With little fanfare or attention, the main investor-owned utilities in California released their first Integration Capacity Analyses (ICA) and supporting distribution system maps at the beginning of 2019. ICA is California’s term for hosting capacity analysis, which is an evolving analytical tool that provides a snapshot in time of the conditions on a utility’s distribution grid that reflect its ability to “host” additional distributed energy resources (DERs), such as rooftop solar, energy storage and/or electric vehicle charging stations, at specific locations on the grid.

The ICA is a revolutionary leap forward in grid transparency, in terms of providing customers, developers, and regulators with truly useful, accessible, and in-depth distribution grid information. California’s long-standing leadership on this effort provides critical lessons and insights that can help other utilities and states as they undertake similar efforts across the country. Among the three California utilities – Southern California Edison (SCE), Pacific Gas & Electric (PGE), and San Diego Gas & Electric (SDG&E) – (and really across the country), SCE’s ICA and map stand out as an impactful and well-designed grid modernization tool for several reasons.

As an active intervenor before the California Public Utilities Commission, IREC has been at the forefront of the effort over the past four years to guide, inform and shape the development of the California ICA and maps. Since the full-scale maps were released in January, IREC has done an in-depth exploration of the capabilities of the maps and advocated for ongoing improvements, encouraging the commission to establish a process for ensuring the utilities remedied both the data quality and usability issues. Throughout this effort, we have learned a lot about what is working, what is not, and what needs refinement.

This article provides a brief overview of California’s ICA and why it matters. It highlights the features, capabilities, and merits of the different utilities’ ICA results and maps, including outstanding issues to address. Next steps are then previewed, including how these tools will be applied to streamline the process of interconnecting DERs to the grid and to inform distribution planning.

California’s ICA Is a Transformative Grid Transparency Tool

ICA models how much new load and generation can be accommodated on the grid at specific locations, using actual grid conditions instead of generic screens, rules of thumb, or more time-consuming power flow analyses. The idea underpinning the ICA is that, by providing greater transparency into the grid – displayed in the form of maps with supporting datasets—such analyses can help reveal the operational limits of the grid, which might impact the ability of new DERs to interconnect quickly or affordably.

These tools can also identify areas where DERs may be able to provide beneficial services by addressing existing grid constraints, informing more strategic grid investments over the long term. In addition, the information gleaned from an ICA can help regulators, utilities, developers and customers make more proactive, cost-effective and efficient decisions about DER investments.

The commission required the California utilities to complete a full model of all their three-phase distribution circuits by July of 2018, with the intent that it be capable of being used in the interconnection process. It also convened a separate stakeholder working group to discuss how to integrate the results of the ICA into the interconnection tariff (Rule 21). That group produced a report earlier this year, which is now awaiting commission approval. The ICA could be used in California’s interconnection process as early as the first or second quarter of 2020.

SCE’s Map is Best in Class for Transparency and Usability  

The layout, accessibility and functionality of SCE’s map makes a tool that customers would want to use, one that will help optimize DER projects. Throughout the development process, SCE has also been flexible and responsive to stakeholder requests for fixes and improvements. Let’s explore some of the highlights.

SCE does not require any login credentials to use the map, so within just a few clicks, a user can immediately zoom in on a precise location and see the color-coded three-phase lines connecting to that location, with the colors indicating the level of available capacity (e.g., red is limited capacity, green is ample capacity, and yellow is somewhere in between).

Southern California Edison Color-Code 3-Phase Lines Map

Clicking on the color-coded lines produces a pop-up box that provides a wealth of information about the distribution system at that location, including the bottom line in terms of the number of MWs (or kWs) that likely can be hosted on that specific line section (with some exceptions). The box also provides highly useful supporting information that can help inform project decision-making. For example, you can see how much capacity may be ahead of your proposed project in SCE’s interconnection queue, the breakdown of customer type by circuit, and the substation it connects to.

Southern California Edison Pop-Up Box View

A user guide is available to help you navigate the map and data.

For each grid location, SCE publishes a few ICA values: an Operational Flexibility Value (OpFlex) and a Non-Operational Flexibility or Static Grid Value (non-OpFlex/SG) for both a typical solar PV profile and for a uniform generation system (i.e., a system outputting its full capacity 24 hours a day, 7 days a week). ICA values are published for load as well.

The non-OpFlex/SG value represents the amount of generation that can be hosted without violating one of four different technical criteria: Thermal, Steady-State Voltage, Voltage Fluctuation, and Protection. The OpFlex value includes an additional criteria that is intended to be a proxy for evaluating whether the construction of a DER project would limit the utility’s ability to reconfigure circuits in the case of an emergency fault or other event. The OpFlex value is likely to be the one used in the initial interconnection screening process, but in most cases it is expected that projects will be able to interconnect, without major upgrades, using the non-OpFlex/SG values.

It is also important to recognize that the values you see in the pop-up box represent the grid conditions at the single most limiting hour of an entire year. Clicking over to the second and third tabs in the pop-up box, a user can see an interactive load profile for the circuit and for the substation, which provides maximum and minimum load for the entire year on a 576-hour basis (each hour of the highest and lowest load days of each month, or 24 x 2 x 12 = 576).

Southern California Edison Pop-Up Box View

In the third tab, a user can download those profiles and the detailed ICA results that provide the underlying, hour-by-hour capacity limitations by technical criteria.

SCE download data

Such detailed grid information enables DER customers and developers to propose systems that can be designed around the capabilities of the circuit, in a more responsive way. For example, generation can be curtailed during the periods of the year or hours of the day when grid constraints exist. Or, if the primary constraint is a voltage limitation, the system might be able to be designed to address the voltage concerns (using inverter capabilities) without needing to pay for massive system upgrades.

In other words, the downloadable ICA results and underlying data have the potential to transform how projects are designed before an interconnection application is submitted, such that they address and respond to the actual grid constraints at their proposed site. Of note, discussions continue within the Rule 21 docket about the extent to which projects will be allowed to actually use the ICA curves to remain within seasonal or more granular ICA limits.

Another key distinguishing feature of SCE’s map – that neither SDG&E nor PG&E’s maps have – is the ability to search and sort for locations using a built-in function that enables users to identify and filter sites based on available capacity above a certain threshold, to help with site scouting and selection.

SCE Search Function

SCE also offers an Application Programming Interface (API)  that enables users to import the data into their internal systems to support more streamlined project location identification.

All of the aforementioned attributes of SCE’s map (and many others not described here) make it a truly impressive and impactful grid transparency tool, which will support more strategic, streamlined, and affordable deployment of DERs.

SDG&E’s Map Passes, but Not with Flying Colors

By comparison, SDG&E’s ICA map lacks several key user-friendly components. Though initially reluctant to make some basic usability improvements, SDG&E has started to fix issues that made their map difficult to use. Three big issues remain.

After navigating the slow and rather clunky process of obtaining a log-in for SDG&E’s map, there is no ability to search, sort, and filter the data to identify interconnection locations based on relevant criteria. Users can search for a particular address within the map, but they cannot search for all sites with, say, 1 MW or more of capacity for new generation. SDG&E also lagged behind in its release of an API, but just notified the commission of its plans to do so.

The next issue is that SDG&E’s map still does not display substation locations, despite several orders from the commission to do so. Rather than showing the exact locations of the substations, like SCE does, they have included color blocks that ostensibly show the area served by the substation.

SDG&E substations

Finally, SDG&E is applying an overly strict approach to redacting information on their map. A topic of much discussion throughout the proceeding, IREC and the other involved stakeholders agreed that the utilities should take appropriate measures to protect customer confidentiality and not share information that would allow someone to identify the load of individual customers. This means that for the ICA data, the load profiles for certain substations and circuits will need to be redacted if they contain data on fewer than 15 customers, or if a single customer constitutes 15 percent of the load or more (aka the 15/15 rule).

In addition, since the Operational Flexibility criteria violation is essentially a calculation of the minimum load, it is also appropriate to redact that value for line sections that violate the 15/15 rule. SDG&E has gone well beyond this, however, and is redacting all information about locations that violate the 15/15 rule, including entirely removing the circuit from the map. As such, users of SDG&E’s map may discover numerous blanks on the map until the data redaction issues are resolved.

Notwithstanding the above issues, several of the initial issues with SDG&E’s map have been largely resolved to make it more functional for customers—particularly for those who have known potential project sites they would like to learn more about before they submit an interconnection application.

PG&E’s Map Fails to Deliver

When the California utilities put together their first test case of the ICA in 2015, PG&E was well ahead of the pack, being the only utility to deploy an analysis across its entire distribution system. Unfortunately, their deployment of the ICA methodology selected by the commission is riddled with challenges and errors.

The first issue is that virtually the entire map is red, showing little to no capacity for new generation or load of any sort.

PG&E circuits

In addition, at the time of the map’s rollout, roughly 30 percent of PG&E’s circuits were not showing at all. By contrast, SCE and SDG&E’s results showed significantly greater capacity across their systems in all sizes. Following some persistent questions from IREC and other stakeholders, PG&E eventually acknowledged substantial quality control issues with their results.

As of today, PG&E’s ICA results are unreliable, and therefore, essentially unusable. The map does provide access to some basic information that is still useful, and has some features that could be valuable going forward, but over a year after the ICA was supposed to be complete, PG&E still has not produced a quality and complete analysis.

In addition, like SDG&E, PG&E has gone beyond what is allowed or necessary in their redactions, including removing the ICA operational flexibility value for every location because they are having technical challenges just redacting the information for the circuits where the 15/15 rule would apply.

PG&E’s map itself (underlying results aside) should be workable once the results are corrected. Similar to SDG&E, though, PG&E’s map also lacks a function that allows users to search for locations with specific characteristics and the company has still not made an API available.

What Do the Maps Tell Us About Capacity for New Load on the Grid?

While much of the focus on hosting capacity maps has been on helping to identify good locations for new renewable generation projects, these tools should be able to accurately analyze the grid’s capacity for new load as well. The capacity for new load is particularly relevant in the context of the push to electrify the transportation and building sectors, but is also useful for energy storage projects, which can be both load and generation.

The California commission required the utilities to publish an ICA that looks at both load and generation. Unfortunately, after seeing the results on SCE and PG&E’s maps, we have come to suspect that there is something flawed in the manner in which the load ICA is being calculated.

As shown in the table below, SCE is showing that nearly 70 percent of the nodes on their system have zero capacity for new load. PG&E’s reported that 63 percent of their nodes have zero capacity, while SDG&E’s shows roughly 32 percent with no capacity.

Percentage of nodes with ZERO capacity for new load
according to ICA results


If these results are accurate, it could have very serious implications for California’s ability to electrify its vehicle fleet without incurring truly significant upgrade costs almost immediately. IREC flagged this concern for the commission, and we look forward to discussing this further with the utilities to better understand whether the models are producing accurate results; whether overly conservative assumptions in the methodology are causing these results; or whether this is really the state of the grid.

If ultimately these results are an accurate representation of where new load can be interconnected, then a much more complex discussion about EV integration awaits us. We suspect at this time that these results are overly conservative or simply incorrect.

What Now?

A July 2019 ruling issued by the Administrative Law Judge requested comments on what changes needed to be made to the ICA, including what needs to be remedied with the current rollout of the ICA and what more should be done with it for use in the planning process and policy context. IREC and other parties filed comments on August 1st and there will be a workshop on September 9th and reply comments due on September 30th.

Meanwhile, we are awaiting an order to clarify exactly how the ICA is to be used in the Rule 21 process, which will be integral to moving forward expeditiously in using the ICA as a tool for interconnection reform.

Although this initial rollout of the ICA had mixed results among the three California utilities, IREC remains optimistic about the ability of ICA to transform the way in which DERs are developed, integrated and optimized on the grid. We will continue to encourage swift action to remedy the issues identified in the maps and ensure that the ICA is expanded and improved upon over time.

If you are a DER developer or customer in California, we encourage you to start using the maps (be sure to check out their user guides) and share your experiences with the commission, the utilities, and IREC. Share your findings about what works well and what needs further tweaking. Consider participating in the September 9th workshop to learn more and weigh in on next steps.

Ideally, more utilities and states will take steps to adopt and implement a hosting capacity analysis as a highly useful tool to enable greater visibility into the grid to inform planning and investment decisions, while also streamlining the process for all involved. The SCE map provides a great example to emulate, and California’s efforts will enable others to leapfrog over identified shortcomings and challenges to the process.