Solar energy is the radiant energy produced by the Sun. It is both light and heat. It, along with secondary solar-powered resources such as wind and wave power, account for the majority of the renewable energy on Earth.

The Earth receives 174 petawatts(PW) of solar radiation at the upper atmosphere. 30% of that is reflected back to space and the rest is absorbed by clouds, oceans and land masses. Land surfaces, oceans, and atmosphere absorb solar radiation, which increases their temperature. Warm air containing evaporated water from the oceans rises, causing convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds and causes rain. The latent heat of water condensation increases convection, producing wind.

Incoming Solar Energy

The total solar energy absorbed by Earth’s atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year. In 2002, this was more energy in one hour than the world used in one year. Photosynthesis captures approximately 3,000 EJ per year in biomass. The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth’s non-renewable resources of coal, oil, natural gas, and mined uranium combined.

Energy absorbed by the oceans and land masses keeps the surface at an average temperature of 14°C. Green plants convert solar energy into chemical energy through photosynthesis. Our food supply is completely dependent on solar energy. After plants die, they decay in the Earth, so solar energy can be said to provide the biomass that has created the fossil fuels that we are dependent on.

Humans harness solar energy in many different ways: space heating and cooling, the production of potable water by distillation, disinfection, lighting, hot water, and cooking. The applications for solar energy are only limited by human ingenuity. Solar technologies are characterized as either passive or active depending on the way the energy is captured, converted, and distributed. Active solar techniques use photovoltaic panels and solar thermal collectors to harness the energy. Passive techniques include orienting a building to the Sun, selecting materials with thermal mass properties, and using materials with light dispersing properties.

Our current dependence on fossil fuels is slowly being replaced by alternative energies. Some are fuels that may eventually become useless, but solar energy will never be obsolete, controlled by foreign powers, or run out. Even when the Sun uses up its hydrogen, it will produce useable energy until it explodes. The challenge facing humans is to capture that energy instead of taking the easiest way out by using fossil fuels.

PV Applications & Types

Sunlight is abundant and it is everywhere. More and more emphasis on the use of this abundant energy source has led to the maximum development in this field. The solar energy can be utilized through various means form building concentrating solar power systems, photovoltaic, solar heating systems , solar cars, solar batteries, solar satellite systems , solar updraft power houses and solar lighting systems. Concentrate solar power systems use mirrors and lenses to store light and heat carrying photons. Photovoltaic effect can be used by deploying solar cells. Solar lighting system can be used by designing the architecture to support day lighting procedure. Solar lighting reduces the load and dependence on electric lighting systems. Solar cars contain e solar panels installed on the roof top of the car. These solar panels convert the sunlight into electric charge and furthermore it can be stored into battery to be used later on. Solar updraft power plants are another addition in the application of the solar energy. These power houses are designed to support the heating of air through sunrays. This hot air rises to the tower and then it runs the turbines to support electricity generation. Solar power satellite is an expensive way to produce electricity form unhindered sunlight day and night.

Solar Power Systems

Depending upon your needs and where you live, there are a variety of solar power systems that could work for you.

: Solar Power System

Solar Power Systems – Grid-Tied (On Grid)

Most people install grid-tied solar power systems -most often in cities, suburbs and industrial areas where access to utility-generated power is available. You can supplement your solar powered electricity with utility-generated energy if you use more electricity than the solar power system supplies.

When your solar power system produces more electricity you need, you can sell the excess to the PG&E, who delivers the clean, renewable energy to other customers. Consequently, the good you do for the environment doesn’t stop at your home or office. Even neighbors without solar power can draw upon the renewable energy of the sun – while you bank credit to offset the utility-generated power you use at night.

: Grid Tied Solar Power System

Solar Power Systems – Grid-Tied with Battery Backup

Solar energy panels combined with batteries and generators for grid-tie applications couple the clean, power supplied by solar panels with the assurance that you will have electricity even during power outages that last for extended periods. During the day, the solar panels generate electricity as needed and charges batteries. If more power is required, or the batteries begin to run low, the natural gas or propane generator kicks in to recharge the batteries. It automatically shuts off when the batteries are fully charged.

: Grid Connected with Battery Bank

Solar Power Systems – Off-Grid

Standalone, or off-grid, solar power systems consist of solar panels and a battery bank. They are typically used in rural areas and regions where there is no access to the utility grid. They may also be appropriate where the grid is somewhat close to the site, but expensive to bring in – for example, across a neighbor’s property. We have installed a number of systems with battery back-up where the grid is available but where the homeowner has experienced unreliable power in the past or believes that he/she will be subject to power outages in the future. We have seen a number of property owners install battery back-up system just for philosophical reasons, for the desire to be independent of the grid and the “gaming” to which utility companies and their power suppliers have subjected customers in the past.

It may cost you as high as $50 per foot to bring utility power to your property, after which you’ll continue to pay for power forever. It’s often less expensive to add a solar energy system from the start and be your own power company. You can add the solar power system cost to your mortgage, reducing the combined costs of mortgage and utility bills.

When your off-grid solar power system produces excess electricity during the day, it is used to charge the batteries. When the sun’s not shining, electricity is drawn from the batteries to power the home or business. The advantage is greater independence for you. The disadvantage is greater complexity and cost.

Solar Power System – Direct DC

Simple, direct DC solar power systems produce energy where and when it’s needed. Common uses include powering water pumps and fans. There is no complex wiring, so storage and control systems aren’t required. Small systems are easy to transport and install.

: Solar Power Solutions (DC System)

Hybrid Power Systems

Hybrid power systems combine various sources of electrical generation, and are well suited for electrification. Solar and wind technologies are modular, and seasonal variations of sun and wind often complement each other.