Maximise your solar panels with optimisers

Solar panel optimisers can significantly boost the energy output of your home's solar photovoltaic (PV) system. They help homeowners gain greater control over their energy generation and reduce electricity bills. Investing in these devices is a strategic move for homeowners, shifting the balance of energy generation in their favour.

What are solar panel optimisers?

Understanding the basics of solar PV systems

A typical solar PV system on a UK home consists of multiple solar panels connected in series, forming a 'string', which then feeds into a central string inverter. This inverter converts the direct current (DC) electricity generated by the panels into alternating current (AC) electricity usable in your home. However, this series connection has a notable drawback: the performance of the entire string is limited by its weakest link. If even one panel in a string is partially shaded by a chimney, a tree, or even dirt, its reduced output can drag down the performance of all other panels in that same string. This phenomenon, known as "mismatch loss," means that a small shadow can have a disproportionately large impact on your system's overall energy harvest.

The role of optimisers in energy harvest

Solar panel optimisers are electronic devices that address this fundamental challenge. They are fitted to individual solar panels, acting as intelligent intermediaries between each panel and the string inverter. Their primary role is to maximise the energy harvest from each panel independently, ensuring that a suboptimal performance from one panel does not compromise the output of the entire system. This approach allows homeowners to unlock greater energy abundance from their solar setup.

How solar panel optimisers work

Module-level maximum power Point Tracking (MPPT)

The core technology behind solar panel optimisers is Maximum Power Point Tracking (MPPT) at the module level. In traditional string inverter systems, MPPT is performed for the entire string of panels. An optimiser, however, performs MPPT for each individual solar panel. This means it constantly adjusts the electrical current and voltage of that specific panel to ensure it operates at its peak power output, regardless of how other panels in the array are performing.

Mitigating the impact of shading and panel mismatch

By performing MPPT at the module level, optimisers effectively mitigate the impact of partial shading, soiling, or panel degradation. If one panel is shaded, its optimiser will adjust its output to its maximum possible, preventing it from limiting the current and voltage of the unshaded panels in the string. This allows the rest of the array to continue producing at full capacity. This module-level control can significantly increase energy harvest, with systems affected by shading or panel mismatch seeing notable gains. Even minor differences between panels, known as module mismatch, can reduce string output, which optimisers also address.

Enhanced safety features

Beyond performance, many solar panel optimisers also incorporate enhanced safety features. They can reduce the DC voltage of the solar array to safe levels when the inverter is switched off or during an emergency, such as a fire. This provides an additional layer of protection for installers and emergency services.

Key benefits for UK homeowners

Maximising energy output and reducing electricity bills

The most compelling benefit for UK homeowners is the direct impact on energy output and, consequently, electricity bills. By ensuring each solar panel operates at its maximum potential, optimisers can significantly increase the overall energy generated by your system. This additional generation means less reliance on grid electricity, leading to tangible reductions in your energy costs. The average UK home uses around 2,700 kWh of electricity per year1, so any increase in self-generated power directly translates into savings.

Granular monitoring and diagnostics

Solar panel optimisers often come with module-level monitoring capabilities. This means you can track the performance of each individual solar panel in real-time, rather than just the overall system output. This granular data provides unparalleled transparency and insight into your solar system's health. If a panel is underperforming due to shading, dirt, or a fault, you'll know exactly which one it is. This level of detail aligns with Fuse's vision for app-based control, empowering homeowners with clear data and the ability to identify and address issues promptly.

Increased system resilience and longevity

Optimisers contribute to the resilience and longevity of your solar PV system. By preventing shaded or underperforming panels from negatively affecting others, they protect the entire array from undue stress. This can help extend the lifespan of your panels and inverter. Solar panel optimisers typically come with warranties of 20-25 years, matching the long lifespan of solar panels themselves. This long-term guarantee provides peace of mind, knowing your investment is protected for decades.

Solar panel optimisers vs microinverters

Understanding the differences in system architecture

When considering module-level power electronics (MLPEs) for your solar system, optimisers and microinverters are the two main options. Both offer panel-level performance maximisation, but their system architectures differ significantly.

Optimisers work in conjunction with a central string inverter. Each optimiser is attached to a solar panel, and these optimiser-equipped panels are then connected in strings to a single string inverter. The optimiser conditions the DC power at the panel level before sending it to the string inverter for conversion to AC.

Microinverters, on the other hand, replace the string inverter entirely. Each microinverter is attached directly to an individual solar panel and converts the DC power to AC power right at the panel level. This means there is no central string inverter in a microinverter system.

When to choose optimisers over microinverters

Optimisers are often a suitable choice for systems where there is some, but not extreme, shading, or where panel mismatch is a concern. They offer a hybrid solution, combining the benefits of module-level optimisation with the familiarity and often lower cost of a string inverter. They are particularly beneficial on roofs with complex layouts or varying orientations, as they allow panels facing different directions to be on the same string without significant performance loss. If you already have a string inverter and want to upgrade its performance, adding optimisers can be a cost-effective retrofit.

Cost and complexity considerations

Generally, microinverter systems tend to have a higher upfront cost than string inverter systems with optimisers. The cost of solar panel optimisers can add to the upfront investment per panel, excluding installation. Installation complexity can also vary. While both require installation at the panel level, optimiser systems still rely on a central inverter, which can simplify some aspects compared to managing multiple microinverters. However, for existing systems, retrofitting optimisers might involve additional labour.

Are solar panel optimisers worth it?

Assessing the return on investment for your home

Deciding if solar panel optimisers are worth the investment for your UK home involves weighing the upfront cost against the potential long-term gains in energy production and savings. While optimisers add to the initial installation cost, the increased energy harvest, especially in systems prone to shading or panel mismatch, can lead to a quicker return on investment. The additional energy generated directly reduces your reliance on grid electricity, translating into lower bills over the system's 20-25 year lifespan.

Factors influencing cost-effectiveness

Several factors influence whether optimisers are a sound investment for your specific situation:

• Shading: If your roof experiences partial shading throughout the day from trees, chimneys, or neighbouring buildings, optimisers are highly likely to be cost-effective. They can recover significant amounts of lost energy in these scenarios.
• Panel mismatch: Variations in panel performance due to manufacturing tolerances, different ages, or slight degradation can be effectively managed by optimisers, boosting overall output.
• Complex roofs: For roofs with multiple angles, orientations, or limited space requiring panels to be installed in different directions, optimisers ensure each panel performs optimally.
• Monitoring desire: If you value granular, panel-level monitoring to keep a close eye on your system's performance, optimisers provide this data, offering peace of mind and proactive fault detection.

Real-world scenarios where optimisers excel

Optimisers truly excel in situations where a traditional string inverter system would suffer significant performance losses. This includes urban environments with unavoidable shadows, properties with architectural features that create shading, or systems where future shading (e.g., from growing trees) is anticipated. They are not a 'magic bullet' for every solar installation, but for those facing specific challenges, they are a highly effective solution.

Choosing and installing solar panel optimisers

What to look for in an optimiser

When selecting solar panel optimisers, consider compatibility with your existing or planned solar panels and inverter. Research reputable brands known for reliability and strong warranties. Look for features like advanced monitoring capabilities and robust safety mechanisms. Ensure the optimisers are designed to withstand UK weather conditions and come with a warranty that matches the expected lifespan of your solar panels, typically 20-25 years.

Professional installation and system integration

Given the technical nature of solar PV systems, professional installation is crucial. A qualified solar installer will assess your roof, shading patterns, and energy needs to determine if optimisers are suitable for your specific system. They will ensure proper integration with your panels and inverter, optimising performance and adhering to all safety standards. Obtaining quotes from several installers allows you to compare costs and expected benefits, ensuring you make an informed decision.

Ongoing monitoring and maintenance

Once installed, utilising the module-level monitoring data provided by optimisers is key to long-term performance. This data, often accessible via a user-friendly app, allows you to track energy generation, identify any underperforming panels, and spot potential issues early. This transparent control over your energy generation aligns with Fuse's mission to provide homeowners with unparalleled insight into their solar system's performance, ensuring you never settle for suboptimal output. Regular checks and professional maintenance will help ensure your optimiser-equipped solar system continues to deliver maximum energy and savings for years to come.

Making the most of your home's solar energy is a smart way to reduce bills and boost your energy independence. Fuse Energy is here to support you on your journey to a more sustainable and efficient home. We offer clear pricing, real-time usage data, and 24/7 human customer support to help you manage your energy with ease.

References

1. UK Government. Subnational electricity and gas consumption summary report 2021