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Ques: How does sunlight affect life on Earth?
Ans: The energy from the Sun is critical to all life on Earth. Evolutionary scientists have shown that the Sun's energy played an essential role in 'spontaneous generation', whereby the very first single-cell amoebae split and developed into more complex lifeforms. Plants require sunlight for the process of photosynthesis or the production of sugars, and a by-product of the photosynthetic process is cellular respiration, which releases the oxygen that we must have to stay alive. All types of animals, including humans, also rely on the Sun's heat to maintain body temperatures and sustain life. Thankfully, the Sun has sufficient helium mass to provide the Earth with energy for another 5 billion years.
Ques: How do we get electricity from the sun?
Ans: Sunlight is made up of small particles of energy called photons. Photovoltaic (PV) systems use semi-conducting materials such as silicon to absorb some of these photons and transfer them to electrons. This process is known as the photoelectric effect and it is the basic physical process by which PV cells convert sunlight to electricity. Special electrical properties of the Photovoltaic cell provide the voltage needed to drive the current through an external load (such as a light bulb).
Ques: What does energy conversion efficiency mean?
Ans: Energy conversion efficiency is an expression of the amount of energy produced in proportion to the amount of energy consumed, or available to a device. The Sun produces a lot of energy in a wide light spectrum, but we have so far learned to capture only small portions of that spectrum for conversion to electricity using photovoltaics. Today's commercial PV systems are about 7% to 17% efficient. By comparison, a typical fossil fuel generator has an efficiency of about 28%. However, some experimental PV cells now convert nearly 40% of the energy in sunlight to electricity.
Ques: What does photovoltaic (PV) mean?
Ans: The word 'photovoltaic' essentially means electricity from the energy of sunlight. First used in about 1890, the word has two parts: photo, derived from the Greek 'phos' meaning light, and volt, a unit of measurement named for Alessandro Volta (1745-1827), a pioneer in the study of electricity.
Ques: How does PV differ from other solar energy technologies?
Ans: There are four main types of solar energy technologies:
  1. Photovoltaic (PV) systems, which convert sunlight directly to electricity by means of PV cells made of semiconductor materials.
  2. Concentrating solar power (CSP) systems, which concentrate the sun's energy using reflective devices such as troughs or mirror panels to produce heat that is then used to generate electricity.
  3. Solar water heating systems, which contain a solar collector that faces the sun and either heats water directly or heats a 'working fluid' that, in turn, is used to heat water.
  4. Transpired solar collectors, or 'solar walls', which use solar energy to preheat ventilation air for a building.
Ques: What are the components of a PV system?
Ans: A PV system is made up of several different components. These include groups of PV cells called 'modules' (also known as 'panels'); one or more batteries; a charge regulator or controller for a stand-alone system; an inverter for a utility-grid-connected system or when alternating current (AC) rather than direct current (DC) is required; wiring; and mounting hardware or a framework.
Ques: How long do PV systems last?
Ans: A PV system that is well designed, installed and maintained can operate for more than 20 years. The basic PV module has no moving parts and can last more than 30 years. The best way to ensure and extend the life and effectiveness of your PV system is by having it properly installed and well maintained.
Ques: Where are PV systems being used?
Ans: PV systems are generating clean power in a whole host of applications right across the world - from urban skyscrapers to remote villages in developing countries. PV electricity can be used to power all manner of household appliances, computing and communications equipment, water pumping and lighting. Cost-effective examples of lighting powered by PV include small garden lights, street lights, lighting for recreational areas, highway signs, warning signs and signals, and lighting for businesses and homes. Virtually any power need can be met with PV.
Ques: How does solar PV work?
Ans: Solar Photovoltaic (PV) panels are generally fitted on the roof in a northerly direction and at an angle to maximize the amount of sunlight that hits the panels.

Solar PV panels on the roofs of homes and businesses generate clean electricity by converting the energy in sunlight. This conversion takes place within modules of specially fabricated materials that make up the solar panels. It is a relatively simple process that requires no moving parts. In most cases solar panels are connected to the mains power supply through a device called an inverter. Solar panels are different to solar hot water systems, which are also mounted on household roof-tops but use the heat from the sun to provide hot water for household uses.

The technology to convert sunlight into electricity was developed in the 19th century, but it was only in the second half of the 20th century that development accelerated behind the need to provide reliable supplies of electricity in remote locations – from satellites in space to outback Australia.

Solar panels have been installed on the rooftops of houses and other buildings in Australia since the 1970s. Currently there are more than 100,000 solar panel systems safely and reliably delivering clean electricity across Australia

Ques: Grid-connected solar PV systems
Ans: Most suburban homes in Australia are connected to the electricity grid, which uses alternating current electricity (AC). But the electricity generated by solar panels is direct current (DC). That means grid-connected (GC) solar PV systems need an inverter to transform the DC electricity into AC electricity suitable for ordinary household needs. Houses with solar systems use solar power first before sourcing electricity from the grid. When the panels are not producing electricity at night, electricity is supplied from the existing electricity grid. For systems with a battery backup (optional), the inverter regulates the charge of batteries. The electricity stored in the atteries can be used at night or during lackouts.
Ques: How much power do they generate?
Ans: The output of a solar PV system depends on its size. The most common household systems are either 1 kilowatt (kW) or 1.5 kilowatts, although some property owners have installed systems of up to 10 kilowatts. The table below shows the average daily production of some common grid-connected systems throughout Australia.
Ques: What size solar PV system should I install?
Ans: size of your solar PV system will depend on:
  • The physical unshaded area available for the installation of your panels
  • How much you are prepared to spend
  • What portion of your electrical consumption you wish to generate.

To work out what size solar PV system you require, you need to analyse your household’s daily electricity consumption. Your monthly or quarterly electricity bill measures your household’s electricity consumption in kilowatt hours. From this figure, you can calculate your average daily electricity consumption, and the average amount of electricity your solar PV system needs to produce to cover your electricity needs.

This process will be completed by your accredited designer during the design and specification stage, as part of their load analysis.

Ques: What size panels should I buy?
Ans: Solar PV panels come in different wattages. The main issues are your budget and whether the solar panels will physically fit in the space you want to install them.

Each solar panel is approximately 1.6 metres long and 0.8 metres wide. A 1kW solar panel system will require around 8-10m² of roof space, and a 1.5kW solar panel system requires around 12 m². This will vary depending on the type of panel installed on your roof.

Ques: What angle should the solar panels be on?
Ans: Solar PV panels produce most power when they are pointed directly at the sun. In Australia, solar modules should face north for optimum electricity production. The orientation of the panels will often have a greater effect on annual energy production than the angle they are tilted at. A minimum tilt of 10° is recommended to ensure self cleaning by rainfall.

For grid-connected solar PV power systems, the solar panels should be positioned at the angle of latitude to maximise the amount of energy produced annually. Most Australian homes have a roof pitch of 20° to 30°.

If your roof’s slope is not ideal, your accredited designer can create an appropriate mounting frame to correct the orientation and elevation of your panel. Failing this, the designer can advise you on the difference in energy output for different tilt and orientation.

Ques: How much sunlight should the panels receive?
Ans: The amount of energy in sunlight that a solar PV panel receives over a day is expressed in peak sun hours. As the amount of energy generated by a panel is directly proportional to the amount of energy it receives from sunlight, it is important to install panels so they receive maximum sunlight.

Your accredited designer will calculate the amount of energy generated by the solar PV panel from the peak sun hours available. Peak sun hours vary throughout the year

Ques: How much space would be needed for PV systems to meet the entire world's electricity needs?
Ans: Contrary to some popular notions, the landscape of a world relying on PV would be almost indistinguishable from the landscape we know today. There are three reasons for this. First, PV systems have siting advantages over other technologies. They can be put on roofs and can even be an integral part of a building, such as a skylight. Second, even ground-mounted PV collectors are efficient from the perspective of land use. Flat-plate PV technology is the most land-efficient means to produce renewable energy. Third, adequate sunlight is ubiquitous and often abundant, and present in predictable amounts almost everywhere.

For example, in the United States, cities and residences cover about 140 million acres of land. The nation's energy requirements could be met simply by applying PV to 7% of this area - on roofs, on parking lots, along highway walls, on the sides of buildings, and in other dual-use scenarios. Not one single acre of new land would need to be appropriated to make PV the primary energy source.

Ques: Why should I use PV-generated electricity?
Ans: For a growing number of users, particularly those who are environmentally aware, PV is the clear choice. PV provides sustainable energy, operates silently, produces no toxic emissions or greenhouse gases, and causes no hazardous waste. PV systems generate electricity using the Sun's free energy, so the ongoing costs are minimal. Moreover, continued R&D means installation costs are gradually being reduced. Some people would rather invest capital on an energy-producing improvement to their property than continually send money to a power company. Others like the security of reducing the amount of electricity they buy from power utilities, because it makes them less vulnerable to power outages and future increases in the price of electricity.
Ques: Can I use PV to power my home?
Ans: PV can be used to power your entire home's electrical systems, including lights, cooling systems, and appliances. PV systems today can be blended easily into both traditional and non-traditional homes.
Ques: Can I use PV to power my business?
Ans: PV systems can be blended into virtually every conceivable structure for commercial buildings. You will find PV being used outdoors for security lighting as well as in structures that serve as covers for parking lots and bus shelters, generating power at the same time. Architects can use building-integrated PV to design buildings that are environmentally responsive, aesthetically pleasing, and produce their own power. Building-integrated PV provides a dual-use building material, reduces PV system costs by using the building as the mounting or support structure, and reduces utility bills through on-site power production.
Ques: How do I know if I have enough sunlight for PV?
Ans: A PV system needs unobstructed access to the sun's rays for most or all of the day. Climate is not really a concern because PV systems are relatively unaffected by severe weather. In fact, some PV modules actually work better in colder weather. There is enough sunlight to make solar energy systems useful and effective almost anywhere in the world. Most homes have adequate roof space for a PV system, and this can be complemented by integrating the system into walls or by using modules to cover a porch or patio in the backyard.
Ques: How big a PV system do I need?
Ans: The size of solar system you need depends on several factors-such as how much electricity or hot water or space heat you use, how much sunshine is available where you are, the size of your roof, and how much you're willing to invest. A PV system does not necessarily have to cover 100% of your energy needs. In most cases a PV system is connected to the grid so that the solar electricity generated is sold to the utility company and you continue to buy electricity as normal.
Ques: Are there disadvantages to using solar energy?
Ans: Solar energy technologies often have a higher initial cost outlay. This means that a person is likely to pay more money up front to purchase and install a solar system. Still, in nearly all cases, the high initial cost is recovered through substantial fuel savings over the life of the product (15-30 years).