Design of solar power plants: how to account for every detail

In order to paint a picture, an artist starts with a sketch. In order to build a solar power plant that will generate clean electricity for decades, it all starts with preparing detailed project documentation. So as to say, with a “sketch” of the future solar station. Why is this important? A responsible approach to design work determines the success of the power facility’s implementation and its efficiency throughout the entire operation period. How to take into account all the nuances even before the power plant construction? Our team of KNESS designers explains what stages the preparation of project documentation consists of and shares the characteristics of a proficient design.

What precedes the process of designing an electric power facility?

“First of all, we receive input data from the customer. We find out what kind of facility needs to be designed and the purpose, the desired power and other electrical parameters. Also, before starting the design, it is important to understand where the future facility will be located and have all the information about the arrangement of the selected land plot or roof. If necessary, we provide recommendations and help the customer decide on the concept of what their future power facility should look like. After that, we can start designing,” Borys Errera Vitiuk, Deputy Director of Design in KNESS describes the design preparation work.

What are the design stages?

The design process includes three main stages: pre-design analysis, feasibility study, and the actual development of a full package of design documentation. Each of these stages plays an important role and has its own purpose. Further on, experts provide a more in-depth overview of each of them.

First stage — analytics

“At this stage, we begin to work with the input data from the customer: we develop drawings of the photovoltaic modules’ layout and project equipment’s placement. This is like a sketch of a future picture. In the case of building a solar power plant, we select the main equipment and calculate the forecast generation. Plant’s efficiency forecast is performed in special PVsyst software, the results of which are recognized by powerful international energy companies, as well as audit companies and banks. The plant’s generation forecast  is based on the location, the equipment to be installed, the configuration of the mounting structures relative to each other, and many other factors.

Insolation, or the amount of solar radiation that reaches the site, is of utmost importance for forecasting efficiency. This indicator must be taken into account at the analytical stage. It determines the choice of the inclination angle of solar modules, the distance between them, and the equipment type. 

The level of solar insolation in Ukraine is quite diverse and varies not only across the country, but also depending on the season. For example, according to the PVsyst program, the insolation level in Vinnytsia is 1233 kWh/m² per year. In order to build a solar power plant with high efficiency and capacity that will meet the facility’s consumption or occupy the entire optimal area allocated for it, it is necessary to choose the ideal placement of modules in relation to the south, select the appropriate metal structures, module and inverter characteristics so that the peak generation of the solar power plant is maximized throughout the year. For a station of the same capacity in Chernihiv, where the insolation level is 1156 kWh/m², it is worth choosing a different inclination angle, installing more solar modules if possible, and choosing more powerful equipment.

Each facility has individual characteristics, taking into account the customer wishes and the limiting factors that directly affect the construction and photovoltaic plant’s operation. The feasibility analysis takes into account such features in each individual case and draws a conclusion on the feasibility and estimated cost of building a facility at the selected site,” says Maksym Tokar, a Design Engineer of the Power Plant Design Department in KNESS. 

Such calculations solve several problems at once. Firstly, the customer can understand whether it is profitable to build such a plant under such conditions and the payback period. In addition, by comparing different options for the station’s layout, the most optimal one can be found.  Secondly, a preliminary technical calculation makes it possible to assess the SPP’s impact on the adjacent power grid, which helps to determine the amount of grid reconstruction or construction of its new elements required to connect the SPP.

How to find the best option for connecting a solar power plant?

“In order to do this, we need to determine what the customer means by ‘the best connection option,’” says Yevhen Kostiuk, a Leading Design Engineer Feasibility Study Department of KNESS. “Usually, in the process of selecting sites, preference is given to those near substations or power lines. However, there are always nuances. The line capacity may not be enough to deliver the full capacity of the future plant, or the capacity of the transformers at the substation may not be enough. Many other generation sources might be already connected to this power node, and there might not be enough balancing capacity to connect new ones. The best connection option should take into account all the features and be optimal both in terms of price and reliability,” Yevhen shares his experience.

Second stage — feasibility study

At this stage, our conditional sketch becomes clearer. 

“Unlike the analysis stage, at the feasibility stage we make our adjustments based not only on the customer’s data but also on a whole range of calculations. We calculate the grid operation modes at the connection point to the transmission system operator (TSO)/distribution system operator (DSO) or user facility, as well as the dynamic and static stability of future RES facilities. We prepare external power output schemes for generating power facilities. We also calculate the facility’s cost and economic efficiency and determine the best option for connecting to the TSO/TSO grids or the user’s facility. As a result, we have a set of calculation and analytical documents containing both initial data and basic technical and organizational solutions, estimates and other indicators, i.e. we get a holistic picture of the feasibility and efficiency of the investment project,” Volodymyr Rozghoniuk, Head of the Feasibility Study Department describes its work.

Third stage — preparing a full package of project documentation

At this final stage, a design task is developed, which is agreed with the customer and the TSO/DSO, the parameters of the power equipment are calculated, and the actual design is developed. “When it comes to onshore power facilities, engineering, geodetic, and geological surveys are also carried out to obtain accurate data about the site. In particular, geological soil surveys help to determine the level of the aquifer, the likelihood of ground movements and the presence of karst formations. Such work makes it possible to choose the optimal and safe route for cable lines, plan the placement of metal structures taking into account the terrain, and guarantee the unchanged angles of the solar panels for further efficient and uninterrupted operation of the solar power plant. At the same time, geodetic work is required to mark the location for the installation of solar modules within the coordinates specified in the technical documentation, as well as to conduct a topographic survey and create a correct plan of the site allocated for the construction of the SPP.

If there is a need, at the same stage, the terms of reference for the implementation of the ACEMS project (automated commercial electricity metering system) are developed. After a thorough check, the ready design solutions are agreed with all the necessary organizations (TSO, DSO, owners of existing utilities),” says Vitalii Bespiatchuk, Head of the Power Plant Design Department in KNESS.

This stage is the most crucial one, as the implementation success of the power plant and, accordingly, its efficiency during operation depends on the documentation received.

“The full package of project documentation contains comprehensive information about all the features of the future solar power plant. The package includes an explanatory note, architectural and construction solutions, master plan and transportation, detailed calculations, diagrams, and estimates. The design documentation must also describe in detail all electrical solutions, features of the relay protection and automation, electricity metering, as well as dispatch and process control equipment. If necessary, an environmental impact assessment is attached to the project,” explains Vitalii Bespiatchuk.

Design by KNESS is always about a thorough and competent approach to the electrical facility implementation

During the project design phase, all the nuances of implementing a solar power plant are carefully accounted for. The period of the plant’s uninterrupted operation within the declared capacity, and thus the payback period of the project, depends on the right solutions. To take into account every detail, you need the qualifications of specialists of different profiles and levels. Comprehensive experience in the implementation of power facilities and a responsible approach are equally important.

“Our goal is the most efficient solution and long-term mutually beneficial cooperation with partners. In designing a plant with maximum efficiency, this can only be achieved through an individual approach and accurate calculations. For over 14 years, we have been trusted by both domestic and foreign partners and customers. KNESS design team brings together more than 40 highly qualified specialists, including certified specialists with experience in designing CC1, CC2, and CC3 facilities, which guarantees the highest quality of work and project implementation of any complexity. We are constantly working to improve the efficiency of our projects by carefully developing and implementing modern engineering solutions. We carry out the design of solar and wind power plants, high-voltage substations, and distribution grids both in the format of separate services and as part of an EPC contract. We take a comprehensive approach to the implementation of each project, starting with the selection of a land plot, consulting services, design and selection of equipment, and ending with commissioning and preparation of all necessary documentation,” summarizes Dmytro Pyskliarov, Head of Design Department in KNESS.