You are interested in purchasing a solar system for your Bayside home, but you keeping coming across the term solar inverter and are not sure what it is? Typically, advertising for solar systems and colloquial discussion suggests that installing solar panels is the entirety of the project. Realistically, solar panels are only one component of the system that is needed for you to harness the power of the sun within your home or business.
To briefly summarise, a solar inverter converts the variable direct current (DC) that is generated and output from the photovoltaic (PV) circuit of your solar panels to utility frequency alternating current (AC).
AC is the power that you can use functionally within your house to do things such as turn on the TV or boil the electric kettle. Unless you are an electrical engineer or a renewable energy electrician this jargon probably does not answer your question.
This article intends to provide you with a plain language explanation of why solar inverters are an essential component of solar systems in your local area and around the world.
AC and DC Electricity
These acronyms are used a lot and understanding what they mean will assist in your understanding of how a solar inverter works and why it is important.
Electricity is formed by electrons moving across a circuit providing energy to cause an action, for example generating heat and light, or making a motor spin. There are two ways that the electrons can move across the circuit, this is DC or AC. DC means that the electrons are flowing in only one direction, AC means that the electrons are changing their direction of flow.
In a DC circuit, the polarity remains constant. As electrons have a negative charge they will constantly be drawn toward to positive charge, generating the unidirectional flow. DC is typically used in anything that has a circuit board such as laptops, phones, battery-powered appliances, as these require a steady power output this encompasses most household appliances.
AC is what is used to transport electricity across power lines and is what comes out of your walls power point socket. The polarity of the circuit changes very quickly and results in an oscillation of the electrons. The number of times this switch occurs per second is measured in a unit called hertz (Hz). You can see this oscillation when you try to film a light globe with your mobile, and it starts flickering despite not flickering to your naked eye.
If most of the appliances in our home run off DC, why should we even bother converting it? The main reason is that the DC does not transport across wires very well. Wires carrying DC can easily heat up which is not practical over long distances that electricity must traditionally travel. Accordingly, all our appliances have been designed to have an AC input which the device then converts to DC itself. To feed power back into the grid it must be in the AC format so that it is compatible. This makes the solar inverter an important part of your solar energy system.
Conversion of DC to AC
When sunlight hits your PV solar panels, it results in the displacement of electrons which begin to flow as DC into the solar inverter. The inverter then converts this to a sine wave, which you may remember from high school trigonometry. In case you do not, it is a line that forms two semi-circles in a wave pattern that can then repeat. The sine wave is how AC is visually represented.
Different types of inverters perform this step differently.
Better-quality units tend to produce a cleaner sine wave, free from disturbances ensuring a better electricity flow for use with your appliances. This involves tracking the input from your solar and adjusting its output accordingly to produce the maximum output for any given moment.
For further reading on sine waves and electrical currents please click here.
Interfacing with Mains Power Grid
Inverters are also involved in communication with the mains power supply. Some inverters require the mains power to be active for them to run, so when there is a power outage it will switch off, meaning you will be without power regardless of whether your panels are producing electricity. This prevents any feedback into the grid while workers may be troubleshooting or repairing the damage so that they do not get shocked.
Some inverters, such as hybrid inverters, are connected to home battery storage, so they will still be able to provide you electricity in the case of a blackout while preventing power from being redistributed into the mains grid.
Inverters are required to be able to detect arc faults, which are large surges of electricity that can overwhelm the insulation of your wiring causing it to overheat, resulting in an electrical fire. Arc fault detection is a vital feature of your inverter. It is essential that detection is highly accurate and that it can perform an emergency shut off preventing house fires.
Types of Solar Inverters
Household solar inverters can be broadly classified into three main types:
- String inverters
A string inverter is one inverter that is connected to the entire array of solar panels.
Each of the panels is connected via a wire, known as “stringing”. This wire is then connected into the inverter which converts the DC to AC. These are a basic type of inverter and are relatively inexpensive.
However, due to the nature of the stringing connection, if one panel is in shade or operating at a lower efficiency for some reason, the output of the entire system will be affected. For some home owners, this may be an issue, especially if there is a high chance that some panels will be shaded at different points throughout the day.
Microinverters are smaller as the name suggests, and there is one microinverter attached to each solar panel. This means that each panel will be treated as an individual unit which removes the partial shading issue that is present in string inverters.
This setup allows you to monitor the output of each panel separately so you can easily determine if one is not working optimally. One downside of microinverters is that they are more expensive overall than a single unit string inverter. However, as technology improves prices will continue to fall.
Having multiple inverters also means potentially more maintenance costs. Additionally, their attachment site on the back of panels makes them less accessible for a solar energy electrician to perform maintenance.
- Intelligent Hybrid Inverters
Hybrid inverters are like string inverters, but they are coupled with a solar battery storage option. They can convert the DC from your panels into AC for your household and the mains grid, while also feeding DC into batteries for storage of electricity.
Need help deciding which inverter is best for you? Call our solar electricians on 1300 347 786 or contact us today for some assistance. We are happy to help!