Image [Christian Delbert]©

With service delivery being the ultimate goal of utilities and municipalities, it is essential to invest in the correct tools to accomplish the task. Finding the best fit-for-purpose metering solutions will ultimately grow revenue and improve service delivery.

The article appeared in ESI Africa Issue 1-2021.
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Along the electricity value chain, the specification of electricity meters occurs in conjunction with the design of the generation, transmission and distribution networks according to the application. However, on reaching the consumer, the meter is no longer designed around the application. In most cases, the end users’ energy demand profiles are given little consideration.

In any municipality or city, electricity consumers have diverse profiles ranging from small households with a few appliances to large consumption footprints and some with rooftop solar installations. However, the same electricity meter specifications are purchased and installed across residential types and light business districts, leading to wasted municipal budgets. It is at the metering tender stage where municipalities and metering manufactures can rectify this.

Before technology advancements changed the market, municipalities lack of choice led to high-end meters installed across end-user demand profiles. The best course of action for municipalities’ to pursue to cater to the typical household electricity profile was to purchase ‘one size fits all’ meters to meet a broad set of specifications.

Tender specifications influencing metering solutions

A typical tender will request the meter form factor, current rating, communication type, functionality and compliance (refer Graph 1). Usually, the request is for a split meter where the metering element and the customer interface are physically separate components. While a split meter is more tolerant of tampering, it is more challenging to maintain when a fault is on the customer’s side. Combo meters are inherently more straightforward and cheaper; however, where tampering will be a risk factor for the municipality, a split meter is more fit-for-purpose.

Graph 1: The potential cost-savings when selecting
a fit-for-purpose solution

Historically, combo meters were the first type of prepaid meters available. In comparison, it is more expensive to install a split meter because of the different wiring arrangements. It also results in municipalities replacing conventional or combo meters with similar form factor to save on the costs of installing a split meter.

In South Africa, the 100A rated electricity meter is only required for approximately 7% of consumers. At the same time, a 60A meter could address 85% of consumers’ profiles and be significantly cheaper for the municipality.

In terms of tender communication specifications, whether to use Radio Frequency or PLC is determined by the municipality’s objective and existing metering infrastructure. If the aim is to achieve basic interoperability between multiple manufacturers’ meters, PLC connectivity based on open standards is preferred. However, if the purpose is to achieve reliable connectivity independent of the consumers’ load profile, radio frequency would be preferred. Internationally, there is significantly more research and development into radio frequency technology than there is for PLC.

Unpacking four metering fit-for-purpose elements

While considering value over cost, the element of functionality needs careful consideration in a fit-for-purpose metering solution. For instance, measuring power quality (harmonic distortion, dips, swells, etc.) requires advanced electronics within the meter, which adds significantly to the cost. The challenge is deciding on the value the function delivers to the municipality and whether this value will be used.

The increase in rooftop solar PV systems will progressively determine the functionality of meters in the residential and C&I markets. As this market of distributed energy resources (DER) grows, and the relevant legislation is published, municipalities will require net metering functionality. However, this element adds additional cost to the meter. It will, therefore, not be fit-for-purpose to deploy all meters with this functionality where the vast majority of customer do not have nor intend to install a DER.

This Cover Story is brought to you by Conlog.
Solutions for utilities

The dominant functionality, which gives the most value for cost, is AMI. By adding a data concentrator in the customer area, the meters can be monitored remotely. This system provides valuable data such as tamper information, electricity consumption and buying patterns. The investment cost is relatively small versus the value gained by adding AMI support to meters – and is an excellent example of fit-for-purpose across all customer profiles.

Regardless of which meter and specifications are selected, compliance to the relevant specifications is mandatory for a fit-for-purpose solution.

Desigan Govender, product manager at Conlog, states: “In achieving a fit-for-purpose metering solution, municipalities must carefully consider the meters’ application… Know why you’re specifying a feature, and only choose those that will add value to yourself or your customer. Don’t adopt a, one size fits all, approach – it may result in wasteful expenditure, and a very poor return on investment.”

During the tender process, municipalities are more likely to request a 100A meter solution for all of their customers. However, considering that the maximum current requirement for the majority of end-users is 60A, municipalities are missing out on a cost savings of up to 15% on the meter (refer Graph 2).

Graph 2: The elements included in a typical electricity meter tender

A further 15% cost saving can be realised where the tender specifies radio frequency over PLC communications. While the typical requirement in terms of functionality may include four-quadrant measurement, time of use support and profile logging, careful consideration must examine the probability of using these functionalities for the majority of customers.

In summary, where municipalities specify a fit-for-purpose matrix solution, the physical meter purchased could be 40% cheaper than a typical requirement; and these can be used for 85% of the customer profiles. The cost-saving also filters down the value chain: as in lighter cables, lower capacity transformers, cheaper circuit breakers and reduced copper theft. Taking a fit-for-purpose approach also enhances the municipal budget by allowing for more meter rollouts, which decreases the number of unmetered connections and increases the customer base, resulting in improved service delivery and revenue. ESI