Utility interconnection is vital to completing a successful project. Therefore, successfully managing this critical step helps keep projects on schedule and budget. Unfortunately, interconnection issues can degrade customer satisfaction, so effective management is essential. Understanding how a solar farm connects to the grid and the point of interconnection for solar projects is critical.
The Importance Of Solar Interconnection
Commercial solar projects must be connected to the power grid to receive compensation for electricity production from distributed generation. Most commercial solar projects are not financially viable without compensation from the utility company. The interconnection process varies depending on the electric utility, the property, and local policies and includes load-side and line-side requirements.
The utility company must authorize this connection to receive approval to interconnect. In addition, the solar panels and equipment must meet specific qualifications to ensure the proper voltage, power quality, and reliability.
Therefore, interconnection management can be relatively complex, especially for larger projects. However, utility interconnection might not be much more complicated for small commercial projects than residential solar installations.
Not correctly identifying all the costs related to interconnection can result in numerous change orders and can increase the total cost of the solar system. This can lead to dissatisfied customers and delays.
The Commercial Interconnection Process
In the United States, state-level public utility commissions (PUCs) create interconnection policies that utility companies and solar installers must follow. Many states have also enacted safety requirements based on IEEE 1547 and UL 1741 standards.
This also means the interconnection policies vary by state, with some having more complicated and unclear standards than others. Unfortunately, this increases the soft costs of installing a solar PV project. Also, varying requirements make it more difficult for solar contractors that operate in numerous states because they need to learn the requirements in all states where they complete installations.
In general, the solar system must satisfy grounding, power quality, and voltage requirements to navigate the process successfully. In addition, some commercial solar projects will require an impact study. The utility interconnection process consists of two main steps that need to be completed in the correct order.
Interconnection Application Process
Like residential projects, commercial projects require filling out an interconnection application. The applications contain basic information, such as the system size, solar PV equipment, location, and solar electricity production estimates. For large commercial projects, this application can be relatively complicated. In particular, solar with battery storage can be incredibly complex because of the impact of the battery on the electric grid.
During the application process, contractors and project developers need to show that the renewable energy system meets various requirements. The application must also explain the point of interconnection for solar. If changes or modifications are made to the solar project, the solar contractor or developer must update the application.
Permission To Operate
Before a system can be turned on, it must receive permission to operate (PTO) and an approved interconnection agreement. The system must be installed, inspected, and approved by the utility provider. Now, the solar system has the authorization to operate and connect to the utility grid because it fulfills all the interconnection requirements.
How Long Can Commercial Interconnection Take?
The length of the process depends a lot on the utility company, if there are complications, and how quickly the solar contractor or developer responds to requests from the utility company. Also, solar systems with energy storage can take longer to receive approval. This is because the solar installation is both a load and a generator, depending on how the project is operating. Some jurisdictions have simplified interconnection approval processes, especially for residential and small commercial solar systems. Other jurisdictions have not.
According to a 2015 study by the National Renewable Energy Laboratory, the average small commercial project (10 – 50 kilowatts) took an average of 62 days from when the contractor applied for interconnection to when they received permission to operate. Keep in mind that timeframes vary a lot by the jurisdiction and scale of the photovoltaic solar project. Large commercial projects can take significantly longer.
What Causes Solar Interconnection Delays?
Solar interconnection delays can result from factors such as utility administrative processes, permitting issues, technical reviews, and grid capacity constraints. Administrative hurdles, paperwork, and regulatory approvals may extend timelines. Also, upgrades to the grid infrastructure to accommodate solar integration and coordination with various stakeholders can contribute to delays. Local regulations and the complexity of the interconnection process may vary, influencing the overall timeframe.
GreenLancer was designed to accelerate the adoption of renewable energy, and we specialize in overcoming solar permitting, engineering, and interconnection issues. Create a free account to begin shopping for solar design services.
The Difference Between Residential And Commercial Interconnection
Most residential and small commercial PV projects can connect to the power grid without equipment modifications beyond the meter. However, because of the scale and voltage of larger projects, this often isn’t the case, and interconnection is typically more complex.
Point Of Interconnection for Solar
It is typically not cost-effective to connect a small solar project to a high-voltage transmission line because the cost of interconnection typically increases by the voltage of the power line.
Larger commercial projects, such as a community solar farm, usually need to be connected to a three-phase distribution line. Utility-scale projects either connect directly to a substation or a transmission line of 69 kV or higher.
Unless a solar farm is installed next to transmission lines or substations, the solar contractor needs to install a generation tie to connect the clean energy project to the grid. These are expensive to construct and can have a significant impact on the project’s return on investment. Therefore, close proximity to transmission lines or a substation is preferable.
Unfortunately, just because a high-voltage line is located near a proposed solar farm doesn’t mean that it has the capacity to handle the additional power from the solar project. Sometimes, electrical equipment needs to be upgraded to increase its capacity, which can be costly.
Solar Interconnection Voltage
It is also essential to consider interconnection voltage. Commercial customers typically receive 208V from the utility. However, most inverters over 20 kilowatts output 480 volts. Therefore, unlike residential PV systems, many commercial properties require a transformer to step down the voltage.
A combiner panel is needed to combine the outputs if a solar system is large enough to have multiple inverters. This is often installed on the roof or sometimes in a mechanical room or basement.
Utility Compensation
Under net metering laws, many residential and some commercial solar customers are compensated for solar electricity at the retail rate. However, laws vary by state, and some states don’t have a net energy metering program. For commercial power customers, policies also vary by the type of commercial account. For example, some commercial customers can offset demand charges on their power bills with solar power, while others cannot.
What is a Solar Farm Substation?
A solar farm substation is a key infrastructure component that facilitates the connection of a solar farm to the electrical grid. Here’s a breakdown of its role and function:
Step Up Voltage
The solar farm substation houses transformers that increase the voltage of the electricity produced at the solar farm. Solar panels typically produce electricity at a lower voltage, which is then converted to a much higher voltage needed for efficient transmission over long distances.
Point of Interconnection
The substation is the point of interconnection between the solar farm and the grid. It ensures that the electricity generated by the solar farm is synchronized with the grid’s voltage, frequency, and phase, allowing it to be fed into the wider electrical network.
Protection and Control
Modern solar farm substations are equipped with protection devices, such as circuit breakers and relays, that safeguard both the solar farm and the grid from electrical faults or anomalies. It also includes control systems that manage the flow of electricity, ensuring that the power output meets the grid’s requirements.
Monitoring and Communication
Substations often include monitoring and communication systems that track the performance of the solar farm, control the operation of the transformers and other equipment, and report data back to the utility or solar farm operators.
Energy Storage
Some solar farm substations may also incorporate energy storage systems, such as batteries, to store excess energy generated during peak sunlight hours. This stored energy can then be dispatched when solar generation is low, enhancing the reliability of the solar power supply.
Solar Interconnection FAQs
Read on to gain answers to common questions about the solar interconnection process and the point of interconnection for solar.
How does a solar farm connect to the grid?
Solar farms connect to the grid by converting the direct current (DC) generated by solar panels into alternating current (AC) through inverters. The AC electricity is then transmitted to a substation within the solar farm, where it is further transformed and connected to the broader electrical grid. This allows the solar farm to distribute the generated electricity across the grid for consumption by homes, businesses, and other users.
What role do transformers play in connecting a solar farm to the grid?
Transformers or substations play a crucial role in connecting a solar farm to the grid by stepping up the voltage of the electricity generated by the solar panels to match the grid’s high voltage levels. This is essential for efficient long-distance electricity transmission from the solar farm to the grid. Without transformers or substations, the generated power would not be compatible with the grid's infrastructure, hindering its distribution.
When do solar farms need a substation vs a transformer?
Transformers step up voltage in small—to medium-sized solar farms to connect to local distribution grids. Large-scale solar farms require substations to provide additional protection and control and step up voltage for high-voltage transmission. Substations are essential when connecting solar farms to the high-voltage transmission network.
What is the point of interconnection for solar?
The point of interconnection (POI) in a solar energy system is where the solar power project connects to the electrical grid. It’s the physical and electrical point where the electricity produced by the solar panels is fed to the utility grid or used within a building. This connection is essential for integrating solar power into the broader energy infrastructure.
It includes:
Location: The point of interconnection for solar can be at the main service panel (for residential or commercial systems) or at a utility substation (for larger-scale solar farms).
Grid Connection: At the POI, the AC power generated by the solar system (after being converted from DC by the inverter) is synchronized with the grid. This allows excess electricity to be fed back into the grid (often through net metering), or it enables the building to draw power from the grid when solar production is insufficient.
Safety and Compliance: The point of interconnection is critical for safety, and its design and installation must comply with local electrical codes and utility requirements to ensure proper operation and avoid issues like backfeeding, which can be dangerous to utility workers during a grid outage.
Connecting Solar Farms to the Grid
The interconnection process becomes easier with experience, especially if the technical requirements remain consistent or are streamlined.
Bringing expert knowledge to the interconnection process is critical. Unfortunately, many solar companies lack this knowledge in-house, or they simply don’t have the time to properly manage the interconnection process and site solar equipment optimally.
GreenLancer solar interconnection and engineering services can help mitigate costs and ensure project success through their professional solar development services. To learn more, sign up for free and shop our interconnection services, or complete the form below to learn more.