When module and BOS prices are high, new installations become less profitable and the focus shifts back to renovating and optimizing existing systems. Although there are signs that the upward price spiral is slowly winding down, there is still no evidence that prices are stabilizing or falling. As already predicted, a few remaining stocks of new modules - some of them quite large - have come onto the European market over the past few weeks. However, that these were quickly snapped up by the big system houses and others wanting to restock their warehouses to be on the safe side for the next quarter. Although module prices are unlikely to rise any further for the time being, the major manufacturers' production facilities are already fully booked for months, which means that there is no short-term capacity for new orders.
Springtime is maintenance time, and especially after a severe winter it is a good idea to have PV plants checked for damage. Even for smaller roof systems regular checks are recommended, along with taking care of any maintenance and repairs. This is even more important for large rooftop and ground-mounted systems with thousands of modules. Of course, installations that are getting on in years often need to be optimized. But inspection and repair work, especially on larger PV plants, is often underestimated. The technical optimization of existing systems is not just a matter of installing new parts, but also involves complex issues that can lead to serious risks for the operator. Often these risks remain undetected, and the operators are not aware of their responsibility.
In addition to technical defects and problems that lead to noticeable yield losses and erosion of profitability, product faults may also be present. And although they are not visible at first in performance analyses, they can create serious safety hazards and operator risks. Cracks in backsheet films are a good example of an issue that is getting increased attention in the solar industry. These cracks can cause PV panels to lose their class 2 protection rating and essentially revert to protection class 0 devices. This has huge repercussions for the system operator, who has to ensure that only qualified electricians can enter the PV plant because it is then considered an electrical operating facility. Modules with defective backsheets therefore must be replaced, but such a large-scale replacement operation is anything but easy.
But what makes the refurbishment and optimization of existing systems so difficult?
The old module types used in the plant are usually no longer available and if they are, they have to be purchased or reproduced at prices often significantly above the market rate for standard products. Such products are only economical in individual cases, which is why as a rule the only option is to replace them with current module types that have a much higher individual output. Because the replacement products have different electrical characteristics, new calculations for current carrying capacities have to be performed for cable and fuse design in accordance with standards. When more powerful modules are used, the strings often have to be configured differently. It is critical that the total DC output of the original PV system is not exceeded. Overshooting even by a small amount can lead to a loss of EEG feed-in tariffs, and not just in Germany.
As early as the planning phase it is advisable to coordinate the refurbishment and optimization concept in advance with the network operator responsible for the plant. Another issue that is important to clarify is whether planned modifications to the medium-voltage system are grandfathered or new guidelines have to be met. Although EEG conformity should be the top priority when replacing modules, an inverter replacement for systems over 135 kWp will generally entail an adjustment of the system certificate required. This is always the case if the new inverter has a different unit certificate than the defective inverter. If this is ignored, then the plant certificate loses its validity. An invalid plant certificate can in turn lead to the loss of the feed-in tariff. Of course, one can and should discuss with the network operator whether such a costly renewal of the plant certificate is really necessary, provided that the installer can ensure that the protection settings of the new inverters do not bypass the central plant safeguards and that the correct settings are made on the new inverter.
Simply adapting the plant certificate is not enough, however. After that, a new declaration of conformity also has to be issued based on the commissioning declaration, the plant certificate and an on-site inspection. The certificate and the declaration of conformity demonstrate that the plant meets the requirements of the respective application rule and the relevant technical connection conditions of the network operator (called TAB in German). And, of course, the refurbishing measures also have to be carried out correctly - in Germany, this includes updating the system documentation, a documented commissioning measurement, and an installer's confirmation in accordance with Art. 5 of the DGUV regulation. Other countries have similar regulations that must be observed and complied with.
Thus, major repair work is not solely a matter of installing parts but also of process reliability, conformity and minimizing operator risks. Specialized service providers can offer support in this area by carrying out measurement and documentation obligations for their customers or by conducting specialized training courses.
The co-author of this article, Falko Krause, is co-founder and CTO of GME clean power AG. As a TÜV-certified appraiser, he is nationally and internationally active in technical advice, system planning and quality assessment. GME clean power AG focuses on optimizing existing systems (revamping & repowering) and developing ecologically and economically sensible photovoltaic projects.
Overview of price points broken down by technology in December 2021 including changes over the previous month (as of 13 December 2021):