Optimizing solar PV systems

Many mistakes, which later lead to a reduction in yield, already occur during the planning of the solar system. Therefore, it is important to consider all critical aspects already in the planning phase. In addition to the known factors such as alignment of the modules, minimization of shading, a sun angle of 90°, there are other factors that play a role especially when planning larger PV installations:

Module interconnection: Different interconnection concepts have a direct effect on the photovoltaic yield. It should already be determined during the planning of the solar system how the interconnection should look like later. For example, only modules with the same orientation and inclination may be interconnected. Furthermore, the modules in a string must all be of the same type. Exceptions only apply if optimizers are used. You will learn more about this in the course of this article. When interconnecting modules, you should also keep in mind that a weak module (e.g. due to dirt or shading) can limit the total power of a string. 

Selection of suitable inverters: Inverters with several MPP trackers are often advantageous here, since module fields with different characteristics (string length, orientation, etc.) can be controlled with separate MPP tracking. Depending on the size of the plant, there are devices with up to 12 MPP trackers (e.g. SMA Core 2). 

For a time-saving and accurate planning of the photovoltaic system, we recommend the use of a planning tool. These usually offer the possibility to calculate module fields with different properties. The ideal string connection can also be determined very quickly, depending on the module and inverter type. Additional information such as the degree of energy utilization up to yield forecasts are often included. Many of our inverter manufacturers provide free planning tools to help you plan your PV system quickly and easily. Here are a few examples:

SolarEdge: The SolarEdge Designer is a web-based planning and layout software that provides comprehensive support for planning, implementing and evaluating the solar PV system. SolarEdge recently added several new features to the free PV planning tool. For example, the Designer now also offers an auto-string design feature for electrical design that quickly and automatically follows SolarEdge's flexible design rules at the touch of a button. The Designer provides highly accurate energy simulations by providing insight into the expected energy production of the planned and designed PV system. Shading analysis, system loss analysis, or irradiance analysis help to optimize the PV design. For a quick initial planning or to determine the appropriate optimizer, we recommend using the minimized basic mode (the blue plus on the start page on the lower right).

SMA: Also with the tool from SMA, Sunny Design, the solar system can be planned and designed quickly and conveniently with just a few clicks. The tool generates design proposals, provides relevant data for the economic evaluation of the system and determines optimal inverter dimensions. The design tool is available in your web browser.

Kostal: The KOSTAL Solar Plan helps you with the inverter layout. In addition to the improved inverter design, you can also use the software tool for preparing quotations. You can add customer or project data to the technical data entered and attach it to your quotation in an overview in PDF format. The KOSTAL design tool is only available as a downloaded version and not web-based.

Fronius: The Fronius Solar.configurator supports you in the exact dimensioning of PV systems. The online tool calculates the optimum number of modules and their interconnection or the ideal inverter type, even for complex systems. This provides you with different configuration options and yield forecasts quickly and easily.

With the help of module or performance optimizers, more yield can be achieved even in the case of shading, different alignment, or different module types than in systems without optimizers. Monitoring at module level and shutdown in case of power failure are popular side effects of many power optimizers. Power optimizers can be used on almost any photovoltaic system because they optimize the MPP (Maximum Power Point) for each individual module. As mentioned above, normally the weakest module (e.g. due to dirt or shading) limits the total power output of a string. By using the power optimizers, the affected module does not influence the others and the string power remains correspondingly high. Thus, PV power optimization at module level is a cost-efficient solution for commercial and large-scale plants.

Monitoring also plays a major role in order to directly detect yield-reducing circumstances and then to remedy them as quickly as possible. Automated and simplified plant monitoring is possible with the help of a data logger. The data logger permanently records yields and other key data about the plant performance. A data logger is particularly worthwhile for commercial plants, so that yields can be secured permanently, and your customers quickly know about problems or even failures of the solar plant. The good news is that data loggers are already installed as standard in most modern inverters.

Integrierte Monitoring Systeme im Wechselrichter oder Speicher:

SolarEdge inverters also feature a standard Internet connection and integrated data loggers, making it easy to monitor the installation via an app or PC using the SolarEdge monitoring platform.

SMA relies on system monitoring for all inverters, without additional costs for a data logger. The required data can be directly accessed in the Sunny Portal. Here PV systems can be professionally monitored, managed, and presented.

Fronius also offers data logger integration as standard on all model series. With a complete set of interfaces, the systems can be quickly and easily brought to the free portal via Ethernet or WLAN.

KOSTAL inverters offer an integrated data logger as standard, which stores all relevant data on energy production and the operating states of the device. If the inverter is connected to the in-house network, the data can be transferred to the KOSTAL Solar Portal and visualized. In parallel, mobile data retrieval via the KOSTAL Solar App is possible.

Do you have any further questions on this topic? As always, your personal contact at Krannich is at your disposal. Just give us a call or use the contact form. We look forward to hearing from you.