Solar panel efficiency is the ratio of electrical output from a module as compared to the total energy input derived from sunlight. The ratio is in percentage form and portrays the amount of energy expected from a panel when it is exposed to Solar Energy.
What is available today are natural sunlight units that are capable of converting between 6% and 20% of the total solar energy that they are exposed to. A module that has an efficiency level of 9% is expected to yield 9 parts for every 100 that goes through the Photovoltaic cells for example.
It may seem obvious that the best choice is purchasing the modules which are more energy efficient but cost and other factors may be limiting. The cheaper ones may in fact make some economic sense when you consider the cost per watt of some of the more expensive choices.
The manufacturers have no choice in this really. This is because production of photovoltaic (PV) cells such crystalline silicon, which is more energy productive, is an expensive affair. That is the reason why some factories opt to make modules having thinner cells of solar-grade silicon even if cutting reduces the energy conversion ratio.
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.
In other scenarios the headache is not space nor purchase price but functionality. In places where the sun shines down throughout the year one may make do with the cheaper versions but this may not suffice where it snows heavily. If an area is covered by power lines one might want to calculate the cost per watt if they chose to go solar so as to determine what is worth buying and after how long they are going to recover their cost.
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.
However, the question still remains of how to easily and affordably produce solar-standard semiconductors with energy conversion rates of 80% or more. Scientists believe that nanotechnology is the answer and some prototypes are working to some degree in laboratories. Nanotechnology is also dealing with the loss of electrical power that has always occurred in the transfer and conversion of the captured energy from DC to AC by use of micro-inverters.
Scientists are scratching their heads in many laboratories across the world and every now and again you will hear that this or that facility has come up with a novel idea to beat these problems. What now remains to be done is for an efficient concept to be commercialized at a cost that achieves parity with other energy sources such as nuclear.
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