Renewable energy feasibility at Pengelli Isaf farm

Key Results

  • Best financial return: 6kWp solar PV system on existing single-phase electricity supply.
    Payback period: 9 years for 6kWp PV; 10 years for 15kWp PV with three phase electrical supply upgrade.
  • Net profit over 25 years: £25,574 (6kWp PV); £52,298 (15kWp PV).
  • Wind turbine options: Less financially viable than PV options due to higher capital, operational and planning costs.
  • Battery storage: Improves self-consumption of onsite generated electricity however slightly reduces financial return for PV projects due to high capital cost of the battery but improves wind turbine viability slightly.
  • Hybrid PV-wind system: Technically beneficial in terms of maximising self-consumption of onsite generated electricity but financially less attractive than a standalone PV project due to the high costs of the wind turbine.

Background

Pengelli Isaf is a mixed enterprise family farm located on the outskirts of the town of Caernarfon. They farm 330 acres with a dairy herd of 140 Holstein Friesian cows calving from September to March, but heavily weighted to the autumn being the main farm enterprise.

As with any other dairy farming business, energy and electricity is a major cost. The family was keen to complete a feasibility study to investigate what renewable electricity production systems best suit their farming business, and work out a return on investment figure on payback time. The farm currently consumes approximately 74,000kWh of electricity each year, costing around £24,000 per annum.

Purpose of the work

The feasibility study explored the viability of expanding renewable energy generation at the farm in relation to the following points:

  • Detailed evaluation of solar PV and wind turbine options
  • Evaluation of battery storage and hybrid systems
  • Consideration of other renewable technologies, particularly hydroelectricity, biomass, anaerobic digestion and heat pumps
  • Recommendation of energy efficiency improvements
  • Provision of financial modelling to guide decision making

What we did

  • Site assessment: Reviewed existing site energy use, infrastructure, and land suitability for renewable energy.
  • Grid analysis: Liaised with Scottish Power Energy Networks to determine capacity constraints and supply upgrade costs.
  • Technology modelling:
    • Simulated PV system performance using PVSol software.
    • Assessed wind speed resource at the site using NOABL, JRC, and European Wind Atlas models.
    • Evaluated performance of battery storage and hybrid system configurations.
  • Financial modelling: Calculated project payback times, Internal Rate of Returns (IRR), Levelised Costs of Electricity (LCOE), and net profit over a 25-year project lifetime.
  • Energy efficiency audit: Identified potential improvements to the farmhouse and process on the farm.

Outcomes

  • Solar PV:
    • 6kWp system: Provides best financial return with small constraint on exported electricity back to the grid.
    • 15kWp system: Provides higher energy output but lower return than smaller 6kW system.
  • Wind turbines:
    • Britwind H5 (5kW): Marginal viability, long payback time.
    • Britwind H11 (11kW): Better performance but significantly higher capital cost than 5kW turbine. Would require grid supply upgrade to three phases.
  • Battery storage:
    • Increases self-consumption of onsite generated electricity.
    • Improved financial viability only when paired with a wind turbine.
  • Hybrid (solar and wind) system:
    • Technically complementary in terms of improved self-consumption of onsite generated electricity.
    • Financially less attractive than standalone PV or wind turbines with a battery.
  • Other technologies:
    • Hydroelectricity, anaerobic digestion, biomass, and heat pumps: Technically possible but financially or practically challenging.
  • Energy efficiency:
    • LED lighting, insulation upgrades, and heat recovery on the milking system are recommended.

How to apply on your farm

  • Energy usage: Quantify annual energy consumption from bills and meter readings.
  • Efficiency: Consider ways that energy could be used more efficiently on the farm e.g. lighting, insulation levels, windows, heating and hot water, heat recovery, farm processes and vehicles.
  • Electricity supply: Understand the electrical supply type to the farm; is it a single phase, split phase or three phase supply.
  • Renewable energy: Look for potential opportunities where renewable energy could be applied on the farm in particular land areas, large roofs on buildings, streams or rivers with large falls, exposed hilltops, potential supply of biofuels such as slurry, waste crops and wood waste.
  • Consult specialists: Seek expert advice.