LEAG x CAMOPO: Case Study and Interview

on Optimizing and Developing a 215 MWp Hybrid PV Plant with Integrated Battery Storage

LEAG, a leading German energy supplier, plans to build a photovoltaic (PV) plant with a peak capacity of 215 MWp. LEAG has partnered with CAMOPO to evaluate the hybridization of the PV plant with a Battery Energy Storage System (BESS) through simulation.

Here are four questions we asked to LEAG’s representative, followed by the case study:

CAMOPO: How important do you consider the topic of renewable hybrid power plants and the possibility of optimizing operations through the combination of technologies such as PV and battery storage? What considerations are there at LEAG regarding this?

Tobias Funk, LEAG: The utilization of hybrid grid connections for the co-location of various generation plants and battery storage represents a central planning tool for us. By correlating the feed-in curves of wind and photovoltaic (PV), the available connection capacities can be utilized much more effectively, and additionally, the necessary investment costs can be reduced. With the integration of battery storage, we will be able to further optimize this planning approach.

CAMOPO: What insights have you gained from working with CAMOPO?

Tobias Funk, LEAG:  Fundamentally, it confirms our approach to plan more cost-effectively through hybrid projects by coupling PV plants and battery storage, thereby contributing to increasing the profitability of the projects. Nevertheless, it is crucial to establish the business case on a solid foundation, as merely shifting feed-in to prevent curtailments will not suffice. Therefore, we always assess the entire context in every project.

CAMOPO: What advantages do you see in the AC- or DC-coupled connection of the battery, based on the results of the simulations?

Tobias Funk, LEAG:  From the perspective of the robustness of the technical solution and the maturity of development in higher power classes, we currently still see an advantage in the AC-coupled connection over the DC-coupled connection. Nevertheless, further aspects such as losses in the operating phase or the necessary space requirement must be considered to achieve an optimal solution for each project.

CAMOPO: Why do you think there is a need for hybrid optimizers, like CAMOPO?

Tobias Funk, LEAG: The complexity of this topic is extremely high, as not only commercial aspects play a role, but also technical and regulatory factors influence our investment decisions. For that reason, we work closely with experts from the industry to develop suitable solutions together.

Project Background:

In a designated area for the development, construction, and operation of renewable energy plants, LEAG, a leading German energy supplier, is planning a photovoltaic (PV) system with a peak capacity of 215 MWp.

A particular challenge here is the available grid connection capacity, which is limited to 2x 45 MVA. This means that at certain times the full generation capacity of the PV plant cannot physically be fed into the grid. Expanding the plant with a Battery Energy Storage System (BESS) can be a solution, by using the battery to store excess PV energy and feed it into the grid at a later time. Based on this initial situation and due to current and changing energy market conditions, various questions arise regarding the investment decision for this plant:

Investment Decision Questions:

> What economic benefit results from expanding the PV plant with a Battery Energy Storage System (BESS)?

> Which technical setup (AC- vs. DC-coupling) and what dimensioning of the BESS is optimal for this case?

> Which revenue streams can be used with the plant and how does an optimized energy management and dispatching strategy look like?

Project Goal:

The goal of the project was to access various scenarios and marketing possibilities in Germany using the CAMOPO optimization software for renewable hybrid power plants. With the help of a detailed simulation, a proper dimensioning of the battery should be determined, and it should be shown, what sort of influence various factors such as AC/DC coupling, battery power and capacity, and the use of different marketing options (Revenue Stacking) have on the business case.”

Methodology:

We proceeded in a structured manner in the project investigation. First, we created the data basis by precisely analyzing the size of the PV plant, the feed-in profile, and the grid connection capacity of 2x 45 MVA. These parameters were fixed and formed the basis for all further steps.

Subsequently, we determined various scenarios and simulated them with our algorithm to identify the best marketing opportunities for the generated energy.

We considered various types of revenue streams currently available in Germany. On the one hand, trading on spot markets (Day-Ahead / Intraday, continuous intraday) was examined, and on the other hand, the possibility of providing grid services with the battery. Therefore, potential participation in ancillary services, especially primary and secondary frequency control reserves (FCR, aFFR), was also incorporated.

We paid special attention to the investigation of an AC or DC-coupled connection of the battery. Besides the technical differences of the two concepts, the difference in Internal Rate of Return (IRR) and Net Present Value (NPV) was particularly presented. It turned out that DC-coupled solutions can be more cost-effective, although they are sometimes technically more complex. AC-coupled systems, on the other hand, offer more technical flexibility.

Additionally, we differentiated between scenarios in which the plant is allowed to be charged from the grid (loading of “grey electricity”) and scenarios in which this is not allowed or desired, and the battery is charged exclusively from the PV asset. This was important because at the time of the study, charging from the grid, for example, would result in a loss of the EEG attribute of the stored electricity. Also, when claiming funding programs, such as the innovation tender by the Federal Network Agency (BNetzA), charging the battery from the grid is not allowed. Both scenarios were compared to show the full scope of possibilities and their effects.

Another result of the investigation was that the DC-coupled solutions call for lower investment costs for the Power Conversion System, as in this setup a common inverter is used for PV and battery. However, due to the technical maturity of current DC-coupled solutions, restrictions in the possibilities for providing grid services and therefore potential revenue streams must be taken into account. The CAMOPO software therefore recommends continuously updating the results to stay up to date.

Findings:

The analysis showed that using a battery system improves the project’s business case overall and that a hybridized plant with an optimized operating strategy through CAMOPO can contribute to increased profitability. Depending on whether charging from the grid is allowed or not, a recommended battery size with a power of 60-90 MW and a capacity of 2h or 4h was determined.

Conclusion:

Due to the given situation of the limited grid connection and the significantly oversized PV generation capacity, losses due to technically induced curtailments are likely if a BESS is not utilized. The use of a battery system can mitigate these losses, enhancing the project’s profitability.

The CAMOPO software provides valuable insights and optimization strategies to ensure the economic and technical viability of the hybrid plant.

We want to thank LEAG and all project participants for the good and constructive cooperation, and to Mr. Funk for the interview