In a recent post, titled solar basis, I gave a quick overview on solar energy and its conversion into other, more useful, forms of energy (e.g. electricity). In this article however, I will delve a little into solar electric systems. But before I jump into it, I will briefly recap from that article what I think might be relevant here for those of you who did not read it as yet.
As outlined in the article, solar energy systems fall into two main categories: 1) solar thermal systems, which uses the thermal energy from the sun to heat a working fluid that in-turn can be used for heating and cooling in buildings (e.g. solar hot water heaters) or for electricity generation (e.g CSP’s) and 2) solar electric systems, which uses the concept of photoelectric to convert the light (irradiation) from the sun directly into electricity (e.g. photovoltaic cells). The later
is of interest here and thus from here on out will be referred to as solar photovoltaic (PV) systems.
The main components of a solar PV system is the PV Cells, which are grouped together to form a single PV Module. In solar installations several of these PV modules are typically connected (in series) to form an Array, as show in the diagram that follows.
The PV cells themselves are semiconductor electronic devices that convert the sunlight directly into electricity and thus forms the heart of a solar PV power generation system. The modern form of the PV cell was invented in 1954 at Bell Telephone Laboratories.
Currently, solar PV systems are one of the most “democratic” renewable technologies available. This is as a result of their modular size, which puts them within the reach of individuals and small-businesses who want to access their own power generation and lock-in electricity prices.
Solar PV technology offers a number of significant benefits, including:
- Solar power is a renewable resource that is available everywhere in the world.
- Solar PV technologies are small and highly modular and can be used virtually anywhere, unlike many other electricity generation technologies.
- Unlike conventional power plants using coal, nuclear, oil and gas; solar PV has no fuel costs and relatively low operation and maintenance (O&M) costs. PV can therefore offer a price hedge against volatile fossil fuel prices.
- PV, although variable, has a high coincidence with peak electricity demand driven by cooling in summer and year round in hot countries.
A wide range of PV cell technology is now available on the market, using different types of materials. PV cell technologies are usually classified into three generations, depending on the basic material used and the level of commercial maturity:
- First-generation PV modules (fully commercial) uses a wafer-based crystalline silicon (c-Si) technology, either single crystalline (sc-Si) or multi-crystalline (mc-Si).
- Second-generation PV systems (early market deployment) are based on thin-film PV technologies and generally include three main families: 1) amorphous silicon (a-Si) and micromorph silicon (a-Si/μc-Si); 2) Cadmium-Telluride (CdTe); and 3) Copper-Indium-Selenide (CIS) and Copper-Indium-Gallium-Diselenide (CIGS).
- Third-generation PV systems include technologies, such as concentrating PV (CPV) and organic PV cells that are still under demonstration or have not yet been widely commercialised, as well as novel concepts under development.
On average a PV cells life expectancy is 25 years and the cells are able to harness both direct and diffuse radiation from the sun. The amount of energy harnessed depends on the type of semiconductor material used in the solar cells, ambient operating temperature, cloud cover, shading, tilt angle and the direction in which the PV modules are installed. As the earth rotates continuously, PV cells which have sun ‘tracking’ capability are able to harness more energy. Jamaica and Barbados is located 18 and 13 degrees north of the equator respectively, thus it is a recommended best practice to install PV modules facing south at an angle of 18 and 13 degrees respectively.
Some simple questions to ask yourself before investing in Solar Energy:
- How readily available is the natural resource – sunshine? How readily can you access it – shading etc?
- Why are you interested in implementing a solar PV system – high cost of electricity or you are environmentally conscious?
- What is the initial cost of implementing a solar PV system in your area – total cost and the cost of the individual components?
- What is the maintenance requirements of your system of choice and estimated cost to maintain it?
- Where can you install your PV system – on the roof or in your yard?
- What is the warranty periods offered on PV modules, and other components of the system?
- What are the impacts on the natural environment? Will it reduce your carbon footprint or contribute to other environmental issues?
The answers to most of the questions are pretty much straight forward. My final line to you is that solar PV is one of the fastest growing renewable energy technologies today and it is expected that it will play a major role in future global electricity generation mix. So embrace your future today, by making steps to start generating your own electricity as the sun shines!
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