When do solar panels and a battery pay off on a farm?

A business battery pays off on a farm when it avoids a bigger cost. Think of a medium voltage cabin, a heavier connection for a new pump, or a generator that runs day and night because there is no grid. In those cases, Belgian farms have seen paybacks of 4 years. A battery that only stores surplus solar power, on a farm whose connection is big enough, pays back much more slowly. There, cheaper steps usually come first.

You milk twice a day, or a robot milks around the clock. The cooling tank starts right after milking, pumps move water, and fans run all summer. Then the farm grows: more cows, a new shed, a new irrigation pump. And the grid operator tells you the connection cannot follow without a switch to medium voltage.

That answer costs more than it seems. A cabin is an investment you need for nothing else: Inagro puts a medium voltage cabin at 40,000 to 75,000 euro on average. Meanwhile one installer promises a three-year payback, and a neighbour says his battery never earned its money. Both can be true, because the payback depends on what the battery has to solve.

A dairy farm in Lokeren faced exactly that choice. Fluvius could only guarantee more power with a switch to medium voltage. The farm put that budget into solar panels, a wind turbine and a battery system instead. The investment was recouped within four years, because the medium voltage connection was never needed.

How much electricity does a farm use, and where does it go?

It depends heavily on the type of farm, so measure before you size anything. Research does give a useful order of magnitude.

A study by the Flemish government followed specialised dairy farms in its farm monitoring network from 2007 to 2013. In 2013 the average farm had 67 dairy cows and produced about 504,000 litres of milk. Electricity for milking, cooling, cleaning and the like was 22% of the direct energy use. Diesel, mostly for tractors, was the largest energy carrier at 62%. Contract work added another 16%.

Per 100 litres of milk, the study measured 20.5 MJ of electricity, which is about 5.7 kWh. For a farm that produces 700,000 litres, it estimates almost 40,000 kWh of electricity a year. Other farms use much more. The pig farm Varkenscampus, described by ILVO, needs 115 MWh of electricity a year, mainly for ventilation, feed motors and piglet lamps. That is about 30 times the use of an average Flemish household.

For a battery, the yearly total matters less than the moment you use power. Milk cooling starts right after milking. With classic milking twice a day, that gives a peak in the morning and one in the evening. A milking robot spreads the milking over the day and the night, so the load is flatter.

When does a battery pay off on a farm?

A battery earns money in two ways: it avoids a big one-off cost, or it saves a little every day. On farms, the fast paybacks come from the first.

At the dairy farm in Londerzeel, avoiding the medium voltage cabin meant immediate savings of at least 60,000 euro. No heavy cables had to be laid on the property either. In Lokeren the whole system paid for itself within 4 years for the same reason. Without such an avoided cost, the payback of an off-grid system is usually 6 to 8 years.

Inagro spoke with a dairy and pig farmer in Lo-Reninge. He added solar panels and an 80 kWh battery that covers the evening peaks of classic milking. His words: thanks to the storage, he no longer has to take that electricity from the grid.

Battery, ice bank or frequency drive: what should a farm do first?

Many farmers say a battery is the last step, not the first. They often have a point. A battery is one way to store energy, but a farm has cheaper ones.

• Frequency drives on the heaviest pumps. A frequency drive lets a motor start gently and run at the speed you need. At the plant nursery in Jabbeke, frequency drives on the heaviest pumps are part of the solution.
• Store cold or heat instead of electricity. An ice bank stores cooling for later, and a boiler stores heat. At a farm in Tielt, smart control sends surplus solar power to boilers.
• Shift flexible loads to sunny hours. Grain handling, pumping water to a tank or charging machines can often move to the middle of the day.

Then size the battery on what is left: the peaks you cannot shift and the grid limit you cannot move.

How does semi-off-grid work on a farm?

Semi-off-grid keeps the grid connection, but only as a charger. The farm runs on solar power, sometimes with wind, and a battery. Only when the battery is low does it switch to the grid.

The battery system raises the power the farm can use, so the connection did not need reinforcing. This farm expects to take only 5% of its total yearly use from the public grid. See the farm in Tielt and our semi-off-grid systems.

Solar and wind work well together on a farm. Solar panels produce mostly in summer and during the day. A wind turbine gives an almost constant output, also at night and mostly in winter. That is why the dairy farms in Lokeren and Londerzeel combine both.

Can a farm run without a grid connection?

Yes, if the system is designed for it. A farm in St-Georges-sur-Meuse, in the province of Liège, had no electricity connection in its street. It ran entirely on a generator, day and night.

Solar panels with a battery system of 30 kVA and 46.2 kWh now carry the farm. The generator only serves as back-up, and the farm never needed a street connection. Running on a generator today? Read whether your off-grid generator really has to run 24/7.

Can a battery keep milking and cooling going during a power cut?

Only if the system can run as an island. A battery that simply follows the grid switches off when the grid fails. A system with an island function separates from the grid and keeps the chosen circuits running.

If your farm sits at the end of a long rural line, you know how long a cut can last. Decide in advance which circuits must keep going: milking, milk cooling, water for the animals, ventilation. That list sets the power and the storage the battery needs. More on the options is in emergency power for businesses: UPS, generator or battery. For pig and poultry barns, read how to keep barn ventilation running in a power cut.

What does a farm battery cost, and how do you judge a payback claim?

The price depends on the power you need (kVA) and the storage (kWh). Business systems range from small set-ups to installations of up to 1 MW, so one general price says little. A good offer answers these questions:

• Is the sum made on your own quarter-hour data? A calculation on yearly totals misses your milking peaks and your winter shortfall.
• Does it assume you use all your solar power yourself? On a farm with a big roof, part of the summer production goes to the grid and earns much less.
• What does the battery avoid? A cabin of 40,000 to 75,000 euro, a heavier connection, a generator's fuel, or only some grid power. The first three pay back fast; the last one slowly.
• Can the system grow with the farm? In Londerzeel the solar panels and batteries simply grow along when the farm expands.

What happens when you contact YouPower?

Every business installation is engineered for your consumption, your production and your plans. A heavy installation is not always needed to get the best return.

1. Step 1: Analysis and sizing. We look at when you use power, what your roof can produce and how the farm will grow. Your quarter-hour data and a list of your largest motors help most.
2. Step 2: Technical design. We design the full installation and calculate the savings clearly.
3. Step 3: Installation and commissioning. We install the system and put it into service.
4. Step 4: Monitoring and support. You follow consumption, production and the battery level in real time in the app, 24/7.

Everything about our business batteries, from peak shaving to back-up, is on the product page.