How Solar Panels Work

What exactly is solar power?

By Barbara Young from

Solar power is radiant energy that's produced by the sun. Every day the sun radiates, or sends out, a huge volume of energy. The sun radiates more energy in a single second than people have used since the beginning of time!

The energy of the Sun comes from within the sun itself. Like other stars, the sun is mostly a big ball of gases - mostly hydrogen and helium atoms.

The hydrogen atoms in the sun's core combine to create helium and generate energy in a process called nuclear fusion.

During nuclear fusion, the sun's extremely high pressure and temperature cause hydrogen atoms to come apart and their nuclei (the central cores of the atoms) to fuse or combine. Four hydrogen nuclei fuse to become one helium atom. But the helium atom contains less mass compared to four hydrogen atoms that fused. Some matter is lost during nuclear fusion. The lost matter is emitted into space as radiant energy.

It requires many years for the energy in the sun's core to make its way to the solar surface, and then just a little over eight minutes to travel the 150 million kilometres to earth. The solar energy travels to the earth at a speed of 300,000 kilometres per second, the velocity of light.

Simply a small percentage of the energy radiated by the sun into space strikes the earth, one part in two billion. Yet this amount of energy is enormous. Daily enough energy strikes the USA to provide the nation's energy needs for one and a half years!

0.5% of the world's desert areas can provide all of mankind's present power needs – 15 trillion watts.

About 15 percent of the sun's energy which hits our planet is reflected back into space. Another 30 percent is used to evaporate water, which, lifted into the atmosphere, produces rainfall. Solar energy is absorbed by plants, the land, and the oceans. The remaining could be employed to supply our energy needs.

Who invented solar power?

Folks have harnessed solar power for centuries. Since the 7th century B.C., people used simple magnifying glasses to concentrate the light of the sun into beams so hot they'd cause wood to catch fire. Over a century ago in France, a scientist used heat from a solar collector to make steam to drive a steam engine. In the beginning of this century, scientists and engineers began researching ways to use solar technology in earnest. One important development was obviously a remarkably efficient solar boiler introduced by Charles Greeley Abbott, a United States astrophysicist, in 1936.

The solar water heater gained popularity at this time in Florida, California, and the South-west. The industry started in the early 1920s and was in full swing just before the second world war. This growth lasted prior to the mid-1950s when low-cost natural gas took over as primary fuel for heating American homes.

The public and world governments remained largely indifferent to the possibilities of solar energy prior to the oil shortages of the1970s. Today, people use solar energy to heat buildings and water and also to generate electricity.

How we use solar power today?

Solar power is used in a number of different ways, of course. There are two simple kinds of solar power:

Solar thermal energy collects the sun's warmth through one of two means: in water or in an anti-freeze (glycol) mixture.

Solar photovoltaic energy converts the sun's radiation to usable electricity.

Here are the five most practical and popular methods solar power is employed:

1. Small portable solar photovoltaic systems. We see these used everywhere, from calculators to solar garden products. Portable units can be used for everything from RV appliances while single panel systems are used for traffic signs and remote monitoring stations.

2. Solar pool heating. Running water in direct circulation systems through a solar collector is an extremely practical method to heat water for your pool or hot tub.

3. Thermal glycol energy to heat water. In this method (indirect circulation), glycol is heated by natural sunlight and the heat is then transferred to water in a warm water tank. This process of collecting the sun's energy is much more practical now than in the past. In areas as far north as Edmonton, Alberta, solar thermal to heat water is economically sound. It can pay for itself in 36 months or less.

4. Integrating solar photovoltaic energy into your home or business power. In most parts of the world, solar photovoltaic is an economically feasible solution to supplement the power of your home. In Japan, photovoltaics are competitive with other forms of power. In America, new incentive programs make this form of solar power ever more viable in many states. A frequent and practical method of integrating solar energy into the power of your home or business is through the usage of building integrated solar photovoltaics.

5. Large independent photovoltaic systems. If you have enough sun power at your site, you could possibly go off grid. You may also integrate or hybridise your solar power system with wind power or other types of renewable energy to stay 'off the grid.'

Pro Solar Arguments

- Heating our homes with oil or propane or using electricity from power plants running with oil and coal is a reason for climate change and climate disruption. Solar power, on the contrary, is clean and environmentally-friendly.

- Solar hot-water heaters require little maintenance, and their initial investment can be recovered in just a relatively short time.

- Solar hot-water heaters can work in almost any climate, even in very cold ones. You just have to choose the right system for your climate: drain-back, thermosyphon, batch-ICS, etc.

- Maintenance costs of solar powered systems are minimal and the warranties large.

- Financial incentives (USA, Canada, European states…) can reduce the price of the first investment in solar technologies. The U.S. government, for instance, offers tax credits for solar systems certified by the SRCC (Solar Rating and Certification Corporation), which amount to 30 percent of the investment (2009-2016 period).

Con Solar Arguments

- The initial investment in Solar Hot water heaters or in Solar PV Electric Systems is higher than that required by conventional electric and gas heaters systems.

- The payback period of solar PV-electric systems is high, as well as those of solar space heating or solar cooling (only the solar warm water heating payback is short or relatively short).

- Solar water heating do not support a direct combination with radiators (including baseboard ones).

- Some air cooling (solar space heating and the solar cooling systems) are costly, and rather untested technologies: solar ac isn't, till now, a truly economical option.

- The efficiency of solar powered systems is rather influenced by sunlight resources. It's in colder climates, where heating or electricity needs are higher, that the efficiency is smaller.