As a modern homesteader, I’m often asked why I don’t have solar power and live off the grid.
That sounds like a great idea, right? Imagine no monthly electric bills, no dependency on the power company and no worries about power outages!
To answer it as simply as possible, I can’t afford it. Or, to be more specific, I can’t afford an off-grid system that would provide all of my electricity.
With each passing year, the costs of solar power are getting lower, and the technology is getting better. But an off-grid system with enough battery backup to power an 1,800-square-foot house both day and night would cost more than $85,000. And on those days when a solar array can’t produce and store enough electricity to meet my needs, I would need a whole-house generator or else remain connected to the grid.
Sure, there are compromises that can be made, such as having a big array of solar panels installed without battery backup. The panels would produce electricity during the day, but at night and on cloudy days, you would still need to rely upon your power company. Still, that system would cost more than I can afford.
Instead, I’ve adopted a few cheaper applications involving solar panels on my homestead. But before I describe them, let’s consider some basic information about solar panel systems and the electricity they can produce.
Electricity is commonly measured in watts. A watt is a specific amount of energy produced or used per second. Some approximate wattage requirements for common household devices are shown in the accompanying graphic.
As you can see, there’s a wide range in the wattage requirements for different appliances in your home. Without getting into detailed calculations, suffice it to say that anything more than a couple of hundred watts can’t be powered with a small, inexpensive solar panel setup. That means no air conditioning, heating, pumping water from a well or other basic necessities. So the best application for small solar panels is for powering small devices.
One application of solar power on my homestead is electric fencing for my goats. For less than the cost of extending a dedicated power line from my house to the pasture, I bought a solar charger that can power up to 5 miles of electric fencing. The unit is self-contained and portable, and it has a small solar panel and a built-in battery. The fence charger is maintenance-free, and it works night and day, far away from any electrical service.
Another application I have is a small solar panel connected to a battery to power an electric gate opener at the end of my driveway. For years, I had to get out of the truck to open the gate, then get back inside to drive my truck through the open gate, and then go back out to close the gate. It’s really convenient to just push the button on a remote control inside my truck to open and close the gate. But because I don’t have electricity extending that far from the house, I needed the solar panel and battery hookup to power the gate opener.
Another application I have is a 100-watt solar panel array on the roof of my car port. I built an adjustable stand for the array of panels so I can change the angle of the panels depending on the season. In the summer, the panels are almost parallel to the ground, and in the winter, they are almost at a 45-degree angle. There are online calculators to determine the optimum angle for your solar panels, depending on where you live and the time of year.
That solar panel array is connected to a charge controller, which is connected to a battery. The controller prevents overcharging the battery, and it has USB outputs for charging a cell phone, laptop or other devices that charge with a USB cable. It also has an output for an LED light that’s surprisingly bright.
The battery is a deep cycle, 12-volt battery. It stores the electricity coming from the solar panels. However, to run a small appliance from the battery, the direct current (DC) of the battery needs to be converted into alternating current (AC). So I connected a power inverter to the battery that has 2 outlets for plugging in household appliances.
The maximum output from that inverter is 200 watts. That means that the battery can run a device that requires more than the 100 watts produced by the solar panels. Weird, right? Think of it like a rain barrel. On a rainy day, water from the roof enters the barrel at a certain rate, let’s say 5 gallons per minute. You could open a large valve on the side of the barrel and discharge 10 gallons of water per minute, but it’s not sustainable.
Likewise, keep in mind that the battery can’t discharge more than 100 watts for very long. If I wanted more electricity output, or for longer periods, I would need additional batteries for storage and a power inverter that discharges more wattage.
To power several high-wattage appliances, including a heat pump/air conditioner, hot water heater and well pump, I would need many more solar panels, more batteries and a high-output power inverter. That’s why a whole-house solar panel system is so prohibitively expensive and why it’s simply not feasible for most people to live off the grid.
Greg Pryor, Ph.D., is a professor of biology at Francis Marion University and enjoys a self-sufficient lifestyle on his 100-acre homestead. Email him at email@example.com.