One of the main network services that neighbourhood batteries can provide is to increase hosting capacity in the neighbourhood without increasing peak electricity demand (as this can trigger unwanted and expensive network upgrades).
What is hosting capacity?
During the day, energy generation from rooftop solar panels often exceeds that needed to meet local demand. Some excess solar energy can be exported to the distribution network, however, there are limitations on how much can be exported before the network becomes overloaded (e.g. due to overvoltage, frequency changes). (Note: it is the role of DNSPs to ensure that such overloading, and therefore potential damage to the poles, wires and other electricity infrastructure, doesn’t occur on the distribution network). The amount of rooftop solar (and other customer energy resources) that can be managed in a particular part of the network is referred to as the network’s ‘hosting capacity’.
If the local network is becoming overloaded, excess solar may have to be curtailed, which refers to a process that occurs at a household’s rooftop solar inverter, to reduce solar exports to the grid.
There are several ways to increase hosting capacity of a distribution network. These include upgrading from single phase to three phase, upgrading transformers, use of Dynamic Operating Envelopes (DOEs), and the use of battery energy storage systems (BESS).
Examples of such BESS able to improve hosting capacity include coordinated Behind The Meter batteries (e.g. household batteries in a Virtual Power Plant (VPP)) and neighbourhood batteries, which can store excess solar generation on the network at times of high solar irradiance (meaning less solar energy at those times can be wasted).
Metrics for assessing impact on hosting capacity
The main metric for assessing the impact a neighbourhood battery is having on hosting capacity is analysing the aggregate community daily peak load. In some cases, this can be obtained from the DNSP e.g. through an appropriate metering point on the network.
When analysing it, you want to see the daily peak load being shaved as a result of the neighbourhood battery. For example, the battery is discharging at times when there is the highest electricity demand in the neighbourhood (like the evening peak). It is also important to ensure the battery is not charging during the evening peak, leading to increased daily peak load.
Data
You will want two key datasets for estimating the impact a neighbourhood battery can have on hosting capacity. These are:
- Battery meter data (to understand its charging/discharging patterns and impact on network voltage)
- Distribution substation meter data (to understand changes in peak imports and exports as a result of the battery’s operation)
In Victoria, households all have smart meters however due to privacy and other regulations, this data is inaccessible (potentially available in aggregate form). You will have access to your battery’s meter data (hopefully displayed on a public dashboard for all to access)
Community-level data, such as community load, solar penetration and solar generation, may be accessible through your DNSP. The AEMO DER register, which is beginning to register all new solar installations, may also provide some insight on the community-level of solar penetration/generation.
Distribution substation level data access will depend on your DNSP, and on whether or not your distribution transformer even has the required smart meter for collecting such data. Not all transformers will have one, and there are some limits around what network usage data can be shared with third parties in real time. In this case you will have to rely on battery meter data and, if available, community or household-level data (e.g. household solar exports/imports).