Solar Energy System
For meeting temporary needs, solar power is the sole renewable energy that’s used. Solar power in California differs and is within the range of anyone with a couple dollars to spend and a tiny motivation. Solar power is a large portion of the nation’s future.
Effectiveness of Solar Power - How Efficient is It?
Any discussion regarding the effectiveness of solar power and its efficiency should first of all be qualified by the fact that we're talking here about a technology that is in its relative infancy and is improving all the time.
That having been said, it's fair to say that, while massive improvements have been made in the overall efficiency of solar panels, there's still a long way to go.
Let's take a look at how solar panels work and get some background as to why this is and what can be done to improve solar panel efficiency.
The Secret's In The Cell
The solar cell is the basic building block of a solar panel and is where all the action takes place as far as the conversion of sunlight into electricity is concerned. A cell consists of a negative and a positive silicon wafer, which work together in reaction to the sunlight striking them to cause electrons to literally jump out of the wafers to create a DC (Direct Current) electrical circuit. This is known as the photovoltaic (PV) effect.
Several cells (normally 30-40) are wired together to create a panel and the electricity generated by each cell is accumulated to supply enough power from a panel to power a small electronic device or charge a battery, but not enough to supply the power needed to run a household or business. To do that, a number of solar panels are wired together to supply the kind of electricity needed to run household appliances, etc.
What's Meant By Solar Cell Efficiency?
When we talk about the efficiency of solar cells and, consequently, solar panels, we're actually referring to the amount of sunlight that the cell converts to usable electricity. The efficiency of cells has come a long way since the early days of PV when cells were 1-2% efficient (i.e. about 1-2% of sunlight was converted into electrical energy). Nowadays, cells are between 7% and 17% efficient, which is a massive improvement, but that still means that 83-93% of the available sunlight remains unused.
The efficiency of a solar cell is dependent on several variables, including cell type and temperature. The higher the temperature of a cell is, the lower its output and, as a result, the lower its efficiency. The type of cell used will also affect its efficiency, with monocrystalline being the most efficient (14-17%), polycrystalline next most efficient (13-15%) and amorphous (or thin film) the least efficient (5-7%), with the relative cost of each directly proportional to its efficiency, i.e. monocrystalline being the most expensive while amorphous is the least expensive.
How About Giving Me 100% Efficiency?
Unfortunately, despite advances being made in production processes, and work being done to improve cell efficiency, even at its best the maximum efficiency level that can be achieved for crystal silicon is still only around 28%. This is due to certain physical limits caused by the materials themselves, in addition to certain loss mechanisms such as the fact that photons having too little energy end up not being absorbed, and excess energy from the photons is converted into heat.
So, even with the best will in the world, 100% efficiency is simply not achievable. Certain techniques are being used to improve cell efficiency, such as reducing reflection loss through surface structuring, or stacked (or tandem) cells, or concentrator cells, so there's plenty of room for optimism for the future efficiency of cells.
But, even with the restrictions on the potential efficiency of solar cells, the fact that we're able to produce usable electricity from such an unlimited source of energy as the sun is nothing less than miraculous in and of itself. Add to that the fact that this is clean, renewable energy with no carbon emissions or harmful effects that can reduce and potentially help eliminate our dependence on dangerous fossil fuels and it's clear that solar is a wonderful and effective technology whose time has come.