The Earth is bathed in ample energy from the sun. This power plant in the sky can fulfill many times over all the needs for power in the world. It is free, it won’t run out and it is not generating carbon dioxide emissions. People can turn the sun rays into useful electricity. The energy turns into electrical current when the light hits certain materials.
The sun is a natural nuclear reactor that releases photons, tiny packets of energy. These photons travel from the sun to Earth over a distance of 93 million miles in only around 8.5 minutes. According to experts enough photons impact our planet every hour to generate as much solar energy to cover global energy needs for an entire year. However, the solar energy sector is not yet developed to its full capacity. In the U.S., only five-tenths of one percent of the energy consumed comes from solar energy. But the cost is dropping rapidly and solar technology is improving.
The first solar technology used large crystals made out of silicon to produce an electrical current. But newer materials use cheaper, smaller crystals such as copper-indium-gallium-selenide. It is possible to make flexible films from this material, but it is not as efficient as silicon at generating electricity from light.
The solar panels are made of solar cells that are devices converting sunlight into electricity. The bonds between silicon atoms in a crystal are made of electrons shared between all of the crystal’s atoms. Electrons in one of the bonds get excited up to a higher energy level when light gets absorbed. They can move around the crystal more freely, generating a current.
Photovoltaic solar panels generate direct current electricity (DC). Electrons flow in one direction around a circuit in case of the DC electricity, while they are periodically reversing direction being pushed and pulled in alternating current electricity (AC).
Generators create AC electricity and AC electricity was chosen for the U.S. electrical power grid because it can transmit over long distances at lower costs. Because solar panels create DC electricity, their output needs to be transformed in AC electricity. This is done by using an inverter.
A solar inverter creates AC electricity from the DC electricity generated by the solar array. Along with inverting DC to AC power, inverters also provide system stats and ground fault protection. Among system stats provided are included energy production, voltage and current on AC and DC circuits, and maximum power point tracking.
In the past were used central inverters but the introduction of micro-inverters is an important improvement. Rather than optimizing for the entire solar system like central inverters, these micro-invertors optimize for each individual solar panel.
The current solar cells are quite good at capturing light energy. This characteristic is called power efficiency. A typical crystalline silicon cell has a power efficiency of around 22 to 23 percent. This means that they are able to convert into electricity as much as 23 percent of the light striking them. However, the ones that you typically afford to install on your rooftop have power efficiency lower than that, somewhere in the range of 15 to 18 percent. The most efficient solar cells are those installed on satellites, with a power efficiency of around 50 percent.