A dairy farm in Dumfries and Galloway has sidestepped soaring energy costs by turning to the renewables sector.

Broompark Farm, owned by Billy and Marion Muir, was faced with a stark choice when a fixed tariff energy rate came to an end, with the prospect of their electricity bill rising from less than £18,000 per annum, to £55,000.

With other cost pressures, including dropping milk prices squeezing margins, the couple decided to explore alternatives, including solar PV panels.

While many farm buildings now feature solar panels on the roof, unpredictable energy prices are now seeing solar PV firms offering to dramatically increase the number of panels on farm to reduce costs.

This is not always the simple solution it might appear to be and there are a number of challenges to this approach. At its most basic level, the farm must have sufficient grid capacity to take the power produced by the PV panels. Without this, a larger connection may be required at potentially significant costs.

Another issue is the timing of energy demand. Dairy farms can fall into two categories in terms of energy usage.

The first is those who traditionally milk twice a day, creating an energy demand peak first thing in the morning and again in the early evening – missing the bulk of the electricity produced by PV system which occurs in the middle of the day.

This means the ability of the business to consume its self-generated energy is restricted. While the unused energy can be exported into the grid and sold, currently at around 15p/kWh to more than 20p/kWh, energy used by the farm could cost several times more than the farm receives exporting its own power.

The second type of dairy farm uses robotic milking technology which consumes power at a steady rate over a 24-hour period.

With 140 head of cattle to milk, Broompark Farm is in the latter category and also has a limited grid supply, with no possibility of increasing capacity.

Instead, the farm has utilised a solution widely used across marine and industrial sectors, called a custom micro-grid (CMG).

A CMG uses industrial inverters, designed for large-scale off-grid power generation, combined with modular industrial battery storage to create a personal and scalable 'virtual grid' to cope with the power demand on the farm. This can operate in isolation of the grid, in combination with it, or in a hybrid configuration.

A micro-grid can be configured in a number ways. They can convert a limited single-phase grid connection into a fully-fledged three-phase powerhouse, without the need for an expensive grid upgrade.

They can also convert split-phase into a three-phase, or can simply expand the capacity of any type of existing supply.

In addition, they can combine power from different sources, for example from solar PV, generators, grid supplies, combined heat and power (CHP) systems, wind, hydro turbines and any other electrical resource, making them extremely versatile and configurable.

They can also be programmed to export unused power to the grid, even where the grid has limited capacity, by spreading the export across many hours, if required.

With advice provided by South Ayrshire-based Beyond Innovation, the owners of Broompark opted to install CMG combining 75kWh of battery storage with a significant solar PV array. This approach involved two stages, where their initial micro-grid will operate for 12-months to gather power data and statistics.

These will then be used to expand the capacity of the system to include more solar PV and increased battery storage, to achieve their intended goal of achieving over 80% self-reliance on power.

The system is funded from bill savings and once repaid, the micro-grid will then provide Broompark with free power for 80% of its entire annual usage.