thin-film cells. They produce a relatively high-efficiency conversion for the low cost compared to other solar technologies.

Mono crystalline PV module:

Solar PV cells used in this type are made of Single crystalline material (mono - Si). These are made into wafers from the cylindrical silicon ingots and typical appears in a dark black color before making into a cell.


Mono crystalline silicon Solar PV module

Advantages:

  • Mono crystalline solar panels have the highest efficiency rates since they are made out of the highest-grade silicon. The efficiency rates of mono crystalline solar panels are typically 15-20%. But the recent advancements in the manufacturing industries can have higher efficiencies.
  • A mono crystalline is more efficient in converting solar energy into electricity per sq meter area than a multi-crystalline PV. Thus the space required for the same amount of wattage is less in mono crystalline PV panel. Thus it is costlier than a multi-crystalline PV.
  • During low light conditions they perform better than the multi crystalline modules.

Disadvantages:
  • Mono crystalline solar panels are the most expensive. In a financial view, a solar panel that is made of polycrystalline silicon (and in some cases thin-film) can be a better choice for some residential applications.
  • Mono crystalline solar panels tend to be more efficient in warm weather. Performance suffers as temperature rises, but less than polycrystalline solar panels.

Poly Crystalline PV Modules: 

These modules consisting cells which are based on polycrystalline silicon, known as poly silicon (p-Si) and multi-crystalline silicon (mc-Si). The manufacturing involves raw silicon is melted and poured into a square mold, which is cooled and cut into perfectly square wafers. It is identifiable by its signature light or dark blue color, but not uniformly so, some patches are lighter than others. The differences appear as a result of the manufacturing process.
Poly crystalline silicon Solar PV module

Advantages:

  • The manufacturing process is simple and cost effective. The amount of waste silicon is less compared to mono crystalline.
  • Polycrystalline solar panels tend to have slightly lower heat tolerance than mono crystalline solar panels. Which means they perform slightly worse than mono crystalline solar panels in high temperatures. Heat can affect the performance of solar panels and shorten their lifespans. However, this effect is minor and will not be a problem for residential users. A good way to separate mono & polycrystalline solar panels is that polycrystalline solar cells look perfectly rectangular with no rounded edges.

Disadvantages:

  • The efficiency of polycrystalline-based solar panels is typically 13-16%. Because of lower silicon purity, polycrystalline solar panels are not quite as efficient as mono crystalline solar panels.
  • Lower space-efficiency. User generally need to cover a larger surface to get the same electrical power as he would with a solar panel made of mono crystalline silicon. However, this does not mean every mono crystalline solar panel performs better than those based on polycrystalline silicon.

Thin – film PV module:

A thin-film solar cell is made by depositing one or more thin layers or thin film (TF) of photovoltaic material on a substrate, such as glass, plastic or metal. Thin-film solar cells are commercially used in several technologies like,
  • Cadmium telluride (Cd- Te)
  • Copper indium gallium Diselenide (CIGS)
  • Amorphous thin-film silicon (A-Si, TF-Si).
Cadmium telluride (Cd-Te): Cadmium telluride (Cd-Te) is the predominant thin film technology consists about 5 percent of worldwide PV production, it accounts for more than half of the thin film market. The cell's lab efficiency has also increased significantly in recent years and is on a par with CIGS thin film and close to the efficiency of multi-crystalline silicon as of 2013. Cd-Te has the lowest Energy payback time of all mass-produced PV technologies, and can be as short as eight months in favorable locations.

  • A prominent manufacturer is the US-company First Solar based in Tempe, Arizona, that produces Cd-Te panels with an efficiency of about 14 percent at a reported cost of $0.59(Rs. 36) per watt.
Copper indium gallium diselenide (CIGS): CIGS cells are made up of copper, indium, gallium, selenide (CIGS), while gallium-free variants of the semiconductor material are abbreviated CIS. With a lab-efficiency above 20 percent, shares 2% in the overall PV market in 2013.

 Amorphous thin- film silicon:  Amorphous silicon (a-Si) is a non-crystalline, allotropic form of silicon and the most well-developed thin film technology to-date. Thin-film silicon is an alternative to conventional wafer (or bulk) crystalline silicon. Silicon-based devices exhibit fewer problems than Cd-Te and CIS such as toxicity and humidity issues with Cd-Te cells and low manufacturing yields of CIS due to material complexity.


Thin film Solar PV modules

Advantages:
  • Thin-film technology has always been cheaper than conventional c-Si technology    (almost 10 times less).
  •  Homogeneous appearance is made possible, lower manufacturing cost.
Disadvantages:
  • Present disadvantages, such as low-conversion efficiencies and requiring larger areas of PV arrays and more material (cables, support structures) to produce the same amount of electricity.
  •  Lab tests reports that somewhat faster degradation compared to conventional PV, while a lifetime of 20 years or more is generally expected.



 Solar PV module important characteristics:

  • Rated power (Wp) at STC: This is the maximum output power of the module during standard test conditions, this rating is provided at the back of the module. Standard Test conditions: STC conditions are given by NEC (National Electro technical commission) refers to the irradiance, Temperature, Air mass values. Typical values are 1000W/m2, 250C, AM (Air mass) = 1.5.
  • Type of cell: The type of the cell used in the module, for the price stand point this is very important as price varies with the different existing models like mono – Si, Poly – Si, thin film.
  • Cell efficiency (%): It is the energy conversion rate of the Solar cell, usually it is always greater than Module efficiency (in a general case cell efficiency would be 25%).
  • Module efficiency (%): It is defined as the ratio of electrical equivalent of the irradiance input to the output of the module, in short it gives the energy conversion rate of a module which is very important in selecting module, the higher the efficiency results higher output.

Eg: If the module (1mX1m) is able to generate 200W as it is getting 1000 W/sq.m irradiation from the sun, then the module efficiency is taken as 20%.
  • Rated Tolerance (+ or - %): It is range based on which the PV module perform. The range can varies up to +10% to -10% which means a 200 Wp module can actually produce 180 Wp (Under perform) to 220 Wp (over perform).
Most of the panels have tolerance in the range of +/- 3%.To ensure the panel to be good, always make sure the panel should have less negative tolerance (up to -3%). Some manufacturers provide like 0% to -3% which are very reliable & practical.

  • NOCT data: The data of the module (performance) at normal operating cell temperatures.
  • Capacity factor (%):  It is the average power delivered over a year compared to the rated power. It is a measure of the actual output compared to the output it could deliver. It will be less than 100% always because

1. Variations in irradiance levels.
2. Performance lag due to maintenance (dust).
  • Max Power temp coefficient (% per 0C): It is the decrement of output power of the module due to the temperature rise.

Electrical Equivalent of a solar Module:


Generally solar module has two output terminals produces V and I.



  • Iph is the output current from the cell. It depends on the area (A), intensity of incoming light & response factor.
  • Id is the leakage current (due to recombination of charges inside the cell).
  • Rp & Rs are the resistances due to the parallel and series connections of the cell.

·               As Module consists of no of cells connected series and parallel,

V= output voltage of the cell is given by (Np x Voltage of each cell), where Np is the no.   of cells connected in series.

I = Output current of the cell is given by (Ns x Current produced by each cell), where Ns is the no. of cells connected in parallel.


PV module I-V characteristics:


In the following graph, Y- Axis determines the current and X- Axis determines voltage of a solar module. The maximum points on Y and X axes give the Short circuit current and open circuit voltage of the module.

  • ISC is the short circuit current at full load (shorting the end terminals and measuring the current through it).
  • VOC is the open circuit voltage at no load (measuring the voltage across the open terminals of the module).
  • As the current (I) always depends on the irradiance parameter, also it depends on the temperature of the cell.

  • Module Voltage (V) also depends on the temperature (as the module have Rp & Rs resistances which are the negative temperature coefficient elements and as temperature goes up Rp and Rs decreases).
  • As Rp decreases (non-linearly) Current through it increases, Voltage of the module falls accordingly. Similarly as Rs decreases (non-linearly) current through it increases results in increased output current.


I-V, Power-Voltage characteristics of solar module STC




MPPT (Maximum power point tracking): 

It is the mechanism employed in solar PV system which makes the panel to output the maximum power at every instant; however the maximum power does depends on the conditions (irradiation, temperature) at that moment.

  • Vmpp is the voltage of the module, Impp is the current of the module at which maximum power generation is possible, however these parameters always depends on the respective conditions (irradiation, temperature).
  • For any characteristic curve, the voltage (Vmpp), current (Impp) are always less than Voc, Isc.

MPP analysis from V-I characteristics


Solar PV Datasheet: 

The following link directs to the Technical datasheet of a module.(company-Tata solar power)



Solar panels pricing:

From the solar PV industry, cost of a PV module (just the panel) costs anywhere between Rs 30 to Rs 60 per watt of power generated (depending on the quantity you are buying). A good imported module will cost around Rs 40-45 per watt (for bulk transactions, not for retail). Good ones manufactured in India would come as low as Rs 30-32 per watt (for bulk transactions, not for retail).

Here is the Price list example of a particular company which gives an idea of the price per Watt of solar module.

Products
Inputs / Watt
Price / INR
Special SPV Mono
180W / 190W
Rs. 34/W
Special SPV Multi
230W,240W, 245W, 280W,290W
Rs. 32/W
SPV Mono
10W
Rs. 53/W
SPV Mono
20W – 30W
Rs. 43/W
SPV Mono
30W – 300W
Rs. 41/W
SPV Multi
10W
Rs. 50/W
SPV Multi
20W – 30W
Rs. 40/W
SPV Multi
30W – 300W
Rs. 38/W
Thin Film Multi SPV
100W
Rs. 32/W



Solar PV manufacturers:


Following are the reputed international PV manufacturers (information based on 2015 yr data.)

Name of the Comapany
Country


Bosch
Germany
Bp solar
Spain/Australia
Green shine new energy
USA
Canadian solar
Canada
China solar
China
Conergy
Germany
Delsolar
Taiwan
E-Ton solar
Taiwan
Evergreen solar
USA/Germany/China
First Solar
USA/Germany/Malaysia
Gintech
Taiwan
Grape Solar
USA
Isofoton
Spain
JA solar holdings
China
Just Solar Co. Ltd
China
Kyocera
Japan
Mitsubishi Electric
Japan
Mitsubishi Heavy
Japan
Motech
Taiwan/China
MX Group
Italy
Neo solar Power
Taiwan
Ningbo Solar Electric
China
Photowatt
France
Photovoltech NV
Belgium
Q-Cells
Germany/Malyasia
Renewable Energy Corporation
Norway
Panasonic
Japan
Schott Solar
Germany/USA
Sharp
Japan
Solarday
Italy
Solarpark Korea
South korea
Solar World
Germany/USA
Solland
Netherlands
SunPower
USA/Malaysia
Suntech
China
Sunways
Germany
Trina Solar
China
United solar ovonic
USA
Vikram Solar
India
Yingli
China


Here is the list of reputed Indian PV manufacturers list:

S. No
Name of the Company
Manufacturing Capacity (MW)
Technology




1
TATA SOLAR POWER
200
Polycrystalline
2
LANCO SOLAR
75
Polycrystalline/silicon ingots/wafers
3
VIKRAM SOLAR
500
Polycrystalline
4
WAREE
250
Mono/Poly crystalline
5
MOSER BAER
185/200/50
Crystalline cells &modules /Thinfilm modules
6
INDO SOLAR
450
Mono/Poly crystalline
7
WEBSOL ENERGY SYSTEM
120
Monocrystalline
8
XL ENERGY LTD.
25
Polycrystalline
9
EMVEE
135
Mono/Poly crystalline
10
SOLAR SEMICONDUCTOR PV LTD.
195
Mono/poly crystalline
11
PHOTON ENGERGY
50
Mono/Poly crystalline
12
SWELECT ENGERGY SYSTEMS
40+
Mono/Poly crystalline
13
SURAN VENTURES LTD
130
Mono/Poly crystalline
14
PREMIER SOLAR
50
Mono/Poly crystalline and thinfilm
15
JUPITER SOLAR
130
Poly crystalline
16
TITAN ENERGY
110
Mono/Poly crystalline
17
HHV SOLAR
100
Mono/poly crystalline
18
CENTRAL ELECTRONICS INDIA
40
Crystalline Silicon
19
ACCESS SOLAR
80
Mono/poly crystalline

* Note: The above information may subject to vary without any notice and we will be not responsible for such happenings.

Here, the source for the manufacturers list is Wikipedia.


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