10. Applications of photovoltaic systems

Satheesh Krishnamurthy OPEN University UK

Learning outcomes

After studying this chapter, the reader should possess knowledge of the major application

possibilities of photovoltaics, ranging from large scale electricity production installations to

on-device portable chargers.

Introduction

With the ever increasing demand for energy, the search for alternative energy

sources has increased. The worldwide use of fossil fuels has led to the critical situation of

global warming, significantly effecting our health, environment and climate. Extensive

emphasis have been put on the implementation of renewable energy sources. Solar energy

is by far the most abundant form of renewable energy and has the potential to partially

replace fossil fuels. The amount of solar radiation striking our earth's surface is about ten

thousand times higher than the current global electrical energy consumption. Photovoltaic

(PV) cells is one of the way to harness solar energy. PV cells convert sunlight directly to

electricity and can be influential in meeting the world’s energy demand. PV systems are

being used in a variety of applications. These applications may be grouped into two

categories: “utility interactive systems” and “stand-alone systems” [1].

Utility Interactive Applications:

In utility interactive (or grid-connected) PV systems, PV modules are connected to

inverters that convert the DC produced by the PV modules to AC. This electricity can then

power household appliances or can be sold directly to the grid. As a building receives this

energy, it is distributed to appliances and lighting, or other devices where needed. Since PV

systems are restricted to function only exposed to the sun, a backup system is frequently

required to ensure continuous supply of electricity irrespective of the weather conditions.

These systems are most commonly used in houses or commercial buildings to offset

electricity cost. A well designed PV system with a proper storage facility can be an attractive

prospect for displacing power during the peak hours.

FIG. 1 Schematics of utility interactive applications. [2]

The schematic above shows a typical photovoltaic panel system, on the roof of a

house. This system allows the owner to sell generated electricity to the National Grid,

effectively lowering the house owners' electricity bills.

FIG. 2 PV panels on the roof of a house in UK

Stand-Alone Systems

Stand-alone systems directly use the generated produced electricity. Stand-alone

systems do not rely on utility/grid connections. When the requirement arises during night

time or poor sunlight, a battery storage system is used. In some situations, stand-alone

systems use conventional generators as backup systems. There are numerous applications

of stand-alone PV systems, some of which are mentioned below.

Lighting:

With the invention of LED (light emitting diode) technology as low power lighting

sources, PV systems find an ideal application in remote or mobile lighting systems. PV

systems combined with battery storage facilties are mostly used to provide lighting for

billboards, highway in formation signs, public-use facilities, parking lots, vacation cabins,

lighting for trains.

FIG. 3 A street light powered by PV.

FIG. 4 Portable lighting system along with mobile charging facility.

FIG. 5 Example of a bill board powered by solar panels

Communications: Signals required by communication systems need amplification after

intervals. Various relay towers are stationed to boost

High grounds are mostly favoured as the sites for repeater stations. Th

far from power lines. To reduce the difficulty and

systems are being installed as a viable alternative.

FIG. 6 Repeater

Example of a bill board powered by solar panels.

Signals required by communication systems need amplification after

Various relay towers are stationed to boost radio, television, and

High grounds are mostly favoured as the sites for repeater stations. These

far from power lines. To reduce the difficulty and cost associated with generators

systems are being installed as a viable alternative.

epeater at an elevated location can be powered by PV.

.

Signals required by communication systems need amplification after particular distance

adio, television, and phone signals.

e sites are generally

with generators, PV

elevated location can be powered by PV.

FIG. 7 Satellites used for communication are powered by PV.

Electricity for remote areas:

Some areas are quite far from the distribution network to establish connection with the

grid. Areas under construction also need power supply before they are connected. PV

systems are an attractive option for these cases. Furthermore, PV systems can be backed up

by conventional generators to provide uninterrupted supply.

FIG. 8 Remote area in Africa powered by PV.

Disaster Relief:

Natural calamities often bring about an electricity crisis. As the disasters such as

hurricanes, floods, tornadoes, and earthquakes destroy electricity generation and

distribution systems. In situations like these, where power will be out for an extended

period, portable PV systems can provide temporary solutions for light, communication, food

and water systems. Emergency health clinics opt for PV based electricity over conventional

systems in lieu to problems of fuel transport and pollution.

FIG. 9 Portable PV systems powering area struck by natural disaster.

Scientific experiments:

In various cases, scientific experiments are set up in areas far from power supply. PV

systems can be effectively used to carry out scientific activities in remote areas. Systems

monitoring seismic activities, highway conditions, meteorological information and other

research activities can be powered by PV systems.

FIG. 10 Remote scientific experiment powered by PV.

Signal Systems:

Navigational systems, such as light houses, highway and aircraft warning signals can

be far from the electric grid. PV systems can be a reliable power source for these important

applications. Even portable traffic lights can be powered by PV systems.

FIG. 11 Light house being powered by PV.

FIG. 12 Portable traffic lights powered by PV.

Water Pumping:

PV is a perfect candidate for agricultural and livestock purposes

water during the periods with bright sunshine. Th

directly to fields, or can store water for the time of need. Th

provide water to remote areas and villages.

Fig 13. Solar water pumps can be very cost effective for remote agricultural activities

FIG. 14 Solar water pumps can supply water to areas with no connection to grid.

candidate for agricultural and livestock purposes due to

water during the periods with bright sunshine. These pumping systems can supply water

or can store water for the time of need. These systems can

de water to remote areas and villages.

Solar water pumps can be very cost effective for remote agricultural activities

Solar water pumps can supply water to areas with no connection to grid.

ue to the need for

pumping systems can supply water

can even be used to

Solar water pumps can be very cost effective for remote agricultural activities [3].

Solar water pumps can supply water to areas with no connection to grid.

Charging Vehicle Batteries:

Vehicles running on electric power can be charged at PV powered stations. Such vehicles

can also maintain their critical battery states using PV powered sources. Boats and other

leisure vehicles can be charged directly using PV systems.

FIG. 15 Electric vehicles at PV charging station.

FIG. 16 Boat with a PV charging system.

Solar Power Cathodic Protection:

Pipelines, well heads and other metallic structures are prone to corrosion due to

exposure to water. Corrosion occurs due to the electrolytic activity of metals as they lose

ions in contact with water. This electrolytic process leading to corrosion can be reduced by

applying an external voltage. This external voltage will prevent the ion loss from the metal.

To that end, only a small DC voltage will be enough. PV are a suitable candidate for this

purpose as they produce low voltage DC power that can be used directly.

FIG. 17 Cathodic protection using PV.

Refrigeration:

PV system can be exceptionally suitable for storage and transport of medicines and vaccines

that require refrigeration.

FIG. 18 Solar powered refrigerator.

Consumer Products:

PV technology is being used for variety of commercially available consumer based products.

Small DC appliances such as toys, watches, calculators, radios, televisions, flashlights, fans

etc. can operate with PV based energy systems.

FIG. 19 Solar powered calculator and radio.

Public utilities:

Various public utility systems such as teller machines and telephone booths can also be

powered by PV systems.

FIG. 20 ATM and telephone booth powered by PV.

Conclusion The huge amount of research that has been carried over the past decade has led to an

increased interest in implementing PV systems to satisfy energy needs. PV systems can be

mounted directly to the building structure instead of putting on separate support

structures, thus reducing space requirements. PV systems are available on flexible modules

and can be mounted on almost every surface to harness solar energy. Finally, we should

mention that, with the advance of technology, transparent and wearable PV systems are not

far.

Bibliography

[1] www.ncsc.ncsu.edu.

[2] http://www.kewsolar.co.uk/techinfo/panels.aspx

[3] http://lightbysolar.co.uk/solar-water-pumps-irrigation-water-purifier/

[4] http://www.amerescosolar.com/solar-power-cathodic-protection