How Solar Energy Works
Taking Energy From The Sun
The sun is like a naturally occurring nuclear reactor. It releases tiny packets of energy called photons, which travel 93 million miles from the sun to Earth in about eight-and-a-half minutes. Every hour, enough photons impact earth to theoretically satisfy global energy needs for an entire year.
Photovoltaic (PV) Solar Panels
Photovoltaic (PV) solar panels are made up of many solar cells. Solar cells are made of silicon, like semiconductors. They are constructed with a positive layer and a negative layer, which together create an electric field, just like in a battery.
When photons hit a solar cell, they knock electrons loose from their atoms. If conductors are attached to the positive and negative sides of a cell, it forms an electrical circuit. When electrons flow through such a circuit, they generate electricity.
Multiple cells make up a solar panel, and multiple panels (modules) can be wired together to form a solar array. The more panels you can deploy, the more energy you can expect to generate.
PV solar panels generate DC (direct current) electricity. With DC electricity, electrons flow in one direction around a circuit. This example shows a battery powering a light bulb. The electrons move from the negative side of the battery, through the lamp, and return to the positive side of the battery.
With AC (alternating current) electricity, electrons are pushed and pulled, periodically reversing direction, much like the cylinder of a car’s engine. Generators create AC electricity when a coil of wire is spun next to a magnet.
AC electricity was chosen primarily because it is less expensive to transmit over long distances. However, solar panels create DC electricity. How do we get DC electricity into the AC grid? We use an inverter.
A solar inverter takes the DC electricity from the solar array and uses that to create AC electricity. Inverters are like the brains of the system. Along with inverting DC to AC power, they also provide ground fault protection and system stats including voltage and current on AC and DC circuits, energy production, and maximum power point tracking.
Central inverters have dominated the solar industry since the beginning. The introduction of micro-inverters is one of the biggest technology shifts in the PV industry. Micro-inverters optimize for each individual solar panel, not for an entire solar system, as central inverts do. This enables every solar panel to perform at maximum potential. One solar panel won’t drag down the performance of entire solar array, as opposed to central inverters that optimize for the weakest link.