‘Peak lopping’ otherwise known as ‘peak shaving’, is the use of an additional power source (such as a generator) in synchronisation with the mains power supply, to deliver enough power to meet the peak demand that cannot be met by the mains supply.

Using a generator to provide a ‘peak lopping’ power supply, will enable the use of the most cost-effective mains power but provide the added support to reinforce the mains power during periods of high demand.

Peak lopping is required when a facility runs out of power, rather than making standby provision for power failure. The most common application for the use of a peak lopping generator is when a building goes through a change of use.

Example of ‘peak demand’ power failure

An agricultural building that may have been used as a chicken house, cattle shed or feed storage may be subject to change of use. The power supply provided to the original use will be enough to run light, and possibly heat. This usually has a 100amp 3 phase supply.

If the building’s use is changed to a holiday let or industrial unit (such as one providing power to a wood working or paint finishing business) the electrical demand will increase significantly.

For a large proportion of the day and at weekends, the existing power supply will be sufficient however, there will be peak times when demand exceeds supply. This unsupported demand will cause the power supply to ‘trip’ and the mains power will fail.

The chart below is an example of a power demand shared between the mains and generator. This solution ensures that there is no drop in power when the site load goes above the maximum kW level.

Peak lopping chart

Distribution Network Operators

In this instance, the first point of contact is your local Distribution Network Operator (DNO). You will advise them that you need more power. The DNO will then need to assess whether they can deliver the extra power… and more importantly at what cost.

If the DNO is unable to supply the additional power required or, more commonly, if the cost associated with bringing in the additional power supply are more than is commercially viable, then a peak lopping generator can provide a supporting power solution.

How does a peak lopplarge peak lopping generator ing generator work?

In a peak lopping application, the generator will use a Programmable Logic Controller (PLC) to monitor the supply of power from the mains. Once the demand begins to reach the maximum level for mains power at that location (in the case of a 100amp supply) at around 80amps, the generator will register the demand and start up to synchronise with the mains supply.

The generator will then top up the power supply from the mains, to provide the power required to meet the peak demand. The generator will ‘Lop’ the peak demand and supply the additional power required. When the load decreases below the mains capacity threshold, the generator will ramp off, disconnect and shutdown.

Can a peak lopping generator provide standby power?

Yes, in addition to supporting the mains power supply, a peak lopping generator can also provide a standby power solution.

Careful consideration should be given as the the size of the generator, depending on the standby power load that it can support in an emergency. For peace-of-mind, the generator can be set up to support just some of the critical power demands on the premises.

What is meant by peak shaving?

Peak shaving refers to the levelling out of peaks in electricity use by commercial power users, are crucial to grid stability and impact on procurement costs. Peak shaving involves reducing the amount of energy used by utility power companies during the peak hours of electrical demand.

To find out more about peak lopping and standby power read our case studies or request a power site survey.

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