The American software provider Solesca presents new ways not to make the PV system available and relegation of the solar module. Engineers play a key role in this evolution and ensure more accurate and reliable energy statements for solar projects.
For a long time, engineers have satisfied themselves with determining strict relegation and non -availability figures, often led by the recommendation of an independent engineer, and handed those assumptions to the financial team. I don’t say anymore!
The designer and engineer of the Zonne -Array should have all energy numbers for the life of the system. Why are you asking? Because overseeing nuanced relegation and unavailability can lead to underestimation of project trends and challenges in securing financing. We notice that 0.5% demolition is no longer a good standard for System and that unavailability Is very variable from year to year. By using the data in the 8760 (energy) file, you can not only take the best assumptions that the independent engineer gives, but also get more production for your financial team to use! Does it seem too good to be true? That’s not, and here is why.
Let’s start with relegation. Everyone knows that the performance of modules decreases over time. The process of continuous cycling through heating through the sun and cooling results in the layers of the module that separates somewhat over time. An interesting fact is that modules are really the only part of the system that relegates. Wiring is constant and stretching is designed for the entire life of the system. Inverters and transformers have determined efficiency that do not decrease.
That is why we have to look at modules to calculate demolition. In one DNV White paperThe best standard for demolition of linear module is 0.64%. What we would usually do as an engineer is to tell our financial team: “… here is the 8760 and we have to use 0.64% as a relegation year.” Stop there! Let’s reconsider this. If the relegation comes from the DC side of the system and the financial team takes the AC power output and breaks down, do we treat the relegation well? The industry consistently designs systems with a high DC/AC ratio, and that is in cutting the inverter. By relegating the entire system, production can be lost while it breaks down the cut AC current and not the DC power that flows into the inverter. The graph below shows an example of the difference between Y1 and Y10 of the summer day for a solar array. One with demolition applicable to the AC and one in the DC.
You can clearly see that when the Y1 AC values are broken down (displayed in Y10 AC (AC broken)), the system produces considerably less energy than when Y1 DC values are broken down and cut is exercised (shown in Y10 AC (DC broken down)). In this example, it is shown that 3.8% less energy is generated through traditional methods. Every body in which your 8760 has a perfect value and you pass it on to your financial team, you lose production data that must be recorded in the model. That is why the solar professional who generates the 8760 must generate several years at the same time with the correct demolition speed. Solesca has built this methodology into our life -monthly energy numbers, so you do not have to do the annoying calculations for each year.
Now it’s time for unavailability, everyone’s favorite boogeyman. For too long we have adopted constant unavailability every year of the project, regardless of the size and system type. For too long we have not taken into account the first few business years, replacement of inverter and preventive maintenance. Not anymore!
Based on a webinar and data from three different providers, DNV has updated guidance for Estimates of not being available. In the webinar, DNV presents 10 years in real company data with availability. They also provide recommendations for systems larger than 10 MW and Single Axis Tracker (SAT) Racking type. Let’s start with the basic model, a system with a capacity of up to 10 MW. In the DNV data presented, the first year the unavailability increased due to the commissioning and startup considerations. Then it decreased until it decreases on years 8 and 9. This is due to inverters who start to reach and fail their end of life, with an increased unavailability to be able to handle their downtime and replacement. Secondly, an increase across the board by 0.5% is not available for more than 10 MW systems. Finally, an increase of 0.5% in unavailability for SAT systems is recommended due to downtime at Tracker.
Synthetizing the information that has been learned in this webinar can discover a better way not to make the system of the system available. We can use the basic model presented, add the extra unavailability for the systems of more than 10 MW or that are SAT and have good projections for the first 10 years of the system. But what about the other 15 to 25 years? There are no substantial available data to distinguish this question, so we must trust logic. If the unavailability increases as a result of the inverter downtime in year 9, is it not logical that this would then decrease once the inverters have been replaced? This assumption is crucial for the way in which Solesca deals with assumed unavailability.
We take those first 10 years and assume that unavailability is reset as soon as you completely replace the inverters for the life of those inverters. This is supposed to happen on years 12 and 25, but can be changed to meet your assumptions. The unavailability decreases after the replacement of the inverter and then increases as those new inverters reach their end of life. Finally, as the system gets older, we assume that there will be more general downtime due to problems such as soil errors, bloated fuses, broken modules, etc. Solesca tries to take into account the O&M wrestings as Arrays grow up for another 0.5% unavailability for years 25 or more. Although the data is limited, this assumption corresponds to the typical operational experience in aging solar assets.
By implementing both accurate relegation and estimates of non -availability based on current data from the respected independent engineer, the solar designer can project energy in a more accurate way in the future than before. The demolition of the DC side of the system leads to considerably more energy for systems with a DC/AC ratio higher than 1 as the years increase. Accounting for annual unavailability leads to a more realistic view of each year, because you take your assumptions into account and it forms for published data.
The ways to allow the financial team to handle energy calculations must go the way of the Dodo Bird. Both the relegation and the unavailability for every year in the right way is a difficult company. While the paradigm shifts of engineers who use 8760 and handle the finances the rest, Solesca offers our lifetime energy model. We deal with both relegation and unavailability described above. We also record an extra production day for jump years. By using this method, we find the generations of system generation during the lifetime of the series of up to 1% compared to the standard model. This leads to increased accuracy, possibly better financing numbers and a more realistic picture of project performance. We strive to be paramount in heralding this shift in the process.
Current data collection and industrial cooperation will be crucial to further refine the assumptions of the long-term unavailability in the future. Engineers play a key role in this evolution and ensure more accurate and reliable energy statements for solar projects.
Author: Rocco Fucetola
Solesca Energy, Inc. Offers pre-CAD software for C&I and solar energy made on the ground. It helped evaluate more than 100 GW projects with unparalleled accuracy and speed.
The views and opinions expressed in this article are the author, and do not necessarily reflect it by PV -Magazine.
This content is protected by copyright and may not be reused. If you want to work with us and reuse part of our content, please contact: editors@pv-magazine.com.
Popular content
