With rising energy costs, many farmers are looking at alternatives when it comes to standard energy sources such as electricity, oil and gas.
The majority of farmers use electricity for heating water but an increasing number of farmers have opted for gas and even oil on some of the bigger farms.
With more emphasis on renewable energy, many farmers are asking if solar panels will provide enough electricity for their farm’s needs.
The short answer to this is that solar can help to reduce energy costs on the farm, but it is highly unlikely to provide all the electricity needed to run a modern dairy farm.
When discussing solar, it’s important to remember that there are two types of solar; solar water heating and solar photovoltaic (PV).
Solar water will heat water to a maximum of about 400C on very warm days.
Solar PV panels generate actual electricity which can be used to power equipment on the farm
While sufficient for home use, it’s not hot enough to wash dairy equipment without further heating.
Solar PV panels generate actual electricity which can be used to power equipment on the farm and can be used to heat water to whatever temperature is required.
When solar is discussed now, it generally refers to solar PV.
Speaking at the Teagasc dairy conference recently, Teagasc researcher John Upton said that water heating accounts for 23% of the energy used on dairy farms, so it’s a significant user of energy.
While solar PV has the ability to supply electricity to the grid, there is currently no mechanism to get paid for the electricity sent to the grid but this may change in the future.
However, Upton said that any payment for electricity exported to the grid is likely to be small in nature and not give an economical return.
Battery storage options are very expensive so many operators have looked to electric water heaters
Therefore, farmers thinking of installing solar PV should only size the project big enough to supply enough electricity for their own use, which John says is 9kW of power output for every 100 dairy cows.
The issue with solar PV is that the electricity generated needs to be consumed on the farm to make it worthwhile.
Battery storage options are very expensive so many operators have looked to electric water heaters as a mechanism to provide storage of the energy.
Effectively, the electricity generated by the panels is used to heat the water which is then used to clean the milking parlour, bulk tank, etc.
Obviously, other equipment that is operating at the time the electricity is being generated can also be powered by the panels, but water heating is commonly used as a cost effective storage option.
According to John Upton, a typical system for a 100-cow herd is a solar PV system with 6kWp of installed capacity, which costs €7,500 excluding VAT.
He said the payback for such an investment would be 10 years in the absence of a TAMS grant. With a 40% TAMS grant, the payback reduces to six years, while a 60% grant has a four-year payback.
However, the maximum size that can be funded through TAMS is 11kWp. It’s also possible to claim accelerated capital allowances on the costs incurred in installing solar PV.
This means that the total capital cost can be re-claimed in the year it is installed.
We’ve seen that it’s very achievable to reduce on-farm energy use by 50%
In terms of energy savings, the system described above would result in 30% of the farm’s electricity being provided by a renewable source and would offset more than 2.4 tonnes of CO2 per year.
“We’ve seen that it’s very achievable to reduce on-farm energy use by 50%, with 20% coming from the use of efficient technologies [plate coolers, variable speed drives, heat recovery systems] and a further 30% from the renewable technologies.
In a lot of cases, if the supports are available the payback period can be very good,” Upton said.