Voltage Optimisation - worth it? — Bulb Community

Voltage Optimisation - worth it?

We currently use about 120,000 kWh/year (commercial site).
Does anyone have an experience or opinions about Voltage Optimisation systems?

The basic idea as I understand it: is that the National Grid supply voltage to sites between 230-242V, whereas all devices after 1993 have a voltage requirement of 210-220V. They come and install a VO unit which stabilises the voltage to 220V and saves you anywhere between 10-16% off your bill.

The rate of return of this is probably 2-3 years, which sounds almost too good to be true. Almost as good as the switch to LED's.

Thanks for your input!


  • The short answer is: it depends on what kind of equipment you're using, but if it's standard office equipment (computers, photocopiers, lighting, etc) then probably not. You pay for your electricity in kilowatt-hours, not volt-hours or ampere-hours.

    To explain this, imagine a machine that needs water instead of electricity, so instead of drawing, say, 1 kilowatt of electricity it draws 1 cubic meter of water per second. If you've got a pipe with a cross-section of 2 square meters then the water would need to flow at 0.5 meters per second to meet your needs. If the pipe's cross section was 0.5 square meters the flow would need to be 2 meters per second and so on.

    Cross Section × Flow Rate = Water Use

    In this analogy, the cross-section of the pipe is like the voltage and the flow rate is the current (measured in amperes). Multiply the volts by the amperes to get the total rate of energy use (measured in watts).

    Voltage × Current = Energy Use

    Since you're paying for the amount of energy used and how long it was used for (one kilowatt of use for one hour is one kilowatt-hour) then voltage doesn't make any real difference. If you drop the voltage, the current increases to make up the difference. If a machine needs one kilowatt to run, it'll just pull the current it needs at the voltage it's given to get that.

    Now, with all that said, there is another consideration: some very specialised or industrial equipment might need a very specific voltage range to work optimally (certain types of AC motor can be very tightly calibrated, for example). If your business has a particular type of equipment that makes up a large chunk of your energy use I'd recommend speaking to the manufacturer who would be able to give you a better answer.
    edited July 9
    @rmuk, thank you for you for your reply!!!
    We're using computers and all, but we do have two large walk in fridges running 24/7.

    Our lighting is in the process of being switched over to LED's on sensors, so hopefully that will be a significant saving there too.

    I am having a few meetings coming up to explore the Voltage Optimisation some more, let's see if it makes any financial sense!

    Thanks, VNS
  • I always though inductive loads such as fridge motors could benefit from voltage optimisation? Depending on the size of the set up here it is still worth investigating. The analogy previously suggested does apply to resistive loads- for example heaters- it takes a set amount of energy to heat a certain amount, if you dropped the voltage you would draw more current or simply take longer to heat. But other appliances perform exactly as intended with significantly lower voltages than the grid supplies... it's a complicated subject and you really need expert advice. Try to get a guarantee of some kind out of the equipment provider in terms of power usage reduction- obviously they have a vested interest in telling you what you want to hear and are likely to give you best case scenarios to get you to sign on the dotted line!
  • edited July 14
    Things like computers are slightly more efficient with a lower voltage, however it's probably not much in the grand scheme of things. In UPS equipment at work we will generally use a UPS that steps down the voltage to 220v, rather than the 238v - 252v we get from the grid. It saves a couple of watts on each server, but it's not about saving money as much as ensuring the power supply is always perfectly clean.
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