solar 101-pv - na u · slide 2 solarcity confidential what is solar energy? solar energy is energy...

SolarCity CONFIDENTIAL

Solar 101-PVPresented by:

James D. Beard


What is Solar Energy?

Solar Energy is energy radiated from the sun, mainly in the

form of heat and light

It is required for photosynthesis and is also harnessed as a

renewable energy source, e.g.: in photovoltaics (PV) to

provide electricity

On a bright, sunny day, the sun provides approximately

1,000 watts of energy per square meter of the planet’s

surface

If we could collect all of that energy we could easily power

our homes and businesses for free


Arizona’s Solar Potential

Arizona has the

natural resources to

lead the nation in

Solar PV adoption


Solar Facts

Arizona receives more sunshine than any other

state in the nation

Using current technology, the sunlight falling on just

half of Maricopa County could produce all the

electricity required for the entire United States!

The energy stored in the earth’s reserves of coal,

oil, and natural gas combined is equal to the energy

produced from 20 days of sunshine


Benefits of Solar PV


Benefits of Solar PV

Solar PV systems can reduce, or completely eliminate, the amount of electricity you have to purchase from your utility or electric service provider

Using solar power helps reduce our reliance on fossil fuels and helps to reduce the amount of greenhouse gases – a major contributor to global climate change

The electricity generated is clean, renewable and reliable

Solar PV generated electricity saves money on your utility bill and acts as a hedge against future price increases

Solar power systems can provide owners with fixed energy costs


How Solar PV Works


How Solar PV Works

Photovoltaics (PV) as the word implies (photo=light,

voltaic=electricity), convert sunlight (photons) directly into

electricity

PV cells are made of special materials called

semiconductors such as silicon and other conductive

materials

When light strikes the cell, a certain portion of it is absorbed

within the semiconductor material

The flow of electrons causes a current, and by placing metal

contacts on the top and bottom of the PV cell, we can draw

that current off to use externally


Anatomy of a Solar Cell


Making a Photovoltaic Panel


PV Modules (Panels)

Each PV module (sometimes called PV panel) is typically built from a front layer of tempered iron glass, a matrix of cells, a back layer of encapsulant, and an aluminum perimeter frame

Solar modules are made by connecting several cells in series and parallel to achieve useful levels of voltage and current

Solar modules are then connected in series and parallel to form an array of the desired output


Different Cell Technologies - Mono, Poly, Thinfilm

Monocrystalline cells are cut from ingots of purified silicon, grown as a single crystal; they have a uniform dark blue or blue-grey appearance.

Polycrystalline cells are cut from ingots of cast molten silicon. The silicon solidifies into multiple interlocked crystals. Polycrystalline cells show the multiple crystal pattern in their surface.

Amorphous, thin film cells are

fabricated using a molten

deposition process. Materials

technologies differ. The resulting

material has different photovoltaic

characteristics than crystalline cells,

and the surface appearance is more

uniform in color.


The Evolution of Solar Technology

1950 1960 1970 1980 1990 2000

1954Silicon PV cell invented at Bell Labs

1950s-60sSilicon-based solar gains credibility by powering the space race. Cost is $100/watt

1970sSilicon-based solar drops to $20/watt –widens potential applications

1980sSilicon-based solar drops to $10/watt and gains popularity in residential applications

1986ARCO solar introduces first commercial thin-film module

1990sPrice of silicon-based solar flattens-out at $4/watt, thin-film costs drop and efficiencies increase

2000sThin-film solar gains credibility by powering multi-MW plants in Europe

Crystalline Silicon (50+ years)

Thin Film (20+ years)


Inverters

Inverters convert the DC

electricity generated by the

solar array to AC electricity we

can use to meet common

electrical demands

Inverters are available to meet

a wide range of energy

demands


Inverter Interconnection

The inverter is connected on the customer’s main electrical panel, just

as another appliance would be. The inverter supplies household loads

first –that’s the path of least resistance for the current to flow.

When the inverter’s output exceeds the loads in the house, the surplus

current flows “backwards” through the utility meter, and onto the utility

grid. Turning the utility meter backwards generates credits.

Anytime the loads in the house exceed the output of the inverter (if you

turn on lots of appliances, or the sun sets), additional current to power

the loads comes from the utility, and the meter turns forward.

There is no storage, no batteries. During a black-out, the system turns

itself off (and back on, after the blackout).


More about inverters

Inverters are rated by maximum continuous output capacity, in watts. – Manufacturer’s naming

conventions often use this number in the model designation, i.e. “Fronius 5100” or “Xantrex GT3.0” .

Inverters are designed to work with certain AC grid voltages –which grid voltage an inverter works with varies by make and model. – For residential scale grid-tie,

most systems will be 120 VAC or 120/240 VAC.

Inverters can be small or big. Often, multiple inverters are used on one system


200

Solar Array

DC Disconnect Switch

InverterSolar Meter

AC Disconnect

SwitchElectrical Service Panel

Utility Service

Schematic Diagram of a Solar PV System

Display

DC Energy

AC Energy

Backfeed breaker

Electrical Loads


PV Production Considerations


Important Solar PV Production Considerations

The energy produced by a Solar PV system is affected by a

number of factors:

– Solar irradiation which varies by geographical location (Arizona has

great solar resources)

– Fixed or tracking arrays (tracking arrays follow the sun and produce

more energy)

– Tilt angle of the array (18 degrees is better than flat)

– Roof orientation (due South is best)

– Shading of PV arrays


Roof Orientation

WEST EAST

SOUTH

WESTNORTHWEST

EASTNORTHEAST


Shading Will Impact Solar Production

Solmetric SunEyeTM

models shading

throughout the year

Trees to the south

and west have

biggest impact


Electricity Basics


Electrical Units

Three basic units in electricity are

– Voltage (V)

– Current (I)

– Resistance (ohms)

Let’s use water as an analogy

– The voltage is equivalent to the water pressure, the current

is equivalent to the flow rate, and the resistance is

affected by the pipe size

Basic equation in electrical engineering states: V/I = R

What’s important to us? Volts x Amps = Watts


Volts x Amps = Watts

Volts x Amps = Watts: Whether in DC or AC

In the United States, power outlets deliver 120 volts A/C.

– A space heater plugged into a wall outlet consumes 10 amps

– That means that it is a 1,200-watt heater (120V x 10A =

1,200 watts)

1 kilowatt (kW) = 1,000 watts (power)

Kilowatt Hour (kWh) = 1 kilowatt x 1 hour (a measure of

energy)

You are billed for kilowatt hours (kWh)


Other Considerations


Maintenance Considerations

Solar systems are passive and have low maintenance

requirements (keep modules clean)

Solar modules have a standard 20-25 year warranty against

power loss (life expectancy is estimated to be 40 years)

Inverters have a 10 year warranty with optional extended

warranties available at extra cost (life expectancy is

estimated to be 15 - 20 years)


Economics of Solar PV

Financial incentives have never been better in Arizona

Residential utility rebates (purchase REC’s) $2.25 -

$3.00/watt of PV system size (UFI)

Non-residential utility rebates generally paid as Production

Based Incentive ($0.16 – 0.25/kWh)

Federal Investment Tax credit 30% (no cap)

Arizona State Tax credit (residential capped at $1,000, non-

residential capped at $25,000)

Save over 50% on PV system cost


888.SOL.CITY I 888.765.2489 I SOLARCITY.COM

James D. Beard

[email protected]

(602) 639-3777

solar 101-pv - na u · slide 2 solarcity confidential what is solar energy? solar energy is energy...

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