If does not make much sense to spend money on an off-grid system without first looking at energy efficient appliances. The use of efficient appliances and lighting, as well as non-electric alternatives, can pay large dividends after designing your off-grid system and its time to plop down the money. Living off the grid using low energy lights and appliances can not only save you money up front, on those dark days when you are trying to save every watt of power you can out of you’re battery bank, you will be glad you put a little thought into energy conservation up front. The type of lights and appliances that can be used living off-grid depends on how much sun is available, and the voltage of the off-grid system.
Cooking, Heating and Cooling
Each burner on an electric range uses about 1,500 watts per hour, which is why propane, wood burning stove or natural gas are all better choices for cooking. A microwave oven has about the same power draw, but since food cooks more quickly in a microwave, the amount of watts consumed is usually lower. Propane, wood or solar hot water are generally better alternatives for space heating. Good passive solar design and proper insulation can also reduce the need for winter heating. Swamp coolers are a more reasonable load than air conditioning and in locations with low humidity such as the SW, they are a great alternative.
Lighting requires careful study since type, size, voltage and placement can all significantly impact the power required. In a small home, or off-grid cabin, low voltage DC lighting with LEDs is often the best choice. DC wiring runs can be kept short, allowing the use of fairly small gauge wire. Since an inverter is not required, the system cost is lower. In a large installation or one with many lights, using an inverter to supply AC power for conventional lighting is often more cost-effective. AC compact fluorescent lights are common and efficient, but it is a good idea to have a DC-powered light in the room where the inverter and batteries are in case of an inverter fault. Also, AC light dimmers and overhead fan speed controlls will only function properly on AC power from inverters that have sine wave output.
Propane refrigerators can work well in small off-grid systems if propane is available. Modern propane refrigerators consume 5-10 gallons per month. If an electric refrigerator is used for off-grid living DC is usually a better choice than AC refrigerators. A DC refrigerator can cost 2X as much as an AC but they consume less than a quarter of the energy which means less solar or wind and fewer batteries.
Televisions, Washing Machines and Other Appliances Off-Grid
Televisions; look for an efficient DC TV. Power in your television set can vary widely depending on the type. Standard AC electric motors in washing machines, larger shop machinery and tools, swamp coolers, pumps, etc. (usually 1/4 to 3/4 horsepower) consume relatively large amounts of electricity and require a large inverter. Often, a 2,000 watt or larger inverter will be required. These electric motors can also be hard to start on inverter power, due to large surge loads at start-up, and they are very wasteful compared to high-efficiency motors, which use 50% to 75% less electricity.
TIP; Surge is the amount of short term power needed to turn over the locked rotor on an electrical motor.
A standard washing machine uses between 300 and 500 watt-hours per load, but new front-loading models use less than 1/2 as much power. If the appliance is used more than a few hours per week, it is often more economical to pay more for a high-efficiency appliance rather than make the off-grid system larger to support a low efficiency load. Vacuum cleaners usually consume 600 to 1,000 watts, depending on how powerful they are, but most vacuum cleaners will operate on inverters as small as 1,000 watts since they have low-surge motors.
Many small appliances with heating elements such as irons, toasters and hair dryers consume a very large amount of power when they are used but, by their nature, require only short or infrequent use. With a sufficiently large system inverter and batteries, they will operate, but the user may need to schedule those activities with respect to the battery charging cycle for example, ironing in the morning so that the solar or wind system can recharge the battery bank during the day. Electronic equipment, such as stereos, televisions, VCRs and computers, draw less power than appliances with heating elements, but these loads can add up as well, so opt for more efficient models, such as an LCD TV instead of a plasma or CRT design.
Computers, Music Systems and Cell Phone Chargers
Laptop computers us about 25% of the power a desktop computer uses. You should try and avoid desktop computers altogether. Music systems should be powered using pure sine wave power instead of a modified sine wave inverter. There is nothing that can kill the zen faster in the evening living off the grid than static from a modified or cheap pure sine wave inverter not to mention safety. Cell phone chargers from the manufacture are usually more efficient than cell phone chargers you buy elsewhere. Every watt you consume by inefficient electrical equipment matters not only to your wallet but also your piece of mind living off-grid.