solar powered aircrafts

دانشکده برق و کامپیوتر - دانشگاه صنعتی اصفهان

SOLAR AIRCRAFTS

sBy Abolfazl Mazloom

November 2012


Why solar energy?

Infinity Availability Inexpensive No pollution No preservation cost High power-to-weight ratio Easy to Product …


World Solar Energy Map


Proportion of Utilization

Europe80%

North Amer-ica

16%

Asia4%•Six Countries hosting the

majority of large photovoltaic power plants:

USA Italy Germany Spain Japan South Korea


Total Global PV Power


Dissection Solar


THE BAND GAP

In solid state physics and related applied fields, the band gap is the energy difference between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. It is often spelt "band gap".


PV Technology Classification

Silicon Crystalline Technology

Mono Crystalline

PV Cells

Multi Crystalline

PV Cells

Thin Film Technology

Amorphous Silicon PV

Cells

Poly Crystalline

PV Cells


Silicon Crystalline Technology

Currently makes up 86% of PV market Very stable with module efficiencies 10-

16%Mono crystalline PV Cells

•Made using saw-cut from single cylindrical crystal of Si

•Operating efficiency up to 15% Multi Crystalline PV

Cells

•Caste from ingot of melted and recrystallised silicon

•Cell efficiency ~12%

•Accounts for 90% of crystalline Si market


Thin Film Technology

Silicon deposited in a continuous on a base material such as glass, metal or polymers

Thin-film crystalline solar cell consists of layers about 10μm thick compared with 200-300μm layers for crystalline silicon cells

PROS• Low cost substrate and fabrication process

CONS• Not very stable


Amorphous Silicon PV Cells

Operating efficiency ~6%

Makes up about 13% of PV market

PROS• Mature manufacturing technologies available

CONS• Initial 20-40% loss in efficiency

Poly Crystalline PV Cells

Copper Indium

High absorption coefficient High efficiency levels

PROS

• 18% laboratory efficiency• >11% module efficiency

CONS

• Immature manufacturing process

Non – Silicon Based Technology


Semiconductor Material Efficiencies


Future Technologies

Ultra Thin Wafer Solar Cells

Thickness ~ 45μm Cell Efficiency as high as

20.3%

Anti- Reflection Coating

Low cost deposition techniques use a metal organic titanium or tantanum mixed with suitable organic additives


Structure Solar Cells


Si is first choice for solar cells because for good knowledge of Si processing in micro electronics industry

Efficiency- 26% theoretical.24.7% obtained in

laboratory.12-16% commercial.


Silicon Solar Cells

Losses

Reflection losses.Recombination

losses.Resistive losses.Thermal losses.

Reflection loss

Recombination loss

Resistive loss


Losses in Si solar cells, causes efficiency to reduce.

Primary Energy Collection Parameters

latitudeTime of the yearTime of the day

Altitude (Cloudy , Humidity)

Cell TemperatureCell Orientation - اصفهان صنعتی دانشگاه کامپیوتر و برق دانشکده

High Efficiency Solar CellsSolutions

lightly phosphorus diffused emitters, to minimise recombination losses and avoid the existence of a "dead layer" at the cell surface;

closely spaced metal lines, to minimise emitter lateral resistive power losses;

very fine metal lines, typically less than 20 µm wide, to minimise shading losses;

small area devices and good metal conductivities, to minimise resistive losses in the metal grid;

use of elaborate metallization schemes, such as titanium/palladium/silver, that give very low contact resistances;

use of anti-reflection coatings, which can reduce surface reflection from 30% to well below 10%;

…

اصفهان - صنعتی دانشگاه کامپیوتر و برق دانشکده

V/I Curve


Effect temperature on Solar Cells


A Question?

How we must set Voltage and Current in solar cell’s output for production maximum power?


Maximum Power Point Tracking

a device is needed that finds the maximum power point (MPP) and converts that voltage to a voltage equal to the system voltage.

Maximum Power Point Tracking , frequently referred to as MPPT, is an electronic system that operates the Photovoltaic (PV) modules in a manner that allows the modules to produce all the power they are capable of.


Structure A MPPT


Solar panel set


Maximum Continuous Power Output : 225W Nominal Voltage : 240 V Nominal Frequency : 60 Hz

DC Output Voltage: 250V Nominal Output Current : 0.9375

A Total Harmonic Distortion: < 5%

Batteries

Several technologies are available and currently: Lithium polymer lithium-ion nickel-metal-hydride (NiMH) nickel-cadmium (NiCd) lead-acid Lithium-ion (or lithium-ion-polymer where the electrolyte is a gel and not a liquid) technology is the best concerning gravimetric energy density. They have upper efficiency and less weight as compared to another batteries.


Lithium Batteries evolution over the last years



Solar Powered Aircraft

Advantages

They haven’t any fuel tank; High Safety Non require to refuel; Possible long term flightLow speed; Gangling fight on a regionLesser mechanical section; Lesser upkeep Environmentally friendly

Require to Technology

lightweight composite structureslightweight and low power avionics systemshigh efficiency electric motors & batteriesthermal control systems for high altitude

flighthigh specific power solar arraystratospheric flight operations fault tolerant flight control system


Block diagram of typical solar powered AC

Solar CellsMPPT Board

Batteries

DC/DCDC/AC

Motor Driver

Motors

X BOARD

Navigation Systems

Communication Systems

communication system

OtherSystems

To All Sections

Power Line

Data Line


Day & Night


Altitude Flight

1) Fly at minimum night altitude2) Climb3) Cruise at max altitude; if power is available4) Descent at idle power 5) Fly at minimum night altitude


Losses

From solar energy to propeller ~ 89% losses!!اصفهان - صنعتی دانشگاه کامپیوتر و برق دانشکده

History of solar flight


70’s 80’s 90’s 2000’s

Solar Riser

Solar Challenger

Sunseeker

Solair II

Pathfinder

Helius

Solar-Impulse

Solar Impulse


Solar Impulse

Objective: Develop a manned solar powered aircraft which can fly around the world with solar power only

Approach:The goal for the Solar Impulse

community is to have this aircraft fly across the world one day

Consequence: Fly for 26 hours; Nine of these hours were during the night


Specification

Wingspan: 63,4m Length: 21.85m Height: 6.4m Maximum altitude: 8500m Weight: 1600Kg

Motor power: 4x10HP electric engines

Solar cells: 11628 (10748 on the wing, 880 on the horizontal stabilizer)

Average flying speed: 70 km/h Take off speed: 35 km/h


Flight Altitude


References

solar cells- materials, manufacture and operation; by Tom Markvart

Design of Solar Powered Airplanes for Continuous Flight; by André Noth

http://www.wholesalesolar.com/solar-panels.htmlhttp://en.wikipedia.org/wiki/Solar_Cellshttp://en.wikipedia.org/wiki/Solar_Impulsehttp://www.solarimpulse.com/


Thank you for attention