Once an inverter takes in DC current, it runs the energy through a duo of power-switching transistors that are turned on and off repeatedly, thus simulating a sine wave or an alternating current (AC). According to Solar-facts.com, the transformer being fed the current believes it is receiving actual AC. Whether the inverter produces a modified sine wave (stepped square wave) or a true sine wave is contingent upon its complexity. More expensive, high-quality inverters generate true sine waves.
The core of the inverter revolves around a real-time microcontroller, reports Texas Instruments. The specific algorithms needed to transform the direct current from the PV panel into AC are performed by the controller. Leveraging a continuous tracking and adjusting system, the controller ensures that the maximum amount of energy comes out of the solar module. For solar systems with battery backup, the controller manages charging the battery as well as switching over to battery energy when there’s no sunlight.
According to the Solar Guide, the three basic types of solar inverters are stand-alone, synchronous and multi-function. Stand-alone inverters convert the direct current from a battery into alternating current typically used for laptop computers, fax machines and other small business machines. Synchronous inverters are an integral component of grid-tie PV systems; they use the power grid for backup energy as well as for purchase of surplus energy. A multi-function inverter is connected to both the battery storage and the utility mains, and switches between the two sources, depending on the battery output.
Compatible inverters can be stacked to boost energy supply or voltage. If a household requires both 120 and 240 volts AC, inverters can be configured as a series whereby voltage is doubled. A parallel configuration allows PV system owners to double power; that is, twin 5,000-watt inverters will generate 10,000 watts of electricity.
A typical inverter has two primary functions: it converts direct current into alternating current, and it runs the algorithms to track PV panel output and maximize energy drawn from the sun. A number of innovative companies have come up with technology known as distributed inverter architecture, according to Eric Wesoff, senior analyst with GTM Research. In this technology, the algorithm-running electronics are embedded in the PV panels themselves as opposed to being integrated into one central inverter. PV system owners can monitor the output of each panel. If the inverter goes down due to one faulty panel, the other panels continue to produce energy without interruption.