The sun bathes the earth with more energy each minute than the world

consumes in one year.

Electric power generated by using sunlight either to create electron flow in a photovoltaic cell or to heat a fluid that is used in the operation of an engine or turbine-generator.

Photovoltaic>>Light from the Sun

Thermal>>Heat from the Sun

1. Photovoltaic Solar System

It is made up of semiconductor materials that converts incident solar energy directly into electrical energy

Efficiencies from a few percent up to 20-30%

No moving parts No noise Lifetimes of 20-30 years or more

Typical module efficiencies ~12% Screen printed multi-crystalline solar cells

Efficiency range is 6-30% 6% for amorphous silicon-based PV cells Best retail systems approaching 17%

efficiency 30% for multi-junction research cells

~1 kW/m2 reaches the ground (sunny day) ~20% efficiency 200W/m2 electricity

The junction of dissimilar materials (n and p type silicon) creates a voltage

Energy from sunlight knocks out electrons, creating a electron and a hole in the junction

Connecting both sides to an external circuit causes current to flow

In essence, sunlight on a solar cell creates a small battery with voltages typically 0.5 v. DC

Solar cells can be electrically connected in series (voltages add) or in parallel (currents add) to give any desired voltage and current (or power) output since P = I x V

Photovoltaic cells are typically sold in modules (or panels) of 12 volts with power outputs of 50 to 100+ watts. These are then combined into arrays to give the desired power or watts.

Major component and cost of a PV system is the Solar / PV cell array

Charge Controller Batteries The inverter – DC to AC electricity AC Service Panels AC utility Net Meter Monitor – (optional but a good idea)

A charge controller, charge regulator or battery regulator limits the rate at which electric current is added to or drawn from electric batteries. It prevents overcharging and may prevent against overvoltage.

A series charge controller or series regulator disables further current flow into batteries when they are full. A shunt charge controller or shunt regulator diverts excess electricity to an auxiliary or "shunt" load, such as an electric water heater, when batteries are full.

Simple charge controllers stop charging a battery when they exceed a set high voltage level, and re-enable charging when battery voltage drops back below that level. Pulse width modulation (PWM) and maximum power point tracker (MPPT) technologies are more electronically sophisticated, adjusting charging rates depending on the battery's level, to allow charging closer to its maximum capacity.

Batteries can be used to provide short-term electrical supply in case of grid failure.

Many grid-connected houses choose to have an electrical battery system to provide loads with power up to 3 days or even more in case of outage.

Larger number of batteries are typically

used for remote grid-independent systems.

Deep Cycle Battery is used for solar backup power purposes.

Deep Cycle Battery is used where discharging and charging occurs frequently and provide less current in long time, in contrast with Slow Cycle Battery (e.g. car batteries).

Deep cycle batteries are designed to be discharged down as much as 80% time after time, and have much thicker plates.

The Depth of Discharge (DOD) is a measure of how deeply a battery is discharged. When a battery is 100% full, then the DOD is 0%. Conversely, when a battery is 100% empty, the DOD is 100%.

An inverter is an electrical device that converts direct current (DC) to alternating current (AC) or vice versa; the resulting AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits.

Inverters are commonly used to supply AC power from DC sources such as solar panels and batteries.

When your system produces more electricity than your home uses electricity flows backward out to the grid

Meter runs backward and you get credit for the electricity you sell to the utility

( World solar photovoltaic (PV) installations were 2.826 Giga watts peak (GWp) in 2007, and 5.95 Giga watts in 2008, a 110% increase. )

Power Location Year60 MW Spain, Olmedilla 2008

50 MW Spain, Puertollano 2008

46 MW Portugal, Moura 2008

40 MW Germany, Brandis 2007, 2008

34 MW Spain, Arnedo 2008

30 MW Spain, Merida 2008

28 MW Spain, Casas de Los Pinos 2008

27 MW(52 MW planned) Germany, Turnow-Preilack 2009

26 MW Spain, Fuente Álamo 2008

24 MW Korea, Sinan 2008

TOP 10 PV Solar Plants in the World

2. Thermal Solar System

Solar thermal electric power plant generates heat by using lenses and reflectors to concentrate the sun's energy. Because the heat can be stored, these plants are unique because they can generate power when it is needed, day or night, rain or shine.

In solar thermal power plants the incoming radiation is tracked by large mirror fields which concentrate the energy towards absorbers. They, in turn, receive the concentrated radiation and transfer it thermally to the working medium. The heated fluid operates as in conventional power stations directly (if steam or air is used as medium) or indirectly through a heat exchanging steam generator on the turbine unit which then drives the generator.

Efficiency of Solar Thermal Power is fully dependent on the Temperature Collectors.

TYPES OF COLLECTORS LOW TEMPERATURE COLLECTORS MEDIUM TEMPERATURE COLLECTORS HIGH TEMPERATURE COLLECTORS

(Low and Medium Temperature collectors are used on very small scales, so let’s talk about High Temperature Collectors.)

Solar Radiations are concentrated to obtain very High Temperature.

Concentrating Solar Power (CSP) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. The concentrated heat is then used as a heat source for a conventional power plant.

1. PARABOLIC TROUGH DESIGNS2. POWER TOWER DESIGNS3. DISH DESIGNS4. FRESNEL REFLECTORS

Heat of sun is concentrated on absorber tubes in which Synthetic Oil, Molten Salt and Pressurized Steam are used as HEAT TRANSFER FLUID.

The receiver can be in a vacuum chamber of glass.

The substance with the heat is transported to a heat engine where the heat is converted to electricity.

Full-scale parabolic trough systems consist of many such troughs laid out in parallel over a large area of land.

Power Tower is also known as 'CENTRAL TOWER' Or, 'HELIOSTAT'

Use an array of flat, moveable mirrors (called Heliostats) to focus the sun rays on a collector tower (The Receiver).

The Advantage of this design above the parabolic trough design is achievement of higher temperature.

The Disadvantage is that each mirror must have its own Dual-Axis control.

Solar One (CA) Steam Heat

Transfer 10 MW

Solar Two (CA) Molten Salt Heat

Transfer 10 MW

Solar Tres (Spain) Molten Salt Heat

Transfer 15 MW

Flat mirrors focus the light on the top of the tower PS10(LOCATED IN SPAIN) PRODUCES ELECTRICITY FROM THE SUN USING 624 MOVABLE MIRRORS CALLED HELIOSTATS.

Solar Parabolic Dish systems consist of a parabolic-shaped concentrator (similar in shape to a satellite dish) that reflects solar radiation onto a receiver mounted at the focal point at the center. The collected heat is utilized directly by a heat engine mounted on the receiver which generates electricity.

The reflector tracks the Sun along two axes. Parabolic dish systems give the highest efficiency among CSP technologies.

It is supposed to be the World’s Most Efficient Solar Technology Coming Early 2010)

The Sun Catcher consists of a solar concentrator in a dish structure that supports an array of curved glass mirrors.

Iterations of the Sun Catcher have been among the world’s most efficient machines for solar-to-grid electric conversion for twenty years, most recently breaking the record last year with the highest-ever conversion rate of 31.25%.

The Sun Catcher mixes old technology with new design. By employing a system of mirrors attached to a parabolic dish to concentrate the sun’s energy onto a high efficiency Stirling Engine, each dish can generate up to 25,000 watts of power.

The Sun Catcher is a 40-foot wide, 25 (kWe)solar dish Stirling systemdesigned to automatically track the sun and to collectand focus solar energy ontoa Power Conversion Unit (PCU),which then generates electricity.

The PCU converts the focused solar thermal energy into grid-quality electricity with a closed-cycle, four-cylinder, reciprocating Solar Stirling Engine utilizing an internal working fluid that is recycled through the engine. The hydrogen gas in the PCU’s solar receiver tubes heats up and this gas in turn powers the Solar Stirling Engine.

An additional advantage of the technology is that the Sun Catcher requires no water for heating or cooling and a minimal amount of water is required to wash the mirrors.

A Linear Fresnel Reflector Power Plant uses a series of long, narrow, A Linear Fresnel Reflector Power Plant uses a series of long, narrow, shallow-curvature (or even flat) mirrors to focus light onto one or more shallow-curvature (or even flat) mirrors to focus light onto one or more

linear receivers positioned above the mirrors.linear receivers positioned above the mirrors.

ARRANGEMENT OF FRESENAL REFLECTOR (under experimental phase)ARRANGEMENT OF FRESENAL REFLECTOR (under experimental phase)

http://www.solarmillennium.de/upload/Animationen/andasol_blue_engl.swf

Power Tower Parabolic Dish Parabolic Trough

Applications

Grid-connected electric plants; process heat for industrial use.

Stand-alone small power systems; grid support.

Grid-connected electric plants; process heat for industrial use.

Advantages

Dispatchable base load electricity; high conversion efficiencies; energy storage; hybrid (solar/fossil) operation.

Dispatchable electricity, high conversion efficiencies; modularity; hybrid (solar/fossil) operation.

Dispatchable peaking electricity; commercially available with 4,500 GWh operating experience; hybrid (solar/fossil) operation.

Power Technology Type

Location

354 MW Parabolic Trough USA, Mojave Desert California

64 MW Parabolic Trough USA, Las Vegas, Nevada

50 MW Parabolic Trough Spain, Granada

50 MW Parabolic Trough Spain, Puertollano, Ciudad Real

20 MW & 11 MW Solar Power Tower Spain, Seville

5 MW Fresnel Reflector USA, Bakersfield, California

5 MW Solar Power Tower USA, Lancaster,  California

2 MW Fresnel Reflector Australia, New South Wales

1.5 MW Solar Power Tower Germany, Jülich

1.4 MW Solar Power Tower France, Pyrénées-Orientales

TOP 10 Thermal Solar Plants in the World

1. On Grid

2. Off Grid

In an on-grid system, the system is connected to the electricity grid which is why it is called “on-grid.” A back-up battery can be included as part of the solar power system.  Batteries can store excess energy generated by the solar panels, and even send the surplus electricity out to the grid.

In an off-grid system, a back-up battery is included as part of the solar power system but the system is directly connected to the load not and electricity grid is not included in this technique which is why it is called “off-grid.”

The difference between an off grid inverter and a grid tie inverter is: An off grid inverter converts stored DC power in the battery banks to AC and directly supply it to the loadwhere as,

A grid tie inverter on the other hand takes solar energy from PV cells or battery banks and stores it in an electrical grid.

The sun is always there and always will be, though of course the solar energy received at any site depends on season and amount of cloud cover, whilst fossil fuels will be used up at some future time, and can't be replaced.

Use of solar power does not produce CO2 or other undesirable emissions whilst fossil fuels do.

Solar power only requires initial investment. The cost of setting up solar panels is high, but after that, the cost of maintenance is negligible. So, More expensive to install but cheaper to run whereas fossil fuels based power plants have initial and an huge cost for running as well which depends upon price of fuel used.

Solar doesn't pollute. It gives us as much power as fossil fuels do but it helps the environment.

National Renewable Energy Lab (NREL) of USA. (NREL Solar Map of Pakistan)

IFL

ANIQUE AHMED(ELECTRICAL ENGINEER)