Fully flexible loads: Making the most of PV, batteries, DREDs in virtual power plants (1/2)


SwitchDin CEO Andrew Mears’ presentation at All-Energy 2019 focussed on the concept of ‘fully flexible loads’ in virtual power plants (VPPs) & distributed energy resource (DER) management, with case studies from our project portfolio.

This article (part one of this series) is an overview of what FFLs are and what purpose they can serve in tomorrow’s energy system. Part two examines some examples - both theoretical & real-life.


DER management: A puzzle wrapped in a balancing act

Sidebar 1: Key items in support of the DER transition

Key documents include:

Key projects, platforms & approaches currently being developed include:

SwitchDin will be looking into these in further detail in our presentation at EECON in November.

Through the energy transition, the energy industry’s collective mission is to maximise the value of DERs on the grid while ensuring that their proliferation doesn’t throw the system out of whack. Equipment manufacturers, meanwhile, want to make sure that their equipment is future-ready and brings the greatest potential value to their customers.

This means that DERs need to be - at a minimum - visible to the system operators, but preferably also be controllable. Activity in this space have gained a lot of steam in the last year, with several high-level documents being published and a number of projects/initiatives getting underway (see Sidebar 1).

But the juggernaut rooftop solar market isn’t going to wait for frameworks to be finalised as it continues to add tens of thousands of systems to distribution networks around the country every month. This means that while each DER is potentially a piece of the overall energy system puzzle, their ongoing integration is happening and real time, and must be balanced against current energy system realities.

Major energy system changes in the pipeline

To drive the ‘balancing act’ point home, there are a number of major changes to the energy system that are soon to come into effect and which will reshape the energy landscape in Australia. DER management will need to keep up with these trends.

These changes come in on two levels:

Effectively incorporating these changes into the future energy system will require a fundamental rethinking of Australia’s approach to distributed energy.


Sidebar 2: FFL features & benefits

Key FFL features:

  • FFLs allow upwards & downwards flexibility in load management

  • FFLs are nodal, looking at available resource on a site-by-site basis as opposed to on a device-by-device level

  • FFLs incorporate all forms of DER as policy & market landscapes change

  • FFLs can respond to a range of challenges, with more capacity flexibility than battery storage

Key FFL benefits:

  • For energy retailers & aggregators: FLLs can participate in markets to hedge forward spot prices while improving engagement & maximising value for their customers

  • For energy network operators: Smarter use of distributed assets (both privately-owned and utility-owned) to benefit all customers by - for example - enabling more solar on the grid and making the grid more cost-effective to run

  • For DER owners: Unlocking further value to maximise benefits to self - e.g. compensation for providing energy to markets or delivering services to networks

Fully flexible loads: More than batteries

These days, much of the popular discussion around VPPs has relates to battery storage. This is understandable, as batteries are by nature flexible and can be controlled to strategically service energy system needs in a way that weather-reliant solar PV generation can’t.

Furthermore, battery products can be designed in the lab & equipped in the factory to take commands and actively participate in VPP programs, potentially giving VPP operators direct access to their functionality.

That being said, in the context of the energy system in transition, we’d like to put forward the idea that it’s most useful to look beyond batteries - to view DERs as ‘fully flexible loads’. Like batteries, fully flexible loads are resources that can ramp up or down to respond to local (e.g. for the home or business), network & NEM conditions but with an expanded range of capacity that incorporates other resources within the home.

SwitchDin is already helping utilities to implement the FFL approach in practice with the aim of building more flexibility into the energy system. (See Horizon Power / DevelopmentWA Smart Sun Pilot case study & further examples in part two of this series for more info.)

What is a fully flexible load?

A fully flexible load (FFL) is a collection of one or more energy resources connected to the grid at a single point (e.g. by smart meter or communications gateway device) that can respond to externally generated control signals (e.g. from an electricity retailer, VPP operator or network company) to increase or decrease loads from the site to deliver energy market and/or grid services.

Fully flexible loads may be comprised of any combination of:

  • Solar PV inverters

  • Battery storage systems

  • Demand response-enabled devices (DREDs)

  • Other loads & energy equipment (such as electric vehicle chargers)

The assets comprising a FFL may be mixed & matched in different ways to provide services to the grid in a holistic, technology-agnostic way. Importantly, as DERs, each of these assets may be privately owned, meaning that access to their function will be subject to contracts & agreements between the owner and the operator(s).


The fully flexible load spectrum

It’s easy to imagine a fleet of batteries being discharged in unison to meet energy demand. Similarly, not hard to imagine why a fleet of solar PV systems would be inherently less flexible - producing power when the sun is out and producing none otherwise.

But bundling both of these up alongside a number of controllable loads gives an even larger range of capacity and flexibility. In the grid of the future, where we envision system operators having visibility and some degree of control of DERs (directly or mediated through an aggregator, etc) each FFL will be a lever that can be slid up or down depending on what the situation requires.


The diagram provides an overview of how resource types at a home or business might be dispatched (in order of merit) to respond to market events, network service requests/commands and more. The examples provided are not set in stone, and may vary depending on the purpose of the VPP and the agreement in place between the operator and participants.

The basic idea behind the FFL spectrum is that there are degrees of deviation away from an unmanaged, ‘business as usual’ DER - e.g. a grid-connected solar+battery system with no external orchestration. We’ve colour-coded these degrees of deviation in the diagram.

  • Control options closer to the ‘not intervention / BAU scenario (in green) will have a neutral or positive financial impact for the assets’ owners with no impact on their comfort or convenience. These might include scheduling of pool pump operation or water heating, or even occasional PV de-limiting (in relation to a default export limit).

  • Items in the orange bands may have some potential financial impact but not necessarily an impact on comfort. In the future energy system where prosumers play an active part, they would be compensated for these actions in some way - either per event or as part of an ongoing agreement / flat payout. Alternatively, networks may require controls of this sort in exchange for an overall more financially lucrative or flexible connection agreement (as opposed to, for example, static export limit of 3kW or blanket zero export limit).

  • The red bands represent the control options likely to have the biggest potential financial or comfort-related impacts on end users at the shortest notice. Items in these sections might only be allowed with explicit, case-by-case buy-in from households in exchange for above-and-beyond compensation. Alternatively, these items may only be called into action sparingly and spread across VPP participants to minimise impact as part of an agreed-upon framework.

Part 2 of this series covers some examples of how FFLs will work in theory - and in practice.