Prezentace aplikace PowerPoint

Division of photovoltaic systems by the connection

In terms of mode of operation, PV systems can be divided into:

- autonomous (also called off-grid, stand-alone)

- connected to the electrical network (on-grid)

- hybrid.

- they are usually installed in places where there is no available electrical distribution system (eg

cottages, traffic lights, telecommunications equipment, monitoring devices in the terrain, garden

lighting, illuminated signs)

- solar panels supply energy to the whole system and are used as a basis for supply
- battery supplies accumulated power for the appliance in case of the sudden consuming or when panels

do not produce enough energy, for example in the time of low light or in the night

- solar controller controls the battery charging and protects battery against the discharging
- voltage converter - converts 12V or 24 V DC (from battery) to 230 V AC.

Autonomous systems (off-grid, stand-alone)

http://urobsisam.topky.sk/stavba-a-rekonstrukcia/instalacie-a-
rozvody/vsetko-o-vlastnej-fotovoltickej-elektrarni-1448.html

http://energyinformative.org/grid-tied-off-grid-and-

hybrid-solar-systems/

A - PV panel,

B - inverter

C - controller,

D - battery

- they are applied in areas with a dense network of electrical wiring

a) all the produced energy can be supplied to the grid

Connected to the electrical network (on-grid)

http://www.solar-electric.sk/Grafika%20WEB%201_page4.htm

http://www.solarenvi.sk/s5article6p.html

A – PV panel,

B – striedač,

C – napájací elektromer,

D – odberný elektromer

E – verejná sieť

b) the excess energy (the difference between production and consumption) can be supplied to the grid

http://www.solar-electric.sk/Grafika%20WEB%201_page4.htm

http://www.solarenvi.sk/s5article6p.html

Technical solutions of PV power plants

- installation of photovoltaic power plants can be divided according to three basic indicators:

a) installed capacity

- small systems - to 25 kWp (for example on the roof of the house) - connection to the low

voltage network (1 kV)

- medium systems - from 50 kWp to 250 kWp (for example on the roofs of industrial

buildings) - connection to the medium voltage network (22 kV)

- large systems - from 500 kWp (free areas) - to the medium voltage network (22 kV)

- very large systems - from 5 MW (free areas) - to high voltage network (110 kV)

http://www.sciencedirect.com/science/article/pii/S0196890408004615

b) supporting structure

- fixed (static) systems

- trackers (1-axis, 2-axis)

http://www.wholesalesolar.com/Information-SolarFolder/solar-panel-efficiency.html

http://solargis.info/doc/103

Optimal orientation of panels

- SOUTH

Optimal inclination:

- depends on the season

Comparison of power

without and with trackers

The movement of the sun across the sky at 50 °

north latitude

c) location

- roofs of buildings

- integration into the building envelope

- free areas

http://www.pvresources.com/PVPowerPlants/Top50.aspx

Concentrated Photovoltaic Technology

- is when sunlight is concentrated into a small area of PV cells in order to generate

electricity, by using optics such us curved mirrors or lenses

http://www.ires.ma/sites/default/files/rencontresetdebats/pdf_cpv_storage_grid_sergio_asenjo_rev_1_0.pdf

http://rge360.com/cpv

http://www.ekobydleni.eu/solarni-energie/zenithsolar-solarni-system-s-nejvetsi-ucinnosti-na-svete

- it is a combination of CPV system in which solar energy is concentrated by lenses or

mirrors and so-called hybrid cell, which combines solar collectors for hot water and

photovoltaic panels for electricity. A significant efficiency was achieved (75%).

Currently, the company ZenithSolar installed the first systems in Kibbutz Yavne in central Israel.

Hybrid concentrated photovoltaic and thermal system

http://www.bp.com/en/global/corporate/about-bp/statistical-review-of-world-energy-2013/review-by-energy-type/renewable-energy/solar-energy.html

Solar power starts to show up at scale

New installations

totalling 30.2 GW in 2012

took global solar power generating capacity to 100 GW by year-end, a 43.3%

increase versus the end of 2011. Capacity has grown more than ten-fold over the past 5 years.

More than half of the growth in capacity was in Europe, led by

Germany (7.6 GW)

and Italy

(3.4 GW)

. Germany remains the

world leader for cumulative installed capacity (32.6 GW), with Italy (16.2 GW) in second place.

China

, already the leading manufacturer of solar PV, has started to develop its domestic solar market, adding

5 GW

in 2012. The

also saw strong growth in 2012, adding

3.3 GW

Solar power generation enjoyed another year of very rapid growth in 2012, with a 58% increase. Its overall share of renewable

power remains low (8.9%), but 2012 confirmed the arrival of solar power at scale, contributing 24.4% of the growth of

renewable power in 2012.

The price of solar photovoltaic cells has

dropped 99% in the past quarter century. So

in an increasing number of markets around the

country, solar is at or very close to grid parity.

http://theenergycollective.com/josephromm/285416/must-see-chart-cost-pv-cells-has-dropped-amazing-99-1977-bringing-solar-power-grid

5.2.2 The conversion of solar energy into electricity indirect form

(solar-thermal power plants)

Thermal solar tower

- solar towers use a circular array of the large mirrors (heliostats) that are rotated towards the

sun and they concentrate the rays into a focus of the central tower.

- absorbed heat is conveyed to the liquid from which the steam generator produces steam

driving the turbine, generating electricity.

- rotation is controlled by computer and 2-axial device ensures that the mirrors constantly direct

the rays into focus of the tower.

- circulating liquid in the absorber heat also the thermal reservoir from which heat is taken not

only for electricity but also for industrial applications.

- temperature range, which is achieved in an absorber is from 530 °C to 1480 °C

http://www.oze.stuba.sk/oze/slnecna-energia/

Schematic view of solar tower power plant

Solar power tower near Seville in Spain PS 20

- the PS20 plant generates 20 megawatts (MW) of electricity,
- at the PS20 plant each heliostat is 120 m

, which gives the entire heliostat field a massive

area of 155,000 m

- each heliostat tracks the sun throughout the day on two axes and concentrates the

radiation onto a receiver located on the upper part of the 162 m tower.

- the receiver converts 92% of received sunlight into steam which is piped down to a turbine

driven generator at the base of the tower

http://www.sciencedirect.com/science/article/pii/S1364032112002250

Linear parabolic mirrors

- the liquid (eg, oil) is flowing in pipes and heats to nearly 400 °C by using mirrors Sun,
- the liquid is pumped through a heat exchanger, the steam with high temperature drives a

turbine, the generator is producing an electricity.

- pipe at the focus of parabolic mirrors is made of glass and the whole system is rotated

towards the sun

- as the heat transfer medium is used oil.

Parabolic mirrors

- these systems use a set of parabolic mirrors in the shape of plates (similar to satellite

antennas) that concentrate the solar radiation to the absorber which is placed at the focus of

plate.

- the liquid in the absorber is heated up to 1000 °C, which is used directly to generate

electricity in a small turbine (e.g. Stirling engine) attached to the absorber

- advantage of these devices is their modular character, allowing their use in remote locations.
- power of the unit is about 10-25 kWe, mirror diameter is about 10 m
- parabolic mirrors are the most efficient solar power generation equipments due to high

optical efficiency and low energy losses.

Solar chimney power plant

- principle of operation of solar chimney power plant is the heating of the air under

greenhouses (glass, polycarbonate, foil).

- sun-heated air creates air flow that rises through the chimney towards upward and rotates

the turbine at the bottom of the chimney

http://www.sciencedirect.com/science/article/pii/S0038092X09001200

http://www.cez.cz/edee/content/microsites/solarni/k23.htm

- in 1982 in Manzanares, about 150 km south of

Madrid was built solar chimney power plant

- on the area of 46 000 m2 was created low glazed

energy collector, based on the greenhouse

phenomenon.

- chimney height 195 m, diameter 10 m.
- power of the experimental plants was only 50 kW.

The project was completed in the year. 1989, when

the chimney was damaged in a storm.

http://www.sciencedirect.com/science/article/pii/S0038092X09001200

http://www.cez.cz/edee/content/microsites/solarni/k23.htm

Currently is under construction chimney power

plant in Australia
- height of chimney : 1000 meters
- diameter of chimney: 150 meters
- diameter of collector: 5000 meters
- power: 200 MW

Arizona
- power: 200 MW

5.2.3 The conversion of solar energy into thermal energy

Solar radiation incident on the

collector absorber

is transformed into heat, which

accumulates and transmits heat transfer liquid flowing in a stainless steel absorber collector.
Accumulated energy is passed through a heat transfer medium to heated water in the

heat

exchanger

. The

expansion reservoir

keeps uniform pressure and balances the changes in

fluid volume. Automatic operation provides electronic control that switch off and switch on

the

circulation pump

. During cloudy days the water is heated by the electric heater,

boiler

or other heat source.

1 solar collectors
2 reservoir with heat exchanger
3 expansion reservoir
4 circulation pump
5 regulation
6 boiler