1. What is a Solar Inverter?

A solar inverter is an essential electronic device used in solar power systems. It transforms electricity generated from solar panels, which is DC electricity in nature, into the kind of electricity used in homes and businesses, also known as AC or electricity. 

2. Types of Solar Inverters

1. String inverters

 String Inverters are the most common type, where multiple solar panels are connected in series (a string) and fed into a single inverter. They are cost-effective but less efficient in shaded conditions or when panels face different directions.

2. Microinverters

 Each solar panel has a small inverter connected to it. This setup works well in partially shaded areas and allows for the monitoring of individual panels. However, it is initially more expensive than string inverters.

3. Power Optimizers

 These devices are used with string inverters to optimise the power output of each panel, similar to microinverters, but the DC to AC conversion still happens at a central inverter.

4. Hybrid Inverters

Hybrid inverters are designed to handle solar panels and battery storage inputs effectively. They are particularly well-suited for solar energy systems incorporating battery storage for backup power or for selling excess energy back to the grid.

5. Off-Grid Inverters

These are designed to work independently of the electrical grid and often include battery charging and management functions. They are used in off-grid solar systems.

3. Choosing the Right Solar Inverter in Australia

Selecting the best solar inverter for your Australian needs involves considering factors like local standards compliance, cost, efficiency, and potential for future expansion. Here’s a comprehensive guide to assist you in making the right choice.

1. Compliance and Approval:

Can it be used in Australia, and has it been approved?

• Australian Standards (AS 4777): The first step is to ensure the inverter complies with AS 4777. This standard governs the connection of inverters to the grid and provides safety and performance.
• Clean Energy Council (CEC) Approval: Check the CEC’s approved products list. Only inverters on this list qualify for Australia’s significant solar subsidy and meet the required safety and efficiency standards.
• Manufacturer Reputation: Please seek out reputable manufacturers with a demonstrated history of creating dependable and long-lasting inverters. Companies such as Fronius, SMA, SolarEdge, and Enphase are highly respected.

2. Cost Considerations for 2024

How much should I pay in 2024?

• Budget Models: Prices for 5kW single-phase inverters start at around $1,000. Examples include Sungrow.
• Premium Models: High-quality 5kW inverters from brands like Fronius and SMA can cost up to $2,000.
• Three-Phase Inverters: If you require a 3-phase, 5kW inverter, add approximately $400 to the above prices.
• Avoiding Cheap Options: Remember that inexpensive inverters may have a brief lifespan and could struggle to endure the challenging conditions in Australia. Opting for a high-quality inverter lowers the long-term expenses of repairs and substitutions.

3. Inverter Size and Capacity

What solar inverter capacity is best to purchase?

• Matching Capacity: It’s important to ensure that the capacity of your solar inverter matches the capacity of your solar panel system. For example, if you have a 5kW solar panel system, it’s recommended that you use a 5kW inverter to ensure optimal performance and efficiency. Matching the inverter capacity to the solar panel system capacity helps maximise energy production and overall system effectiveness.
• System Losses: Due to inefficiencies, inverters can be rated up to 25% less than the panel array capacity. For example, a 5kW inverter can support up to 6.6kW of panels.
• DC Input vs. AC Output: Ensure the inverter’s DC input rating suits your solar panels’ output. This ensures compatibility and optimal performance.

4. Installation and Physical Considerations

• Physical Size: When installing an inverter, it’s essential to consider the available space. Inverters come in various sizes, from large briefcase-sized units to smaller travel case-sized ones. Make sure there is adequate space near your electricity meter for the installation.
• Location: Install the inverter in a shaded area to enhance performance and comply with warranty conditions. Direct sunlight and extreme weather can degrade inverter performance and lifespan.
• Shade Cover: Consider installing a simple shade cover if a naturally shaded location isn’t available.

5. Weather-Proofing

• IP Rating: While most inverters are IP65 rated to protect against dust and water, providing additional protection from direct sunlight and extreme weather is still beneficial.
• Warranty Conditions: Some warranties require installing the inverter out of direct sunlight. Check these requirements to avoid voiding your warranty.

6. Warranty and Longevity

How good is the warranty?

• Warranty Duration: Inverter warranties generally span 5 to 10 years, while some manufacturers provide extended warranties for up to 5 years at an extra cost.
• Types of Warranty: For example, Fronius offers a “5 + 5” year warranty—five years covering parts and labour and an additional five years covering only parts. Understand these terms to assess the total cost of ownership.
• Expected Lifespan: High-quality inverters are expected to last at least ten years, with many lasting up to 20 years.

7. Expandability

Is the inverter expandable?

• Future Expansion: If you plan to expand your solar system, consider an inverter with multiple MPPTs (Maximum PowerPoint Tracking) to add additional panels later.
• Alternative Approach: Installing a second solar system later might be more straightforward than upgrading the current one.

8. Monitoring and Display

• Display Features: Solar Inverters typically have display lights and digital readouts showing energy production, current power generation, and operational hours.
• Remote Monitoring: Modern inverters often come with remote monitoring capabilities through data logging, allowing users to monitor performance using a PC, smartphone, or in-home display. This feature is crucial for consistent monitoring and ensuring optimal system performance

9. Efficiency

How efficient is a grid-connected inverter?

• Efficiency Rates: Modern transformerless inverters typically have 96% or higher efficiency ratings. Older, transformer-based models have slightly lower efficiencies.
• Cooling Systems: Inverters with active cooling (e.g., Fronius) might have slightly lower efficiency but can have longer lifespans due to better thermal management

Conclusion

When you’re picking a solar inverter in Australia, it’s important to think about a few things: making sure it meets local standards, being cost-effective, working efficiently, having the option to expand, and being reliable. If you focus on these points and consider your needs, you can find an inverter to help your solar power system work well for a long time. Remember to consider the long-term benefits rather than the initial cost of a durable and efficient solar energy solution.