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Solar Optimizers & Optimized String Inverters Explained + Other Options

When sourcing solar inverters for solar projects or business, you would often come across solar optimizers AND optimized string inverters. Actually, they are not completely different products; rather, they correlate closely.

What Are Solar Optimizers?

Solar optimizers are devices that are attached to each solar panel in an array.

The primary function of a solar optimizer is to manage the output of each individual and combine the power of maximum power point tracking (MPPT) technology to ensure each panel is generating power at its maximum potential.

The invention of solar optimizers stems from the need to mitigate the shading and 'mismatch' effects on solar panels, as these effects will lead to underperformance not merely at the panel level but greatly in the entire system.

Solar Optimizers Below Solar Panels
"Solar optimizers" (cropping) by Asurnipal is licensed under CC BY-SA 4.0.

What Are Optimized String Inverters?

Optimized string inverters, aka string inverters with optimizers, are generally deemed as an improved version of standard string inverters. The concept is more inclined to portray an inverter structure or system.

In a primary solar power system, most often a residential rooftop or ground-mounted one, all solar panels are connected in series and tied to a string inverter, which aggregates all output of the panels and processes the DC-AC conversion. The ultimate efficiency and power output of the system will be impacted by the poorly performing panels owing to the effects just skimmed over.

By incorporating solar optimizers, each panel’s peak output and voltage is well tracked and regulated before their power is sent to the central string inverter. This can dramatically improve the efficiency and ultimate AC delivery of the system.

Summing up, an optimized string inverter comprises distributed solar optimizers installed on the back of each panel, and a string inverter installed generally on the wall near the system.

What Other Benefits Do Solar Optimizers Offer?

Solar optimizers not just function as power output optimizers, they also provide panel-leveling monitoring, which is essential in modern solar systems for various reasons.

Firstly, monitoring at the panel level enables early detection of any issues or malfunctions in individual panels, allowing for prompt maintenance or replacement to ensure a constant and smooth operation of the system.

Secondly, panel-level monitoring supplies insightful data on the performance of each panel, facilitating the identification of underperforming panels whether ascribed to shading, physical defects or other factors. By addressing these issues rapidly, the optimal performance of the system can be approached, leading to increased production, favorable ROI and cost savings.

Some might think that solar energy is free and no need to stir up hassle for the optimum as long as the capacity is sufficient to meet daily demand.

This could possibly be nothing wrong for off-grid applications. But for grid-tied applications or when self-generated solar cannot suffice daily consumption, implementing optimization measures with investments like solar optimizers for improved efficiency and output of the system is of more practical significance.

The recent states of inflation are placing a heavy burden on both society and the economy globally. In the U.S., The Bureau of Labor Statistics reported that over the last 12 months, the inflation rate reached 3.2% while the electricity prices in the country rose 3.6%. Though the energy inflation in the EU has fallen since the early period of the Russia-Ukraine war, homes and businesses are still struggling to pay their bills.

Optimized String Inverters vs. Microinverters: A Brief Contrast

Microinverters are typically installed on the back of individual solar panels as well. They are two-in-one devices that function in both power optimization and conversion.

Unlike the ‘distributed plus centralized’ structure of optimized string inverters, microinverters perform panel-level output optimization and DC-AC conversion, eliminating the need for a central inverter. This feature also reduces the need for high-voltage DC wiring that could occur in string inverter projects, enhancing system safety.

In optimized string inverter projects, the expansion is limited by the capacity of the string inverters. On the contrary, the expansion in microinverter solar projects is straightforward; simply adding more panels with microinverters to the system. 

Providing centralized monitoring and control is an attractive benefit of optimized string inverters. But coupled with smart algorithms and effective communication between each unit, microinverters can also furnish this functionality.

In terms of lifespan, most microinverter products come with longer warranties and offer peace of mind and potentially lower long-term costs. The relatively more complex design of string inverters with optimizers makes them more prone to failure.

However, optimized string inverters are generally more cost-effective than microinverters.

Pros and Cons of Optimized String Inverters

By comparing with other inverter options on different benchmarks, the pros and cons of optimized string inverters can be refined as follows.

Pros of Optimized String Inverters

  • Improved Production in Shaded Conditions: By optimizing the output of each panel with the optimizers, optimized string inverters allow each panel to operate at its own maximum power point, thereby reducing the impact of shading or underperforming panels on the overall system performance.
  • Enhanced Monitoring & Maintenance: The panel-level monitoring capability allows for detailed tracking of each panel’s performance. This advantage assists in troubleshooting issues for targeted maintenance promptly. If the string inverter fails, diagnosing and fixing the issue is easier than fixing a microinverter.
  • Flexibility in System Design: For sites that lack feasibility for optimal positioning of panels, the optimizers provide backing for flexible system design without greatly compromising efficiency and output.
  • Enhanced Safety: As one type of module-level power electronics, the optimizers in these inverter structures can provide module-level rapid shutdown capabilities in case of electrical shock, while getting your or your clients’ projects to comply with local rapid shutdown codes.
  • Cost-Effectiveness: While optimized string inverters are generally more expensive than standard string inverters, they are typically less costly than microinverters, being a cost-effective solution that balances performance with economic considerations. On the flip side, the optimizers add panel-level optimizing and monitoring to your current string inverter solar projects, avoiding the need for a brand-new replacement for microinverters.

Cons of Optimized String Inverters

  • Increased Complexity & Cost: The design of optimized string inverters causes increased complexity for the system, as their added components and distributed design demand more consumption of materials, labor and time. While they would be more costly than microinverters, the cost of installation and maintenance might add up.
  • Inconvenient Expansion: Similar to standard string inverter solar projects, when capacity is concerned, the expansion is limited by the capacity of the string inverter.
  • Warranty Considerations: As a whole, a complete optimized string inverter structure might come along with a relatively shorter lifespan than the more advanced microinverters. Since there are more components in these structures; in some projects the brands and/or manufacturing dates can vary; managing their warranties can be challenging.

The DC applications of Solar Optimizers

We have used plenty of words to elaborate on the DC-AC applications of optimizers in inverter solar projects. Actually, the use of solar optimizers in DC applications is more straightforward.

By connecting solar optimizers to rechargeable solar batteries, sometimes necessitating the integration of a charge controller or BMS, the DC output of solar panels can be optimized and stored into batteries without the extra steps of DC-AC and then AC-DC conversion. Other than the utilization of more advanced hybrid solar inverters, this is one of the most efficient ways to adopt DC power. 

Final Thoughts

Optimized string inverters are a cost-effective option to add panel-level optimizing and monitoring capabilities to solar systems. With several decent benefits, they work well for small-to-medium projects to improve the efficiency and increase power output of the systems.

The optimizer components can separately be adopted to upgrade current solar systems with standard string inverters installed. This presents great flexibility for your marketing.

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