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Solar PV systems are ideally suited to poultry sheds and the technology can be part of a wider solution to meet future farm energy needs, an expert in the sector has suggested.
Speaking at an online conference organised by the Ulster Farmers’ Union (UFU) and the College of Agriculture, Food and Rural Enterprise (CAFRE), Richard Bell told farmers that electricity and fossil fuel prices will never return to where they were.
“My advice is act now. Take the initiative and take as much of the energy production into your own hands on your own farm, where you can control it,” said Bell.
While he is no longer involved in the supply of solar PV, Bell, along with his wife Norah-Anne founded Solmatix on the family farm in Co Antrim in 2008, which grew to become the largest provider of solar PV in Ireland before being bought over by Harvey Group plc in 2015.
During his presentation, Bell pointed out that while some technologies might not have been financially attractive in the past, soaring electricity prices could mean payback periods now look fundamentally different.
Starting point
The starting point in every situation is to assess carefully what energy is being used on the farm across each 24 hour period and the year as a whole. Renewable energy providers should be able to assist with an audit or pass on contact details for a suitable industry professional to undertake this work.
In the case of solar PV, Bell described the technology as simple, reliable and easily fitted, with low service requirements, but the main downside is that it does have seasonal and wet day limitations.
“What happens on a bad day or in hours of darkness? You have a few options, such as adding in another source like wind, water or buying from the grid to supplement those periods, or oversize your PV system and store in a battery,” he said.
Bell presented actual data from a poultry farm in Northern Ireland, where a 50kW solar PV system was fitted in 2015.
Across the subsequent eight years, peak output is in May and early June, and from March to August, about 5,500 units (kWh) of energy are produced each month. This falls to below 1,000 units per month in December and January.
Across the year, Bell said that every kilowatt peak (kWp) of solar installed should generate 820 units of energy across the year, so a 50kW system should produce 41,000 units.
“You can bank on that,” he suggested, adding that in the farm example, it has averaged a total of 45,000 units per year.
Installation costs should be in the region of £850 to £1,000 per KWp (€990 to €1,160).
South facing
Where the poultry house roof is not facing due south, there are also east-west systems available that capture initially on the east side, and then shut off and capture on the west side as the sun moves around.
“The efficiency wasn’t quite as good, but now in new dispensation with the energy price as it is, it is very realistic. The lovely thing about poultry houses is that the pitch on the roof is not high, so you get much less shading,” said Bell.
Consumption pattern
He also maintained that solar PV is generally well matched to the daily energy consumption pattern in a poultry house.
Wind, water and AD options
Solar PV might be a reasonably simple system, but it does have the drawback of being limited to daylight hours and with seasonal and wet day limitations.
Unlike solar, wind turbines often have higher output on days when sun energy is lacking. However, a turbine will have higher service and maintenance requirements than solar, and there are also the various hurdles around planning, grid connections and ensuring the farm has a suitable site.
“In my view, there haven’t been many good quality mid-size wind turbines over the years – there have certainly been many low-quality ones around. But wind turbines are a good complement to things like PV,” said Richard Bell.
The most consistent power source is probably water, although it does require the right site and there is constant work keeping water races clean, Bell added.
The other main alternative is anaerobic digestion (AD), which can deliver both heat and power to a poultry unit. According to Bell, poultry manure can be a challenge as a feedstock because of high nitrogen contents, although the manure can be diluted with water or cattle slurry. He believes there will be opportunities to put in place small and medium-sized AD plants across the country to deliver individual farm energy needs.
“AD is more feasible now than ever. Watch out – there will definitely be more companies pushing this type of technology,” he said.
Batteries to store power needs
Where a renewable energy system such as solar PV does not deliver a consistent supply of power each day, there is the option to store excess in batteries, said Richard Bell.
Lithium batteries cost considerably more than lead acid alternatives, but can be discharged down to 20% (rather than 50%) and have a higher tolerance to over-current when equipment is switched on.
“There is a fair bit of system design to get the optimum out of what you are doing. You need to have the system configured in such a way that it gives you the greatest efficiency and safety. There are huge currents,” said Bell.
SHARING OPTIONS: