One feature of a robotic dairy farm is the steady use of electricity, day and night, as cows are milked on a 24/7 pattern.

They do not have the morning and evening peaks in electricity use found on farms with a conventional parlour.

Many farmers are turning to renewable sources of power in an effort to keep energy costs under control. Recent steep rises in the cost of electricity make the need more pertinent than ever.


The Lely Centre Eglish has teamed up with local company Start Solar to supply and install solar systems on robotic dairy farms.

The objective is to reduce the amount of electricity purchased from the power company and to replace it with power generated by the array of solar panels.

Recently, Lely demonstrated a solar system installed at the dairy farm of Jackie and Stephen Hamilton near Collone in Co Armagh.

The Hamilton farm has 245 cows milked in four A5 Lely robots which use 43% of the farm’s total power consumption.

Andrew McKee of Start Solar speaking on solar power at the Hamilton farm, Collone.

The remaining 57% is needed to run the milk tank, water heaters, meal augers, a bore well pump, lights, fans, the calf feeder and the dwelling house, via the farm’s three-phase power supply.

Measurements of electricity consumption over the past six months show usage of 9,295 kWh (units) per month, costing £2,770 per month, the equivalent of 111,542 kWh (units) per year, or £33,240 per year.

The power of solar

Start Solar installed a 15KVA photovoltaic (PV) system on to the roof of two cattle sheds. In total, the system has 34 PV panels. Planning permission was not required for the installation.

Measurements of the power captured by the PV panels show an average of 35 kWh (units) per day or 12,775 kWh (units) per year worth £3,807 at present-day electricity costs.

This makes a reasonable dent in the farm’s electricity bill and after paying off the installed cost of the panels (£11,500 excluding VAT), gives a payback period of just over three years and, in effect, gives free power for a further 20 or more years. And depending on the farm’s status, the capital cost can be written off on one year or be the subject of a 130% super tax break (if a limited company).

Start Solar gives 25 year guarantees on both the product and the performance of the product; 10 years on the inverter (which converts power from direct current to alternating current), and a five-year warranty on workmanship. The latter is covered by an insurance company and available in the event of Start Solar going out of business.

Individual attention

Andrew McKee of Start Solar emphasises that each farm is different and needs an assessment on an individual basis.

His starting point is the hourly draw of power for all uses on the farm.

He can then recommend the size of a solar system needed to provide power up to the maximum draw. Beyond that point, extra panels and the capital cost involved give no additional savings.

Next step

At the Hamilton farm, they have two main choices for a further development – either they could install a second array of panels for a second 15KVA system or they could install a battery system to store surplus power from the existing system and use it for night-time power requirements. Either way, the recoupment period of the capital cost will be of the order of three to four years.

Using solar power has, of course, great green credentials. The system is capturing energy from an infinite renewable source and can make a difference in combating the climate crisis and reducing our dependence on fossil fuels.

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