To optimise or stabilise?

17th June 2024
Paige West

Voltage optimisers and voltage stabilisers are similar in many respects and investing in this equipment can deliver a saving on your energy bill.

A stabiliser is a more sophisticated piece of equipment, but is the extra cost worth it? Here, Ged Hebdige, Technical Director at Powerdown220, explains the difference between the two technologies and how to make the right choice for your business when deciding where to invest.

To understand voltage stabilisation, it is easiest to begin with voltage optimisation (VO). With average voltage supply from the UK National Grid at 242 volts, most consumers are paying for excess voltage they do not need. As CE marked equipment is designed to work optimally at 220 volts, by installing a voltage optimiser to lower your supply voltage, you can achieve a cost saving.

For most businesses I have worked with, the cost saving is around 8% and the return on investment is within eighteen months. This makes it an attractive investment for companies looking to save money on their energy bills, but it also ticks the box of reducing your carbon footprint too.

Fine tuning the VO engine

An optimiser will typically offer a reduction of between six and 10% in voltage. You select the appropriate setting during the commissioning process, depending on the supply level and the energy saving you want to achieve. In theory, the higher the percentage of reduction, the higher the saving.

However, if you are too aggressive in your quest to lower voltage, it can potentially backfire. The optimiser will effectively turn itself off, or switch to ‘inhibit mode’ if the voltage supply becomes too low. While in inhibit mode it simply lets voltage from the Grid pass straight through it. This means there is no reduction of energy consumption in inhibit mode, so you will not see a saving.

There is therefore a delicate balancing act to achieve the optimal settings and deliver the best saving possible. This is a manual process involving the commissioning engineer. They will enter the initial settings, and adjustments will be made after two weeks’ worth of data has been generated. After this initial process of fine tuning, the optimiser is generally left alone and will continue to deliver the fixed percentage reduction it has been told to achieve.

Automating the fine tuning with a stabiliser

While a voltage optimiser will have fixed settings in terms of the reductions it can offer, a voltage stabiliser will be able to offer a range from zero to ten, 15 or 20% depending on the model. Furthermore, it will be able to adjust the voltage level, in real-time, to ensure it continues to provide the correct voltage supply regardless of fluctuations in Grid supply. The manual process of fine-tuning described above is automated.

As it automates the process and continues to adjust in real-time, the stabiliser is a more sophisticated piece of equipment that is generally capable of providing a greater cost saving. In the right circumstances, a stabiliser might be able to deliver a cost saving that is 20% higher than an optimiser. Sounds impressive, right?

The first issue here is that the 20% saving is 20% of the 8% saving that VO can deliver (recall that VO typically delivers a saving of seven to eight per cent). The additional energy saving reduction is therefore only really a further one or 2%. This could be a worthwhile investment for a business that is a high consumer of electricity, but the equipment still has to pay for itself. And there is your problem: as a stabiliser is generally more expensive to begin with, the return on investment tends to be longer than for VO.

When is the extra investment worth it?

Traditionally, most businesses investing in voltage stabilisation are dealing with a power quality issue. Fluctuations in voltage supply may cause problems on a production line, for example, and a customer is looking for a piece of equipment that delivers a performance enhancement to their manufacturing process. In this type of scenario, the superior payback of VO is irrelevant.

However, there may be scenarios where voltage stabilisation is a viable solution for businesses looking for energy savings, even where there are no power quality issues at stake. A key factor to consider is for how long and at what times your facility is consuming electricity. As demand generally falls later in the evening and at night, the supply of volts tends to increase at this time, creating a greater opportunity for energy savings.

Yet if your business is not operating during this time, there is less opportunity for a saving. In this scenario, it is increasingly unlikely that a stabiliser is worth the additional investment as the ROI will be much longer. It is predominantly those operations that require energy 24-7 that will see a saving from voltage stabilisation.

If money was no object, the voltage stabiliser would win every time. By automating the fine-tuning process and adjusting in real-time to continually deliver the target reduction level, a stabiliser can offer a greater reduction in consumption, and therefore a bigger chunk off your energy bills. However, this technological superiority comes at a cost. In most scenarios, VO will offer a similar level of reduction and with the initial capital expenditure being lower, the ROI is significantly quicker. Determining which is right for you requires taking into consideration the specific factors that are unique to your business.

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