What does an inverter do in a solar power system?

Solar inverters: what you need to know

What is a solar inverter?

A solar inverter is a device that either sits on the wall of your home or on the back of each individual solar panel, depending on the type. Its main functions include:

• Power conversion - The inverter converts direct current (DC) electricity into alternating current (AC) electricity. This is vital in a solar system as solar panels capture sunlight and turn it into DC electricity, but devices and systems in the home run on AC electricity.
• Grid integration - The inverter allows the solar system to integrate with the electricity grid. It’s responsible for exporting any excess solar power not being used in your home back to the grid.
• Monitoring - Inverters link to solar system monitoring software, which makes it possible to track your system’s performance. Some inverters have a display panel for basic monitoring, however most also come with remote monitoring through websites or apps.
• Safety - Solar inverters are critical in maintaining the safety and stability of your solar system. They regulate voltage, ensuring the solar output matches grid voltage and shut down the system during power outages. This prevents solar power going back into the grid during a blackout, which protects equipment and technicians until the power is restored

More: How do solar panels and solar power work?

Types of solar inverters

There are different types of inverters, suitable for different homes and system requirements.

What is a string inverter?

The most common type of solar inverter, a string inverter, is a single unit into which all the solar panels connect. It usually sits on the wall of the home and is generally the most cost-effective inverter option for simple solar systems.

String inverters pose limitations for solar systems that are impacted by shading, as shade that hits one solar panel will impact the output of the entire system.

What is a microinverter?

Microinverters are small inverters that sit on the back of each individual solar panel. Unlike string inverters, which handle the output of multiple panels, microinverters convert the DC electricity from each panel into AC electricity independently.

This makes microinverters a better option for solar systems impacted by shading. They’re also more suitable for complex systems installed across multiple roof faces because the solar panels don’t have to be connected into one centralised string inverter.

What is a power optimiser?

Power optimisers work with string inverters to maximise the energy output of each solar panel. They’re installed on individual panels and, like microinverters, allow the panels to function independently of one another, improving performance for complex or shaded systems.

What is a hybrid inverter?

When a battery is included in a solar system, you need an inverter that can handle not only solar panel generation and the electricity grid, but the charging and discharging of a battery as well.

Hybrid inverters are often used in this case, as they support more flexible energy management, allowing solar power to be stored in a battery for use during non-sunny periods or power outages. 

While not essential for solar and battery systems (batteries can be added to solar systems with standard solar inverters by adding an additional inverter or connection), they tend to be more efficient and come with extra features.

More: How do solar batteries work and are they worth it?

What size solar inverter do I need for my home?

The size of your inverter will depend on the size of your solar panel system and your energy consumption.

Generally, the inverter should match or slightly exceed the capacity of your solar panels. For example, if you have a 5kW solar panel system, you might need a 5kW inverter. However, other factors to consider include:

• Panel capacity - ensure the inverter can handle the total output of your solar panels
• Efficiency - higher efficiency inverters convert more solar energy into usable electricity
• Voltage - the inverter's voltage range needs to match your solar panels (and battery, if applicable)
• Future expansion - if you plan to add more panels later, consider an inverter with higher capacity.

In some cases, inverters may need to be over- or undersized. Your installer will be able to recommend the right inverter for your needs.

How much do solar inverters cost?

The cost of a solar inverter varies based on the type, brand and capacity. A good quality string inverter, for example, can cost between $1,000-$2,000. Microinverters tend to be a bit more expensive, however the cost will depend on the number of solar panels you have and therefore how many microinverters you need.

How long do solar inverters last?

Solar inverters usually last 10-15 years. However, this can vary based on the type of inverter and environmental conditions. Regular maintenance and monitoring can help extend an inverter's life. Some manufacturers offer warranties of up to 20 years.

What are the signs of a failing solar inverter?

If you notice a drop in energy production, frequent system shutdowns, error messages on the inverter's display or unusual noises, it’s best to get your inverter serviced. Start by contacting the installer of your system as your inverter might still be under warranty.

More: Solar panel maintenance and system troubleshooting