Photovoltaic power generation household small inverter

Common single phase grid-tied PV inverters are usually current-controlled voltage-source types (Fig. 16.5 A) in which instantaneous current waveform is produced using a simple pulsed width modulation (PWM) control, reference to the grid voltage, and is injected to the grid at a high PF.

Small-scale domestic applications accommodate a significant number of low efficiency PV cells in a usable form, PV modules. In addition, to convert the PV energy timely and effectively, a range of converter/inverter topologies are adapted using two major system configurations such as stand-alone or widely used grid-connected form.

The grid-connected (grid-tied) inverters (Fig. 16.2 E and F), which are the most common inverter systems, can supply energy not only to local loads within the household, but can also supply power to distant loads connected elsewhere on the electrical grid (as the grid acts as an infinitely large energy storage system!).

A solar PV cell is simply a diode that is optimized to absorb photons from the sun and convert them into electrical energy. The amount of solar power available per unit area is called the irradiance and is usually expressed in watts per square meter.

The topology in Fig. 16.10 D can eliminate the central inverter by accommodating multiple miniature (PV panel-rated) inverters that operate in isolation from each other and directly connected to the AC grid. Hence, each micro inverter tracks the MPP of a PV panel and eliminates power mismatch issues in series strings.

In small-scale grid-tied PV inverters, since power electronic circuits cannot offer ideal voltage and current waveforms, this is measured by two quantities (1) the total harmonic distortion (THD) and (2) power factor (PF).