Harnessing of

Solar energy

By: Maged Mohamed

Keywords

• Solar energy• PV cells • Solar tower• Evacuated tubes• Flat plate collector• Symbols used in control systems

Solar energy

Energy types which can be derived from Solar energy

• Thermal energy • Electric energy• Both Thermal and electric (hybrid)

Different systems for getting thermal energy from solar energy directly

(a) Thermal collectors: Flat plate collector. Evacuated tubes. Integrated Storage Collector (ISC).

(c) Solar Central Concentrating Reciever: - Movable heliostats (mirrors) follow the sun to reflect the incoming sun rays on a receiver. - Steam is produced at the receiver. - Steam passes over a turbine to turn an electrical generator producing electricity.

(d) Solar Power Tower:- Parabolic trough collectors. Working fluid is oil. - Solar Dish with Sterling engine.

1st form of harnessing Solar Energy

In 1767 ( Horace_Benedict ) created the first solar collector an insulated box covered with 3 layers of glass to absorb heat energy its temp reaches 230c.

Solar energy (Thermal collectors)

Flat plate collector

Evacuated tubes

Solar parks

Different systems for getting electric energy from solar energy directly

(b) Photovoltaic Modules: Photovoltaic collectors. Hybrid PV-thermal: (Produces both electricity and heat) o Active cooling by water. o Passive cooling be air.

(e) Solar Power Concentrated Photovoltaic (PV):• Lenses Concentrates sun rays on photovoltaic cells.• Cells must be cooled by air or water.

Solar energy (Photovoltaic modules)

Solar Thermal Power (Concentrated)

Efficiency of photovoltaic cell

In (2006) the efficiency of the solar panels reached from 12% to 18%.

1) as some of photons don’t have enough energy to free the electrons .

2) if a photon has energy more than the required, it will be lost in form of radiation.

Currently the efficiency of which reaches about 25% and it can reach about 44% but with a huge cost.

Symbols used in control systems

Symbols used in control systems

Symbols used in control systems