What is a photovoltaic inverter?
A photovoltaic inverter is an essential device in solar systemsphotovoltaic, because it converts the direct current (DC) produced by thepanels photovoltaicin alternating current (AC) usable by household electrical appliances and compatible with thenetworkelectric. Its role is crucial to optimize theyieldenergy efficiency of the system, maximizing the amount of solar energy converted into usable electricity. In addition, the inverter ensures synchronization with thenetworkelectric, thus allowing the excess electricity produced to be reinjected into thenetworkor use it directly for domestic consumption.
The role of the inverter in a solar installation
The role of the inverter in a solar installation is essential to ensure the efficiency and functionality of the system. Whether it is a microinverter, installed individually on each solar panel, or a string inverter, connected to several panels, the inverter converts the direct current produced by the panels into alternating current, compatible with household appliances and the electrical grid.
The less knowledgeable will choose a complete solar kit including the inverter, scrupulously respecting the dimensioning of the installed power while the most seasoned "photovoltaicians" will be able to choose either the inverter type: micro or string inverter; as well as the power of the inverter, sometimes preferring to oversize initially while waiting to add solar panels to their installations. In any case, the choice of inverter is an essential criterion not only for the overall profitability of your project but also for the duration, knowing that on average an inverter is guaranteed for 7 to 10 years (25 years for Enphase brand micro inverters).
The different types of photovoltaic inverters
Micro-Inverters
Solar microinverters are devices installed individually on each solar panel, allowing more efficient conversion and optimized management of energy production for each panel. Some brands develop microinverters that can connect to several panels, usually 2 but it can go up to 4. Another leading brand APSystem has a range of micro, the DS3 and DS3L which connect to 2 panels. In this case, you should consider providing MC4 extensions in order to be able to arrange the panels without cable length constraints. Their use is particularly advantageous for small installations (up to 8-10 panels), because they maximize yield by reducing losses due to shading or individual panel failures. However, the price criterion plays a crucial role in the choice of inverter. For installations with more than 10 panels, it is often more economical to opt for a string inverter or hybrid systems. These allow for cost reduction while maintaining good conversion efficiency, making them a pragmatic choice for larger installations.
String Inverters
String inverters are key components in larger solar installations, especially for home systems with more than ten solar panels. These inverters typically incorporate one to two MPPT (Maximum Power Point Tracking) inputs, which optimize energy production by constantly adjusting the load to reach the maximum power point of the panels. With these MPPT inputs, it is possible to connect two series of panels, also called solar fields, and independently manage their production to maximize overall yield.
Hybrid Inverters
Hybrid inverters are versatile devices that integrate the charge controller function, allowing the integration of batteries into solar installations. This feature makes hybrid inverters the only types of inverters capable of connecting batteries, thus offering a complete solution for the storage and flexible use of solar energy. Manufacturers have developed battery ranges specifically adapted to their inverters, avoiding any universal compatibility. For example, Enphase has designed batteries for its latest generations of microinverters, Huawei offers the Luna battery for its systems, and Growatt has introduced the APX battery for the latest generations of its XH series inverters. This specificity ensures optimized performance and seamless integration between inverters and batteries, maximizing the efficiency and reliability of hybrid solar installations, particularly for remote monitoring and control systems.
What are the advantages of micro inverters over central inverters in a photovoltaic system?
Micro inverters are increasingly used in solar installations, offering many advantages.
First of all, micro inverters are designed to work with individual solar panels rather than with groups of panels connected in series. This means that in the event of a failure or performance problem of a single panel, it does not affect the performance of the entire installation. In addition, their installation is more flexible and allows to optimize the production of electricity according to the specific conditions of each solar panel. Implementation is simplified due to the absence of DC cable in the installation, only AC current circulates, so the connection to the electrical panel is made with AC cable.
In terms of efficiency, micro inverters also have the advantage of optimizing electricity production. Indeed, each solar panel can operate at its own maximum power, which improves the overall efficiency of the system. In addition, micro inverters allow panels to be installed on several roof sections, at different inclinations and orientations without affecting overall production.
Another advantage of micro inverters is the individual monitoring of each solar panel. This allows for early detection of potential performance issues and easier resolution. In addition, micro inverters allow for monitoring the electricity production of each panel, which is extremely useful for maintenance and monitoring of the installation.
When it comes to price, micro inverters can be more advantageous than string inverters when purchasing. Although the initial costs are generally higher for micro inverters due to their higher number (one per panel, i.e. as many micro inverters as panels), this can be offset by the advantages mentioned above, particularly for its flexibility of implementation. In addition, micro inverters have a lifespan similar to or even longer than central inverters, thus offering a long-term guarantee for the solar installation. This is the case for Enphase, which offers a 25-year warranty for an installation equipped with an Envoy gateway.
Thus, micro inverters offer many advantages over central inverters in a photovoltaic system. Their use improves the efficiency, flexibility and reliability of the installation, while providing better monitoring and tracking of electricity production. Even if their initial price may be slightly higher, their lifespan and many advantages make them an interesting choice for a high-performance solar installation.
What are the differences between a hybrid photovoltaic system and a conventional solar system?
The differences between a hybrid photovoltaic system and a solar system with string inverter are mainly in their storage capacity and flexibility of use. A hybrid photovoltaic system integrates batteries, allowing excess solar energy to be stored for later use, which provides energy autonomy and backup power in the event of a grid failure. In contrast, a solar system with string inverter does not have batteries and relies entirely on the grid for excess energy management, meaning that the energy produced must be consumed immediately or fed into the grid. Hybrid inverters allow for more intelligent and flexible management of home energy, reducing dependence on the electricity grid, while string inverters, being simpler and often less expensive, are more suitable for installations where energy storage is not a priority and where access to the grid is reliable.
Sizing the inverter according to the power of the solar panels
Sizing inverters according to the power of the solar panels is a crucial step in optimizing the energy production of a photovoltaic installation. Contrary to the popular belief that "who can do more can do less", optimal sizing is not achieved by choosing an inverter with a power equal to that of the solar installation. In reality, it is recommended to choose an inverter whose power represents approximately 80% of the nominal power of the solar panels. For example, for a 3.75 kWp solar field, a 3 kW inverter would be appropriate. Similarly, a 295 W IQ7+ microinverter is suitable for a 390 Wp panel.
This approach allows to optimize the annual energy production, because an oversized inverter would operate most of the time at a low load rate, resulting in a lower conversion efficiency. Indeed, an inverter too powerful for the solar installation would not be used at full capacity, which would reduce its efficiency. For example, for a 3 kWp solar system, a 2.5 kVA inverter (such as the Sunny Boy 2.5) would be optimal.
For microinverter technologies, the optimal ratio is even lower, around 75%. Enphase recommends this approach to maximize conversion efficiency and annual energy production. An inverter sized at approximately 80% of the nominal panel power optimizes overall system efficiency, balancing the energy loss due to undersizing with the gain in conversion efficiency. A properly sized inverter ensures that the system operates at its best potential throughout the year.
To learn more about the optimal sizing of photovoltaic inverters and its impact on the overall efficiency of your installation, consult thisarticle from the Solar Dictionary.
The Most Reliable Photovoltaic Inverter Brands on the Market
The choice of inverter is crucial for the performance and longevity of a photovoltaic installation. Several brands stand out on the market for their reliability, innovation and after-sales service. Here is an overview of the most reputable brands.
Enphase Energy
Specializing in microinverters, U.S.-based Enphase Energy offers innovative solutions for residential installations. Enphase IQ microinverters allow individual management of each panel, maximizing overall efficiency, especially in complex environments with partial shading.
APsystems
APsystems is a renowned manufacturer of solar micro inverters, offering a wide range of inverters suitable for photovoltaic installations.
Thanks to their solar micro inverters with 2 MPPT outputs, i.e. able to connect to 2 panels, they offer a very interesting quality-price ratio. The DS3 series offers an MPPT voltage range between 25V-55V for the DS3L and 32V-55V for the DS3, thus allowing you to connect high-power panels. You can maximize the power of your solar panels and increase your renewable energy production.
Huawei
Chinese tech giant Huawei has quickly established itself in the inverter market with its FusionSolar line. These inverters are renowned for their high efficiency, battery compatibility and easy integration into hybrid systems.
Growatt
Growatt, a Chinese company, has gained popularity for its affordable and reliable inverters. The battery-compatible Growatt XH series is particularly suitable for small to medium-sized residential and commercial systems.
Fronius
Based in Austria, Fronius offers robust and efficient inverters. The Fronius Symo series is often chosen for domestic and commercial installations. Fronius is also appreciated for its responsive customer service and sophisticated monitoring solutions.
SMA Solar Technology
SMA is a German company known worldwide for its photovoltaic inverters. The Sunny Boy range is particularly popular for residential installations. SMA stands out for its cutting-edge technology, including monitoring functions and MPPT inputs that optimize energy yield.
What certifications should be checked to ensure the quality of a solar inverter?
First, CE certification ensures compliance with European electrical safety standards. The CE mark indicates that the inverter complies with European safety, health and environmental protection directives. This is a requirement for products sold in the European Union.
Then, the essential standard is VDE 0126-1-1, particularly important in France and Germany for solar inverters. It concerns the protection of energy production systems connected to the low voltage network, ensuring that the inverter can connect and operate safely with the public electricity network.
Furthermore, the EN 50530 certification is specific to solar inverters and attests to their performance and durability. This certification evaluates in particular the efficiency of the inverter at different output powers and voltages, as well as its ability to operate reliably in varied environmental conditions. It specifies the methods for measuring the efficiency of solar inverters, making it possible to compare their efficiency in real conditions of use.
These certifications and standards ensure that the solar inverter is safe, efficient and compliant with regulatory requirements in France and Europe. When purchasing a solar inverter, it is crucial to check for these certifications to ensure the quality and reliability of the product.
