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Youlgrave Farmer also Farms the Sun and his Compressor!

Posted Thursday, November 25, 2010

Hollow Farm solar panels.

Having decided to stay put, progressive farmers, John and Christine Eley, are putting their money where their minds are and conserving their savings and the environment. Not only does their farmhouse roof now support a 4 m2 solar panel to provide them with free domestic hot water, but the dairy refrigerant compressor that cools the milk also provides ‘free’ hot water for washing the plant and making up the calves feed.

Detail of Hollow Farm solar panels.

Last January, determined to take action to reduce the £8,000 cost of their farm annual electricity bill, John spent half of that amount getting Bayley Dairy Engineers of Hulland Ward to install a new insulated water storage cylinder with an internal heat exchanger coil to recover the waste heat from the refrigerant compressor. Two associated fans also had to run on the radiator to cool down the very hot compressor! Now, each day as the 5 h.p. compressor runs for 4 hours to cool down the milk from his prize herd of Friesians, the waste heat is circulated through the large storage tank to heat cold water from 7°- 45/60°C (80° in summer!) instead of having to rely previously on an off-peak immersion heater. The financial outlay is expected to payback in 3-4 years, and should provide about 50% of dairy hot water annually. Since January, the new system has recovered (saved) about 2,451 kWh of heat, say equal to nearly £200 of electricity. John is eagerly awaiting the promised government feed-in heating tariff payments next April, to recover more of his financial outlay.

Then in the summer John and Christine spent a further £4,000 commissioning Mycocks Plumbing of Chelmorton to replace the old electric off-peak storage heaters in their farmhouse with a new oil-fired boiler and wet radiator central heating system and two roof-mounted, solar water heating panels. The central heating and hot water storage cylinder has a second heat exchange coil which the heated water from the solar panel is pumped through to pre-heat cold water before topping it up with the oil boiler. Previously, by the time they were able to sit down in the evening and relax, the electric storage heaters were already cooling down! The farmhouse roof faces almost due south and in the first 24 hours following the 20th July installation completion, the solar panels generated 13.5 kWh of heat from the cold water fill, and by mid-November the system has totalled 442 kWh of savings, say equal to £36 of hitherto off-peak electricity. On the day of my visit on a sunny November afternoon the control panel was registering a water temperature of 37°C, and the expected payback on the solar installation is 7-8 years, and should provide over 50% of domestic hot water requirements.

Heat recovery system from milk cooling compressor.

Still determined to do more, John and Christine are now investigating the economic feasibility of installing several m2 of solar photovoltaic panels on one of their agricultural building roofs, to generate electricity and off-set further their annual farming costs. This would also earn them around 40p for every kWh their panels generated. It is certainly paying them to think ‘green’!

Heat recovery from milk cooling system.
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