Solar is the Latin word for sun -a powerful source of energy that can be used to heat, cool, and light our homes and businesses. That’s because more energy from the sun falls on the earth in one hour than is used by everyone in the world in one year. The amount of solar energy that the earth receives each day is many times greater than the total amount of energy consumed around the world. However, solar energy is a variable and intermittent energy source. The amount and intensity of sunlight varies by location, and weather and climate conditions affect its availability on a daily and seasonal basis. The type and size of a solar energy collection and conversion system determines how much of available solar energy can be converted into useful energy.
Common uses for solar technology
The most commonly used solar technologies for homes and businesses are solar water heating, passive solar design for space heating and cooling, and solar photovoltaics for electricity. Two main types of solar energy systems are in use today: photovoltaics, and thermal systems. Let’s look at the difference between two systems.
How Solar Technology is Used
Solar thermal systems seek to store heat from the sun that can be used for a variety of purposes. It is most often used for heating water in homes and in swimming pools. It is also used to heat the insides of buildings. Solar heating systems can be classified as passive or active.
Passive Solar Heating System
Passive space heating happens in a car on a hot summer day.The sun’s rays pass through the windows and heat up the inside of the car. In passive solar heated buildings, air is circulated past a solar heat-absorbing surface and through the building by natural convection. No mechanical equipment is needed for passive solar heating.
Active Solar Heating System
Active heating systems use a collector and a fluid to collect and absorb solar radiation. Fans or pumps circulate air or heat-absorbing liquids through collectors and then transfer the heated fluid directly to a room or to a heat storage system. Active water heating systems usually include a tank for storing water heated by the system.
Photovoltaics
Solar photovoltaics (PV) systems can be built to meet almost any electric power need, small or large. A PV cells convert sunlight directly into electricity. A PV cell is a nonmechanical device usually made from silicon alloys. An individual PV cell is usually small, typically producing about 1 or 2 watts of power. To boost the power output of PV cells, they are connected together to form larger units called modules. Modules, in turn, can be connected to form even larger units called arrays, which can be interconnected to produce more power, and so on.
Simple PV systems provide power for small consumer items such as calculators and wristwatches. More complicated systems provide power for communications satellites, water pumps, and the lights, appliances, and machines in some homes and workplaces. Many road and traffic signs also are now powered by PV. In many cases, PV power is the least expensive form of electricity for these tasks.
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