Efficiency & Energy Conservation for On & Off Grid Living

Efficiency and energy conservation? When we speak of efficiency and energy conservation, we usually tell you that there is much more to living an energy-efficient lifestyle besides getting solar panels for your home or business. The use of energy-efficient appliances and lighting, as well as non-electric alternatives, makes solar electricity a cost-competitive alternative to gasoline generators and, in some cases, utility power.

Here are the typical energy consumption values for various appliances and lighting as well as what you can do to be more efficient:

Cooking, Heating, and Cooling

  1. Each burner on an electric range uses about 1,500 W, which is why bottled propane or natural gas is a popular alternative for cooking. A microwave oven has about the same power draw, but since food cooks more quickly in a microwave oven, the amount of kilowatt hours used is typically lower.
  2. As far as space heating goes, propane, wood, or solar-heated water are generally better alternatives than electric baseboards which can use from 10 kilowatts to 50 kilowatts. Good passive solar panel design and proper insulation can also reduce the need for winter heating.
  3. Evaporative cooling is a more reasonable load than air conditioning and in locations with low humidity, it’s a great alternative with approximately  a 700 W demand.

Off-Grid Electricity & Lighting

  1. Lighting requires careful study since type, size, voltage and placement can all significantly impact the power required. In a small home, an RV, or a boat, low voltage DC lighting with 7-25 W LEDs are often the best choice.
  2. 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.
  3. 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 will only function properly on AC power from inverters that have sine wave output.

Refrigeration

  1. Gas-powered absorption refrigerators can work well in small systems if bottled gas is available. Modern absorption refrigerators consume 5-10 gallons of LP gas per month.
  2. If an electric refrigerator will be used in a standalone system, it should be a high-efficiency type. High-efficiency DC refrigerators at roughly 750 W per day are also available and can offer significant energy savings.

Major Appliances

  1. Standard AC electric motors in washing machines, larger shop machinery and tools, swamp coolers, pumps, etc. (usually ¼ to ¾ 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.
  2. A standard washing machine uses between 300 and 500 watt-hours per load, but new front-loading models use less than ½ 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 electrical system larger to support a low efficiency load.
  3. 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.

Small Appliances

  1. Many small appliances with heating elements such as irons , toasters (1200 W) 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 PV system can recharge the battery bank during the day.
  2. Electronic equipment, such as stereos (40 W), televisions (140 W), VCRs , DVD players and computers, draw less power than appliances with heating elements, but these loads can add up as well (see our article on Phantom Loads), so opt for more efficient models, such as an LCD TV instead of a plasma or CRT design.

If you’re interested in setting up or upgrading to a more efficient off-grid living power system with solar panels for your conserving home, Contact Us at Backwoods Solar at 208-263-4290.  Get our Planning Guide and Catalog to help you design a customized renewable energy system that works efficiently and saves you money.