Solar power

SOLAR POWER

INTRODUCTIONPhotovoltaic Devices Solar Thermal Electric Power Plant

Photovoltaic effect recognized In 1839 followed by the first photovoltaic cell in 1883.

Converts energy from the sundirectly into electricity

Used to power or recharge portable devices and for residential commercial use.

The first application of solar thermal in 1767 known as ‘hot box’, later in 1891 the first solar thermal system was built.

Generate electricity indirectly from the sun. Most commonly used - Solar Power Tower, Parabolic Trough.

Used in large electric power production and for residential commercial use.

Construction of

Photovoltaic Devices

- Solar Panels are made up of a collection of solar cells that are then bonded to a sheet of glass. It converts sunlight into electricity which can be used immediately or stored in a battery.

- Solar Cell is made of semiconductors, like silicon, that has special materialproperties that allow the sun light that strikes a cell to be absorbed in the material.

Charge controller - Also known as charge regulator, monitors the battery's charge state.- Protect the battery from discharging, below its lowest acceptable voltage, to prevent damage by over discharge. - Protects against wrong connection of the battery and reverse voltage to the panel.

Batteries - Stores the power generated by the solar modules during the day to be used during the night. - The type of battery used is Deep Cycle (Lead Acid) Maintenance Free type. - This battery is designed to be fully charged and discharged over and over again without causing damage.

DC-AC Inverter

- DC-AC inverters are used to convert Direct Current (DC) from the battery into Alternating Current (AC) to run AC appliances. - Types of inverters available are Stand-alone inverters, Synchronous inverter and multi-function inverter

Stand-alone Inverter Synchronous Inverter Multi-function Inverter

Construction of Solar Electric

Plant

~ Solar Power Tower ~

Central Receiver ~ Receives concentrated solar radiation and transform it to thermal power.

Condenser ~ Condense exhaust steam from the steam turbine and channels it back to steam generator.

Heliostat ~ Mirrors which reflectsthe sun’s energy to the correct spot on the tower.

Storage Tanks ~ Stores fluid, one at high temperature and one at low temperature.

Turbine ~ Receives steam from steam generator that turns the turbine blades to generate electricity.

Molten Salt ~ Stores the sun's heat and release it in a controlled manner for steady steam turbine power generation.

SOLAR POWER TOWER

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~ Parabolic Trough ~

Steel tube ~Surrounded by a glass envelope to reduce convection heat losses. Functions as a receiver that can accept optical input from any direction.

Mirrors ~ Usually coated with silver or polished aluminum. Reflects the suns energy to the receiver.

Drive ~ Positions the collector to track the sun during the day. It can be either a standard motor and gear box configuration or can use a hydraulic drive System.

Collector Interconnect ~ Connects the receivers on two adjacent collectors and allows them to track independently.

Collector ~ Structure of collector must :- Supports the mirrors and receivers, maintaining them in optical alignment- Withstands external forces(winds).- Allows the collector to rotate, so the mirrors and receiver can track the sun.

PARABOLIC TROUGH

Fluid ~ Normally oil, absorbs sunlight, increases temperature and heats steam in turbine.

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PhotovoltaicGENERATION PROCESS

Converts energy from the sun

into electricity.

Where required, an inverter is used to change the Direct Current (DC) to Alternating Current (AC) to power most

AC appliances.

Multiple solar or photovoltaic cells are connected to

form a solar module.

The solar cells will convert sunlight

directly into electricity (DC).

The electricity from the solar cells is stored in the battery for immediate

or later .

The role of the charge controller is to regulate

the voltage and current from the solar cells before it is stored

in the battery.

It monitors the condition of the

battery state of charge and protects the

battery from being over-charged.

The charge controller will also protect the

battery from discharging below its

lowest acceptable voltage.

SOLA

R PLANT

GENERATION

PROCESS

Solar Power Tower

Parabolic Trough

ADVANTAGES1. Greatly reduced

pollution.2. Greatly reduced

contribution to global warming.

3. Infinite energy resource.

4. Reduced maintenance costs.

5. Falling production costs.

6. Low running costs.7. Local application.

DISADVANTAGES1. It is available most

abundantly in areas with a high number of sunshine hours.

2. It is not directly available at night or under cloud cover.

3. DC power must be converted to AC power before it can be used.

4. Initial installation cost may be too expensive.

5. Solar panels require large land/roof areas to be effective.

• With the threat of global warming, and the gradual depletion of petroleum supplies, “Why we don't use more solar energy?”1) The energy intensity of solar energy is relatively low.2) The technology is expensive.

• Solar Thermal Vs Photovoltaic.– Solar Thermal has an efficiency of 70% whereas PV 12%.– Solar Thermal requires much less space than PV.– Solar Thermal are 5 times cheaper than PV.– Difficult to add thermal walls and other passive solar collectors to an

existing home which gives an advantage to PV.– Solar thermal space heating system will sit idly by during the long summer

months while a solar PV system will provide usable electricity all year.• Differences between Solar panels and Solar Modules :

– Technically, there is a difference, but even within the solar industry there is no clear cut answer. For all practical purposes, a solar panel is the same as a solar module.

DISCUSSION

• Solar power is a good alternative energy source. It does not hurt the environment and it is a renewable energy source.

• Can be used to power houses and their electronic appliances, such as flashlights, electric motors and even refrigerators. It can also be used to heat water and cool buildings.

• Two ways to capture the suns energy, by Photovoltaic devices and Solar Thermal Electric Power Plant.

• Learned how solar energy can be used to make electricity and power everyday appliances.

• Also learned about structures of Photovoltaic Panels, Solar Thermal and how it works.

CONCLUSION

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