solar system

Solar Energy

Introduction

Usage Projection

      The problem what the world is facing nowadays  is  the  energy  problem. So, everyone should create  awareness  about solar energy because  Government  is  also  planning  to  do  a  lot  of awareness  regarding  the  renewable  energy. In Malaysia there are a lot of organization organizing green campaign such as Environmental Protection Society Malaysia (EPSM), Malaysia Environment NGOs (MENGO) and Treat Every Environment Special Sdn Bhd (TRESS). Hopefully in the future, solar energy would be the world’s largest source of electricity.

Consumption of Solar Energy

Solar panels

 Longyangxia Dam Solar Park

TWO MAIN CATEGORIES

1) Solar Thermal                                                                                   

Water heating and cooking  

2) Solar Photovoltaic (PV)

                                         

Electricity production

Solar Thermal Energy

Cooking

Water Heating

Solar Water Heating

How Does it Work?

Solar Photovoltaic (PV)

Solar Electric System

•Photovoltaic (PV) systems convert light energy directly into electricity. 

•Commonly known as “solar cells.”

•The simplest systems power the small calculators we use every day. More complicated systems will  provide a large portion of the electricity in the near future. 

•PV represents one of the most promising means of maintaining our energy intensive standard of living while not contributing to global warming and pollution.

How Does it Work? 

•Sunlight is composed of photons, or bundles of radiant energy. When photons strike a PV cell, they may be reflected or absorbed (transmitted through the cell). Only the absorbed photons generate electricity. When the photons are absorbed, the energy of the photons is transferred to electrons in the atoms of the solar cell.

How Does it Work?

Solar Energy

Passive Solar Energy

Passive solar energy designs use the energy from the sun to heat, cool, and illuminate our buildings. This is called passive solar design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices. Passive systems do not use mechanical devices such as fans, blowers, or pumps to distribute solar heat from a collector. In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer.

Passive systems can be categorized into three types:

·         Direct Gain - Allows the solar energy to come in through the south-facing window panes.

·         Indirect Gain - Allows the solar radiation to heat a wall and then the energy is slowly delivered into the interior of the house. Openings in the wall (called a Trombe Wall), as shown in the figure below, promote convective currents:

o    Cold room air enters the space between the glass panel and the wall through the bottom opening.

o    As this cold air gets heated, it rises to the top and comes in through the top opening.

·         Greenhouse Addition - An attached sunspace and/or solar greenhouse heated by the solar energy - where some of the energy is used to grow the plants and some of it is used to heat the interior of the house.

HOW PASSIVE SOLAR HEATING WORKS

  Solar radiation is trapped by the greenhouse action of correctly oriented (north-facing) glass areas exposed to full sun. Window orientation, shading, frames and glazing type have a significant effect on the efficiency of this process.

   Trapped heat is absorbed and stored by materials with high thermal mass (usually masonry) inside the house. It is re-released at night when it is needed to offset heat losses to lower outdoor temperatures.

   Passive solar heating is used in conjunction with passive shading, which allows maximum winter solar gain and prevents summer overheating. This is most simply achieved with northerly orientation of appropriate areas of glass and well-designed eaves overhangs.

   A diagram shows how to maximise passive solar heating in the home. Internal walls should be well insulated. There should also be good roof and ceiling insulation. The home should be able to avoid hot summer and cold winter winds. Deciduous trees are good for sun control, and when the sun is lower in winter, allows maximum sun penetration; but during summer, the tree’s foliage blocks the height of the summer sun.

   Re-radiated heat is distributed to where it is needed through good design of air flow and convection. Direct re-radiation is most effective but heat is also conducted through building materials and distributed by air movement. Floor plans should be designed to ensure that the most important rooms (usually day-use living areas) face north and receive the best winter solar access.

   Heat loss is minimised with appropriate window treatments and well-insulated walls, ceilings and raised floors. Thermal mass (the storage system) must be insulated to be effective. Slab-on-ground edges should be insulated in colder climates, or when in-slab heating or cooling is installed within the slab.

PASSIVE SOLAR DESIGN PRINCIPLES

Greenhouse (glasshouse) principles

  

   Passive design relies on greenhouse principles to trap solar radiation.Heat is gained when short wave radiation passes through glass, where it is absorbed by building elements and furnishings and re-radiated as long wave radiation. Long wave radiation cannot pass back through glass as easily.

   A cross-section of a sunny room is shown. Short wave radiation passes through glass and is absorbed by materials inside. The long wave radiation is trapped inside, and is re-radiated around the room. Solar heat gain through standard 3mm glazing. Heat is lost through glass (and other building materials) by conduction, particularly at night. Conductive loss can be controlled by window insulation treatments such as close fitting heavy drapes with snug pelmets, double glazing and other advanced glazing technology.

 Active Solar Energy

    Active solar systems are those which collect solar radiation and convert it in the form of heat to water, air, or some other fluid. A solar collector positioned on the roofs of buildings heats the fluid and then pumps it through a system of pipes to heat the whole building. The most common application of these systems is the production of domestic hot water, known to all as solar water heaters. Solar radiation is absorbed by the collector and the heat collected is transferred to the storage vessel. Besides, active solar systems can be used anywhere low temperature heat is needed.

Advantages of solar heating system

1. Renewable Energy Source

Among all the benefits of solar panels, the most important thing is that solar energy is a truly renewable energy source. It can be harnessed in all areas of the world and is available every day. We cannot run out of solar energy, unlike some of the other sources of energy. Solar energy will be accessible as long as we have the sun, therefore sunlight will be available to us for at least 5 billion years when according to scientists the sun is going to die.

2. Reduces Electricity Bills

Since you will be meeting some of your energy needs with the electricity your solar system has generated, your energy bills will drop. How much you save on your bill will be dependent on the size of the solar system and your electricity or heat usage. Moreover, not only will you be saving on the electricity bill, but if you generate more electricity than you use, the surplus will be exported back to the grid and you will receive bonus payments for that amount (considering that your solar panel system is connected to the grid). Savings can further grow if you sell excess electricity at high rates during the day and then buy electricity from the grid during the evening when the rates are lower.

3. Diverse Applications

Solar energy can be used for diverse purposes. You can generate electricity (photovoltaics) or heat (solar thermal). Solar energy can be used to produce electricity in areas without access to the energy grid, to distill water in regions with limited clean water supplies and to power satellites in space. Solar energy can also be integrated into the materials used for buildings. Not long ago Sharp introduced transparent solar energy windows.

4. Low Maintenance Costs

Solar energy systems generally don’t require a lot of maintenance. You only need to keep them relatively clean, so cleaning them a couple of times per year will do the job. If in doubt, you can always rely on specialised cleaning companies, which offer this service from around £25-£35. Most reliable solar panel manufacturers give 20-25 years warranty. Also, as there are no moving parts, there is no wear and tear. The inverter is usually the only part that needs to changed after 5-10 years because it is continuously working to convert solar energy into electricity (solar PV) and heat (solar thermal). Apart from the inverter, the cables also need maintenance to ensure your solar power system runs at maximum efficiency. So, after covering the initial cost of the solar system, you can expect very little spending on maintenance and repair work.

 5. Technology Development

Technology in the solar power industry is constantly advancing and improvements will intensify in the future. Innovations in quantum physics and nanotechnology can potentially increase the effectiveness of solar panels and double, or even triple, the electrical input of the solar power systems.

Disadvantages of solar heating system

1. Cost

The initial cost of purchasing a solar system is fairly high. Although the UK government has introduced some schemes for encouraging the adoption of renewable energy sources, for example, the Feed-in Tariff, you still have to cover the upfront costs. This includes paying for solar panels, inverter, batteries, wiring and for the installation. Nevertheless, solar technologies are constantly developing, so it is safe to assume that prices will go down in the future.

2. Weather Dependent

Although solar energy can still be collected during cloudy and rainy days, the efficiency of the solar system drops. Solar panels are dependent on sunlight to effectively gather solar energy. Therefore, a few cloudy, rainy days can have a noticeable effect on the energy system. You should also take into account that solar energy cannot be collected during the night. On the other hand, if you also require your water heating solution to work at night or during wintertime, thermodynamic panels are an alternative to consider.

3. Solar Energy Storage Is Expensive

Solar energy has to be used right away, or it can be stored in large batteries. These batteries, used in off-the-grid solar systems, can be charged during the day so that the energy is used at night. This is a good solution for using solar energy all day long but it is also quite expensive. In most cases, it is smarter to just use solar energy during the day and take energy from the grid during the night (you can only do this if your system is connected to the grid). Luckily our energy demand is usually higher during the day so we can meet most of it with solar energy.

 

4. Uses a Lot of Space

The more electricity you want to produce, the more solar panels you will need because you want to collect as much sunlight as possible. Solar panels require a lot of space and some roofs are not big enough to fit the number of solar panels that you would like to have. An alternative is to install some of the panels in your yard but they need to have access to sunlight. Anyways, if you don’t have the space for all the panels that you wanted, you can just get a fewer and they will still be satisfying some of your energy needs.

5. Associated with Pollution

Although pollution related to solar energy systems is far less compared to other sources of energy, solar energy can be associated with pollution. Transportation and installation of solar systems have been associated with the emission of greenhouse gases. There are also some toxic materials and hazardous products used during the manufacturing process of solar photovoltaics, which can indirectly affect the environment. Nevertheless, solar energy pollutes far less than the other alternative energy sources.