Match your energy use to your tariffs

Ensure you understand your contract tariffs and how to maximise the use of day/night tariffs to reduce energy costs.

Demand matching in practice

The profile of energy use for dairy farms fits in well with night rate tariffs rates for a number of reasons. Morning milking often falls into the night rate period which can stretch to as late as 8:30 am in the summer. Loads such as water heating and ice-building are configurable and can be switched to consume most or all of their demand into this period.

How to use timer devices

Timeswitches can control the time that loads operate by delaying start or preventing sequential operation in an on/off manner. Sometimes, these are combined with other control devices to produce more complex control actions.

The two predominant areas for time-based control are for the water heating and the ice building systems. Both areas allow energy storage such that the creation of hot water or ice can be optimised to match lowest cost electricity but able to deliver their energy on demand.

For instance, it’s common to combine a timer device with an ice-level device to control the switch-on of an ice builder. As long as the ice level is sufficient for immediate cooling, the timer will delay the switch-on of the ice builder to a pre-determined point. If however the ice level falls to a low level switch-on is immediately allowed, over-riding the timer.

Water heating a solenoid valve can be employed with a timer to delay the unnecessary filling of the heater with cold water, until the hot water has been used.

Where timeswitches are used, it is essential that the time these devices show is accurate and that their control periods are relevant, timeswitches with internal batteries that save their settings in the event of a power failure are preferred. Regular checking is essential.

Slurry pumping and borehole or irrigation water pumping are examples of other applications for timeswitches worth considering.

Potential savings

An appropriate tariff and good timer control provides some of the biggest savings and shortest payback on investment for a dairy farmer. Tariff changes cost nothing and savings in some cases will exceed 15%, especially for a first-time mover.

Timer controls on water heating and milk cooling are also cheap to implement. Fitted costs of as little as £100 rising to £1,000 for more complex control on ice-bank milk tanks will pay back in anything from a few weeks for the former to possibly 2 years for the latter.

For water heating it’s often worth considering additional water storage capacity to further benefit from timeswitch operation. For example, to enable all water heating to be operated on night rate tariffs. Where 200 litres of water is heated twice daily the addition of a second tank operated entirely on cheap night rate can reduce annual heating costs by over £330 giving a 3-4-year payback.