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Voltage Optimisation Mythbuster

Voltage optimisation can be a highly effective technology for reducing energy usage, but despite being established in the UK for a long time, there is still a great deal of misunderstanding or misinformation regarding VO. This includes both a belief in some areas of the sector that voltage optimisation doesn’t work, or doesn’t provide any benefit from certain sectors, businesses or sites. At the other end of the spectrum, lofty and often unrealistic claims are made by some VO providers regarding energy savings it will provide, often advertised as a guaranteed level of savings or guaranteed payback period.

Here, Powerstar looks to set the record straight on voltage optimisation, including assessing common objections to the technology and how valid they are.

Voltage Optimisation

1. Devices with lower voltage absorb less power, but that does not automatically mean they consume less energy

Broadly, this is true. Some things will, and some things won’t, but almost all electrical equipment will benefit from running at the correct voltage. Changing the voltage doesn’t create savings out of nowhere, which is why blanket statements from VO providers about percentage savings should be questioned. To deliver savings, there has to be losses somewhere, related to the voltage, in the existing electrical infrastructure of a site.

2. Lower voltage means less power, e.g. less light or heating

In practice, if you drop the voltage, you will produce less of whatever a device is intended to provide, be that lighting, heating or something else. This is often cited as an issue with voltage optimisation, as a reduction in useful output means that it isn’t really saving power in real terms.

However, what is important to bear in mind is that VO is designed to rectify overvoltage, not to just provide a blanket reduction. If equipment is running at a higher voltage that necessary, they are overproducing. Reducing them to an optimal voltage of 220V means that they are running at the level they were designed to be used at, rather than reducing the amount of useful output they provide.

3. What is the typical payback period for VO?

There have been instances in the VO market where providers have offered their technology with guaranteed savings as high as 20%, as well as payback periods of less than a year. While it is possible that this could be achieved on a site that is ideally suited to VO, the huge variance in how sites use electricity, the voltage they are supplied with and the equipment they have installed means that it is impossible to give a blanket level of guaranteed savings across all sites without a comprehensive site survey first.

While there is a slight variance in the performance of voltage optimisation from different manufacturers, the reality is that they all broadly perform the same function. It isn’t the voltage optimisation that is providing energy savings, but rather how the existing site infrastructure is impacted by that reduction in voltage. Blanket statements from VO providers about guaranteed savings, when they make no distinction in terms of a potential customer’s sector, location or existing equipment, should be taken with a healthy pinch of salt.


Electricity Meter

4. How VO saves businesses money in another way

One area of savings with voltage optimisation that is significant, but also difficult to properly quantify, is maintenance, replacement and repairs. Many electrical items that are receiving an overvoltage will burn out much quicker than intended, including lighting and motors. For sites where this is a particular issue the savings in terms of reduced replacement and repair costs, and the reduction in the disruption that results from maintenance being needed, can be similar, or even higher, than savings from reduced energy consumption. As an example, an incandescent bulb receiving an overvoltage of 252V will last around four months. The same bulb, supplied with conditioned voltage of 220V, will last around two years.

Many sites may feel that the nature of their equipment, such as a manufacturer with a large number of variable speed drives, are unlikely to see significant savings from VO. While this is true to an extent in terms of outright energy cost savings, the electrolytic capacitors that tend to be the component that fails in variable speed drives are highly sensitive to line voltage, and will last much longer when provided with a lower level of voltage. 

5. Older technologies (pre-1995, 240v) can be disrupted by voltage optimisation

While large amount of electrical infrastructure that is approaching three decades old will have been replaced or updated, there is still plenty of aging infrastructure across the UK in variety of sectors. In theory, a lower voltage of 220V can result in this equipment malfunctioning. While it is rare, this can happen, and it will often be a small circuit or piece of equipment that is largely overlooked until issues begin. One common example is old lifts. While the actual motors that operate the lift typically operate fine, the electrical control panel can fail when supplied with a lower voltage.

Fortunately, these issues can be solved relatively easily with the use of a step-up transformer, but it is vital that your VO provider is able to identify and rectify these potential problems before they become an issue that causes disruption.

6. LED lighting doesn’t benefit from VO

It can be a common view that LED lighting runs the same whatever the incoming voltage, and that there will be no savings when combined with VO. This is the idea that LEDs, which use constant power, will vary their amps to use a constant level of power.

However, LED lighting includes a tiny switch mode power supply with a transistor called an IGBT. These IGBTs do suffer losses, split around half-and-half between conduction losses and switching losses. At higher voltage, the switching losses are affected by the square of the voltage, so for a 220V system if voltage increases 10%, then switching losses will increase by 21%.

7. Devices that rely on thermostats, such as heaters or fridges, don’t provide any savings from voltage optimisation

If you are heating or cooling to a certain temperature, it requires a set amount of electrical energy to achieve that. At a lower voltage, this can often mean that the process simply takes longer, rather than being any more energy efficient. There is still some degree of benefit typically though, as running at a lower voltage means that the thermostat will sit more closely around the temperature aimed for, rather than overheating or overcooling slightly, which can lead to losses.


To summarise, while voltage optimisation will provide a benefit to almost any site in terms of cost, this will vary massively depending on what the current losses linked to voltage may be. For some sites, savings linked directly to reducing consumption may be marginal, but an important to consider additional cost benefit is a significant increase in the lifespan of equipment and the reduced replacement or repair costs this brings.

Voltage optimisation has sometimes been unfairly maligned by some, but many of the accusations made stem from a lack of understanding of the technology or broad assumptions rather than reality. At the same time, some VO providers have been guilty in the past of overpromising, which has contributed to VO’s sometimes questionable reputation.

Broadly, VO technology irrespective of supplier achieves the same thing: reduces losses associated with overvoltage. It is the other aspects of a provider’s performance, including effective project management, reputation and track record, that should help to inform your choice of supplier, not an unquantifiable claim to provide huge levels of savings or very short payback periods.

Find out more about Powerstar’s voltage optimisation technology here

Voltage Optimisation

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