SOLAR PANELS

A solar panel (also solar module, photovoltaic module or photovoltaic panel) is a packaged, connected assembly of photovoltaic cells. The solar panel can be used as a component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications. Each panel is rated by its DC output power under standard test conditions, and typically ranges from 100 to 320 watts. The efficiency of a panel determines the area of a panel given the same rated output - an 8% efficient 230 watt panel will have twice the area of a 16% efficient 230 watt panel. Because a single solar panel can produce only a limited amount of power, most installations contain multiple panels. A photovoltaic system typically includes an array of 

THEORY AND CONSTRUCTION

Solar panels use light energy (photons) from the sun to generate electricity through thephotovoltaic effect.

The majority of modules use wafer-based crystalline silicon cells or thin-film cells based on cadmium

telluride or silicon. The structural (load carrying) member of a module can either be the top layer or the

back layer. Cells must also be protected from mechanical damage and moisture. Most solar panels are

rigid, but semi-flexible ones are available, based on thin-film cells. These early solar panels were first

used in space in 1958.

Electrical connections are made in series to achieve a desired output voltage and/or in parallelto provide

a desired current capability. The conducting wires that take the current off the panels may contain silver,

copper or other non-magnetic conductive transition metals. The cells must be connected electrically to

one another and to the rest of the system. Externally, popular terrestrial usage photovoltaic panels

use MC3 (older) or MC4 connectors to facilitate easy weatherproof connections to the rest of the system.

Bypass diodes may be incorporated or used externally, in case of partial panel shading, to maximize the

output of panel sections still illuminated. The p-n junctions of mono-crystalline silicon cells may have

adequate reverse voltage characteristics to prevent damaging panel section reverse current. Reverse

currents could lead to overheating of shaded cells. Solar cells become less efficient at higher

temperatures and installers try to provide good ventilation behind solar panels.

Some recent solar panel designs include concentrators in which light is focused by lenses or mirrors onto

an array of smaller cells. This enables the use of cells with a high cost per unit area (such as gallium

arsenide) in a cost-effective way

Efficiencies

Depending on construction, photovoltaic panels can produce electricity from a range offrequencies of

light, but usually cannot cover the entire solar range (specifically, ultraviolet,infrared and low or diffused

light). Hence much of the incident sunlight energy is wasted by solar panels, and they can give far higher

efficiencies if illuminated with monochromatic light. Therefore, another design concept is to split the light

into different wavelength ranges and direct the beams onto different cells tuned to those ranges. This has

been projected to be capable of raising efficiency by 50%.

Currently the best achieved sunlight conversion rate (solar panel efficiency) is around 17.4% in new

commercial products typically lower than the efficiencies of their cells in isolation. The energy density of a

solar panel is the efficiency described in terms of peak power output per unit of surface area, commonly

expressed in units of watts per square foot (W/ft2). The most efficient mass-produced solar

panels[disputed – discuss] have energy density values of up to 16.22 W/ft2 (175 W/m2).

TYPES OF SOLAR PANELS

Most solar modules are currently produced from silicon photovoltaic cells. These are typically categorized as monocrystalline orpolycrystalline modules.

The difference between monocrystalline vs polycrystalline solar cells is simply that one is produced from a single crystal of silicon and the other is produced from a piece of silicon consisting of many crystals.

Since polycrystalline cells contain many crystals, they have a less perfect surface than monocrystalline cells. 

This means that they absorb slightly less solar energy and produce slightly less electricity per square metre. On the

plus side, the process of creating the silicon for a polycrystalline cell is much simpler, so these cells are generally

cheaper per square metre.

Polycrystalline Monocrystalline

Low cost Slightly higher cost than polycrystaline

Bigger size with the same watt rating Slightly smaller in size with the same rating

Less efficient in catching sunlight rays Slightly more effecient in catching sunlight rays

On balance, the cost of monocrystalline vs polycrystalline based panels per Watt of power output works out about the

same, but the polycrystalline panels will be slightly larger than equivalent monocrystalline panels.  This is generally

not a problem unless you have a very limited area available for the installation, in which case you will want to

maximise the power output per square metre.

Monocrystalline and polycrystalline can also look different.  Monocrystalline cells will usually have a perfectly uniform

appearance, but polycrystalline cells will appear “grainy” – think of how a granite worktop looks and you’ll get the

idea.  From a distance this will not be noticeable, so if they are going on your roof this is unlikely to worry you.

Thin-film modules

Third generation solar cells are advanced thin-film cells. They produce high-efficiency conversion

at low cost.

Rigid thin-film modules

In rigid thin film modules, the cell and the module are manufactured in the same production line.

The cell is created on a glass substrate or superstrate, and the electrical connections are created in situ,

a so-called "monolithic integration". The substrate or superstrate is laminated with an encapsulant to a

front or back sheet, usually another sheet of glass.

The main cell technologies in this category are CdTe, or a-Si, or a-Si+uc-Si tandem, or CIGS (or

variant). Amorphous silicon has a sunlight conversion rate of 6-12%.

Flexible thin-film modules

Flexible thin film cells and modules are created on the same production line by depositing

the photoactive layer and other necessary layers on a flexible substrate.

If the substrate is an insulator (e.g. polyester or polyimide film) then monolithic integration can be used.

If it is a conductor then another technique for electrical connection must be used.

The cells are assembled into modules by laminating them to a transparent colourless fluoropolymer on

the front side (typically ETFE orFEP) and a polymer suitable for bonding to the final substrate on the other

side. The only commercially available (in MW quantities) flexible module uses amorphous silicon triple

junction (from Unisolar).

So-called inverted metamorphic (IMM) multijunction solar cells made on compound-semiconductor

technology are just becoming commercialized in July 2008. The University of Michigan's solar car that

won the North American Solar Challenge in July 2008 used IMM thin-film flexible solar cells.

The requirements for residential and commercial are different in that the residential needs are simple and

can be packaged so that as solar cell technology progresses, the other base line equipment such as the

battery, inverter and voltage sensing transfer switch still need to be compacted and unitized for residential

use. Commercial use, depending on the size of the service will be limited in the photovoltaic cell arena,

and more complex parabolic reflectors and solar concentrators are becoming the dominant technology.

The global flexible and thin-film photovoltaic (PV) market, despite caution in the overall PV industry, is

expected to experience a CAGRof over 35% to 2019, surpassing 32 GW according to a major new study

by IntertechPira.

Crystalline silicon forms the basis of mono- and polycrystalline silicon solar cells:

 

Monocrystalline Silicon Solar Cells

Solar cells made of monocrystalline silicon (mono-Si), also called single-crystalline silicon (single-crystal-

Si), are quite easily recognizable by an external even coloring and uniform look, indicating high-purity

silicon, as you can see on the picture below:

Monocrystalline solar cells are made out of silicon ingots, which are cylindrical in shape. To optimize

performance and lower costs of a single monocrystalline solar cell, four sides are cut out of the cylindrical

ingots to make silicon wafers, which is what gives monocrystalline solar panels their characteristic look.

A good way to separate mono- and polycrystalline solar panels is that polycrystalline solar cells look

perfectly rectangular with no rounded edges.

 

Advantages

Monocrystalline solar panels have the highest efficiency rates since they are made out of the

highest-grade silicon. The efficiency rates of monocrystalline solar panels are typically 15-20%.

SunPower produces the highest efficiency solar panels on the U.S. market today. Their E20 series

provide panel conversion efficiencies of up to 20.1%.[3]

Monocrystalline silicon solar panels are space-efficient. Since these solar panels yield the highest

power outputs, they also require the least amount of compared to any other types. Monocrystalline solar

panels produce up to four times the amount of electricity as thin-film solar panels.

Monocrystalline solar panels live the longest. Most solar panel manufacturers put a 25-year warranty

on their monocrystalline solar panels.

Tend to perform better than similarly rated polycrystalline solar panels at low-light conditions.

The efficiency of individual solar cells is higher than for entire solar panels/modules. For a complete

overview over how the efficiency rates of the various solar cell technologies have advanced since 1975

check out Best Research-Cell Efficiencies (NREL). The efficiency rates in this article refer to solar

panel/module efficiencies. Check out Solar Panel Efficiency for more information on this subject.

 

Disadvantages

Monocrystalline solar panels are the most expensive. From a financial standpoint, a solar panel that

is made of polycrystalline silicon (and in some cases thin-film) can be a better choice for homeowners.

If the solar panel is partially covered with shade, dirt or snow, the entire circuit can break down. Consider

getting micro-inverters instead of central string inverters if you think coverage will be a problem. Micro-

inverters will make sure that not the entire solar array is affected by shading issues with only one of the

solar panels.

The Czochralski process is used to produce monocrystalline silicon. It results in large cylindrical ingots.

Four sides are cut out of the ingots to make silicon wafers. A significant amount of the original silicon

ends up as waste.

Monocrystalline solar panels tend to be more efficient in warm weather. Performance suffers as

temperature goes up, but less so than polycrystalline solar panels. For most homeowners temperature is

not a concern.

This article is solely about different types of solar panels. If you want to learn about what other equipment

a photovoltaic system consists of, go to Grid-Tied, Off-Grid and Hybrid Solar Systems.

 

Polycrystalline Silicon Solar Cells

The first solar panels based on polycrystalline silicon, which also is known as polysilicon (p-Si) and multi-

crystalline silicon (mc-Si), were introduced to the market in 1981. Unlike monocrystalline-based solar

panels, polycrystalline solar panels do not require the Czochralski process. Raw silicon is melted and

poured into a square mold, which is cooled and cut into perfectly square wafers.

 

Advantages

The process used to make polycrystalline silicon is simpler and cost less. This reduces the amount of

waste silicon.

Polycrystalline solar panels tend to have slightly lower heat tolerance and therefore perform slightly worse

than monocrystalline solar panels in high temperatures. Heat can affect the performance of solar panels

and shorten their lifespans. However, this effect is minor, and most homeowners do not need to take it

into account.

 

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 monocrystalline solar panels.

You need to cover a larger surface to output the same electrical power as you would with a solar panel

made of monocrystalline silicon.

Monocrystalline and thin-film solar panels tend to be more aesthetically pleasing since they have a more

uniform look compared to the speckled blue color of polycrystalline silicon.

PRICE LIST OF SOLAR PANELS

Product Name   ↓

Volts Watts $   /   Watt Price

 

 

 AEE 10W 12V for PV-Direct Circulation Pumps 

 12 V   10 W   $5.90   $59.00 

 

 

 altE ALT10-12P Poly 10W 12V      12 V   10 W   $4.20   $42.00 

 

 

 altE ALT100-12P Poly 100W 12V      12 V   100 W   $2.15   $215.00 

 

 

 altE ALT100-24P Poly 100W 24V      24 V   100 W   $2.55   $255.00 

 

 

 altE ALT120-12P Poly 120W 12V      12 V   120 W   $2.13   $255.00 

 

 

 altE ALT20-12P Poly 20W 12V      12 V   20 W   $3.55   $71.00 

 

 

 altE ALT200-24P Poly 200W 24V      24 V   200 W   $1.50   $299.00 

 

 

 altE ALT30-12P Poly 30W 12V      12 V   30 W   $3.47   $104.00 

 

 

 altE ALT5-12P Poly 5W 12V      12 V   5 W   $5.37   $26.85 

 

 

 altE ALT50-12P Poly 50W 12V      12 V   50 W   $3.10   $155.00 

 

 

 altE ALT80-12P Poly 80W 12V      12 V   80 W   $2.31   $185.00 

 

 

 Ameresco BP330J 30W 12V with J-Box 

 12 V   30 W   $7.33   $220.00 

 

 

 Ameresco BP450J 50W 12V with J-Box 

 12 V   50 W   $5.14   $256.75 

 

 

 Ameresco BP490J 90W 12V with J-Box 

 12 V   90 W   $4.54   $409.00 

 

 

 Ameresco BPSX305M 4.5W 12V with J-Box 

 12 V   4.5 W   $15.89   $71.50 

 

 

 Ameresco BPSX420J 20W 12V with J-Box 

 12 V   20 W   $8.06   $161.20 

 

 

 Ameresco Solar BP440J 40W 12V with J-Box 

 12 V   40 W   $6.83   $273.00 

 

 

 Ameresco Solar BPSX310J 10W 12V with J-Box 

 12 V   10 W   $11.57   $115.70 

 

 

 Canadian Solar CS6P-24M AB 245W 20V    

 20 V   245 W   $0.99   $241.45 

 

 

 Enphase M215 Micro-Inverter and Suntech 240W Package 

 240 V   215 W   $1.68   $361.00 

 

 

 Kyocera 1.4 Watt 12 Volt Mini      12 V   1.4 W   $19.29   $27.00 

 

 

 Kyocera KD140GX-LFBS 140W 12V    

 12 V   140 W   $2.04   $284.99 

 

 

 Kyocera KD140SX-UFBS 140W 12V with J-Box 

 12 V   140 W   $2.06   $288.00 

 

 

 Kyocera KD140SX-UPU 140W 12V with J-Box 

 12 V   140 W   $2.21   $309.00 

 

 

 Kyocera KD215GX-LFBS 215W 18V Dark Blue Cells 

 18 V   215 W   $1.42   $305.70 

 

 

 Kyocera KD240GX-LPB 240W      20 V   240 W   $1.38   $330.00 

 

 

 Kyocera KD245GX-LFB 245W      20 V   245 W   $1.38   $339.00 

 

 

 Kyocera KD315GX-LPB 315W      27 V   315 W   $1.27   $399.00 

 

 

 Kyocera KS10 10W 12V      12 V   10 W   $8.10   $81.00 

 

 

 Kyocera KS5 5W 12V      12 V   5 W   $12.99   $64.95 

 

 

 Sharp ND-130UJF 130W 12V      12 V   130 W   $3.75   $487.50 

 

 

 SolarWorld 235W , SunModule SW235 Poly V2.5 Frame 

 20 V   235 W   $1.00   $235.00 

 

 

 SolarWorld 240W , SunModule SW240 Poly V2.5 Frame 

 20 V   240 W   $0.92   $220.00 

 

 

 SolarWorld 245 Watt , SunModule SW245 Poly, V2.5 Frame 

 20 V   245 W   $1.08   $265.00 

 

 

 SolarWorld 245W Black , Sunmodule SW245 , Type B, Monocrystalline 

 20 V   245 W   $1.12   $275.00 

 

 

 SolarWorld 245W , Sunmodule SW245 Poly v2.0 Frame 

 20 V   245 W   $1.06   $260.00 

 

 

 SolarWorld 250W , Sunmodule SW250 Mono V2.0 Frame 

 20 V   250 W   $1.76   $439.00 

 

 

 SolarWorld 260 Watt , Sunmodule 260W SW260 Mono V2.5 Frame 

 20 V   260 W   $1.25   $324.00 

 

 

 SolarWorld 50 Watt, 12V Poly , SW50 

 12 V   50 W   $3.78   $189.00 

 

 

 SolarWorld Sunmodule SW225 Mono 225W 20V    

 20 V   225 W   $1.15   $259.00 

 

 

 SolarWorld Sunmodule SW240 Poly 240W 20V , Type B 

 20 V   240 W   $1.04   $249.00 

 

 

 SolarWorld Sunmodule SW255 Black 255W 20V Monocrystalline 

 20 V   255 W   $1.35   $343.46 

 

 

 SolarWorld SW135 Poly 135W 12V with J-Box 

 12 V   135 W   $2.00   $270.00 

 

 

 SolarWorld SW140 Poly 140W 12V with J-Box 

 12 V   140 W   $2.00   $279.95 

 

 

 SolarWorld SW80 Poly 80W 12V with J-Box 

 12 V   80 W   $2.49   $199.00 

 

 

 Suntech PLUTO240-Wde 240W 20V    

 20 V   240 W   $0.95   $229.00 

 

 

 Suntech STP240-20/Wde 240W, 20V    

 20 V   240 W   $0.89   $213.00 

 

 

 Suntech STP250-20/Wd 250W, 20V      20 V   250 W   $0.99   $247.00 

 

 

 Suntech STP285-24/Vd 285W 24V      24 V   285 W   $0.98   $279.00 

 

 

 Suntech STP290-24/Vd 290W 24V      24 V   290 W   $1.27   $367.00 

 

 

 Sunwize SolCharger SC12-12V 12W 12V    

 12 V   12 W   $10.33   $124.00 

 

 

 Sunwize SolCharger SC12-6V 12W 6V    

 6 V   12 W   $10.75   $129.00 

 

 

 Sunwize SolCharger SC18-12V 18W 12V    

 12 V   18 W   $8.94   $161.00 

 

 

 Sunwize SolCharger SC24-12V 24W 12V    

 12 V   24 W   $11.29   $271.00 

 

 

 Sunwize SolCharger SC3-12V 3W 12V    

 12 V   3 W   $15.33   $46.00 

 

 

 Sunwize SolCharger SC3-6V 3W 6V    

 6 V   3 W   $13.67   $41.00 

 

 

 Sunwize SolCharger SC6-12V 6W 12V    

 12 V   6 W   $13.00   $78.00 

 

 

 Sunwize SolCharger SC6-6V 6W 6V    

 6 V   6 W   $13.00   $78.00 

 

 

 Sunwize SW-S30P 30W 12V with J-Box 

 12 V   30 W   $5.41   $162.40 

 

 

 Sunwize SW-S40P 40W 12V with J-Box 

 12 V   40 W   $5.68   $227.00 

 

 

 Sunwize SW-S55P 55W 12V with J-Box 

 12 V   55 W   $4.58   $251.72 

 

 

 Sunwize SW-S85P 85W 12V with J-Box 

 12 V   85 W   $3.33   $283.00

Item code Model number Volts Watts Cell Tech

SUC240STP240WDE STP240-20/Wde 20V 240W Polycrystalline

SunTechSTP240-20/Wde240 Watt, 20 VoltPolycrystalline Solar PanelBlack Frame

Suntech's technology yields improvements to BSF structure and anti-reflective coating to increase conversion efficiency. The STP module's new rigid and reliable hollow chamber frame provides additional grounding options for increased design flexibility and easier installation.

Features

High Power Tolerance (0-5%) High conversion efficiency (up to 14.4%) Withstands high wind-pressure, snow load and extreme temperature variations

Excellent performance in low light conditions

Built for long service life

Industry-leading, transferable 25-year power output warranty Rigorous quality control meeting the highest international standards

ISO 9001:2000 (Quality Management System) and ISO 14001:2004(Environmental Management System) certified factories deliverworld class products

Certification and standards: UL1703, IEC 61215, IEC 61730, conformity to CE

Specifications

Model STP240-20/Wde

Maximum Power at STC* 240 W

Number of cells 60 (6 x 10)

Dimensions64.6" x 39.1" x 1.4"

(1640 x 992 x 35mm)

Weight 40.1 lb (18.2 kg)

Open Circuit Voltage (Voc)

37.2 V

Maximum Power Point Voltage (Vmp)

30.2 V

Short Circuit Current (Isc) 8.43 A

Maximum Power Point Current (Imp)

7.95 A

Operating Temperature -40ºC to +85ºC

Maximum System Voltage

1000 VDC (IEC) / 600 VDC (UL)

Output Cables4.0 mm2 (0.006 inches2), symmetrical lengths (-) 1100 mm

(43.3 inches) and (+) 1100 mm (43.3 inches)

Series Fuse Rating 20 A

Connectors MC4 connectors

* STC: Standard Test Conditions - Irradiance 1000 W/m2, Module temperature 25 ºC, AM = 1.5

UL Listed

SAMPLE DIAGRAM FOR SOLAR GENERATOR