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Distribution Grid Integration Costs Under High PV Penetrations Workshop

The Benchmarking Distribution Grid Integration Costs under High Distributed PV Penetrations workshop was held September 19, 2017, on NREL's campus in Golden, Colorado. Sponsored by the U.S. Department of Energy (DOE) Solar Energy Technologies Office, the workshop shared information and elicited stakeholder feedback on methods and terminology used for analyzing the monetizable grid integration costs and benefits of distributed photovoltaic systems (DGPV) on distribution grids.

These distribution grid integration costs are one component of a complete cost-benefit analysis of DGPV (or any energy technology) that also includes societal impacts and effects on the transmission and bulk power systems. Understanding distribution system grid integration costs is specifically important for informing utility planning processes, the design of fair and equitable electric rates, and identifying barriers (technology, policy, market, institutional, data) to achieving low-cost grid integration. Engaging stakeholders to coalesce around transparent and mutually acceptable frameworks for cost-benefit analysis is key for analyses to gain traction and be useful in practice.

Workshop Goals

The purpose of this workshop is to share information and elicit stakeholder feedback on methods and terminology used for analyzing the monetizable grid integration costs and benefits of DGPV on distribution grids (medium- and low-voltage only). In particular, there was be a focus on methods most appropriate for cost-benefit analysis under increasing penetrations of DGPV, including under scenarios where traditional T&D reinforcements are cost prohibitive and/or ad hoc and worst-case interconnection procedures are sub-optimal. The overall goal is to coordinate analysis between the community and improve analysis by obtaining perspectives from a diverse set of stakeholders, including utilities, regulatory bodies, consulting companies, vendors, and national laboratories. Specific feedback on NREL and DOE analysis activities, terminology, and metrics for understanding distribution grid integration costs was also collected as part this workshop.

Workshop Presentations


Panel 1: Perspectives on Cost-Benefit Analysis — Current Practice

Session 1: Frameworks for Distribution Grid Integration Cost-Benefit Analysis

Panel 2: Data Issues

Panel 3: Future Directions in Grid Integration Cost-Benefit Analysis

Notes on Future Needs

All speakers were asked to include their opinions on challenges and future needs in this area. We have aggregated and summarized this information here, highlighting some common themes. Please note that these are only issues identified by the presenters in their talks as key challenges and future needs, and are not based on a survey where the relative importance of each of these issues after reviewing this full list. Many presenters and other attendees resonated with several of the needs and challenges below. There were 13 total presenters.

Need or Challenge Number of Presenters who Highlighted Notes
Increased transparency and common vocabulary 3  
Need to integrate distribution system and bulk system planning and analysis, understand value and operational issues for the full system 3 One specific challenge cited as understanding whether infrastructure investments are truly deferred based on DGPV/DER.
Need more data 4 Specific data gaps mentioned include O&M and component lifetime data, SCADA-based 8760 load curves, DG data (storage/non-PV DER), secondary network data, special protection schemes and operations information, and increased amount of circuit and substation data provided to developers. It was also noted that data that is cleaner and more consistent is required, and that data needs to be available, accessible, and machine-readable.
Issues around fair allocation of costs and associated issues around rate structures and design of incentives 4 There were also comments by multiple presenters on challenges around accurately allocating or assigning costs to different technologies and parties.
A need for proactive instead of reactive planning and analysis 4 This point was generally emphasized/agreed upon by all presenters and multiple other attendees.
Finding technical and commercial solutions that are mutually acceptable to multiple stakeholders; finding analysis to support these frameworks that is trusted by all parties 4 This point was also generally emphasized/agreed upon by most presenters and several other attendees. One presenter noted that finding these solutions requires investments in analytics, modeling tools, communications systems and IT infrastructure, and a question of who will fund this because utilities having trouble getting capital internally).
Probabilistic planning, DER forecasting, risk and scenario analysis 3  
Market and market design challenges, including understanding costs, value, and other issues around centralized control and optimization versus market based DER dispatch 7 One presenter also noted that there are questions around if customer payback is favorable enough to get the right amount of DER adopted in the right places via market forces alone; also mentioned questions about how to fairly incentivize deployment in low-cost, high-value locations.
Challenges around utility business model and structure: policies and regulations, revenue requirements and investment recover issues 3 Several people also noted that utilities can't always implement or aren't always incentivized to implement lowest-cost solutions in the current framework.
Standards and technical requirement development between utilities and developers, quick adoption of the latest IEEE standards (1453 and 1457) 1  
Distribution challenges with location marginal prices 2  
Need for full time-series simulation to properly account for and compare costs (not possible in static regime) 2  


Kelsey Horowitz |