How to build a photovoltaic farm?

How to start building a photovoltaic farm?

Planning and implementing the construction of a photovoltaic farm involves several crucial stages:

• Finding a Location
• Determining the Purpose of the PV Farm
• Selection of Equipment: Photovoltaic modules, structures, inverters, transformer stations, and energy storage
• Photovoltaic Installation Project
• Tender for Execution
• Photovoltaic Farm Service

Where to build a photovoltaic farm?
The choice of location for building a PV farm depends on several important factors:

1. Land Type: Ideal areas are agricultural wastelands or post-industrial areas, such as mines. Agricultural land used should be of the worst class. Industrial wastelands are preferred as they often have fewer local objections.
2. Distance from Medium or High Voltage Lines: Small and medium photovoltaic farms should be close to medium voltage (MV) lines to reduce the load on transmission lines and allow higher connection capacities.
3. Connection Power: The amount of energy that can be sent to the grid is crucial. Lower connection power than the farm’s nominal power requires energy storage solutions to manage power distribution and control.

Once a general location is identified, it should be validated by addressing the following questions:

The key factors for locating a photovoltaic farm are:

• What type of soil is present on the investment site?
• Is the plot as flat as possible?
• Can the PV installation be oriented south or east-west?
• Is the distance to a medium voltage line no more than 200 meters (for on-grid systems and small projects like 1 MW)?
• Is there good road access for transporting construction equipment, panels, transformers, etc.?
• Ideally, the photovoltaic plot should be at least 2 hectares for a 1 MW system.

How to define the purpose of a solar farm?

In most cases, a photovoltaic farm is a business investment aimed at generating profit. It can also help with energy optimization for large enterprises, municipalities, and public administration. The reasons for investing in a PV farm can include:

• Improving energy efficiency for self-consumption within the enterprise.
• Supporting green energy initiatives and corporate social responsibility.
• Engaging in business projects related to selling energy in URE auctions.
• Selling energy on the TGE exchange.
• Investing in energy storage to stabilize and balance the grid connection.
• Following the latest trends by using the PV farm for PEM hydrogen electrolysis.

Tender for a photovoltaic farm

Investing in photovoltaics is becoming increasingly popular, but finding reliable information amid conflicting details can be challenging. The best assembly teams can comprehensively analyze all options during the selection and design phases. Opting for a company specializing in complete project implementation is ideal. After navigating the regulations and permits for a photovoltaic farm, you should select key components such as:

Structures for Photovoltaic Panels: To make the most of the surface and the latest trends, use structures designed for bifacial modules. The most efficient option in terms of production is a tracker system that follows the sun.

Photovoltaic Inverters: For industrial solutions, larger string inverters offer better cost efficiency. The SPI 250 kW from Kehua is a recommended choice. On large, flat photovoltaic farms, central inverters can be considered.

Photovoltaic Modules: Double glass bifacial panels are recommended for photovoltaic farms. Leading technologies include HJT or N-type panels, which promise high yields for up to 30 years.

Photovoltaic modules for a photovoltaic power plant

The photovoltaic structure is the backbone of the entire system, while the photovoltaic modules serve as the shell. Two main technologies dominate the production of photovoltaic panels:

N-Type (HJT): This technology includes leading brands like ACKOME, Huasun, Risen, and Longi.

PERC (P-Type): This technology is divided among several manufacturers, with ZnShine standing out due to its Graphene cover, a 12-year manufacturer’s warranty, and a 30-year power warranty.

The most important elements of photovoltaic panels dedicated to farms and large photovoltaic installations are:

N-Type technology, the fastest-growing in the photovoltaic market, includes n-TOPCON Jolywood and HJT AKCOME panels. P-Type technology offers the widest range of manufacturers but can lead to more challenges in selection and generally has poorer performance. Key features to consider are:

• Bifaciality: Panels that generate energy from both sides, potentially offering up to 30% more power.
• Double Glass or Glass-Glass Modules: These have glass on both sides, reducing risks of degradation from weather and fire.
• Manufacturer Warranty: Jolywood offers the highest 15-year warranty for N-Type, while ZnShine provides 12 years for PERC. HJT manufacturers like Huasun and AKCOME also offer warranties ranging from 15 to 25 years.
• Linear Power Loss Warranty: Choose panels with a 30-year warranty that guarantees at least 83% power retention. ZnShine, Jolywood, Risen, AKCOME, and Jinergy offer warranties of up to 87% or more.
• Initial Degradation: N-Type panels typically show 1% degradation in the first year, while PERC panels with Gallium instead of Boron have 2.5-3%. After the first year, Jolywood and HJT panels degrade at 0.4%, and ZnShine panels at 0.5%, which is among the best for bifacial and glass-glass modules.
• Manufacturer Warranty Security: Secured by Munich RE, offering high protection levels.
• Bloomberg TIER I Ranking: Modules in this ranking are usually leaders in technology and sales.
• Silicon Cells: Standard modules have 120 cells, but Half Cut modules (divided into two parts with 60 cells each) are preferable as they minimize the impact of shadows and dirt.
• 9BB or Multi BusBar Technology: Optimal for energy dissipation from silicon cells.
• Production Technology: Monocrystalline Jolywood N-Type modules and Heterojunction N-Type (Akcome) or ZnShine PERC are recommended.
• Temperature Coefficient: HJT panels achieve the best temperature coefficient of less than <0.3%.

Photovoltaic Inverters and Farms:

• Function: The inverter acts as the heart and brain of the photovoltaic installation, essential for optimizing performance, especially in harsh conditions.
• Kehua Inverters: Known for their industrial reliability, Kehua offers string and central inverters. For farms, Kehua 250kW inverters are effective, with 4 inverters per 1 MW controlling around 3,000 N HJT type bifacial modules.

Choosing a String Inverter:

• Outdoor Conditions: Look for at least IP 65 resistance.
• Housing: A tight aluminum or metal casing enhances durability.
• Temperature Efficiency: Inverters should perform efficiently up to 50°C. Kehua inverters operate at 98.6% efficiency at this temperature.
• Voltage: Maximum load should be at least 1000V.
• MPPT Trackers: Consider the number of MPPT trackers and the maximum current in Amps per tracker. Kehua’s inverter offers 30 Amps.
• Extreme Load Range: A wider range improves adaptation to varying installation conditions.
• Monitoring System: Prefer inverters with a proprietary monitoring system for better management.
• Data Transmission: Look for PLC technology using RS 485.
• Compatibility: Ensure the inverter works optimally with bifacial photovoltaic modules.

When to use Central Inverters?

Central inverters are large devices designed to manage the operation of extensive photovoltaic installations. As the name suggests, a single central inverter controls the entire system. This approach has its pros and cons:

• Advantages: A central inverter simplifies the configuration and optimization of the entire photovoltaic farm by managing the whole setup with one device.
• Disadvantages: It is suited to specific conditions, such as flat terrain, uniform module characteristics, and minimal shading or dirt on the panels. Unlike string inverters, which optimize smaller groups of modules, a central inverter manages the entire installation, resulting in less detailed optimization.

Central inverters are typically used for projects with capacities ranging from several dozen to several hundred megawatts.

Storing energy from photovoltaics

When incorporating a battery into a photovoltaic farm project, several factors should be considered based on the intended use of the energy storage:

• Energy Storage for Connection Power Control: Managing the power connection to the grid.
• Improving Current Characteristics: Enhancing the current quality to meet Distribution System Operator (DSO) requirements.
• Storing Energy During Production Peaks: Accumulating energy when production is high and selling it when there is no sunlight, no wind, or when prices are favorable on the TWE (energy exchange).
• Grid Stabilization and URE Auctions: Using stored energy for grid stability and participating in energy storage auctions.

The purpose of the energy storage determines the selection of components and how they integrate with the photovoltaic farm’s operation. For large-scale projects, containerized energy storage solutions are typically used, scaled according to the project’s needs. The optimal choice is to acquire an energy storage system that includes a PCS (Power Conversion System) converter and a transformer station, which integrates DC and AC energy control into a comprehensive turnkey system. For example, ZPUE offers transformer stations with integrated energy storage solutions.

Autror:

Jacek Serwin,  HJT Solar Panel Sales