From The Team

4 Ways Utilities Can Tackle Distributed Solar Challenges

Authored by:
Nathan Case
Last Updated: 
December 27, 2023

This is the third installment of our series: The Top 5 Challenges Facing Distribution Utilities. Subscribe to automatically receive future installments.

Rapid deployment of distributed solar generation is transforming the energy landscape in the U.S. According to the Solar Energy Industries Association, the U.S. solar industry had a record-setting first quarter in 2023, with 6.1 gigawatts of solar capacity installed—putting the solar market on track to triple in size by 2028. 

This growth benefits society by decarbonizing the power sector, but it also presents challenges for electric utilities that must be carefully managed.  In areas with high solar penetration, generation can exceed a distribution feeder’s hosting capacity (the amount of solar that can be accommodated without adverse grid impacts). This can lead to voltage violations, unreliable power quality, overloading of utility equipment, and backfeeding of power across the substation to transmission lines. Utilities can overcome these challenges, but they must embrace innovative solutions to do so.

Streamlining interconnection

Most utilities today lack real-time awareness of local hosting capacity and aggregated solar generation at the feeder-level. While many utilities have invested in periodic hosting capacity analyses, these analyses are static and quickly become outdated. Without up-to-date awareness of local hosting capacity and solar generation, utilities are limited in their ability to assess the likely grid impacts of new installations – especially at the community and commercial scale. 

The lack of publicly available hosting capacity information also makes it difficult for developers of megawatt- and community-scale solar projects to select suitable sites and design grid-friendly systems.

To address these challenges, some utilities have attempted to streamline interconnection processes by approving projects under a certain capacity, such as 10 or 15 kilowatts. But many continue to rely on time-intensive interconnection studies for each proposed installation, increasing costs and approval timelines. And where the studies identify a need for a local grid upgrade, many utilities require the solar developers or homeowner to pay for grid upgrades – using an approach where the full cost of an upgrade falls onto the marginal project that exceeds local hosting capacity. This inevitably results in projects being canceled and new distributed solar development stymied. 

Preventing backfeed

Another emerging challenge is power backfeeding from large-scale, distribution-connected solar systems to transmission grids. Many utilities, especially distribution cooperatives, have power supply contracts with their generation and transmission providers that prohibit exports of excess solar power onto the transmission system. This is required to protect the reliability of the system, as legacy distribution-side equipment was not designed for two-way power flows.

As a result, if local solar output exceeds the aggregate power demand below the substation, the distribution utility must either curtail the solar generation or store the excess power in distribution-connected batteries. This requires utilities to deploy control systems and energy storage for large-scale solar systems along with tools that provide real-time visibility of power flows.

Emerging solutions

The good news is that many innovative solutions to these challenges are emerging. A recent report by the Interstate Renewable Energy Council (IREC) highlights several promising solutions:

  • Utilities can address the challenge of time-intensive, single-project interconnection studies through cluster studies that assess grid impacts of groups of proposed projects. 
  • Utilities can make grid upgrade costs more affordable for developers and customers by allocating costs across a group of projects. Through an approach known as Integrated Distribution Planning, utilities forecast solar deployment and grid capacity constraints to inform proactive, utility-funded investments in advance of new solar proposals.
  • Utilities can enhance grid visibility by providing public maps with information on hosting capacity, interconnection queues, grid constraints, and planned upgrades. Such maps give developers more visibility into project costs and optimal project designs. They can also decrease the number of proposed projects that exceed hosting capacity, streamlining interconnection queues and timelines. 

Another emerging solution is flexible interconnection, which enables a utility to approve solar projects in high penetration areas by curtailing their output only when grid constraints arise. Because constraints occur infrequently—typically less than 5% of the time—projects would have a minimal loss of revenue due to curtailment. This approach can increase hosting capacity without grid upgrades and accelerate interconnection timelines.

Camus’ role in managing local solar 

At Camus, we actively support utilities in navigating the operational impacts of distributed solar. Our grid orchestration platform provides real-time awareness of conditions at substations, feeders, transformers, and individual devices to identify problems ranging from backfeeding to local voltage violations. Empowered with these insights, utility operators can take appropriate action to mitigate issues and prevent future issues from arising.  

Example overview of distributed solar installed capacity and real-time, aggregate generation

For example, a Camus customer can use the platform to optimize charging of batteries to minimize curtailment – while providing the visibility and controls necessary to curtail generation when the battery is full. Facing likely backfeed conditions during low-demand periods, Camus will curtail solar generation when the generation-to-load ratio is greater than a preset value and the battery storage is near full. As the system exports power to the grid, Camus’ platform automatically adjusts the behavior of the solar-plus-storage system so that it stays within the generation:load constraints. This enables the operator to avoid backfeeding across the substation and the related fines from its transmission operator. 

Another emerging use case involves the use of flexible interconnections to manage local grid constraints during both normal and abnormal switching states. To ensure reliability, utilities must be able to ensure distributed generation remains within local hosting capacity even when the grid is operating under abnormal conditions (e.g. during a partial outage). Camus’ platform calculates solar curtailment as a function of system constraints–including thermal overload, reverse power flow through unsupported equipment, and voltage limits– on an ongoing, forward-looking basis using best available data from a utility’s SCADA system and/or ADMS. When the forecast requires solar curtailment, Camus executes the curtailment via real power commands to installed solar systems subject to flexible interconnections. With awareness of current switch state and planned switching, Camus helps utilities ensure reliability across wide-ranging operating conditions.

In summary, Camus is developing the tools needed to embrace increasing amounts of distributed solar and storage as a portion of a utility’s power supply portfolio.

Embracing distributed solar

By embracing a more data-driven approach to managing distributed solar impacts, utilities can accelerate safe and reliable integration of distributed solar systems – keeping their community, regulators, and operators happy.  Solutions like cluster studies, integrated distribution planning, publicly available maps, and flexible interconnections can help utilities embrace distributed solar as a tool for lowering supply costs, investing in local resource development, and achieving decarbonization goals.

For utilities seeking a partner to help transition to this data-driven approach, Camus stands ready to help. To learn more about the challenges and opportunities facing utilities related to distributed solar or about Camus’ grid orchestration platform, please reach out to our team.

Contact Us

Start your community energy transformation.