Pig farms are energy-intensive enterprises. Recent Teagasc audits on 23 pig farms showed a huge variation in energy usage, ranging from 18kWh up to 45kWh/pig produced, with an average figure of 28kWh/pig produced.

For most pig units, the three biggest energy consumers are heating, lighting and ventilation, so it is these areas that offer greatest scope for efficiency savings.

Energy efficiency of pig farms vary significantly depending on how heat is delivered and the quality of buildings on site.

As the following example shows, solar PV has a role to play in tackling high and variable electricity prices but improving the energy efficiency of the building should be considered alongside this. For example, a poor building envelope will result in heat loss through the fabric which will result in increased energy use to maintain farrowing shed temperatures.

The example gives the economics of a solar PV system on an 800-sow pig farm.


  • Annual electricity use: 325,000kWh.
  • Day rate for electricity: 0.25c/kWh, night rate electricity 0.15c/kWh.
  • Annual electricity bill: €119,190 plus VAT.
  • Main uses: farrowing and heat pads (30%), manure processing (20%), feed and water delivery (15%), lighting (15%) ventilation systems (10%), power washing (5%), miscellaneous (5%).
  • Area of roof space available for solar PV: 1,200m2.
  • ESB connection: three-phase.
  • Maximum import capacity: 100kVA.
  • Location of transformer: within 75m.
  • Battery storage: not suitable.
  • ACA: 100%.
  • Solar PV system

    Pig farms have a significant, relatively consistent base load due to the need for heated farrowing units 24/7. The aim of a solar PV system here is to try and spread solar generation across the day as much as possible and utilise all of the electricity on site with no export back to the grid or need for battery storage.

    The maximum import capacity of the site is 100kVA which would be in line with a farm of this size

    For this scenario, a 130kWp (ie the peak output of a solar PV system) was selected. This would require around 975m2 of roof space and needs planning permission and grid connection. The maximum import capacity of the site is 100kVA which would be in line with a farm of this size.

    It is possible to increase the size of the proposed system but this will also increase the cost for the farmer and reduce payback times. This system would cost around €137,750 plus VAT, generate around 109,200kWh each year. The system offsets 18% of the farm’s electricity requirement per annum.

    Grant aid

    The Pig and Poultry Investment Scheme is part of TAMS and is open to all pig farmers who meet the eligibility criteria. The scheme offers a rate of 40% grant aid available up to an investment ceiling of €200,000.

    Other sources of funding exist for projects such as this including the Better Energy Communities grant (up to 25%) or potentially EXEED funding (up to 40%). EXEED is a possible funding route for pig farms based on the opportunity for further upgrades on ventilation, mixing and lighting. Carbon reduction volumes will be the deciding factor in applications.

    130kWp payback

    Table 1 runs through the costs and returns for the solar PV system with various levels of grant support. This is a large rooftop solar PV system and requires planning and consultancy which comes at a cost. EXEED funding will contribute towards the cost of consultancy, however. Maximising grant aid for a project of this scale is vital.

    The solar PV system generates 18% of the farm’s electricity requirements which, in this example, would equate to a saving of €27,300 per annum. This saving increases as electricity prices increase. VAT can be claimed back in year one to the figure of €18,596 and accelerated capital allowance could amount to €17,218.

    The level of grant aid directly affects the solar PV system’s payback periods which ranges from 4.5 years to 2.6 years.

    These returns on investment timelines are very much attractive and, while solar PV may not help with the pig farm’s immediate cost challenges, it will help reduce the farmer’s dependence on imported electricity, future-proofing the business and reducing emissions.

    This system would offset 317t of CO2 from that farm over 10 years.