For this week’s Infrastructure Focus, Agriland made the trip to Co. Galway to see a how a farmer is generating his own electricity through a solar photovoltaic (PV) panel system.
Farming in Milltown, Tom and his wife Niamh McWalter are in their fourth year of dairy production, having made the switch from sucklers and sheep.
This year they are calving down 160 cows onto two Lely Astronaut A5 robots.
Calving is well underway on the farm, with over 50% of cows calved down.
Taking time out of his busy schedule, Tom spoke to Agriland about the recent installation of solar panels on his farm and the benefits he is seeing from them already.
Speaking on his farm, Tom said: “With energy costs at the level they are and the amount of energy we use on the farm, we decided to look at our options.
“Due to converting to dairy, our electrical has gradually been increasing….so with the roof space on the farm, we thought going with a solar PV system would help save some money.
“In the Targeted Agricultural Modernisation Scheme (TAMS II), there was too much red tape with it in terms of getting a solar PV system set up and getting the most out of it.
“Regardless, we had maxed out my grant due to the move to dairy a few years back so we went ahead without any grant aid and funded it ourselves entirely as we wanted didn’t want to waste any time,” the farmer added.
Installing 85 solar panels
The task of installing the solar PV system on the McWalters fell to Joseph O’Malley and his team of WestQuay Energy based in Westport, Co. Mayo.
Joseph was on the farm on the day to explain exactly the system on the farm and how it is performing.
Speaking about the system in place on the farm, Joseph said: “We installed 85 panels (which weigh 22kg each) facing south on the roof of the cubicle shed beside us, with each panel having a capacity of 390 watts.
“Before any work is started, we surveyed the farm infrastructure to see if the roof is suitable.
“So the total solar array between the 85 panels is 33.15 kilowatts (kW) of power.
“They are connected back to two inverters, a 17kW and a 10kW inverter respectively.
“The reason for going with 85 panels here for Tom was that he will be exporting a lot of energy in the summer. It will mean he will get a better return for the energy he produces during the winter months.
“If he had put in a system that just matched his demand, he would end up having to buy in a lot more electricity during the winter.
“So with the way he is set up now, he’s going to be buying less in the winter and exporting more in the summer – which gives him a better return for his investment,” Joseph explained.
Tom was able to put that amount of panels on his roof because he increased his maximum input capacity (MIC) from 15KVA to 28KVA. For reference, one KVA is 1,000 volt amps.
This allowed us to increase the amount of panels we could put on his roof as well as being able to have access to three-phase power on the farm.
“The solar panels generate a direct current (DC) which we can’t use, so to make use of it in the fuseboard, this current flows into the inverter and changes it from DC current to an alternating current (AC),” Joseph explained.
“This current then flows into the fuseboard which supplies power to the entire building, which in Tom’s case is the lights, robotic-milking machines, automatic calf feeders and also the boiler up stairs for hot water via the EDDI.
“So basically solar energy is generated. It’s inverted from DC to AC.
“AC is fed to the mainboard and distributed to where the load [demand] is in the property at the time. Depending on the solar available, it will feed it with what’s available and the rest, if needed, will come from the grid,” he added.
The install period took five days to complete with the connection to the ESB straightforward in Tom’s case.
Getting a return from solar
Tom’s system is currently generating a substantial amount of energy during the day even during a dull period of the year, which sees some of the surplus solar exported to the grid.
Explaining how this works, Joseph said: “Tom is generating a lot of solar energy during the daytime which he is exporting.
“So because he is not using it, it goes back to the grid and he gets a rate for what he exports which is working out at 20c/kWh.
“So for example, if he needs 10kW of energy and the solar is only producing 5kW, it will take a further 5kW from the grid to meet the demand at that time of 10kW.
“Or, if he needs 10kW and he’s producing 20 from solar, 10 will be used to meet the demand wherever it is and the other 10 will be either exported to the grid or diverted to the hot water diverter upstairs in the shed.
“This system, known as an EDDI solar power diverter [or smart immersion] senses where there is energy going back to the grid and if [it] requires some of this surplus energy, it will take it – in essence.”
Speaking about the continuous need for hot water, Tom said: “It’s great that we can generate this renewable energy to heat up water that we need all day, everyday.
“We would spend up to €2,000 on oil fills to keep producing hot water, so hopefully in time we will see that bill get smaller and hopefully gone completely.
“Between the robots and the automatic calf feeders, we have a big demand for hot water and I’m looking at getting a second boiler and possibly EDDI in to ensure there is plenty of hot water available at all times with the oil being a backup if necessary in small amounts.
“Currently, the solar is doing the trick during the day, but at nighttime, because we don’t store any of our solar, the oil burner kicks in to ensure there is hot water there at night.”
Tom said that although he gets the 20c/kWh for the surplus energy he generates during the day, his night rate for buying electricity is 20c – which means he is breaking even.
Options for storing excess energy
Speaking about the options available to Tom to store excess energy on his farm, Joseph said: “The main options would be going with battery storage to store the excess energy.
“Or, put the excess energy into hot water which is the most cost effective,” he said
Tom said that down the road, if the new TAMS allowed for grant aid for battery storage, it would be something he would look into doing.
“We are set up here to take batteries. That is why we have two inverters. One of them (the 10kW) is suitable for holding battery storage,” he said.
“We have the capacity to store with this converted between 15 and 30kW of battery storage on the wall here under the inverter.”
For example, if Tom went with a 10kW battery and he is drawing 5kWh at nighttime, in two hours that battery will be empty, Joesph explained.
“Or if he had a 20kW battery and his demand is 5kW again, that battery will be empty in four hours,” he said.
“The battery will kick in once there is no energy in the inverters, to the fuseboard.”
During the summer, due to Tom having a large solar array of 33.15kW of power, he could potentially generate up to 25kW when the days are longer and have more light as a result, Joseph said.
At the moment, in one of the dullest months of the year, he is generating roughly 10kW, so he will have a huge amount of excess energy in the summer.
Due to having the maximum number of cows on the two robotic-milking machines, Tom says he will require a decent amount of energy as the robots are busy 24 hours/day.
He said however, that during that time of year (in the summer), he should be completely self-sufficient, as the amount he will be exporting to the grid should fully cover what he will be taking in at night-time from the grid.
This is as well as using excess energy to heat water on the farm, rather than having to use oil, as mentioned earlier, to heat the water.
Cost
The cost of the installing the system for Tom and Niamh came to €40,000 (including VAT of €5,000) with a 30-year warranty on the panels and a 10-year warranty on the inverters.
However, the duo hope to write off 20-40% in one year of the cost in tax they paid in 2022.
Joseph said that Tom should see a payback on his return in 3.5-4 years time.
Speaking about going ahead with installing the system, Tom said: “We are very happy we went ahead with it.
“We are already seeing the benefits of it.
“We generated 20% of our energy demand in the dullest month of the year, so we are excited to see how the system performs and the economical benefits it bring to us.
“There’s also no maintenance with the solar panels and they are out of the way as well on the roof of the shed – which is great.
“Furthermore, we can monitor what solar we are generating [on the phone] and so far we have been generating more than we need.”
