Utilities across the US are feeling pressure from developers, local and state governments, and regulators to drastically increase the amount of renewable energy connected to the electrical system. While many of the clean energy goals and standards were set out in the last few years, as we work towards the 2030 goals utilities must find ways to connect distributed energy resources (DERs) in a faster and more cost-effective manner while still maintaining the system reliability that all customers depend on.
As DERs continue to interconnect to the grid, the hosting capacity of grid infrastructure is becoming quickly saturated by the use of conventional interconnection methods. Once the traditional ‘design, build and operate passively’ hosting capacity is reached, utilities typically upgrade the grid infrastructure which can cost millions of dollars and take many months, potentially years, to complete.
Therefore, two major issues have been identified which will stand in the way of utilities achieving these clean energy interconnection targets. These issues are both linked by the lack of hosting capacity at the distribution level for new large DERs. Firstly, these targets will trigger high costs as utilities upgrade infrastructure and thus increase hosting capacity. Secondly, the timescales for planning and implementing the required grid reinforcement will be lengthy.
The traditional design of a DER interconnection is based on the worst-case network conditions, reflecting a static operational state that happens infrequently e.g. concurrent high wind and solar generation output at a period of very low demand. The intermittent nature of renewable DER reduces the likelihood, but does not fully eliminate, the occurrences of these worst-case planning conditions. This introduces greater diversity in network operation and thus more available real time or dynamic hosting capacity if that can be tapped safely and securely.
Flexible Interconnection – one tool to solve the interconnection challenge
It should be noted that flexible and firm interconnections are not mutually exclusive options when it comes to adding renewables to the distribution grid. Flexible interconnections can be standalone solutions for adding DER to the grid, dynamically curtailing the assets in exchange for a lower interconnection fee and a shortened interconnection timeline. Therefore, flexible interconnections can serve as a bridge to firm interconnections. Experience shows that the challenge of network planning and interconnecting renewables can be overcome through a combination of firm and flexible interconnections, as well as other solutions. This combination provides valuable options and pathways for both grid planners and interconnecting customers.
The benefits of flexible interconnections
Flexible interconnections have positive impacts for all stakeholders. There are cost savings for developers, customers and utilities. Connection time is shortened, and clean energy transition speed is gained. Throughout the UK and US Smarter Grid Solutions (SGS) has implemented flexible interconnections that have added 382 MW of renewable energy to the grid while providing over $300 million in grid reinforcement cost savings for distribution utilities, connecting customers and rate payers in just seven schemes where public information on benefits is available. SGS has several additional flexible interconnection schemes in operation and at various stages of delivery and so it can be expected that this number will increase significantly over the coming months as customers connect to these schemes.
Moreover, in terms of time saving, SGS has seen connection time savings typically in the range of 1 to 3 years. In one case a flexible interconnection scheme using SGS technology interconnected multiple PV assets six years faster than if they waited for a firm interconnection. Such timescales are only likely to increase as connection queues continue to grow and grid capacity becomes increasingly scarce.
On top of increasing hosting capacity and providing cost and time savings to utilities and their stakeholders, flexible interconnections provide an economic benefit to the local community. This can be seen in the analysis of the SP Energy Networks (SPEN) Dunbar, UK scheme by Regen, an independent energy and market insight non-profit. This analysis determined the economic benefits of flexible interconnections and showed that for one scheme in SPEN’s service territory, $75 million in Gross Value Add (GVA) economic contribution, $100k in annual community benefit, and 56 new full-time jobs were created by the accelerated development, construction and flexible grid interconnection of renewables generators.
However, it is important to note that while flexible interconnections have many benefits and are a crucial and creative solution for helping nations move towards their 2030 energy goals, they will not replace conventional grid solutions. Traditional grid upgrades are likely to work in tandem with different cost sharing approaches, developer led distribution upgrades, flexible grid market services and other interconnection solutions. Therefore, flexible interconnection is not a competitor to traditional solutions, but another arrow in the quiver that can be utilized by utilities and developers to get more DER onto the distribution grid while modernizing the grid infrastructure to be smarter and more flexible.
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