How to Choose Solar PV Inverters
Inverters are a “balance of system” component for PV solar panel arrays, the solar power component of a solar panel system that convert raw energy harvested from the solar panels into usably AC power for your home or business. There are three types of inverters in common usage with solar panel services. These are standalone, grid-tie, and battery backup. Each kind of inverter has its own advantages and disadvantages, and each has its own specific set of circumstances for use.
- How does a PV inverter work?
- What is Anti-Islanding?
- What is a standalone inverter?
- What is a grid-tie inverter?
- What is a battery backup inverter?
How does a PV inverter work?
PV powered solar inverters take the raw DC current created by PV solar panels and converts it into AC current for compatibility with the electricity we use in our day to day lives. The inverter does not produce power itself, but converts the power output of a solar panel or array of PV panels. They can either be all electronic, or a mix of electronics and mechanical bits. Most inverters require a moderately stable DC current to create Alternating current in the required voltage. They do this by converting the raw electricity generated by your solar panel into a waveform, such as a sine wave, useable by everyday appliances. PV inverter differs from other kinds of inverters in that they are specially designed for use with your PV solar panels, including anti-islanding protection and Maximum Power Point Tracking.
What is Anti-Islanding?
First of all, “Islanding” is what happens when the electrical power supplied to residents and businesses is stopped, as in a power outage, while a steady supply of electricity is still being generated by a fixed point, such as a solar array. This is potentially very dangerous to utility workers attempting to fix the fault in the line, as raw electricity can still be running through lines. Anti-islanding is a precaution that shuts down your inverter upon loss of local utilities, thereby avoiding accidents. Anti-Islanding is required on all inverters which interface with the local utility grid.
What is a standalone inverter?
A standalone inverter is any PV Inverter that is independent of the local utility grid. These are good for single-panel solar units and mobile solar units, as well as units in isolated locations. This may be similar to the kind of inverter used with a car battery. Since these do not normally interact with the local utility grid, they do not need anti-islanding protection.
What is a grid-tie inverter?
A grid-tie inverter connects a solar panel array to the local utility company, converting power to Alternating Current and synchronizing the sine wave to that of the local utility, draining excess electricity away from the solar array and feeding it to the utility grid. These are designed with anti-islanding precautions to shut down automatically should power in the area fail. In many countries, the excess energy generated by solar panel arrays can be sold to the utility company, in exchange for credit on future energy bills. Grid-tie inverters do not offer protection against utility failure unless also equipped with a battery backup.
What is a battery backup inverter?
A battery backup inverter uses a battery bank to store and draw electricity from the solar array, managing charge on the batteries using a built-in charger, and can export excess energy to the local power utility along the lines of a grid-tie inverter. These can supply power to your home or business during an electrical outage, and are required to have anti-islanding operations.