LED lighting, air conditioning, refrigeration equipment, till systems and IT infrastructure have a significant impact on energy consumption in retail outlets. Although retail chains focus mainly on reducing electricity consumption, individual shops’ bills may also include charges for reactive power. These may be small for a single outlet, but when totalled across the entire chain, they become a significant cost. As Paweł Markiewicz, an expert at SPIE Building Solutions, explains, even modern energy-efficient appliances can be a source of these charges. Where do these charges come from and how can they be reduced?
Reactive power is the portion of electrical power that is not directly converted into work by heating or lighting appliances, but is essential for the operation of many of them. Excessive consumption of reactive power or feeding it into the grid places an additional strain on the infrastructure, which is why distribution system operators charge fees for exceeding specified parameters.
In commercial premises, the problem may relate to both inductive and capacitive reactive power. The former is associated, amongst other things, with the operation of motors, compressors, fans and refrigeration equipment. The latter often occurs in LED lighting, power supplies, IT systems, automation and equipment fitted with power electronics.
The variable operating patterns of the installations are also significant. Refrigeration equipment and some technical systems operate round the clock, whilst lighting, air conditioning and till systems are used more intensively during opening hours. The level of reactive power may therefore vary depending on the time of day, the season and the number of devices in operation. This is particularly important in grocery shops, where refrigeration constitutes one of the main loads on the electrical installation. This profile may also change following the modernisation of equipment. It is therefore worth assessing the effects of modernisation more broadly than simply on the basis of a reduction in active energy consumption.
– It is advisable to re-check the network parameters after any major modernisation. Measuring with a network parameter analyser allows you to assess its performance under various conditions and determine whether a change in the type or number of appliances has affected the level of reactive power. This enables the solution to be tailored to the actual load of the premises, rather than based on estimated values – explains Paweł Markiewicz, Project Manager at SPIE Building Solutions.
Compensation tailored to actual needs
In the case of a single shop, reactive energy charges may seem insignificant. However, if the same problem occurs in several dozen or several hundred outlets, their combined cost becomes a significant expense for the entire chain. The first step should be to analyse the bills from individual shops. This allows you to identify the premises where charges are highest and to make a preliminary assessment of the potential for savings. It is also recommended to carry out measurements of the network parameters, as outlets differ in terms of equipment, opening hours and the nature of the load.
Based on the data collected, a suitable compensation system can be selected and the order of implementation planned. In this regard, an SVG (Static Var Generator) works best, as it operates fully automatically, adapting to the current load on the installation. As a result, it can significantly reduce, and in some cases almost completely eliminate, additional charges.
In shops using a large number of power electronic devices, power quality and the level of harmonics – i.e. disturbances in the voltage and current waveforms – must also be taken into account. These can affect the operation of the compensation system and increase the load on the equipment. Therefore, the solution should be tailored not only to the reactive power values but also to the characteristics of the entire installation. Once the system has been commissioned, it is advisable to verify its operation and adjust the settings if necessary. This allows the achieved results to be confirmed and ensures the effectiveness of the compensation is maintained under changing operating conditions in the shop.
SPIE Building Solutions implements such solutions, amongst others, for one of its key clients with a decentralised business model. To date, around 250 power factor correction units have been installed for this client across the same number of branches. Assuming that reactive power charges averaged 1,000 PLN per invoice in each shop, reducing reactive power to virtually zero generates savings of around 250,000 PLN per month. With such high efficiency, the entire investment pays for itself in just a few months
- The implementation of the project for a client managing a network of dispersed facilities has unequivocally confirmed the business case for investing in modern reactive power compensation. The installation of the equipment brought about an immediate and significant reduction in operating costs, almost entirely eliminating the previous charges. The scale of the savings achieved and the rapid return on investment meant that the client recognised the real economic potential of this solution and is already planning to equip further outlets with these systems – adds Paweł Markiewicz.
Savings without changes to shop operations
A correctly selected compensation system does not require any reduction in equipment operation or changes to the shop’s organisation. The outlet continues to use the same infrastructure, whilst reducing costs arising from unfavourable installation parameters.
- However, the benefits need not be limited solely to the amount of the bills. Limiting reactive power flow reduces the load on cables and transformers, as well as losses occurring within the installation. It also allows for better utilisation of the available power. This is important in outlets where, over time, additional refrigeration units, self-service checkouts, IT systems or electric vehicle charging infrastructure are introduced – explains Paweł Markiewicz.
Experience gained from existing shops can also be utilised in subsequent modernisations and the opening of new outlets. It is worth taking power factor and power quality requirements into account right from the stage of selecting equipment and drawing up technical standards for the electrical network. This helps to minimise the risk that solutions designed to reduce electricity consumption will simultaneously generate additional costs associated with reactive power.
Reactive power management should therefore go beyond a short-term response to additional charges. In large retail networks, it can become an integral part of planning for modernisation, infrastructure development and the control of operating costs.
