And How Much Solar Power Would It Take to Supply It?

What kinds of tools and power systems do you use on your farm?

farm buildings

Some of those systems run on gas, such as tractors and generators. But most of them use conventional power where something plugs in to the grid.

When you want to assess your current energy usage on your farm, the main task is to figure out how much power your equipment and tools need to operate. Why might this be helpful?

Because if you want to install solar panels, the cost of installation heavily depends on the number of panels installed – the size of your solar array. So the amount of power your tools use directly relates to how much solar you’ll need. You don’t want to pay for panels you don’t need.

It also matters where this power gets used. Some of your farm’s tools may operate out of your barn. Others get used in the field, like water pumping systems.

When choosing to install a solar array, your options are not just whether to do it or not. For instance, you could just install isolated panels way out in your remote field areas to power well-pumping mechanisms. Or, you could put panels on your barn, but continue powering your other equipment with your current methods.

This is why it’s so helpful to know how much power gets used at your individual stations.

If you have cows, then you might have a cream separator.

If you have sheep, you might have mechanical shearing clippers.

If you rely on a lot of equipment, you probably do a fair amount of repair and maintenance out of your barn, which means you’re using all kinds of power tools.

How much power, in kilowatt-hours (kWh), do all these tools use? Figuring this out can be tricky. Here’s a helpful guide:

Find Your Farm’s Power Usage – the Easy Equipment

equipment on a farm

In some cases, such as lights, the wattage is on the device. So there it is. Just get an estimate of how long the lights are on, and get the kWh. You do this with a simple formula:

Watts * hours / 1000 = kWh

For example: If you have a 60 Watt bulb that’s on for 10 hours a day, then 60 * 10 = 600 Wh. Divide that by 1000 (because there are 1000 Watts in a kilowatt) and you get 0.6 kWh for that light bulb, per day.

For the month, multiply that by 30, and you get 18 kWh for the month. Now, running a bulb for 10 hours a day every day of the month including weekends is probably excessive. But you can get pretty accurate numbers if you just pay attention for a couple weeks to your normal habits.

For any device that gives you the wattage, all you need is the time per day you’re using it and you can find your energy use pretty quickly. Make a table of all this, and add it up at the end.

Finding Power Usage for Less Obvious Equipment

The power used by some other equipment can be harder to determine. For things like grinders and cream separators, you need to find the nameplate, and the wattage should be on there. It may also be in the user manual.

FMCS (Freeborn Mower Cooperative Services) has a handy table you can use to figure out and keep track of how much power all your tools and farm equipment are using.

As they point out, some of these nameplates might report the power in terms of voltage and amperes instead of Watts. Get around that using this formula:

Watts = Volts * Amps

Just multiply volts and Amps and you get the wattage.

The FMCS chart gives average power usage amounts for common farming equipment and tools. Your tools are probably not all listed there. But it doesn’t matter because you might need to get your own estimates either way. If you have different weather or harvesting patterns than the norm, then your average uses might be different, depending on what tool or equipment you’re looking at.

A couple examples:

  • A poultry water warmer uses about 1 kWh per day. But if you have an unusually large or small poultry farm, your number could be different.
  • A grain elevator uses about 4 kWh per 1000 bushels. That’s probably a pretty reliable number since it’s per 1000 bushels. If your farm harvests 100,000 bushels of grain, then you’d be using about 400 kWh of energy to operate your grain elevator.
  • Barn ventilation uses about 2.5 kWh per cow per month. However, if your barn has a more (or less) efficient system for ventilation, then this number could be different.

Our Farm Power Consumption Calculation Recommendation

Unless you know your equipment and tool power usage is very abnormal, we recommend you start by using the estimates on the FMCS Farm Energy Estimator page. They have a long list – click the link to see it – including silo unloaders (for grass and corn), water pumps, cattle, welders, milk coolers, clippers, grain dryers, and much more.

That will give you a good idea of how much energy your various tools and systems are using.

And if you have other tools and equipment not on their list, now you know how to figure out your estimates: Use the nameplate and get an approximate value for the time you use it, then use the formulas given above.

Solar Energy and Farm Equipment – What Size System?

Once you have your farm equipment’s monthly energy use organized in a table, now you can get a more practical idea of how many solar panels it might take to replace your grid-power and save you money.

If, for example, your barn uses 1200 kWh per month, how big a solar array would you need to install on your barn?

Solar arrays get quoted by the size of the system. So, it could be a 10kW system, or a 60 kW system. Or, for very large arrays, it could be in the MegaWatts.

But what does that mean?

To tie this to your farm equipment power usage, follow these two steps:

  • Divide your kWh per month by 30 to get kWh per day. In our example, that’s 1200 / 30 = 40kWh per day.
  • Take that number and divide it by the average hours of direct sunlight per day. In Georgia, 5 hours per day is a good estimate. In our example, that would be 40 / 5 = 8kW.

This means, for a barn using 1200kWh per month, they would need an 8 kW solar array to provide all the power for their barn’s equipment and tools. An 8 kW system isn’t very large and is quite affordable, especially with all the tax incentives and additional FDA options such as REAP grants and loans.

Why does direct sunlight matter so much? Because solar panels only work in the sun, and it has to be at optimal angles unless you have trackers, which allow panels to move as the sun’s position changes during the day. But those increase the costs of installation.

So with cloud cover and the angles not always ideal, it works out to about 5 good hours of direct sunlight per day in Georgia, South Carolina, and other Southeastern states.

Should You Replace Your Farm Equipment’s Power Supply With Solar?

Hopefully this article gives you a better idea of what you need to know to answer this. And your solar consultant can help. If you’d like help, contact Coastal Solar today and we’ll help you walk through and determine all the information you need to find out.