Living Off The Grid

Whether you have an off-grid home with a renewable energy system or just an RV that you use during the summer months, one thing you will quickly start to learn about is DC power.  You might ask the same question many others have to ask: What is the difference between AC and DC, and which type of appliances should I use in my off-grid home or RV?

Generally speaking, you’re not going to have much of a choice when it comes to your RV, as nearly all appliances on the market are going to be DC. But let’s take a step back and take a beginner’s look at the difference between AC and DC…

AC Power is used in nearly all grid-tied homes in the United States. This is because the power companies need to send their electricity over long distances and AC (which stands for Alternating Current) travels farther. The standard voltage of AC power in the United Stats is 120V. Voltage is the difference of electrical potential between two points of an electrical or electronic circuit. Or, to drastically simplify the concept, it is the force at which energy flows within the wires. Your power lines in the city are high voltage.

DC Power is much lower voltage than AC and is often safer for DIY applications (imagine changing the terminals on a high-voltage car battery in the rain!). DC stands for (Direct Current) and is almost always going to be 12 Volts – ten-times lower than the voltage for AC power in the US. The 12V DC battery is standard in automobiles, marine craft and RVs, and DC power is also what comes out of your solar panels or other renewable energy devices prior to being turned into AC power by the inverter on a grid-tied system.

Now comes the question – Which is better, AC or DC?
Really it depends on what the situation calls for. What many people do not realize, however, is that they can get just about any appliance they want made for DC power. There are DC refrigerators, DC washing machines, DC dryers… and many of them are even more energy efficient than the most efficient “Energy Star” appliances in your local big box store.

Another thing to consider is whether you want to be grid-tied or off-grid. In a grid-tied system, you’ll have to work with AC power. One thing you might want to consider is the added cost of storing power (DC power) in a battery bank in case your power goes out. If, like most city-dwellers, your power only goes out for a few hours a year, is it really worth thousands of dollars for batteries when you could have a can of diesel and a generator on-hand for much less?

For the off-grid home owners, the choice is not so simple. AC power has the advantage of working with all standard appliances in the United States and Canada, but can also be more dangerous due to the higher voltage. DC power has the advantage of not requiring an expensive inverter, but only works with special DC appliances. There is also the option of an AC / DC hybrid system that utilizes AC power for most of the house, but also stores power in batteries for DC use – or runs DC power through certain outlets, such as the one going to your DC deep freezer in the garage.

The decision to go AC, DC or hybrid shouldn’t be made on your own (if you’re a novice) because many other issues factor into it, such as wire size, distance between your house and renewable energy supply, etc… But we hope this intro will assist you in asking some of the right questions when consulting with a renewable energy contractor.