A world-wide-web site which comprehends spirituality in a modern context in review of ancient teachings and religious belief-systems.

W e l c o m e T o S c i e n c e   L i n k s   S i t e s)_9 Interaction Of The Universe To The Individual P R O M O T I N G   C O N S C I O U S N E S S    O N    T H E      I N T E R N E T

HYDROPONIC	NATIONAL DEFENCE	BUSINESS	PERPETUAL	SOLAR POWER	FAVORITES LINKS

 

SOLAR POWER

Standard Solar Power Modules and Arrays

Make This WebPage instantly available in other languages

 

Become Energy Independent

We offer a range of complete solar power systems for homes connected to the electric utility grid. Now almost any home can generate its own electricity with a complete GE solar electric home power system. Engineered to install quickly and reliably to provide years of automatic operation, our residential solar electric systems include everything you need in one complete package.

Features and Benefits

Available with or without an uninterruptible power supply, our pre-packaged systems make solar electric home power more convenient than ever. The residential system includes everything you need to make your own electricity. Designed to provide years of automatic operation, our systems come complete with solar modules, plug-and-play wiring, power electronics, patented mounting kits for roof or ground mounting, a power meter to monitor performance and complete documentation for contractors and homeowners. GE solar systems are currently available only in the United States. Please contact us at 800-310-7271or 201-755-6170for further information. Also, please read our frequently asked questions for residential systems and small commercial systems up to 10 KW.
For new home builders, Aten Solar works with the builders and contractors in order for the solar system to be easily integrated into current building plans. The program provides builders with access to experienced, knowledgeable professionals who can provide hands-on assistance with training, permitting, installations, inspections and warranty support. Builders who use Aten Solar have access to the only complete, pre-engineered packaged solar power system on the market today. This fully integrated system gives homebuyers a unique value added feature, a complete packaged system designed and tested for system wide reliability and durability before installation.

 Pre-packaged Systems

• Solar modules are hail-resistant and produce 100 watts DC power in full sunlight
• Solar array sizes available from 12 to 96 modules
• Systems generate 1,200 to 9,600 watts of solar power in full sunlight
• Pre-engineered rooftop mounting systems withstand up to 125 mph wind (50 lbs/ft²)
• High reliability DC-AC inverter continuously converts solar DC current into common household AC current
• Easily mounts above curved and flat tiles and asphalt shingles

Make This WebPage instantly available in other languages

 

System Diagram

             Off Grid System Components: 

For a functional description scroll down to read about the individual System Components.

Electric Panel:

A distribution terminal for electric wiring (also called a circuit breaker panel or breaker box). All the wiring in a home or office terminates at a main electric panel and is supplied with electricity from the inverter.

Engine Powered Generator:

Uses an engine to generate electricity, typically from natural gas, propane, or diesel fuel. Unlike batteries, which store only a fixed amount of energy, a generator can produce electricity for as long as it is supplied with fuel. A high-quality generator can be fairly quiet, but never noise-free. Like all engines, generators require periodic maintenance.

 Battery Bank:

Stores energy for use on demand. In an Off Grid electrical system the battery bank provides the reservoir of energy available to power loads. The size of the battery bank determines how long power will be available before battery recharging becomes necessary. The power rating of the inverter determines how many appliances you can use at any one time. The power rating of the battery charger determines how quickly your battery bank can be recharged by a generator or other outside AC source.

There are a number of types of deep cycle batteries available which are suitable for inverter operation. Some of them are sealed and require virtually no maintenance.

Solar Electric Panels: 
Convert sunlight directly into electricity used to charge storage batteries. One of the most reliable means to generate your own electricity, solar panels can generate power for decades and require little maintenance. Solar electric generating systems may be sized to provide ample power for most typical residential and commercial power requirements.

Inverter/charger:  

Converts the DC power stored in batteries to regular household current. Xantrex inverters, which consistently provide better-than-utility power, make the use of solar power practical. Trace™ inverters have an efficiency rating as high as 96%, are noise-free, and function as the brains of your fully automatic off grid electric system.

Most have built-in battery chargers which are designed to be used with generators to quickly recharge batteries when solar power is not sufficient.

Charge Controllers:
A charge controller is a device used to control the amount of power generated from a PV array, wind turbine, etc., to a battery. It is used to protect the batteries from harmful overcharge conditions.

DC Disconnect:
A DC disconnect is almost identical to the AC circuit breaker found in your home. It is designed to protect DC circuits (batteries, PV arrays, etc) from short circuits or overload conditions.

Wind Turbine:
A wind turbine generates electrical current as its blade spins. The faster the blade spins the more electricity is generated. Residential scale wind turbines produce between 400 and 10,000 watts of power.

I m p o r t a n t    S t u f f

EFFICIENCY

The best first step toward renewable energy is to make sure your home is energy and water efficient. And, there are new federal tax credits to help you!

INSTALLING A RENEWABLE ENERGY SYSTEM

Finding a qualified contractor is an important first step. Here are other steps in the process you should understand, so you can work intelligently with your contractor:

Usually your contractor or installer will handle much of the paperwork for you. But you will need to sign forms and manage some of the steps yourself. We've outlined the main steps here for you.

LEARN ABOUT FINANCING YOUR SYSTEM

Rebates, tax credits and other financial incentives are available today. These can significantly reduce the price of installing a renewable energy system. Also learn about property tax, leases, power purchase agreements and more ...

GREEN TAGS

Are a versatile new way for consumers and businesses to participate in the national transition to renewable energy. Green tags make it possible to support renewable energy regardless of whether your state is deregulating its energy markets. In some markets and situations Green Tags can be sold or traded. Check with a Solar Pro to see what might be available to you.

Make This WebPage instantly available in other languages

 

Configurations From One Appliance to an Entire Business All solar electric systems use solar cells, encapsulated in weatherproof modules, to convert free sunlight into DC electricity instantly. How the modules are connected and what happens to the electricity depends on the particular type of application. Several typical system configurations are described below.

Directly Connected Systems

Solar Module(s) Connected Directly to a DC Motor Load

Components: Solar modules and mounting hardware, DC motor or pump and disconnect switch or circuit breaker.

How it works: The solar module produces DC current that is used immediately by a motor. As sunlight rises and falls, current and voltage rise and fall, and the motor speeds up and slows down proportionally. There is no power storage. The motor operates slowly during cloudy or stormy weather and does not operate at night.

Applications: Remote water pumping, a ceiling or attic fan or a solar thermal (hot water) circulation pump

Small Solar Module Connected to a Large Battery

Components: Solar module, fuse and/or fused disconnect switch

How it works: A small current flows from the solar module through a starting battery to counteract any inherent self-discharge in the battery. A trickle charge flows only during daylight hours, but on average offsets any self-discharge.

Applications: Trickle charging of vehicle starting batteries (fleet vehicles, seasonal road equipment like snowplows) and boat batteries

Stand-Alone Systems

Solar Modules Connected Through a Charge Regulator to Battery Storage

Components: Solar modules and mounting hardware, a charge regulator, storage batteries and disconnect switches or circuit breakers

How it works: A solar array produces DC current that passes through the charge controller into storage batteries. The charge regulator reduces or stops charging current to prevent battery overcharge. Small DC loads may be connected to the charge regulator, which can then prevent battery over-discharge. The battery operates loads at night and during overcast or stormy days. Solar modules recharge the batteries when average or good weather returns.

Applications: Remote industrial areas (telecommunications, navigational aids, cathodic protection and traffic systems) and remote home systems

Above System with DC-AC Inverter Connected to Battery

Components: Above components with the addition of an inverter and an AC distribution center

How it works: Same as above with the addition of an inverter to operate AC loads. The inverter draws power from the battery and changes DC to AC current and voltage. For safety, power is sent to the distribution center which houses circuit breakers for individual AC circuits. The inverter operates from battery energy day or night.

Applications: Remote home systems

Above System with Generator

Components: Above components with the addition of a fuel generator (gasoline, diesel or propane), a rectifier and a sophisticated hybrid system controller

How it works: The system controller monitors the battery voltage. When the voltage drops to a safe but low level, the generator is turned on. AC output is converted to DC power and recharges the battery. AC output can also be used directly to power AC loads. When the battery reaches an almost full recharge level, the generator is turned off. The solar array can be sized to supply average GE needs throughout the year, and the generator is used to fill in during seasonal low output periods and prolonged bad weather.

Applications: Village power systems

Grid-Connected Systems

Solar Modules Connected to a Utility Interactive Type Inverter
and Utility Power Grid

Components: Solar modules and mounting hardware, disconnect switches or circuit breakers and a grid interactive inverter

How it works: The solar array produces DC current that passes through inverter, which converts to AC current and voltage. Power is sent to the utility meter and is either consumed immediately by home or business loads, or is sent out to the general utility grid network. The utility meter spins backwards, or two meters are used to record incoming and outgoing power. At night, loads operate from utility power since the solar power system does not produce power. The inverter shuts down automatically in case of utility power failure for safety, and reconnects automatically when utility power resumes.

Applications: Urban residential and commercial systems and utility-scale power plants

Above System with a Bi-directional Inverter and Battery Backup

Components: Above components with the addition of a battery bank, charge regulator and bi-directional inverter.

How it works: The solar array charges the battery bank through a charge regulator. DC power from the battery passes through the inverter and is converted to AC current and voltage. Power is sent to the utility meter and is either consumed immediately by home or business loads, or is sent out to the general utility grid network. The utility meter spins backwards, or two meters are used to record incoming and outgoing power. At night, loads operate and the battery bank is kept trickle charged from utility power since the solar power system does not produce power. In case of utility power failure, the direct connection to the utility meter is shut down for safety. Selected circuits in the home or business that are connected to a special secondary inverter output continue to operate, drawing energy from battery bank. The solar array recharges the battery each day until normal utility power resumes.

Applications: Urban residential and commercial systems

High Effective Hybrid PV

Environmental pollution and energy shortages are now of global concern. More interest is focusing on photovoltaic (PV) power generation, which can use an unlimited source of clean energy - the sun. Kaneka decided to begin research into thin film silicon PV modules at an early stage. This has allowed the company to assume a leading position in the industry over the past 20 years. Kaneka's accumulated expertise now makes it possible to offer next-generation energy all over the world through its advanced PV systems that empower individuals to take a proactive environmental role in their daily lives. Crystalline-Si PV modules lose some power-generating capability with rises in temperatures. But Amorphous-Si PV modules have higher power generation capability during extreme summer time. Amorphous-Si PV modules can deliver maximum performance during summer afternoons. Therefore the amorphous-Si PV systems can contribute during the time when the electricity is needed most for air-conditioners in houses and offices.  *Kaneka Silicon PV's generated watt-power is approximately same as that of other crystalline silicon PVs during the winter months, but in summer the Kaneka Silicon PV generates significantly more power compared to other crystalline silicon PVs. Source: "NEDO/Ritsumeikan University Demographic Module Field Test and Operational Analysis" presented at the International PV SEC-11, Sapporo, Hokkaido, Japan, 1999. Installation location: Kusatsu, Shiga Prefecture Japan Slope angle: 15.3 degree   *Kaneka Silicon PV's generated watt-power is approximately same as that of other crystalline silicon PVs during the winter months, but in summer the Kaneka Silicon PV generates significantly more power compared to other crystalline silicon PVs. Source: "NEDO/Ritsumeikan University Module Field Test and Operational Analysis" presented at the International PV SEC-11, Sapporo, Hokkaido, Japan, 1999. Installation location: Kusatsu, Shiga Prefecture Japan Slope angle: 15.3 degree   Kaneka's amorphous silicon (a-Si) has superior light absorption per nominal watt power. Compared with mono-crystalline (c-Si) or poly-crystalline (poly-Si), it generates considerably more power per nominal watt power.   Assuming that the total solar radiation per year (1.323kWh/m2) is 100%, Kaneka Silicon PV can produce 90.95% of actually generated watt-power, much higher than that of other crystalline silicon PVs (80 to 84%). Source: "NEDO/Ritsumeikan University Demographic Module Field Test and Operational Analysis" presented at the International PV SEC-11, Sapporo, Hokkaido, Japan, 1999. Installation location: Kusatsu, Shiga Prefecture Japan Slope angle: 15.3 degree *NEDO : New Energy and Industrial Technology Development Organization Another advantage is that the single junction a-Si layer can be made extremely thin. The thickness of a-Si cell is 0.3, which is 1/600 of that of crystalline silicon cell. This uses less material and energy thereby enabling high productivity for mass production (approx. 200).     EPT is the time a PV module to "pay back" the energy used in its manufacture by its own power generation. The EPT of amorphous-Si PV is 1.6 years, which is approximately 6 months shorter than that of crystalline silicon PV (2.2 years). EPT is one of the most important aspects when evaluating the ecological benefit of PV systems. Quality  ·                 IEC 61646 tested and certified ·                 safety class II for 530 V system voltage (projected) Guarantee  ·                 25 years power warranty (80%)* ·                 12 years power warranty (90%)* ·                 5 years product guarantee*   High performance  ·                 power tolerance +10%… -5% ·                 higher yield on plant due to higher power output on delivery ·                 high yields even at high module temperatures   Ecological advantage  ·                 Extremely low consumption on material -> energy payback time less than 2 years   Design  ·                 Homogeneous colouring of frame and module surface -> high-class, harmonic appearance   Electrical Characteristics Stabilised values Initial values Nominal peak power (Wp) 60,0 79,0 Guaranteed minimum power (Wp) 57,0 75,05 Nominal voltage (V) 67,0 74,0 Nominal current (A) 0,90 1,04 Open-circuit voltage (V) 92,0 96,0 Short-circuit current (A) 1,19 1,22     Physical Characteristics Maximum system voltage (V) 530 Length (mm) 960 Width (mm) 990 Height (mm) 40 Weight (kg) 14 Assembly holes ø 8 mm (pieces) 4     Boxing dimensions: 1 crate = 44”W x 42” D x 44”H and 750 lbs. There are 25 modules in a crate. The crate is separated into two compartments, one with 12 modules and one with 13 modules. Each module is separated from the others by a solid cardboard separator sheet. For price quotations on container shipments (1 x 20 FT container = 550 modules) or 1 x 40 FT container = 1100 modules)    Your Price  Qty 1  Total $9800.00 SKU  1.44KWKANTK Product Title  1.44KWTK Kaneka Solar Prepackaged/Turnkey Grid Tie System Image   Weight (lbs)  915.00 Suggested Products 1.8 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System Your Price  Qty 1  Total $5625.00 SKU  GSA-60 Product Title  25 Kaneka Solar 60 Watt Modules Description:  60 Watt Amorphous Silicon Solar Module-Sold as lot of 25 Image   Weight (lbs)  825.00 Your Price  Qty 1  Total $16889.00 SKU  3.0KWKANTK Kaneka Solar Prepackaged/Turnkey Grid Tie System Product Title  3.0 KW Kaneka Solar Prepackaged/Turnkey Grid Tie System Image   Weight (lbs)  1725.00 Suggested Products  1.44KWTK Kaneka Solar Prepackaged/Turnkey Grid Tie System 1.8 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System 25 Kaneka Solar 60 Watt Modules Description: 60 Watt Amorphous Silicon Solar Module-Sold as lot of 25

Lead-free solder is adopted to reduce environmental load.
Dimensions (PDF file) : G-EA060 / G-SA060 Dimensions (PDF file) : T-EC120 / T-SC120 T-ED120 / T-SD120 Dimensions (PDF file) : P-LE055
	- G-TYPE T-TYPE Model G-EA060 T-EC120 T-ED120 Nominal Power (W) 60.0 120.0 120.0 Open Circuit Voltage (V) 91.8 91.8 91.8 Short Circuit Current (A) 1.19 2.38 2.38 Maximum Power Voltage (V) 67.0 67.0 67.0 Maximum Power Current (A) 0.90 1.80 1.80 Maximum System Voltage (V) 530 530 530 Dimensions (mm) L960xW990xD40 L1918.8xW990xD46 L960xW1978.8xD46 Weight (kg) 13.7 27.5 27.0 Connector MC MC MC
	Model G-SA060 T-SC120 T-SD120 Nominal Power (W) 60.0 120.0 120.0 Open Circuit Voltage (V) 91.8 91.8 91.8 Short Circuit Current (A) 1.19 2.38 2.38 Maximum Power Voltage (V) 67.0 67.0 67.0 Maximum Power Current (A) 0.90 1.80 1.80 Maximum System Voltage (V) 530 530 530 UL Fire Rating Class C Class C Class C Fuse Rating (A) 7.0 7.0 7.0 Dimensions (mm) L960xW990xD40 L1918.8xW990xD46 L960xW1978.8xD46 Weight (kg) 13.7 27.5 27.0 Connector MC MC MC
	- P-TYPE Model P-LE055 Nominal Power (W) 55.0 Open Circuit Voltage (V) 23.0 Short Circuit Current (A) 4.68 Maximum Power Voltage (V) 16.5 Maximum Power Current (A) 3.33 Maximum System Voltage (V) 49 Dimensions (mm) L990xW990xD40 Weight (kg) 14.4 Connector None Junction box of P-TYPE G-TYPE, T-TYPE G-TYPE, T-TYPE PV modules wll maintain more than 80% of minimum rated power for 25 years (based on data from silicon PV modules installed over a month under conditions of 25ºC, A.M. 1.5 and 100m W/cm2) P-TYPE P-TYPE PV modules wll maintain more than 90% of minimum rated power for 10 years (based on data from silicon PV modules installed over a month under conditions of 25ºC, A.M. 1.5 and 100m W/cm2) * Data listed herewith are standard values measured using the *JIS testing method but are not guranteed values. * The PV systems's power-generating capacity is represented by the total of individual PV module power outputs calculated based on the JIS (Japanese Industrial Standards)Standards. Power output under actual usage conditions can vary depending on the level of solar radiation, installation conditions (directions, angles and ambient conditions), regional climates and temperatures. * Specifications subject to change without notice. * JIS : Japanese Industrial Standards

 Pre-packaged Systems

• Solar modules are hail-resistant and produce 100 watts DC power in full sunlight
• Solar array sizes available from 12 to 96 modules
• Systems generate 1,200 to 9,600 watts of solar power in full sunlight
• Pre-engineered rooftop mounting systems withstand up to 125 mph wind (50 lbs/ft²)
• High reliability DC-AC inverter continuously converts solar DC current into common household AC current
• Easily mounts above curved and flat tiles and asphalt shingles

Grid Tie- 7.2	Grid Tie-7.4	Part	Description
36	37	GEPV-200M	GE Energy 200 Watt Photovoltaic Module, Silver Frame, White Back Sheet, 25 Year Warranty
0	3	GE-2.5 Inverter	GE  inverter-2500 watts, 240 Vac, 60Hz (Standard 10 Year Warranty)
2	0	GE-3.0 Inverter	GE  inverter-3000 watts, 240 Vac, 60Hz (Standard 10 Year Warranty)
0	0	GE-3.3 Inverter	GE  inverter-3300 watts, 240 Vac, 60Hz (Standard 10 Year Warranty)
0	0	GE-3.8 Inverter	GE  inverter-3800 watts, 240 Vac, 60Hz (Standard 10 Year Warranty)
8	8	GE Mod5Rac	Kit for 5 GEPV-200 Modules, 2 - 204" Rails, 8 Mid-clamps, 4 End clamps, 8 L-feet
7	7	GE Splice-Clip	Splice kit (2 splice bars and mid clamps)
1	1	GEPV-M2	GE Energy Meter Duel Display (Production/Consumption)
$   73,935.16	$   78,535.39	Published Price
$   39,554.69	$   41,820.09	Price Less Discount
Grid Tie- 9.8	Grid Tie- 10.0	Part	Description
49	50	GEPV-200M	GE Energy 200 Watt Photovoltaic Module, Silver Frame, White Back Sheet, 25 Year Warranty
1	0	GE-2.5 Inverter	GE  inverter-2500 watts, 240 Vac, 60Hz (Standard 10 Year Warranty)
2	3	GE-3.0 Inverter	GE  inverter-3000 watts, 240 Vac, 60Hz (Standard 10 Year Warranty)
0	0	GE-3.3 Inverter	GE  inverter-3300 watts, 240 Vac, 60Hz (Standard 10 Year Warranty)
0	0	GE-3.8 Inverter	GE  inverter-3800 watts, 240 Vac, 60Hz (Standard 10 Year Warranty)
10	10	GE Mod5Rac	Kit for 5 GEPV-200 Modules, 2 - 204" Rails, 8 Mid-clamps, 4 End clamps, 8 L-feet
9	9	GE Splice-Clip	Splice kit (2 splice bars and mid clamps)
1	1	GEPV-M2	GE Energy Meter Duel Display (Production/Consumption)
$ 100,589.47	$ 102,529.70	Published Price
$   52,808.70	$   53,827.20	Price Less Discount

View Details	SKU   1.44KWKANTK Product Title   1.44KWTK Kaneka Solar Prepackaged/Turnkey Grid Tie System Weight (lbs)   915.00 Your Price   $9800.00 Qty 1
View Details	SKU   GEB1.8 Product Title   1.8 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System Weight (lbs)   550.00 Your Price   $11490.00 Qty 1
View Details	SKU   GEB2.6 Product Title   2.6 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System Weight (lbs)   667.00 Your Price   $15576.00 Qty 1
View Details	SKU   GEB3.0 Product Title   3.0 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System Weight (lbs)   745.00 Your Price   $17332.00 Qty 1
View Details	SKU   3.0KWKANTK Kaneka Solar Prepackaged/Turnkey Grid Tie System Product Title   3.0 KW Kaneka Solar Prepackaged/Turnkey Grid Tie System Weight (lbs)   1725.00 Your Price   $16889.00 Qty 1
View Details	SKU   GEB3.6 Product Title   3.6 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System Weight (lbs)   823.00 Your Price   $21050.00 Qty 1
View Details	SKU   GEB4.0 Product Title   4.0 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System Weight (lbs)   901.00 Your Price   $22538.74 Qty 1
View Details	SKU   GEB4.6 Product Title   4.6 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System Weight (lbs)   1019.00 Your Price   $27116.56
View Details	SKU   GEB4.8 Product Title   4.8 KW GE Energy Brilliance Prepackaged/Turnkey Grid Tie System Weight (lbs)   1097.00 Your Price   $28064.99 Qty 1

 

Changing System Parameters
If desired, the system parameters may be changed from the default values.

 

DC Rating (0.5 to 1000 kW)
The size of the PV system is the nameplate DC power rating. This is determined by summing the PV module powers listed on the nameplates on the backsides of the PV modules in units of watts and then dividing by 1000 to convert to kilowatts (kW). The PV module power ratings are for Standard Test Conditions (STC) of 1000 W/m2 solar irradiance and 25oC PV module temperature. The default PV system size is 4 kW. This corresponds to a PV array area of approximately 35 m2 (377 ft2). Caution: To achieve proper results, the DC rating input must be the nameplate DC power rating as described above, and not based on other rating conditions, such as PVUSA Test Conditions (PTC). PTC are defined as 1000 W/m2 plane-of-array irradiance, 20oC ambient temperature, and 1 m/s wind speed. PTC differs from standard test conditions (STC) in that its test conditions of ambient temperature and wind speed will result in a PV module temperature of about 50oC, instead of the 25oC for STC. Consequently, for crystalline silicon PV systems with a power degradation due to temperature of -0.5% per degree C, the PV module PTC power rating is about 88% of the PV module nameplate rating. If a user incorrectly uses a DC rating based on PTC power ratings, the energy production calculated by PVWATTS will be reduced by about 12% from the proper calculation. In essence, the effects of temperature will have been erroneously compensated for twice, first with the use of the PTC rating, and again as PVWATTS performs hour-by-hour calculations of PV module temperatures and applies temperature corrections from STC to the hourly PV energy values.
DC to AC Derate Factor
	PVWATTS multiplies the nameplate DC power rating by an overall DC to AC derate factor to determine the AC power rating at STC. The overall DC to AC derate factor accounts for losses from the DC nameplate power rating and is the mathematical product of the derate factors for the components of the PV system. A list of the default component derate factors used by PVWATTS and the ranges that might be encountered in practice are listed in the table. Derate Factors for AC Power Rating at STC Component Derate Factors PVWATTS Default Range PV module nameplate DC rating 0.95 0.80 - 1.05 Inverter and Transformer 0.92 0.88 - 0.96 Mismatch 0.98 0.97 - 0.995 Diodes and connections 0.995 0.99 - 0.997 DC wiring 0.98 0.97 - 0.99 AC wiring 0.99 0.98 - 0.993 Soiling 0.95 0.30 - 0.995 System availabilty 0.98 0.00 - 0.995 Shading 1.00 0.00 - 1.00 Sun-tracking 1.00 0.95 - 1.00 Age 1.00 0.70 - 1.00 Overall DC-to-AC derate factor 0.77   The overall DC to AC derate factor is calculated by multiplying the component derate factors.  For the PVWATTS default values: Overall DC to AC derate factor  = 0.95 x 0.92 x 0.98 x 0.995 x 0.98 x 0.99 x 0.95 x 0.98 x 1.00 x 1.00 x 1.00 = 0.77 The value of 0.77 means that the AC power rating at STC is 77% of the nameplate DC power rating. In most cases, the overall default value of 0.77 will provide a reasonable estimate for modeling the energy production. However, if so warranted, users have two options to change the overall DC to AC derate factor. The first option is to enter in the text box a new overall DC to AC derate factor. The second option is to click the Calculate Derate Factor button which provides the user with the opportunity to change any of the component derate factors in the table and then PVWATTS calculates a new overall DC to AC derate factor. Descriptions of the component derate factors are described in the following paragraphs. The derate factor for the PV module nameplate DC rating accounts for the accuracy of the manufacturer's nameplate rating. Field measurements of a representative sample of PV modules may show that the PV module powers are different than the nameplate rating or that they experienced light-induced degradation upon exposure (even crystalline silicon PV modules typically lose 2% of their initial power before power stabilizes after the first few hours of exposure to sunlight). A derate factor of 0.95 represents that testing yielded power measurements at STC that were 5% less than the manufacturer's nameplate rating. The derate factor for the inverter and transformer is their combined efficiency in converting DC power to AC power. A list of inverter efficiencies by manufacturer is at http://www.consumerenergycenter.org/cgi-bin/eligible_inverters.cgi. These inverter efficiencies include transformer related losses when a transformer is used or required by the manufacturer. The derate factor for PV module mismatch accounts for manufacturing tolerances that yield PV modules with slightly different current-voltage characteristics. Consequently, when connected together electrically they do not operate at their respective peak efficiencies. The default value of 0.98 represents a loss of 2% due to mismatch. The derate factor for diodes and connections accounts for losses from voltage drops across diodes used to block the reverse flow of current and from resistive losses in electrical connections. The derate factor for DC wiring accounts for resistive losses in the wiring between modules and the wiring connecting the PV array to the inverter. The derate factor for AC wiring accounts for resistive losses in the wiring between the inverter and the connection to the local utility service. The derate factor for soiling accounts for dirt, snow, or other foreign matter on the front surface of the PV module that reduces the amount of solar radiation reaching the solar cells of the PV module. Dirt accumulation on the PV module surface is location and weather dependent, with greater soiling losses (up to 25% for some California locations) for high-trafffic, high-pollution areas with infrequent rain. For northern locations in winter, snow will reduce the amount of energy produced, with the severity of the reduction a function of the amount of snow received and how long it remains on the PV modules. Snow remains the longest when sub-freezing temperatures prevail, small PV array tilt angles prevent snow from sliding off, the PV array is closely integrated into the roof, and the roof or other structure in the vicinity facilitates snow drifting onto the PV modules. For a roof-mounted PV system in Minnesota with a tilt angle of 23o, snow was observed to reduce the energy production during the winter by 70%; a nearby roof-mounted PV system with a tilt angle of 40o experienced a 40% reduction. The derate factor for system availability accounts for times when the system is off due to maintenance and inverter and utility outages. The default value of 0.98 represents the system being off for 2% of the year. The derate factor for shading accounts for situations when PV modules are shaded by nearby buildings, objects, or other PV modules and array structure. For the default value of 1.00, PVWATTS assumes the PV modules are not shaded. Tools such as Solar Pathfinder may be used to determine a derate factor for shading by buildings and objects. For PV arrays consisting of multiple rows of PV modules and array structure, the shading derate factor should be changed to account for losses occurring when one row shades an adjacent row. The figure below shows the shading derate factor as a function of the type of PV array (fixed or tracking); the Ground Cover Ratio (GCR), defined as the ratio of the PV array area to the total ground area; and the tilt angle for fixed PV arrays. As shown in the figure, spacing the rows further apart (smaller GCR) corresponds to a larger derate factor (smaller shading loss). For fixed PV arrays, if the tilt angle is decreased the rows may be spaced closer together (larger GCR) to achieve the same shading derate factor. For the same value of shading derate factor, land area requirements are greatest for 2-axis tracking, as indicated by its relatively low GCR values when compared with those for fixed or 1-axis tracking. If you know the GCR value for your PV array, the figure may be used to estimate the appropriate shading derate factor. Industry practice is to optimize the use of space by configuring the PV system for a GCR corresponding to a shading derate factor of 0.975 (2.5% loss). Shading Derate Factor for Multiple-Row PV Arrays as a Function of PV Array Type and Ground Cover Ratio The derate factor for sun-tracking accounts for losses for one- and two-axis tracking systems when the tracking mechanisms do not keep the PV arrays at the optimum orientation with respect to the sun's position. For the default value of 1.00, PVWATTS assumes that the PV arrays of tracking systems are always positioned at their optimum orientation and performance is not adversely affected. The derate factor for age accounts for losses in performance over time due primarily to weathering of the PV modules. The loss in performance is typically 1% per year. For the default value of 1.00, PVWATTS assumes that the PV system is in its 1st year of operation. For the 11th year of operation, a derate factor of 0.90 would be appropriate. Because the PVWATTS overall DC to AC derate factor is determined for STC, a component derate factor for temperature is not part of its determination. Power corrections for PV module operating temperature are performed for each hour of the year as PVWATTS reads the meteorological data for the location and computes the performance. A power correction of -0.5% per oC for crystalline silicon PV modules is used.
Fixed or tracking array
The PV array may either be fixed, sun-tracking with one axis of rotation, or sun-tracking with two axes of rotation. The default value is a fixed PV array.
PV array tilt angle (0° to 90°)
For a fixed PV array, the tilt angle is the angle from horizontal of the inclination of the PV array (0° = horizontal, 90° = vertical). For a sun-tracking PV array with one axis of rotation, the tilt angle is the angle from horizontal of the inclination of the tracker axis. The tilt angle is not applicable for sun-tracking PV arrays with two axes of rotation. The default value is a tilt angle equal to the station's latitude. This normally maximizes annual energy production. Increasing the tilt angle favors energy production in the winter, while decreasing the tilt angle favors energy production in the summer. For roof-mounted PV arrays, the table below gives tilt angles for various roof pitches (ratio of vertical rise to horizontal run).   Roof Pitch     Tilt Angle (°)   4/12 18.4 5/12 22.6 6/12 26.6 7/12 30.3 8/12 33.7 9/12 36.9 10/12 39.8 11/12 42.5 12/12 45.0
PV array azimuth angle (0° to 360°)
For a fixed PV array, the azimuth angle is the angle clockwise from true north of the direction that the PV array faces. For a sun-tracking PV array with one axis of rotation, the azimuth angle is the angle clockwise from true north of the direction of the axis of rotation. The azimuth angle is not applicable for sun-tracking PV arrays with two axes of rotation. The default value is an azimuth angle of 180° (south-facing) for locations in the northern hemisphere, and 0° (north-facing) for locations in the southern hemisphere. This normally maximizes energy production. For the northern hemisphere, increasing the azimuth angle favors afternoon energy production, while decreasing the azimuth angle favors morning energy production. The opposite is true for the southern hemisphere. The table below provides azimuth angles for various headings.   Heading     Azimuth Angle (°)   N 0 or 360 NE 45 E 90 SE 135 S 180 SW 225 W 270 NW 315
Electricity cost
Version 1: For the U.S. and its Territories, the default value is the average 2004 residential electric rate for the state where the station is located. Source: Energy Information Administration. For locations in regions outside the U.S., the default value is the average 2004 or 2005 residential electric rate for the country where the station is located. Sources: IEA Electricity Information 2005; IEA Energy Prices & Taxes, 4th Quarter 2005; and Eurostat Gas and Electricity Market Statistics 2005. For some countries, no electric cost information is available and the default values are set to zero. For these countries, the user should enter a value based on their knowledge. Electric costs are presented in the country's currency. To convert results to another currency, the user may go to http://www.oanda.com/converter/classic. Version 2: Default value is the average 2004 residential electric rate for the cell chosen by the user. Note that some areas are not covered by any utility provider. For these areas the electric rate for the nearest utlity service area is used. Source: Resource Data International.