Is It Better To Have An Inverter For Each Solar Panel?

An inverter is a device that converts the direct current (DC) electricity generated by solar panels into alternating current (AC) electricity that can be used in homes and buildings. Inverters play a critical role in solar power systems by transforming the raw power produced by solar panels into usable electricity.

Without an inverter, the DC electricity from solar panels cannot power most standard appliances and electronics that require AC power. The inverter converts DC into standardized 120 volt or 220 volt AC electricity that is compatible with electrical grids and equipment. By enabling solar panels to interface with existing electrical infrastructure, inverters allow solar power systems to effectively replace or supplement grid-supplied electricity.

In summary, inverters act as the brains of solar power systems by converting DC solar electricity into usable AC power for practical consumption. They are an essential component that enables the generated electricity to be used in buildings.

Table of Contents

Pros of Inverters for Each Panel

One of the biggest advantages of using microinverters for each solar panel is higher efficiency. With a microinverter, each panel can operate at its optimal efficiency point through maximum power point tracking (MPPT). This allows panels to produce as much power as possible based on their individual conditions like shading or orientation, rather than being limited by the performance of the entire string [1]. Traditional string inverters with multiple panels connected can result in underperformance if a single panel is not operating ideally. Microinverters also avoid energy losses that occur from panel mismatched in a string configuration [2].

Cons of Inverters for Each Panel

The main downside of using microinverters for each solar panel is the higher upfront cost compared to string inverters. Microinverters can cost 2-3 times more than central inverters for an equivalent system size according to this source. This increased expense comes from the need to purchase and install a separate microinverter for every solar panel in the array.

Additionally, having an inverter on each panel means more potential points of failure in the system. If one microinverter fails, only that individual panel will stop working rather than the whole array. However, with more inverters comes more maintenance and higher likelihood of needing repairs over time compared to a string inverter setup. The inverters may also need to be replaced after 10-15 years while central inverters can last 20+ years.

Comparative Efficiency

When considering efficiency, a key factor is whether to use a centralized string inverter or individual microinverters for each panel. String inverters convert the DC output of multiple panels into AC current. They offer high efficiency of around 96-98% during peak production hours when the panels are operating at optimal voltage. However, string inverters have a single maximum power point tracking (MPPT), so if one panel is shaded or faulty, it can reduce the output of all panels connected to that inverter.

Microinverters, installed at each panel, can maximize production by MPPT at the panel level. This allows each panel to operate at peak efficiency regardless of variability in sunlight exposure. Microinverter efficiency ranges from 95-96%, slightly lower than string inverters at peak. However, microinverters may achieve higher annual efficiency in shaded or uneven conditions by optimizing per panel. Overall, microinverters can generate around 5-25% more energy annually, with the gain depending on the site specifics.

Sources:

https://www.linkedin.com/posts/saj-electric_saj-solar-solarpower-activity-7135628473968066560-HR52

https://www.linkedin.com/posts/saj-electric_intersolarsouthamerica2022-solarshowafrica2022-activity-6965204428987494400-ok1a?trk=public_profile_like_view

Comparative Reliability

When it comes to reliability and lifespan, microinverters tend to outperform string inverters. Microinverters are typically warrantied to last 25 years, matching the lifespan of most solar panels. In contrast, string inverters usually come with 10-12 year warranties (Source: https://www.solar.com/learn/micro-inverter-string-inverter-comparison-solar-equipment/). This means string inverters may need to be replaced 1-2 times within the system’s lifetime, incurring additional costs.

Microinverters have no single point of failure, so if one unit fails only 1 panel will be affected. With string inverters, a failure takes down the whole series of connected panels. Studies show microinverter systems experience failure rates of only 1.2% over 25 years, compared to up to 10% for string inverters. Real-world data from Tesla solar installs confirms far lower failure rates for microinverters (Source: https://www.solarreviews.com/blog/pros-and-cons-of-string-inverter-vs-microinverter).

Overall, microinverter systems tend to be more reliable and have a longer productive lifespan than string inverter systems. Their distributed nature and panel-level electronics lead to superior robustness and failure tolerance.

Comparative Cost

When comparing the costs of using microinverters versus string inverters, there are both upfront and ongoing maintenance costs to consider. Microinverters have a higher upfront cost, with each panel needing its own individual inverter. According to a 2022 study by SolarQuotes (https://www.solarquotes.com.au/blog/string-vs-micro-inverters-study/), the cost of microinverters is around $130 AUD per panel more than using a centralized string inverter. This adds a significant cost at the time of installation.

However, the maintenance costs over the lifetime of the system may be lower with microinverters. If an individual microinverter fails, only one panel is impacted versus potentially multiple panels going down with a centralized inverter failure. The decentralized design of microinverters limits the impact of potential equipment issues. Overall lifetime costs depend on the system size, equipment reliability, and maintenance fees in a given location.

Optimizing System Design

When designing a solar PV system, there are several factors to consider in order to optimize the system layout and design:

According to Leonics, the inverter size should be about 25-30% larger than the total wattage of the solar panels to allow for efficiency losses and future expansion. Oversizing the inverter slightly helps prevent overloading.

The tilt angle of the solar panels is also an important design consideration, as noted by Illinois Shines. The optimal tilt depends on the latitude, but generally tilting panels 15-45 degrees optimizes seasonal and year-round energy production.

The physical layout should avoid shading from buildings, trees or other obstructions as much as possible. South-facing roofs are ideal in the northern hemisphere. Modules should be spaced apart to allow air flow and cooling.

Wiring should be sized appropriately to minimize losses. Shorter wire runs from panels to inverters are preferable. Inverters should be centrally located if possible.

Ultimately, the system design should balance performance, reliability and cost. Work with reputable installers and leveraging solar design software can help optimize these factors.

Future Trends

In the coming years, we’re likely to see significant innovations in inverter technology that could change the equation around inverters for solar panels. Here are some key developments to watch for:

Microinverters – These small inverters attached to each panel are declining in price. As the cost comes down, microinverters may become standard for solar installations. This would negate the need for central or string inverters.

Integrated modules – Some solar manufacturers are now producing panels with inverters built directly into the module. This integrated product could reduce complexity and costs for installers.

Improved centralized inverters – Large central inverters are also getting more advanced. Models with multiple MPPT tracking can get performance close to microinverters at a lower cost.

Smart inverters – Inverters with smart capabilities can collect performance data, self-diagnose problems, and integrate with the grid more seamlessly. Smart inverter requirements are increasing globally.

Battery integration – Inverters are evolving to integrate with home battery storage systems, opening up new possibilities for solar + storage installations.

As inverter technology improves, solar installers will have more options to customize systems for optimal efficiency and performance in each unique home installation.

Conclusions

Ultimately, there are good arguments both for and against having individual microinverters for each panel versus using string inverters for a group of panels. On the pro side for microinverters, they can maximize energy output from each panel and provide panel-level monitoring and optimization. They also may have higher reliability than string inverters over the long run. On the con side, microinverter systems have a higher upfront equipment cost per watt of capacity. The choice often comes down to individual goals, priorities, and budget when designing a solar array.

Some key pros of microinverters are:

Maximizes energy harvest from each panel (https://www.solarreviews.com/blog/pros-and-cons-of-string-inverter-vs-microinverter)

Panel-level monitoring and troubleshooting (https://www.solarreviews.com/blog/pros-and-cons-of-string-inverter-vs-microinverter)
No single point of failure like a string inverter
Typically 25 year warranty vs. 12 years for string inverters (https://www.solar.com/learn/micro-inverter-string-inverter-comparison-solar-equipment/)

Key cons of microinverters include:

Higher upfront equipment cost per watt
More complex system design and installation

May not work as well for larger or centralized systems

In summary, microinverters shine for smaller, distributed solar arrays where maximizing production and monitoring from each panel is a priority. String inverters can provide a more cost-effective solution for larger systems where panel-level optimization is less critical.