Solar Panel Optimisers & Micro-Inverters UK

A solar panel installation is a fantastic way to generate clean energy for your home for years to come. However, choosing the right components for your system is essential, and one critical decision is selecting the type of inverter to use.

In this guide, we’ll explore microinverters, their benefits, costs, and comparisons with other inverter technologies, including power optimisers and traditional string inverters.

Pro Tip: Avoid upsells and confusing packages—choose a provider with a clear, fixed-price quote that won’t change. Heatable, a Which?-approved solar installer, offers transparent pricing with no surprises.

What is a Microinverter?

A microinverter is a type of inverter used in photovoltaic (PV) solar systems to convert direct current (DC) electricity from individual solar panels into alternating current (AC) electricity, which can be used by your home appliances or exported to the grid.

Unlike traditional string inverters, which convert the combined DC output of multiple panels, a microinverter is installed on each solar panel, enabling independent power conversion.

This offers significant advantages, particularly in terms of system performance, safety, and monitoring.

Benefits of Microinverters

Maximised Energy Production

One key advantage of microinverters is that each panel operates independently, maximising electricity generation by shifting Maximum Power Point Tracking (MPPT) to the panel level.

This is especially beneficial for roofs with multiple orientations or shading, as each panel produces optimal output regardless of the performance of others.

Enhanced Safety

Microinverters eliminate the need for high-voltage DC wiring across the roof, reducing the risk of electrical hazards. Additionally, they comply with modern electrical codes requiring rapid system shutdown in case of an emergency.

Longevity and Warranty

Microinverters generally last longer than string inverters, with warranties ranging from 15 to 25 years, compared to 5 to 10 years for string inverters.

Easier System Expansion

Because microinverters work independently, expanding your solar system is much simpler. In contrast, a string inverter system may require replacing the inverter with a higher-rated unit to accommodate additional panels.

Improved Monitoring and Maintenance

With panel-level monitoring, homeowners can track the performance of each individual panel via a web or mobile app. If an issue arises, it is easier to pinpoint and resolve the problem, unlike with string inverters, where identifying the faulty panel is more challenging.

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Disadvantages of Microinverters

Higher Initial Cost

Microinverters are around 20-30% more expensive than string inverters. However, this may be offset by the increased energy yield over the system’s lifetime.

Complex Repairs and Maintenance

Since microinverters are installed behind solar panels on the roof, diagnosing and replacing faulty units can be more labour-intensive than with a string inverter system.

Potential Lightning Risks

Microinverters, like other rooftop electronics, may attract lightning. Homeowners in storm-prone areas should consider this when designing their solar installations.

Microinverters vs. String Inverters

Standard String Inverters

In a traditional PV system, solar panels are connected in a string to a single inverter, which converts DC to AC.

While this setup is cost-effective, it has a major drawback—if one panel underperforms due to dirt, shading, or degradation, the entire system’s output is reduced to match the weakest panel.

Microinverters vs. String Inverters

Feature:	Microinverters:	String Inverters:
Efficiency	Higher (panel-level MPPT)	Lower (string-level MPPT)
Expansion	Easy—add panels individually	Difficult—may require inverter upgrade
Monitoring	Panel-level monitoring	System-level monitoring
Lifespan & Warranty	15-25 years	5-10 years
Cost	20-30% higher upfront cost	Lower upfront cost
Shading Impact	Minimal	Significant
Safety	No high-voltage DC	High-voltage DC present

Power Optimisers: An Alternative to Microinverters

A power optimiser is a compromise between microinverters and string inverters. Installed at the panel level, an optimiser adjusts DC voltage before sending it to a central string inverter. This setup retains some benefits of microinverters while maintaining the lower costs of a string inverter system.

Advantages of Power Optimisers

• Increased energy yield (5-25%) through panel-level MPPT.
• More cost-effective than microinverters (~15% extra cost vs. string inverters).
• Can improve battery integration, as the output remains in DC.
• Works with different panel orientations and partial shading.

Disadvantages of Power Optimisers

• System expansion is limited by inverter capacity.
• Still requires a central inverter, which may need replacement over time.
• Higher initial cost compared to standard string inverters.

Microinverter Costs

Microinverters come at a premium price, often costing hundreds to thousands of pounds more than traditional inverters, depending on system size and complexity. However, the greater energy output, longer lifespan, and better warranties can justify the higher initial investment.

Additionally, diagnosing and repairing faulty microinverters can be more challenging and expensive, as the technician must work at the roof level to replace the affected unit.

Leading Microinverter & Power Optimiser Brands

Enphase Microinverters

• Market leader in microinverter technology.
• 20-year warranty and tested for durability over 100 years.
• Integrated monitoring via the Enphase Enlighten app.

SolarEdge Power Optimisers

• Combines optimisers with a string inverter for enhanced efficiency.
• 25-year warranty on optimisers, 12 years on inverters (extendable to 25 years).
• Advanced system monitoring and fault detection.

Tigo Power Optimisers

• Compatible with multiple inverter brands.
• Can be selectively placed on shaded panels to lower costs.
• Tigo SMART app for real-time monitoring and fault prediction.

Conclusion: Are Microinverters Worth It?

Whether microinverters are the right choice depends on your needs, budget, and roof conditions.

• If shading, multiple roof orientations, or future system expansion are concerns, microinverters or power optimisers are the best options.
• If cost is the primary concern and shading is minimal, a string inverter is the most economical choice.

Further Reading:

• Can you get free solar panels?
• Solar panels with microinverters
• Solar trackers
• Best solar panels
• Solar panel output calculator