Red Rocks Community College

ENY 130 Grid-tied PVFall 2009Module 1

The Sun is our Primary Energy Source – not an

Alternative !!

What is a Watt?

1 watt = 1 amp x 1 volt

Energy vs. Power?

“Watt” is Power“Watt Hour” is Energy

Energy = Power x Time

A Microwave uses 1000 watts while running, this is the Power it uses

If this microwave runs for 1 hour, it uses 1000 watt hours of Energy = 1kWh

Watts up with Photovoltaics

A PV array is sized at 1000 watts (1kW), this is the Power of the array

If this array produces energy for 5 hours it produces 5000 Whr of Energy = 5kWh

Energy Terms

1 kWh/m² = 3.412 BTU/ft² = 3.6 Mega Joules/m² = 3600 kJ/m² 1 Langley x 0.0116 1 Peak Sun Hour

Solar Constant is at outer atmosphere at 1367 W/m²

kW/m2

Surface Density of Radiant Energy

Electrical Vocabulary

Voltage Amperage Resistance Watts Watt Hours

Photovoltaic Electric Principles

Terminology: Electricity-Flow of electrons through a

circuit Volt (V)- The unit of force (electrical

pressure) that causes electrons to flow. Ampere or Amp (I)- Unit of electrical

current flowing through a wire. 1 amp for one hour is 1Ah

Watt – Unit of electrical power equal to a current of 1 ampere under the pressure of 1 volt.

Electricity is the flow of electrons: using a water analogy….

Copper wire can be thought of as a pipe Voltage can be thought of as the

water Pressure Amperage can be thought of as

volume or gallons per minute (gpm)

Terms expanded…

Watt-hour: the electrical unit of Energy Kilowatt hour-refers to 1000 watt-hours and

abbreviated as 1 kWh This could be 1 watt produced over 1000 hours or 1000 watts produced (or used) over 1 hour

1000 kW (Power) = 1megawatt = 1mW =778 households

1000 mW = 1 gigawatt = 1gW = City of San Francisco

Or 750,000 homes (but you need the area of 2400 football fields)

It takes 1.21 gigawatts to go Back to the Future.

Solar History

Everything begins with the sun

- Evidence of solar architecture goes back 2500 years to ancient Greek and Roman Architecture

- 214 B.C. Archimedes is written to have used bronze mirrors to focus sunlight on ships to set them on fire. In 1973 the US navy is to have recreated this experiment and set fire to a wooden boat 50 meters away.

Some History

Burning Mirrors

Source: Renewable Energy Fair

Myth Busters/MIT experiment

Source: MIT

Anasazi Cliff Dwellings 600 A.D. – note solar orientation (summer)

1839 - Edmond Becquerel discovers photovoltaic effect, at the age of 19, but the discovery was not useful to anyone

1873 Willoughby SmithDiscovered the effects of sunlight on selenium rods while working with telegraph cable

History continued….

1914: The existence of a barrier layer in a PV device was observed

1918: Czochrolsky developed a way to grow single-crystal silicon

1923: Albert Einstein won Nobel Peace Prize for describing theories of Photoelectric effect in 1904

Photovoltaic – The process of turning light into electricity

Solar irradiance 1927: measuring

sunlight to determine level of pollution. New York atmosphere was blocking almost ½ of the sunlight

(1931) Thomas Edison in conversation with Henry Ford and

Harvey Firestone

“We are like tenant farmers chopping down the fence around our house for fuel when we should be using Natures inexhaustible sources of energy — sun, wind and tide. … I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that.”

40’s - Bell Labs PV technology

Source: Bell Labs

50’s – Bell labs continued

Battery systems

Source: Bell Labs

Into the 60’s

Solar Cells make advancements in space technologies

The 70’s

1975: U.S. began Earthbound PV and research and development

1977: Solar Energy Research Institute (SERI) later named National Renewable Energy Laboratory (NREL) opened in Golden Colorado.

1970’s – 1st Solar Concentrator power plant

70’s continued space development

70’ – 80’s

Popular opinion attributes PV system use predominantly in the Emerald Triangle region of Northern California. These residents were engaged in agricultural pursuits that spurred PV innovation while maintaining their independence from the grid.

Late 1970’s – Federal Tax incentives give boost to solar thermal

Mid 1980’s (Reagan) end of Federal tax incentives. This greatly slows solar thermal progress as a heat source

Because of the incentives many flash-in-the-pan companies installed systems of poor quality giving solar a poor reputation

1980’s – Concentrator Solar (thermal) power plants

Kramer Junction, CA

80’s to 2000’s Inverter

technology progresses Square Wave

inverter Modified square

Wave True Sine Wave

1990’s: the grid tied inverter….

Converts Direct Current produced by PV to usable Alternating Current

2000’s – Photovoltaic (PV) Technology becomes more available and affordable

And then Building Integrated systems

2004 – Colorado Voters approve Amendment 37 to have Energy providers offer rebates for installation of PV systems

Habitat for Humanity house in Wheat Ridge:1200 sf $147,000 plus donated items4kW PV 96 sf of collectors w/ 200 ga storage tankDesigned heat load: 4.4 kWhAnnual Energy Savings : 96 MBTU (128,130 kWh)

2007 – Nevada Solar 1 concentrator power plant comes online

64 megawatts capacity300 acres134 million kWh/yearCost 266 million

Fossil Fuel Elect. Generation Plants

Are only 30-35% efficient Which does not include the mining

and transport of fuel And does not include dealing with the

toxic wastes

Solar, though seemingly expensive, is delivered freely, abundantly, has no waste byproducts AND is up to 20%

Efficient

The Future??

PV efficiencies of 20% now, can we get to 50% or even 100%? Silicon cells have a 29% theoretical maximum.

Storage of electricity…better batteries, Spinning storage?

Energy Saving lifestyles – Living Light !

Buildings that produce energy instead of using energy.

Solar Electrolysis for Hydrogen Fuel Cells

Application of Solar Energy Technology

Uses for Solar Energy Heating Air Conditioning Electricity Water Pumping Remote Power/Heat Grid Power/Heat Desalination Transportation Food cooking/Processing Space Applications All Earth Applications

Power and heat for homes

Transportation

Street Lighting

Hybrid Solar Lighting

Sunlight direct

Security Cameras

Battery Charging

Remote Power

Very Remote Power

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