grid connected battery system

8/11/2019 Grid Connected Battery System

1/34

GRID CONNECTED BATTERY SYSTEM

ABSTRACT:

In order to solve the problems which are considered to become the hindrance of

further spread of photovoltaic systems, and in order to pursue added value, we are

studying the grid-connected photovoltaic system which added the storage battery.

This time, the simulation program of the grid-connected photovoltaic system for

residences with battery was developed since it was necessary in order to propose

and optimize new systems. First, a lead-acid battery was modeled by the original

method. Next, the program which simulates the electric power flow of each part in

the system was developed.

Furthermore, as a result of an actual proof examination, since high simulation

accuracy was checked, it is reported.

INTRODUCTION

Most of the photovoltaic system for residences, which began to spread at an

increasing tempo in recent years, is a grid-connected type. Usually, since this

system has no electric storage, the difference between generated and used electric

power is processed according to the electric power flow of the distribution system.

Therefore, when this system connects to distribution system with high density, the

burden of a sudden change of irradiance or a heavy reverse power flow exceeds the

throughput of the power distribution system, and the danger that various problems

will occur is pointed out. Moreover, since it depends for generated electric power


2/34


3/34

System configuration

s

Equivalent circuit of lead-acid battery

Power conditioner model Electric power is lost with three converters shown in

Fig.1. These losses were expressed with the quadratic function of each output

power according to direction.

These 15 coefficients in 5 formulas were determined by the least-squares method

from measured data.

3. DETAILED METHOD OF BATTERY MODELING

Procedure for modeling of a lead-acid battery is described in this chapter. And

results of the battery simulations are also shown. As the battery, special long life

for cycle, 70 Ah VRLA battery [SLC70] made by Japan Storage Battery Co., Ltd.

was selected.


4/34

ELECTRIC utilities and end users of electric power are becoming increasingly

concerned about meeting the growing energy demand. Seventy five percent of total

global energy demand is supplied by the burning of fossil fuels. But increasing air

pollution, global warming concerns, diminishing fossil fuels and their increasing

cost have made it necessary to look towards renewable sources as a future energy

solution. Since the past decade, there has been an enormous interest in many

countries on renewable energy for power generation. The market liberalization and

governments incentives have further accelerated the renewable energy sector

growth Renewable energy source (RES) integrated at distribution level is termed

as distributed generation (DG). The utility is concerned due to the high penetration

level of intermittent RES in distribution systems as it may pose a threat to network

in terms of stability, voltage regulation and power-quality (PQ) issues. Therefore,

the DG systems are required to comply with strict technical and regulatory

frameworks to ensure safe, reliable and efficient operation of overall network.

With the advancement in power electronics and digital control technology, the DG

systems can now be actively controlled to enhance the system operation with

improved PQ at PCC.

However, the extensive use of power electronics based equipment and non-linear

loads at PCC generate harmonic currents, which may deteriorate the quality of

power [1], [2]. Generally, current controlled voltage source inverters are used to

interface the intermittent RES in distributed system. Recently, a few control

strategies for grid connected inverters incorporating PQ solution have been

proposed. In [3] an inverter operates as active inductor at a certain frequency to

absorb the harmonic current. But the exact calculation of network inductance in

real-time is difficult and may deteriorate the control performance. A similar


5/34

approach in which a shunt active filter acts as active conductance to damp out the

harmonics in distribution network is proposed. In, a control strategy for renewable

interfacing inverter based on theory is proposed. In this strategy both load and

inverter current sensing is required to compensate the load current harmonics. The

non-linear load current harmonics may result in voltage harmonics and can create a

serious PQ problem in the power system network. Active power filters (APF) are

extensively used to compensate the load current harmonics and load unbalance at

distribution level. This results in an additional hardware cost. However, in this

paper authors have incorporated the features of APF in the, conventional inverter

interfacing renewable with the grid, without any additional hardware cost.

Here, the main idea is the maximum utilization of inverter rating which is most of

the time underutilized due to intermittent nature of RES. It is shown in this paper

that the grid-interfacing inverter can effectively be utilized to perform following

important functions: 1) transfer of active power harvested from the renewable

resources (wind, solar, etc.); 2) load reactive power demand support; 3) current

harmonics compensation at PCC; and 4) current unbalance and neutral current

compensation in case of 3-phase 4-wire system. Moreover, with adequate control

of grid-interfacing inverter, all the four objectives can be accomplished either

individually or simultaneously. The PQ constraints at the PCC can therefore be

strictly maintained within the utility standards without additional hardware cost.


6/34

Power quality:

Power quality is the set of limits of electrical properties that allows electrical

systems to function in their intended manner without significant loss of

performance or life. The term is used to describe electric power that drives an

electrical load and the load's ability to function properly with that electric power.

Without the proper power, an electrical device (or load) may malfunction, fail

prematurely or not operate at all. There are many ways in which electric power can

be of poor quality and many more causes of such poor quality power.

The electric power industry comprises electricity generation (AC power), electricpower transmission and ultimately electricity distribution to an electricity meter

located at the premises of the end user of the electric power. The electricity then

moves through the wiring system of the end user until it reaches the load. The

complexity of the system to move electric energy from the point of production to

the point of consumption combined with variations in weather, generation, demand

and other factors provide many opportunities for the quality of supply to be

compromised.

While "power quality" is a convenient term for many, it is the quality of the

voltagerather than power or electric currentthat is actually described by the

term. Power is simply the flow of energy and the current demanded by a load is

largely uncontrollable.
http://en.wikipedia.org/wiki/Grid_%28electricity%29http://en.wikipedia.org/wiki/Grid_%28electricity%29http://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electrical_loadhttp://en.wikipedia.org/wiki/Electric_power_industryhttp://en.wikipedia.org/wiki/Electricity_generationhttp://en.wikipedia.org/wiki/AC_powerhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electricity_distributionhttp://en.wikipedia.org/wiki/Electricity_meterhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Electricity_meterhttp://en.wikipedia.org/wiki/Electricity_distributionhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/AC_powerhttp://en.wikipedia.org/wiki/Electricity_generationhttp://en.wikipedia.org/wiki/Electric_power_industryhttp://en.wikipedia.org/wiki/Electrical_loadhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Grid_%28electricity%29http://en.wikipedia.org/wiki/Grid_%28electricity%29


7/34

The quality of electrical power may be described as a set of values of parameters,

such as:

Continuity of service

Variation in voltagemagnitude

Transient voltages and currents

Harmonic content in the waveforms etc.

It is often useful to think of power quality as a compatibility problem: is the

equipment connected to the grid compatible with the events on the grid, and is the

power delivered by the grid, including the events, compatible with the equipmentthat is connected? Compatibility problems always have at least two solutions: in

this case, either clean up the power, or make the equipment tougher.

The tolerance of data-processing equipment to voltage variations is often

characterized by the CBEMA curve, which give the duration and magnitude of

voltage variations that can be tolerated.

Ideally, voltage is supplied by a utility as sinusoidal having an amplitude and

frequency given by national standards (in the case of mains) or system

specifications (in the case of a power feed not directly attached to the mains) with

animpedance of zeroohms at allfrequencies.
http://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Transient_%28oscillation%29http://en.wikipedia.org/wiki/Harmonics_%28electrical_power%29http://en.wikipedia.org/wiki/Compatibilityhttp://en.wikipedia.org/wiki/CBEMAhttp://en.wikipedia.org/wiki/Sinusoidalhttp://en.wikipedia.org/wiki/Mains_electricityhttp://en.wikipedia.org/wiki/Electrical_impedancehttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Frequencieshttp://en.wikipedia.org/wiki/Frequencieshttp://en.wikipedia.org/wiki/Ohmhttp://en.wikipedia.org/wiki/Electrical_impedancehttp://en.wikipedia.org/wiki/Mains_electricityhttp://en.wikipedia.org/wiki/Sinusoidalhttp://en.wikipedia.org/wiki/CBEMAhttp://en.wikipedia.org/wiki/Compatibilityhttp://en.wikipedia.org/wiki/Harmonics_%28electrical_power%29http://en.wikipedia.org/wiki/Transient_%28oscillation%29http://en.wikipedia.org/wiki/Amplitude


8/34

No real-life power source is ideal and generally can deviate in at least the

following ways:

Variations in thepeak orRMS voltage are both important to different types

of equipment.

When the RMS voltage exceeds the nominal voltage by 10 to 80% for 0.5

cycle to 1 minute, the event is called a "swell".

A "dip" (in British English) or a "sag" (in American English - the two terms

are equivalent) is the opposite situation: the RMS voltage is below the

nominal voltage by 10 to 90% for 0.5 cycle to 1 minute.

Random or repetitive variations in the RMS voltage between 90 and 110%

of nominal can produce a phenomenon known as "flicker" in lighting

equipment. Flicker is rapid visible changes of light level. Definition of the

characteristics of voltage fluctuations that produce objectionable light flicker

has been the subject of ongoing research.

Abrupt, very brief increases in voltage, called "spikes", "impulses", or

"surges", generally caused by largeinductive loadsbeing turned off, or more

severely bylightning.

"Undervoltage" occurs when the nominal voltage drops below 90% for more

than 1 minute. The term "brownout" is an apt description for voltage drops

somewhere between full power (bright lights) and a blackout (no power - no

light). It comes from the noticeable to significant dimming of regular

incandescent lights, during system faults or overloading etc., when

insufficient power is available to achieve full brightness in (usually)

domestic lighting. This term is in common usage has no formal definition

but is commonly used to describe a reduction in system voltage by the utility
http://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Root_mean_squarehttp://en.wikipedia.org/wiki/Root_mean_squarehttp://en.wikipedia.org/wiki/Power_line_flickerhttp://en.wikipedia.org/wiki/Voltage_spikehttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Lightninghttp://en.wikipedia.org/wiki/Lightninghttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Voltage_spikehttp://en.wikipedia.org/wiki/Power_line_flickerhttp://en.wikipedia.org/wiki/Root_mean_squarehttp://en.wikipedia.org/wiki/Root_mean_squarehttp://en.wikipedia.org/wiki/Amplitude


9/34

or system operator to decrease demand or to increase system operating

margins.

"Overvoltage"occurs when the nominal voltage rises above 110% for more

than 1 minute.

Variations in thefrequency.

Variations in the wave shape - usually described asharmonics.

Nonzero low-frequency impedance (when a load draws more power, the

voltage drops).

Nonzero high-frequency impedance (when a load demands a large amount

of current, then stops demanding it suddenly, there will be adip orspike in

the voltage due to the inductances in the power supply line).

Each of these power quality problems has a different cause. Some problems are a

result of the shared infrastructure. For example, a fault on the network may cause a

dip that will affect some customers; the higher the level of the fault, the greater the

number affected. A problem on one customers site may cause a transient that

affects all other customers on the same subsystem. Problems, such as harmonics,

arise within the customers own installation and may propagate onto the network

and affect other customers. Harmonic problems can be dealt with by a combination

of good design practice and well proven reduction equipment.

Power conditioning:

Power conditioning is modifying the power to improve its quality.

Anuninterruptible power supply can be used to switch off of mains power if there

is atransient (temporary) condition on the line. However, cheaper UPS units create

poor-quality power themselves, akin to imposing a higher-frequency and lower-
http://en.wikipedia.org/wiki/Overvoltagehttp://en.wikipedia.org/wiki/Utility_frequencyhttp://en.wikipedia.org/wiki/Harmonicshttp://en.wikipedia.org/wiki/Electrical_impedancehttp://en.wikipedia.org/wiki/Diphttp://en.wikipedia.org/wiki/Voltage_spikehttp://en.wikipedia.org/wiki/Uninterruptible_power_supplyhttp://en.wikipedia.org/wiki/Transient_%28oscillation%29http://en.wikipedia.org/wiki/Transient_%28oscillation%29http://en.wikipedia.org/wiki/Uninterruptible_power_supplyhttp://en.wikipedia.org/wiki/Voltage_spikehttp://en.wikipedia.org/wiki/Diphttp://en.wikipedia.org/wiki/Electrical_impedancehttp://en.wikipedia.org/wiki/Harmonicshttp://en.wikipedia.org/wiki/Utility_frequencyhttp://en.wikipedia.org/wiki/Overvoltage


10/34

amplitudesquare wave atop the sine wave. High-quality UPS units utilize a double

conversion topology which breaks down incoming AC power into DC, charges the

batteries, then remanufactures an AC sine wave. This remanufactured sine wave is

of higher quality than the original AC power feed.[2]

A surge protector or simple capacitor or varistor can protect against most

overvoltage conditions, while alightning arrestorprotects against severe spikes.

Electronic filters can remove harmonics.

Smart grids and power quality:

Modern systems use sensors called phasor measurement units (PMU) distributed

throughout their network to monitor power quality and in some cases respond

automatically to them. Using such smart grids features of rapid sensing and

automated self healing of anomalies in the network promises to bring higher

quality power and less downtime while simultaneously supporting power from

intermittent power sources and distributed generation,which would if unchecked

degrade power quality.

WIND ENERGY:

A somewhat hilarious misconception that some people may have is that the

only place that wind power is utilized is in Holland, where windmills have existed

for centuries. It is almost as silly that most books about wind power do not

recognize that wind power has been arguably the most important energy form man

has ever used. When discussing wind power, it is necessary to specify what kind of
http://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Square_wavehttp://en.wikipedia.org/wiki/Power_quality#cite_note-dcf_power_quality-1http://en.wikipedia.org/wiki/Power_quality#cite_note-dcf_power_quality-1http://en.wikipedia.org/wiki/Power_quality#cite_note-dcf_power_quality-1http://en.wikipedia.org/wiki/Surge_protectorhttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Varistorhttp://en.wikipedia.org/wiki/Lightning_arrestorhttp://en.wikipedia.org/wiki/Electronic_filterhttp://en.wikipedia.org/wiki/Phasor_measurement_unithttp://en.wikipedia.org/wiki/Smart_gridhttp://en.wikipedia.org/wiki/Intermittent_power_sourceshttp://en.wikipedia.org/wiki/Distributed_generationhttp://en.wikipedia.org/wiki/Distributed_generationhttp://en.wikipedia.org/wiki/Intermittent_power_sourceshttp://en.wikipedia.org/wiki/Smart_gridhttp://en.wikipedia.org/wiki/Phasor_measurement_unithttp://en.wikipedia.org/wiki/Electronic_filterhttp://en.wikipedia.org/wiki/Lightning_arrestorhttp://en.wikipedia.org/wiki/Varistorhttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Surge_protectorhttp://en.wikipedia.org/wiki/Power_quality#cite_note-dcf_power_quality-1http://en.wikipedia.org/wiki/Square_wavehttp://en.wikipedia.org/wiki/Amplitude


11/34

wind power is meant. As the fuel for transportation, fishers or other people using

boats have used the power of the wind. The United States could truthfully say that

without the power of the wind, Columbus and other European explorers might not

have found the Western world. A more exact presentation of the history of wind

power is discussed at another page devoted to showing the changes in utilization of

wind power over time. The power of the wind is everywhere, and is found in most

abundance in some areas of the world that are not extremely accessible to humans.

As a general rule, as the elevation is increased, the wind speed will also increase.

Suppose a person decided to climb to the of a two story building. Standing on top

of the building, he can feel the great increase of wind speed compared to being on

the ground. Wind power stations are often found in the same place as large radio

station antennae. Just as the high elevation helps the radio signals to travel farther,

the increase high above sea level increases the wind speed and helps the station to

produce more power. These tidbits of wind power geography are expanded at the

wind power geography page.

Wind Power as an electricity provider is popular in many places across the

world. One of the reasons that wind power is implemented across the world is the

simplicity of the physical science processes that make the conversion from

mechanical energy to electricity. The work of the wind moves the blades of the

turbine, and the kinetic energy of the wind is converted to kinetic energy in the

blades. By manipulating some basic physics equations, the energy transfered can

be found. Wind power physics tackles the science of wind machines.

One characteristic of most alternative energy forms (excluding nuclear

power), is the application for use in a home setting. Wind Power is often used on

farms and housing in rural areas where there are fewer visual housing restrictions,

and uses for wind powered devices. Many ancient civilizations used wind power

for grain processing or irrigation, and these routines are still in high demand today.


12/34

It is interesting to compare an industrial size wind power station and a home

implementation of wind power because of the number of similarities. Often the

new technologies of industrial strength wind power machines are passed directly

onto smaller systems. A page complete with diagrams of wind power systems, both

on the industrial level, and the home level are given. After learning about where

the best places are for a wind power station, you can go to some of the different

sites for wind power all over the world. This site offers a limited collection of links

to english web sites in different countries that utilize wind power.

Wind is simply air in motion. It is caused by the uneven heating of the Earths

surface by radiant energy from the sun. Since the Earths surface is made of very

different types of land and water, it absorbs the suns energy at different rates.

Water usually does not heat or cool as quickly as land because of its physical

properties. An ideal situation for the formation of local wind is an area where land

and water meet. During the day, the air above the land heats up more quickly than

the air above water. The warm air over the land expands, becomes less dense and

rises. The heavier, denser, cool air over the water flows in to take its place,

creating wind. In the same way, the atmospheric winds that circle the Earth are

created because the land near the equator is heated more by the sun than land near

the North and South Poles. Today, people use wind energy to make electricity.

Wind is called a renewable energy source because the wind will blow as long as

the sun shines.

Wind power is the conversion of wind energy into a useful form of energy, such as

using wind turbines to make electricity, windmills for mechanical power,

windpumps for water pumping or drainage, or sails to propel ships.

The total amount of economically extractable power available from the wind is

considerably more than present human power use from all sources.[3] At the end

of 2010, worldwide nameplate capacity of wind-powered generators was 197


13/34

gigawatts (GW). Wind power now has the capacity to generate 430 TWh annually,

which is about 2.5% of worldwide electricity usage. Over the past five years the

average annual growth in new installations has been 27.6 percent. Wind power

market penetration is expected to reach 3.35 percent by 2013 and 8 percent by

2018Several countries have already achieved relatively high levels of wind power

penetration, such as 21% of stationary electricity production in Denmark, 18% in

Portugal16% in Spain, 14% in Ireland and 9% in Germany in 2010As of 2011, 83

countries around the world are using wind power on a commercial basis.

A large wind farm may consist of several hundred individual wind turbines which

are connected to the electric power transmission network. Offshore wind power

can harness the better wind speeds that are available offshore compared to on land,

so offshore wind powers contribution in terms of electricity supplied is higher.

Small onshore wind facilities are used to provide electricity to isolated locations

and utility companies increasingly buy back surplus electricity produced by small

domestic wind turbines. Although a variable source of power, the intermittency of

wind seldom creates problems when using wind power to supply up to 20% of total

electricity demand, but as the proportion rises, increased costs, a need to use

storage such as pumped-storage hydroelectricity, upgrade the grid, or a lowered

ability to supplant conventional production may occur. Power management

techniques such as excess capacity, storage, dispatchable backing supply (usually

natural gas), exporting and importing power to neighboring areas or reducing

demand when wind production is low, can mitigate these problems.

Wind power, as an alternative to fossil fuels, is plentiful, renewable, widely

distributed, clean, produces no greenhouse gas emissions during operation, and

uses little land. In operation, the overall cost per unit of energy produced is similar

to the cost for new coal and natural gas installations.[14] The construction of wind


14/34

farms is not universally welcomed, but any effects on the environment from wind

power are generally much less problematic than those of any other power source

Wind Power

Grid Interconnection:

Overview for the Massachusetts Wind Working Group

SOLAR ENERGY:

In today's climate of growing energy needs and increasing environmental

concern, alternatives to the use of non-renewable and polluting fossil fuels have to

be investigated. One such alternative is solar energy.

Solar energy is quite simply the energy produced directly by the sun and

collected elsewhere, normally the Earth. The sun creates its energy through a


15/34

thermonuclear process that converts about 650,000,0001tons of hydrogen to

helium every second. The process creates heat and electromagnetic radiation. The

heat remains in the sun and is instrumental in maintaining the thermonuclear

reaction. The electromagnetic radiation (including visible light, infra-red light, and

ultra-violet radiation) streams out into space in all directions.

Every day, the sun radiates (sends out) an enormous amount of energy

called solar energy. It radiates more energy in one second than the world has used

since time began. This energy comes from within the sun itself. Like most stars,

the sun is a big gas ball made up mostly of hydrogen and helium gas. The sun

makes energy in its inner core in a process called nuclear fusion.It takes the suns

energy just a little over eight minutes to travel the 93 million miles to Earth. Solar

energy travels at a speed of 186,000 miles per second, the speed of light. Only a

small part of the radiant energy that the sun emits into space ever reaches the

Earth, but that is more than enough to supply all our energy needs. Every day

enough solar energy reaches the Earth to supply our nations energy needs for a

year! Solar energy is considered a renewable energy source.Today, people use

solar energy to heat buildings and water and to generate electricity

Only a very small fraction of the total radiation produced reaches the Earth.

The radiation that does reach the Earth is the indirect source of nearly every type of

energy used today. The exceptions are geothermal energy, and nuclear fission and

fusion. Even fossil fuels owe their origins to the sun; they were once living plants

and animals whose life was dependent upon the sun.

Much of the world's required energy can be supplied directly by solar power.

More still can be provided indirectly. The practicality of doing so will be
http://www.ccs.neu.edu/home/feneric/solar.html#Asimov1http://www.ccs.neu.edu/home/feneric/solar.html#Asimov1http://www.ccs.neu.edu/home/feneric/solar.html#Asimov1


16/34

examined, as well as the benefits and drawbacks. In addition, the uses solar energy

is currently applied to will be noted.

Due to the nature of solar energy, two components are required to have a

functional solar energy generator. These two components are a collector and a

storage unit. The collector simply collects the radiation that falls on it and converts

a fraction of it to other forms of energy (either electricity and heat or heat alone).

The storage unit is required because of the non-constant nature of solar energy; at

certain times only a very small amount of radiation will be received. At night or

during heavy cloud cover, for example, the amount of energy produced by the

collector will be quite small. The storage unit can hold the excess energy produced

during the periods of maximum productivity, and release it when the productivity

drops. In practice, a backup power supply is usually added, too, for the situations

when the amount of energy required is greater than both what is being produced

and what is stored in the container.

Methods of collecting and storing solar energy vary depending on the uses

planned for the solar generator. In general, there are three types of collectors and

many forms of storage units.

The three types of collectors are flat-plate collectors, focusing collectors,

and passive collectors.

Flat-plate collectors are the more commonly used type of collector today.

They are arrays of solar panels arranged in a simple plane. They can be of nearly

any size, and have an output that is directly related to a few variables including

size, facing, and cleanliness. These variables all affect the amount of radiation that

falls on the collector. Often these collector panels have automated machinery that

keeps them facing the sun. The additional energy they take in due to the correction


17/34

of facing more than compensates for the energy needed to drive the extra

machinery.

Focusing collectors are essentially flat-plane collectors with optical devices

arranged to maximize the radiation falling on the focus of the collector. These are

currently used only in a few scattered areas. Solar furnaces are examples of this

type of collector. Although they can produce far greater amounts of energy at a

single point than the flat-plane collectors can, they lose some of the radiation that

the flat-plane panels do not. Radiation reflected off the ground will be used by flat-

plane panels but usually will be ignored by focusing collectors (in snow covered

regions, this reflected radiation can be significant). One other problem with

focusing collectors in general is due to temperature. The fragile silicon components

that absorb the incoming radiation lose efficiency at high temperatures, and if they

get too hot they can even be permanently damaged. The focusing collectors by

their very nature can create much higher temperatures and need more safeguards to

protect their silicon components.

Passive collectors are completely different from the other two types of

collectors. The passive collectors absorb radiation and convert it to heat naturally,

without being designed and built to do so. All objects have this property to some

extent, but only some objects (like walls) will be able to produce enough heat to

make it worthwhile. Often their natural ability to convert radiation to heat is

enhanced in some way or another (by being painted black, for example) and a

system for transferring the heat to a different location is generally added.

People use energy for many things, but a few general tasks consume most of the

energy. These tasks include transportation, heating, cooling, and the generation of

electricity. Solar energy can be applied to all four of these tasks with different

levels of success.


18/34

Heating is the business for which solar energy is best suited. Solar heating

requires almost no energy transformation, so it has a very high efficiency. Heat

energy can be stored in a liquid, such as water, or in a packed bed. A packed bed is

a container filled with small objects that can hold heat (such as stones) with air

space between them. Heat energy is also often stored in phase-changer or heat-of-

fusion units. These devices will utilize a chemical that changes phase from solid to

liquid at a temperature that can be produced by the solar collector. The energy of

the collector is used to change the chemical to its liquid phase, and is as a result

stored in the chemical itself. It can be tapped later by allowing the chemical to

revert to its solid form. Solar energy is frequently used in residential homes to heat

water. This is an easy application, as the desired end result (hot water) is the

storage facility. A hot water tank is filled with hot water during the day, and

drained as needed. This application is a very simple adjustment from the normal

fossil fuel water heaters.

Swimming pools are often heated by solar power. Sometimes the pool itself

functions as the storage unit, and sometimes a packed bed is added to store the

heat. Whether or not a packed bed is used, some method of keeping the pool's heat

for longer than normal periods (like a cover) is generally employed to help keep

the water at a warm temperature when it is not in use.

Solar energy is often used to directly heat a house or building. Heating a

building requires much more energy than heating a building's water, so much

larger panels are necessary. Generally a building that is heated by solar power will

have its water heated by solar power as well. The type of storage facility most

often used for such large solar heaters is the heat-of-fusion storage unit, but other

kinds (such as the packed bed or hot water tank) can be used as well. This

application of solar power is less common than the two mentioned above, because


19/34

of the cost of the large panels and storage system required to make it work. Often if

an entire building is heated by solar power, passive collectors are used in addition

to one of the other two types. Passive collectors will generally be an integral part

of the building itself, so buildings taking advantage of passive collectors must be

created with solar heating in mind.

These passive collectors can take a few different forms. The most basic type

is the incidental heat trap. The idea behind the heat trap is fairly simple. Allow the

maximum amount of light possible inside through a window (The window should

be facing towards the equator for this to be achieved) and allow it to fall on a floor

made of stone or another heat holding material. During the day, the area will stay

cool as the floor absorbs most of the heat, and at night, the area will stay warm as

the stone re-emits the heat it absorbed during the day.

Another major form of passive collector is thermos phoning walls and/or

roof. With this passive collector, the heat normally absorbed and wasted in the

walls and roof is re-routed into the area that needs to be heated.

The last major form of passive collector is the solar pond. This is very

similar to the solar heated pool described above, but the emphasis is different. With

swimming pools, the desired result is a warm pool. With the solar pond, the whole

purpose of the pond is to serve as an energy regulator for a building. The pond is

placed either adjacent to or on the building, and it will absorb solar energy and

convert it to heat during the day. This heat can be taken into the building, or if thebuilding has more than enough heat already, heat can be dumped from the building

into the pond.


20/34

Solar energy can be used for other things besides heating. It may seem

strange, but one of the most common uses of solar energy today is cooling. Solar

cooling is far more expensive than solar heating, so it is almost never seen in

private homes. Solar energy is used to cool things by phase changing a liquid to

gas through heat, and then forcing the gas into a lower pressure chamber. The

temperature of a gas is related to the pressure containing it, and all other things

being held equal, the same gas under a lower pressure will have a lower

temperature. This cool gas will be used to absorb heat from the area of interest and

then be forced into a region of higher pressure where the excess heat will be lost to

the outside world. The net effect is that of a pump moving heat from one area into

another, and the first is accordingly cooled.

Besides being used for heating and cooling, solar energy can be directly

converted to electricity. Most of our tools are designed to be driven by electricity,

so if you can create electricity through solar power, you can run almost anything

with solar power. The solar collectors that convert radiation into electricity can be

either flat-plane collectors or focusing collectors, and the silicon components of

these collectors are photovoltaic cells.

Photovoltaic cells, by their very nature, convert radiation to electricity. This

phenomenon has been known for well over half a century, but until recently the

amounts of electricity generated were good for little more than measuring radiation

intensity. Most of the photovoltaic cells on the market today operate at an

efficiency of less than 15%2;that is, of all the radiation that falls upon them, less

than 15% of it is converted to electricity. The maximum theoretical efficiency for a

photovoltaic cell is only 32.3%3, but at this efficiency, solar electricity is very

economical. Most of our other forms of electricity generation are at a lower

efficiency than this. Unfortunately, reality still lags behind theory and a 15%
http://www.ccs.neu.edu/home/feneric/solar.html#Moore1http://www.ccs.neu.edu/home/feneric/solar.html#Moore1http://www.ccs.neu.edu/home/feneric/solar.html#Moore2http://www.ccs.neu.edu/home/feneric/solar.html#Moore2http://www.ccs.neu.edu/home/feneric/solar.html#Moore2http://www.ccs.neu.edu/home/feneric/solar.html#Moore1


21/34

efficiency is not usually considered economical by most power companies, even if

it is fine for toys and pocket calculators. Hope for bulk solar electricity should not

be abandoned, however, for recent scientific advances have created a solar cell

with an efficiency of 28.2%4

efficiency in the laboratory. This type of cell has yet

to be field tested. If it maintains its efficiency in the uncontrolled environment of

the outside world, and if it does not have a tendency to break down, it will be

economical for power companies to build solar power facilities after all.

Of the main types of energy usage, the least suited to solar power is transportation.

While large, relatively slow vehicles like ships could power themselves with large

onboard solar panels, small constantly turning vehicles like cars could not. The

only possible way a car could be completely solar powered would be through the

use of battery that was charged by solar power at some stationary point and then

later loaded into the car. Electric cars that are partially powered by solar energy are

available now, but it is unlikely that solar power will provide the world's

transportation costs in the near future.

Solar power has two big advantages over fossil fuels. The first is in the fact

that it is renewable; it is never going to run out. The second is its effect on the

environment.

While the burning of fossil fuels introduces many harmful pollutants into the

atmosphere and contributes to environmental problems like global warming and

acid rain, solar energy is completely non-polluting. While many acres of land mustbe destroyed to feed a fossil fuel energy plant its required fuel, the only land that

must be destroyed for a solar energy plant is the land that it stands on. Indeed, if a

solar energy system were incorporated into every business and dwelling, no land
http://www.ccs.neu.edu/home/feneric/solar.html#Moore3http://www.ccs.neu.edu/home/feneric/solar.html#Moore3http://www.ccs.neu.edu/home/feneric/solar.html#Moore3


22/34

would have to be destroyed in the name of energy. This ability to decentralize solar

energy is something that fossil fuel burning cannot match.

As the primary element of construction of solar panels, silicon, is the second

most common element on the planet, there is very little environmental disturbance

caused by the creation of solar panels. In fact, solar energy only causes

environmental disruption if it is centralized and produced on a gigantic scale. Solar

power certainly can be produced on a gigantic scale, too.

Among the renewable resources, only in solar power do we find the potential

for an energy source capable of supplying more energy than is used.5

Suppose that of the 4.5x1017kWh per annum that is used by the earth to evaporate

water from the oceans we were to acquire just 0.1% or 4.5x1014kWh per annum.

Dividing by the hours in the year gives a continuous yield of 2.90x1010kW. This

would supply 2.4 kW to 12.1 billion people.6This translates to roughly the amount

of energy used today by the average American available to over twelve billion

people. Since this is greater than the estimated carrying capacity of the Earth, thiswould be enough energy to supply the entire planet regardless of the population.

Unfortunately, at this scale, the production of solar energy would have some

unpredictable negative environmental effects. If all the solar collectors were placed

in one or just a few areas, they would probably have large effects on the local

environment, and possibly have large effects on the world environment.

Everything from changes in local rain conditions to another Ice Age has been

predicted as a result of producing solar energy on this scale. The problem lies in

the change of temperature and humidity near a solar panel; if the energy producing

panels are kept non-centralized, they should not create the same local, mass

temperature change that could have such bad effects on the environment.
http://www.ccs.neu.edu/home/feneric/solar.html#Kuecken1http://www.ccs.neu.edu/home/feneric/solar.html#Kuecken1http://www.ccs.neu.edu/home/feneric/solar.html#Kuecken1http://www.ccs.neu.edu/home/feneric/solar.html#Kuecken2http://www.ccs.neu.edu/home/feneric/solar.html#Kuecken2http://www.ccs.neu.edu/home/feneric/solar.html#Kuecken2http://www.ccs.neu.edu/home/feneric/solar.html#Kuecken2http://www.ccs.neu.edu/home/feneric/solar.html#Kuecken1


23/34

Of all the energy sources available, solar has perhaps the most promise.

Numerically, it is capable of producing the raw power required to satisfy the entire

planet's energy needs. Environmentally, it is one of the least destructive of all the

sources of energy. Practically, it can be adjusted to power nearly everything except

transportation with very little adjustment, and even transportation with some

modest modifications to the current general system of travel. Clearly, solar energy

is a resource of the future.

Solar energy, radiant light and heat from the sun,has been harnessed by humans

since ancient times using a range of ever-evolving technologies. Solar energy

technologies include solar heating, solar photo voltaics, solar thermal electricity

andsolar architecture,which can make considerable contributions to solving some

of the most urgent problems the world now faces.

Solar technologies are broadly characterized as eitherpassive solar oractive solar

depending on the way they capture, convert and distribute solar energy. Active

solar techniques include the use of photovoltaic panels andsolar thermal collectors

to harness the energy. Passive solar techniques include orienting a building to the

Sun, selecting materials with favorablethermal mass or light dispersing properties,

and designing spaces thatnaturally circulate air.

In 2011, theInternational Energy Agency said that "the development of affordable,

inexhaustible and clean solar energy technologies will have huge longer-term

benefits. It will increase countries energy security through reliance on anindigenous, inexhaustible and mostly import-independent resource, enhance

sustainability,reduce pollution, lower the costs of mitigating climate change,and

keep fossil fuel prices lower than otherwise. These advantages are global. Hence
http://en.wikipedia.org/wiki/Lighthttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Sunhttp://en.wikipedia.org/wiki/Ancient_historyhttp://en.wikipedia.org/wiki/Solar_heatinghttp://en.wikipedia.org/wiki/Solar_photovoltaicshttp://en.wikipedia.org/wiki/Solar_thermal_electricityhttp://en.wikipedia.org/wiki/Solar_architecturehttp://en.wikipedia.org/wiki/Passive_solarhttp://en.wikipedia.org/wiki/Active_solarhttp://en.wikipedia.org/wiki/Solar_thermal_energyhttp://en.wikipedia.org/wiki/Thermal_masshttp://en.wikipedia.org/wiki/Ventilation_%28architecture%29http://en.wikipedia.org/wiki/International_Energy_Agencyhttp://en.wikipedia.org/wiki/Sustainabilityhttp://en.wikipedia.org/wiki/Climate_changehttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Climate_changehttp://en.wikipedia.org/wiki/Sustainabilityhttp://en.wikipedia.org/wiki/International_Energy_Agencyhttp://en.wikipedia.org/wiki/Ventilation_%28architecture%29http://en.wikipedia.org/wiki/Thermal_masshttp://en.wikipedia.org/wiki/Solar_thermal_energyhttp://en.wikipedia.org/wiki/Active_solarhttp://en.wikipedia.org/wiki/Passive_solarhttp://en.wikipedia.org/wiki/Solar_architecturehttp://en.wikipedia.org/wiki/Solar_thermal_electricityhttp://en.wikipedia.org/wiki/Solar_photovoltaicshttp://en.wikipedia.org/wiki/Solar_heatinghttp://en.wikipedia.org/wiki/Ancient_historyhttp://en.wikipedia.org/wiki/Sunhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Light


24/34

the additional costs of the incentives for early deployment should be considered

learning investments; they must be wisely spent and need to be widely shared".

The Earth receives 174petawatts (PW) of incoming solar radiation (insolation) at

the upperatmosphere.Approximately 30% is reflected back to space while the rest

is absorbed by clouds, oceans and land masses. The spectrum of solar light at the

Earth's surface is mostly spread across the visible and near-infrared ranges with a

small part in thenear-ultraviolet.

Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises

their temperature. Warm air containing evaporated water from the oceans rises,

causing atmospheric circulation or convection. When the air reaches a high

altitude, where the temperature is low, water vapor condenses into clouds, which

rain onto the Earth's surface, completing the water cycle.Thelatent heat of water

condensation amplifies convection, producing atmospheric phenomena such aswind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land

masses keeps the surface at an average temperature of 14 C. By photosynthesis

green plants convert solar energy into chemical energy, which produces food,

wood and thebiomass from which fossil fuels are derived.
http://en.wikipedia.org/wiki/Orders_of_magnitude_%28power%29#petawatt_.281015_watts.29http://en.wikipedia.org/wiki/Insolationhttp://en.wikipedia.org/wiki/Earth%27s_atmospherehttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Visible_lighthttp://en.wikipedia.org/wiki/Near-infraredhttp://en.wikipedia.org/wiki/Near-ultraviolethttp://en.wikipedia.org/wiki/Oceanhttp://en.wikipedia.org/wiki/Atmospheric_circulationhttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Water_cyclehttp://en.wikipedia.org/wiki/Latent_heathttp://en.wikipedia.org/wiki/Windhttp://en.wikipedia.org/wiki/Cyclonehttp://en.wikipedia.org/wiki/Anti-cyclonehttp://en.wikipedia.org/wiki/Photosynthesishttp://en.wikipedia.org/wiki/Chemical_energyhttp://en.wikipedia.org/wiki/Biomasshttp://en.wikipedia.org/wiki/Biomasshttp://en.wikipedia.org/wiki/Chemical_energyhttp://en.wikipedia.org/wiki/Photosynthesishttp://en.wikipedia.org/wiki/Anti-cyclonehttp://en.wikipedia.org/wiki/Cyclonehttp://en.wikipedia.org/wiki/Windhttp://en.wikipedia.org/wiki/Latent_heathttp://en.wikipedia.org/wiki/Water_cyclehttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Atmospheric_circulationhttp://en.wikipedia.org/wiki/Oceanhttp://en.wikipedia.org/wiki/Near-ultraviolethttp://en.wikipedia.org/wiki/Near-infraredhttp://en.wikipedia.org/wiki/Visible_lighthttp://en.wikipedia.org/wiki/Electromagnetic_spectrumhttp://en.wikipedia.org/wiki/Earth%27s_atmospherehttp://en.wikipedia.org/wiki/Insolationhttp://en.wikipedia.org/wiki/Orders_of_magnitude_%28power%29#petawatt_.281015_watts.29


25/34

The total solar energy absorbed by Earth's atmosphere, oceans and land masses is

approximately 3,850,000exajoules (EJ) per year. In 2002, this was more energy in

one hour than the world used in one year. Photosynthesis captures approximately3,000 EJ per year in biomass. The amount of solar energy reaching the surface of

the planet is so vast that in one year it is about twice as much as will ever be

obtained from all of the Earth's non-renewable resources of coal, oil, natural gas,

and mined uranium combined.

Applications of solar technology :

Solar energy can be harnessed in different levels around the world. Depending on a

geographical location the closer to the equator the more "potential" solar energy is

available.

Solar energy refers primarily to the use of solar radiation for practical ends.

However, all renewable energies, other than geothermal and tidal, derive their

energy from the sun.

Solar technologies are broadly characterized as either passive or active depending

on the way they capture, convert and distribute sunlight. Active solar techniques

use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs.
http://en.wikipedia.org/wiki/Joule#Multipleshttp://en.wikipedia.org/wiki/Solar_radiationhttp://en.wikipedia.org/wiki/Geothermal_powerhttp://en.wikipedia.org/wiki/Tidal_powerhttp://en.wikipedia.org/wiki/Tidal_powerhttp://en.wikipedia.org/wiki/Geothermal_powerhttp://en.wikipedia.org/wiki/Solar_radiationhttp://en.wikipedia.org/wiki/Joule#Multiples


26/34

Passive solar techniques include selecting materials with favorable thermal

properties, designing spaces that naturally circulate air, and referencing the

position of a building to the Sun. Active solar technologies increase the supply of

energy and are considered supply side technologies, while passive solar

technologies reduce the need for alternate resources and are generally considered

demand side technologies.

Solar power:

Solar power is the conversion of sunlight into electricity, either directly using

photovoltaics (PV), or indirectly using concentrated solar power (CSP). CSPsystems use lenses or mirrors and tracking systems to focus a large area of sunlight

into a small beam. PV converts light into electric current using the photoelectric

effect.

Commercial CSP plants were first developed in the 1980s, and the 354 MWSEGS

CSP installation is the largest solar power plant in the world and is located in the

Mojave Desert of California. Other large CSP plants include the Solnova Solar

Power Station (150 MW) and the Andasol solar power station (100 MW), both in

Spain. The 97 MW Sarnia Photovoltaic Power Plant in Canada, is the worlds

largestphotovoltaic plan

Photovoltaics:

A solar cell,or photovoltaic cell (PV), is a device that converts light into electric

current using the photoelectric effect. The first solar cell was constructed by

Charles Fritts in the 1880s. In 1931 a German engineer, Dr Bruno Lange,

developed a photo cell using silver selenide in place of copper oxide. Although the

prototype selenium cells converted less than 1% of incident light into electricity,
http://en.wikipedia.org/wiki/Supply_sidehttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Photovoltaicshttp://en.wikipedia.org/wiki/Concentrated_solar_powerhttp://en.wikipedia.org/wiki/Photoelectric_effecthttp://en.wikipedia.org/wiki/Photoelectric_effecthttp://en.wikipedia.org/wiki/SEGShttp://en.wikipedia.org/wiki/Solnova_Solar_Power_Stationhttp://en.wikipedia.org/wiki/Solnova_Solar_Power_Stationhttp://en.wikipedia.org/wiki/Andasol_solar_power_stationhttp://en.wikipedia.org/wiki/Sarnia_Photovoltaic_Power_Planthttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/List_of_photovoltaic_power_stationshttp://en.wikipedia.org/wiki/List_of_photovoltaic_power_stationshttp://en.wikipedia.org/wiki/Photovoltaic_planthttp://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Photoelectric_effecthttp://en.wikipedia.org/wiki/Charles_Frittshttp://en.wikipedia.org/wiki/Seleniumhttp://en.wikipedia.org/wiki/Seleniumhttp://en.wikipedia.org/wiki/Charles_Frittshttp://en.wikipedia.org/wiki/Photoelectric_effecthttp://en.wikipedia.org/wiki/Solar_cellhttp://en.wikipedia.org/wiki/Photovoltaic_planthttp://en.wikipedia.org/wiki/List_of_photovoltaic_power_stationshttp://en.wikipedia.org/wiki/List_of_photovoltaic_power_stationshttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/Sarnia_Photovoltaic_Power_Planthttp://en.wikipedia.org/wiki/Andasol_solar_power_stationhttp://en.wikipedia.org/wiki/Solnova_Solar_Power_Stationhttp://en.wikipedia.org/wiki/Solnova_Solar_Power_Stationhttp://en.wikipedia.org/wiki/SEGShttp://en.wikipedia.org/wiki/Photoelectric_effecthttp://en.wikipedia.org/wiki/Photoelectric_effecthttp://en.wikipedia.org/wiki/Concentrated_solar_powerhttp://en.wikipedia.org/wiki/Photovoltaicshttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Supply_side


27/34

both Ernst Werner von Siemens and James Clerk Maxwell recognized the

importance of this discovery. Following the work of Russell Ohl in the 1940s,

researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the silicon

solar cell in 1954. These early solar cells cost 286 USD/watt and reached

efficiencies of 4.56%

Energy storage methods:

Solar energy is not available at night, and energy storage is an important issue

because modern energy systems usually assume continuous availability of energy.

Thermal mass systems can store solar energy in the form of heat at domestically

useful temperatures for daily or seasonal durations. Thermal storage systems

generally use readily available materials with high specific heat capacities such as

water, earth and stone. Well-designed systems can lowerpeak demand,shift time-

of-use tooff-peak hours and reduce overall heating and cooling requirements.

Phase change materials such asparaffin wax andGlauber's salt are another thermal

storage media. These materials are inexpensive, readily available, and can deliver

domestically useful temperatures (approximately 64 C). The "Dover House" (in

Dover, Massachusetts)was the first to use a Glauber's salt heating system, in 1948.
http://en.wikipedia.org/wiki/Ernst_Werner_von_Siemenshttp://en.wikipedia.org/wiki/James_Clerk_Maxwellhttp://en.wikipedia.org/wiki/Russell_Ohlhttp://en.wikipedia.org/wiki/Calvin_Fullerhttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Seasonal_thermal_storehttp://en.wikipedia.org/wiki/Specific_heathttp://en.wikipedia.org/wiki/Peak_demandhttp://en.wiktionary.org/wiki/off-peakhttp://en.wikipedia.org/wiki/Paraffin_waxhttp://en.wikipedia.org/wiki/Sodium_sulfate#Thermal_storagehttp://en.wikipedia.org/wiki/Dover,_Massachusettshttp://en.wikipedia.org/wiki/Dover,_Massachusettshttp://en.wikipedia.org/wiki/Sodium_sulfate#Thermal_storagehttp://en.wikipedia.org/wiki/Paraffin_waxhttp://en.wiktionary.org/wiki/off-peakhttp://en.wikipedia.org/wiki/Peak_demandhttp://en.wikipedia.org/wiki/Specific_heathttp://en.wikipedia.org/wiki/Seasonal_thermal_storehttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Calvin_Fullerhttp://en.wikipedia.org/wiki/Russell_Ohlhttp://en.wikipedia.org/wiki/James_Clerk_Maxwellhttp://en.wikipedia.org/wiki/Ernst_Werner_von_Siemens


28/34

Solar energy can be stored at high temperatures using molten salts. Salts are an

effective storage medium because they are low-cost, have a high specific heat

capacity and can deliver heat at temperatures compatible with conventional power

systems. The Solar Two used this method of energy storage, allowing it to store

1.44TJ in its 68m3storage tank with an annual storage efficiency of about 99%.

Off-grid PV systems have traditionally used rechargeable batteries to store excess

electricity. With grid-tied systems, excess electricity can be sent to the

transmission grid,while standard grid electricity can be used to meet shortfalls.

Net metering programs give household systems a credit for any electricity they

deliver to the grid. This is often legally handled by 'rolling back' the meter

whenever the home produces more electricity than it consumes. If the net

electricity use is below zero, the utility is required to pay for the extra at the same

rate as they charge consumers. Other legal approaches involve the use of two

meters, to measure electricity consumed vs. electricity produced. This is less

common due to the increased installation cost of the second meter.

Pumped-storage hydroelectricity stores energy in the form of water pumped when

energy is available from a lower elevation reservoir to a higher elevation one. The

energy is recovered when demand is high by releasing the water to run through a

hydroelectric power generator

Point of common coupling:
http://en.wikipedia.org/wiki/Molten_salthttp://en.wikipedia.org/wiki/The_Solar_Project#Solar_Twohttp://en.wikipedia.org/wiki/Joule#Multipleshttp://en.wikipedia.org/wiki/Cubic_metrehttp://en.wikipedia.org/wiki/Cubic_metrehttp://en.wikipedia.org/wiki/Cubic_metrehttp://en.wikipedia.org/wiki/Rechargeable_batterieshttp://en.wikipedia.org/wiki/Grid-tied_electrical_systemhttp://en.wikipedia.org/wiki/Net_meteringhttp://en.wikipedia.org/wiki/Pumped-storage_hydroelectricityhttp://en.wikipedia.org/wiki/Pumped-storage_hydroelectricityhttp://en.wikipedia.org/wiki/Net_meteringhttp://en.wikipedia.org/wiki/Grid-tied_electrical_systemhttp://en.wikipedia.org/wiki/Rechargeable_batterieshttp://en.wikipedia.org/wiki/Cubic_metrehttp://en.wikipedia.org/wiki/Joule#Multipleshttp://en.wikipedia.org/wiki/The_Solar_Project#Solar_Twohttp://en.wikipedia.org/wiki/Molten_salt


29/34

Definition

A point of metering, or any point as long as both the utility and the

consumer can either access the point for direct measurement of the harmonic

indices meaningful to both or can estimate the harmonic indices at point of

interference (POI) through mutually agreeable methods. Within an industrial

plant, the PCC is the point between the nonlinear load and other loads.

The point in the electrical system where the ownership changes from the

electric utility to the customer.

The location on the systemwhere another customer can be served.

Lets now compare old with new for a few applications:

Missing metering point

Low-side vs. high-side


30/34

Inside industrial plant

Transmission VAR source

Missing Metering Point:

PCC on the high side:


31/34

PCC on low side:

Industrial Plant:


32/34

Within an industrial plant, the PCC is the point between the nonlinear load

and other loads.

SVC with MSCs and TSCs (or TCRs):

Specifying voltage limits is fine.

Specifying current limits doesnt work.

Depending on the location, your voltage harmonic limits might be

different (more restrictive) than IEEE 519.

Need to study in more detail.

A simple tool for harmonic screening:

Electrical Pollution screening tool

Developed for industry by Auburn University with funding from

PacifiCorp.


33/34

Does motor starts, flicker, and harmonics

Can handle multiple PCCs

Inexpensive

Standards based

LOAD CURRENT HORMOICS:

Harmonics are electric voltages and currents that appear on the electric

power system as a result of certain kinds of electric loads.Harmonic frequencies in

the power grid are a frequent cause ofpower qualityproblems.

In a normal alternating current power system, the voltage varies sinusoidally at a

specific frequency, usually 50 or 60 hertz. When a linear electrical load is

connected to the system, it draws a sinusoidal current at the same frequency as the

voltage (though usually not inphase with the voltage).

When a non-linear load, such as arectifier,is connected to the system, it draws a

current that is not necessarily sinusoidal. The current waveform can become quite

complex, depending on the type of load and its interaction with other components

of the system. Regardless of how complex the current waveform becomes, as

described through Fourier series analysis, it is possible to decompose it into a

series of simple sinusoids, which start at the power system fundamental frequency

and occur at integer multiples of the fundamental frequency.
http://en.wikipedia.org/wiki/Electrical_power_industryhttp://en.wikipedia.org/wiki/Electrical_power_industryhttp://en.wikipedia.org/wiki/Harmonichttp://en.wikipedia.org/wiki/Power_qualityhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Sine_wavehttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/Linearhttp://en.wikipedia.org/wiki/Phase_%28waves%29http://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Fourier_serieshttp://en.wikipedia.org/wiki/Fundamental_frequencyhttp://en.wikipedia.org/wiki/Fundamental_frequencyhttp://en.wikipedia.org/wiki/Fourier_serieshttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Phase_%28waves%29http://en.wikipedia.org/wiki/Linearhttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/Sine_wavehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Power_qualityhttp://en.wikipedia.org/wiki/Harmonichttp://en.wikipedia.org/wiki/Electrical_power_industryhttp://en.wikipedia.org/wiki/Electrical_power_industry


34/34

Further examples of non-linear loads include common office equipment such as

computers and printers, and alsoadjustable speed drives.

One of the major effects of power system harmonics is to increase the current in

the system. This is particularly the case for the third harmonic, which causes a

sharp increase in the zero sequence current, and therefore increases the current in

theneutral conductor. This effect can require special consideration in the design of

an electric system to serve non-linear loads.[1]

In addition to the increased line current, different pieces of electrical equipment

can suffer effects from harmonics on the power system.
http://en.wikipedia.org/wiki/Adjustable-speed_drivehttp://en.wikipedia.org/wiki/Power_system_harmonicshttp://en.wikipedia.org/w/index.php?title=Zero_sequence&action=edit&redlink=1http://en.wikipedia.org/wiki/Ground_and_neutralhttp://en.wikipedia.org/wiki/Harmonics_%28electrical_power%29#cite_note-0http://en.wikipedia.org/wiki/Harmonics_%28electrical_power%29#cite_note-0http://en.wikipedia.org/wiki/Harmonics_%28electrical_power%29#cite_note-0http://en.wikipedia.org/wiki/Harmonics_%28electrical_power%29#cite_note-0http://en.wikipedia.org/wiki/Ground_and_neutralhttp://en.wikipedia.org/w/index.php?title=Zero_sequence&action=edit&redlink=1http://en.wikipedia.org/wiki/Power_system_harmonicshttp://en.wikipedia.org/wiki/Adjustable-speed_drive

grid connected battery system

Documents