Solar panel efficiency is a percentage of the solar energy that is converted into electrical power by a module. In other words, it is the rate at which a panel can utilize the amount of energy that it receives from the sun by transforming it into voltage.
The efficiency of say 9% would mean that a module sources 90 watts for every 1000 watts that go through its photovoltaic cells from sunlight. In the market today, solar units are available with energy conversion rates of between 6% and 20% or a little more.
Incidentally, the choice between the highest or the lowest energy conversion ratio is not that simple. The cost of those modules that are more productive is always higher than those with lower conversion rates. The cheap inefficient ones however may have the benefit of having a lower cost per watt as compared to the more efficient ones.
Manufacturing costs are to blame for this situation for it is really expensive to make quality solar cells. Over the years, one of the most productive materials has been crystalline silicone. However, due to the cost of manufacture some electronic companies result to slicing the silicon rods to make a thin film which is a cheaper method but it compromises the energy conversion ratio of the module.
Such a sheet of thinly assembled cells can be widened to expose a larger surface area to the sun and harness more energy and counter the energy efficiency problem. However, this has a disadvantage because space is a limited resource. Where every inch counts on the roof one may opt to buy the more compact alternatives regardless of the cost especially if one really needs the power.
Sometimes the problem is not that clear cut for more factors may be at play when choosing which way to go. An area where there is an abundance of sunlight solar energy is more productive even with modules that have lower energy conversion rates. Where other sources of energy are available it is good to compare the cost per watt and establish how many years it will take to recover the cost of installation.
If an area is not anywhere near the power lines, someone may decide to bite the bullet and buy the expensive modules so as to maximize the output. From an economic point of view this may even be worthwhile even after considering the cost per watt because the modules often last for periods ranging from 20 to 30 years during which return on investment will already have occurred.
For the time being however the problem still persists of how to make cheap semiconductors that can be applied in solar technology with efficiencies of around 80%. Experiments are being conducted using nanotechnology which many believe will provide those answers. Other problem areas such as current conversion and transfer are also being handled using nanotechnology. Micro-inverters have been developed for example that convert DC to AC right at the panel.
Much is being done but a lot is needed from science to provide a way that will transform solar energy to a power source that can compete adequately with options such as nuclear. Innovations are coming up and scientists claim that it is possible to obtain cost parity in the near future. [youtube:MQCTwqzx9Wo?fs=1;Solar Products [link:online];http://www.youtube.com/watch?v=MQCTwqzx9Wo?fs=1&feature=related]
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