How to Use Solar
Throughout history, people have taken advantage of sunshine for warmth and light. Early methods were primitive, but effective, letting the sun shine into buildings for light and heat.
As building design became more sophisticated, the layout and the windows were especially designed to glean the most benefit from solar energy during the cold months of the year. During the warm months the building was designed to be shielded from the unwanted heat.
Modern technology has taken the use of solar energy to new levels.
Energy from the sun can provide either heat or electricity. Each of these uses a completely different technology.
Solar Energy as Heat
We are most familiar with the idea of the sun providing heat – we feel it’s warmth on our skin on a clear summer day. We pick up a garden hose that has been lying in the sun and find that the water pouring from it is hot, an idea that has been used to make simple camp showers.
The heat from the sun can be used to help heat your home — or any building, for that matter — by making good design choices. The idea behind the design is to use the heat from the sun shining in the windows to provide a large percentage of the heating needs. Storage masses inside the buildings, such as concrete floors and brick or stone accent walls, hold the heat for overnight and moderate the daily temperature. In the summer, overhangs, balconies and awnings shield the windows from the high summer sun, keeping the building temperature moderate. This design method is called Passive Solar Design and is called passive because it does not require any solar panels or other hardware – only good design.
The principle of the garden hose is used in high tech solar hot water collectors that will provide solar heating of your domestic hot water and can also assist with in floor heating. A solar hot water collector is a large shallow insulated box with a tempered glass front and copper tubing inside. The tubing is filled with water in warm climates where it never freezes and with an antifreeze solution such as glycol in colder climates. The fluid in the tubing is heated by the sun and then goes through a heat exchanger to heat water in a tank for your showers, laundry and dishes.
It can also heat the fluid that circulates in radiant in floor heating providing some of the heating needed for the winter. Because days are typically shorter in the winter, solar cannot provide all of the heating needed for a building in very cold, northern climates.
Besides these so-called “flat plate collectors”, there are many sophisticated types of solar hot water collectors. One type is the evacuated tube collector that uses vacuum as an ideal insulator to keep the heat inside the tube and prevent it from escaping into the outside air. This system can be more efficient for very cold climates.
Solar Energy as Electricity
Modern technology can also convert solar energy to electricity. The most common way to do this is to convert sunlight to electricity with photovoltaic cells. These cells, usually made of a thin semiconductor material, are connected together as solar panels in a frame and usually with a tempered glass cover to protect them from damage. It is these thin solar panels that most people are used to seeing on homes and for the many solar powered gadgets such as lights and calculators.
The amount of electricity that is produced depends on the size of the panel or array of panels and the amount of sunlight that is received. How many solar panels you need to operate your home, for example, will depend on how much electricity you use and the sunlight available in your area.
Another way that electricity is produced from solar energy is through wind power. We don’t usually think of this as solar power, but the wind is caused by the differential heating of the earth and the atmosphere by the sun. Wind turbines convert the energy in the wind to electricity through a generator. They have a basic cut-in wind speed, usually 7 mph, below which no power is produced although the propellors are spinning. Once above the cut-in wind speed, every time the wind speed doubles the power output increases 8 times.
Why Use Solar Energy?
The big advantage of solar energy in its various forms is that the “fuel” – sunshine or wind – is free, abundant, renewable and pollution free. The challenges that still need to be overcome are to reduce the cost of the initial equipment to make it cost competitive with other forms of energy and to reduce pollutants in the manufacturing and recycling process for the components.
Solar and wind energy are hot research topics and advances are made daily. These technologies will become more and more common in everyday life.