Solar Thermal Versus Solar PV
If you think about it, the sun is the source of most of the power on earth. It is ultimately the sun that causes tidal waves, wind and even carries water to heights that it can then later be converted to hydroelectricity as it falls. In fact, even fossil fuels are nature’s way of storing solar energy.
What solar panels do is use the sun’s energy directly to create power. Therefore the basic principle of all solar panels, be they Solar Thermal or Solar PV, is the same. However the way they do it, is different. While in the case of Solar PV, the sun’s energy is used via a photo voltaic cell to generate electricity. In the case of thermal panels, the heat from the sun is used directly to heat fluids – be it air or water – directly. But which one do you need to use? Well, let us take a closer look at these technologies to understand which one fits our needs best.
Solar thermal has been around for ages. In fact it was first used in 1910 when sunlight was used to heat water to produce steam which went on to run a steam engine.
Let us see how this works. In these devices, sunlight is concentrated to create heat. This heat is then used to power a heat engine. This then generates electricity.
The fluid that is heated up with the Solar Thermal Generator is called a working fluid and can be water, oil, air, nitrogen, helium or salts. There are many different kind of engines including gas turbines, steam engine and stirling engines.
ADVANTAGES OF SOLAR THERMAL ENGINES
EFFICIENT: No matter which type of Solar Thermal Engine you choose, you can be assured of quite high efficiency – about 30 to 40%.
POWERFUL: Solar Thermal Engines can be used to produce quite high volumes of power, sometimes up to hundreds of megawatts.
COMPACT: The main reason why most people opt for a Solar Thermal System is that it takes up far less space. For instance where a photo voltaic system would need ten square meters, the Solar Thermal System would need only three to four square meters. This is because the Solar Thermal Systems are also extremely efficient in converting solar energy into thermal energy. In most cases about 90% of the sunlight is converted as compared to photo voltaic systems where only twenty percent is converted.
As the Solar Thermal Systems convert Solar Energy into heat, the PV systems use a Photo Voltaic reaction to absorb the sunlight and convert it into electricity.
There are essentially three types of Photo Voltaics.
SILICON PHOTO VOLTAICS: This is the most common and traditional form of Photo Voltaic. Most PVs are manufactured using silicon.
THIN FILM PV: These are very popular in industrial application. In these, an extremely thin film of photo voltaic material is coated over another material – glass, plastic or metal.
CONCENTRATED PV: Concentrated Photo Voltaics concentrate the solar energy from a large area into a smaller area. This is done using either lenses or mirrors.
ADVANTAGES OF SOLAR PHOTO VOLTAICS
REDUCING COSTS: There was a time when PV was much more expensive than Solar Thermal Systems. However, in the recent years, PV technology has become almost as inexpensive. In addition, most governments offer huge incentives to the users of PV technology.
GENERATES ELECTRICITY: Solar Thermal Systems produces heat which can only be used locally. PV systems however produce electricity. When produced in excess, it can then be sold off to the national grid.
ENVIRONMENT FRIENDLY: Some claims have been made that Solar Thermal Systems can cause bird deaths. Solar PV systems on the other hand are considered more environment friendly.
COMPARE SOLAR THERMAL WITH SOLAR PV: WHICH ONE’S BETTER?
Solar Thermals or Solar PV? The answer is pretty simple: it all depends on what your needs are. For instance, if you wish to use solar energy to provide hot water or heat your home, Solar Thermal is the best option.
On the other hand, if you wish to use solar energy to power your electrical appliances or to sell off, PV systems are a better bet, at least at the present time.
Many homeowners are nowadays opting for a mixture of both these systems.