Solar Inverters

Solar panels convert solar energy into electricity. But the electricity produced this way is of unidirectional or direct current (DC) nature, whereas the electricity used in our homes is of alternating current (AC) nature. Here is where solar inverters come into play, as they change direct current into alternating current, which is consumed by our homes and offices.

This is a home solar inverter in use.

In other words, we can say that without solar inverters, solar energy won't be of much use to us. Thus both solar panels and solar inverters are important components of a photovoltaic power system, which converts solar power into electricity. The same is true of storing solar power into a DC battery system. An inverter is needed to convert the DC battery into AC for home use and electronics.

Components of Solar Power System

Solar panels
Battery
Charge controller
Inverter

These key components of the solar energy system are essentially a bridge between two different power systems allowing both to work together.

Conversion of Solar Energy into Electricity

When the Sun's energy falls on solar panels, electrons are forced to isolate themselves from silicon cells and start flowing in a single direction, which is known as direct current. This direct current cannot run our home electrical appliances, which rely on alternating current for electricity, thus solar inverters translate the DC power of solar panels into AC to feed the needs of our electrical appliances.

Types of Solar Inverters

Solar inverters are primarily classified into three types:

Stand-alone inverters: Used in isolated off-grid energy systems, the source of DC energy for these inverters is the battery charged by photovoltaic arrays or other generators, such as wind turbines, hydro turbines. These inverters can be run using a charge controller. As the inverters do not interfere with the grid, these do not need anti-islanding protection.

Grid-tie inverters: Used in systems integrated with the grid, the source of DC energy for grid-tie inverters is the solar power collected by the solar panel array. The utility continues to provide power when no solar energy is available at night or even during cloudy days. These do not provide backup power upon loss of utility supply or utility outages. This type of inverter will have an inbuilt anti-islanding protection.

Battery backup inverters: These inverters draw energy from a battery and supply AC energy during utility outage. These inverters use an onboard charger to manage the battery charge and require anti-islanding protection.

Characteristics of Solar Inverters

Start voltage denotes the minimum DC voltage required for the working of the inverter.
Peak efficiency denotes the highest efficiency an inverter can achieve.
NEMA rating indicates the inverter's level of protection against water intrusion. A 3R rating denotes inverter's safety in outdoor situations.
Rated output power denotes output rating in kilowatts or watts.
Output voltage denotes a figure at which utility voltages the inverter can connect.
CEC weighted efficiency represents the operating profile of the inverter.