The answer is efficiency and energy conservation. The use of energy efficient applicances and lighting, as well as non-electric alternatives, can make solar electricity a cost-competitive alternative to gasoline generators and, in some cases, utility power.
Cooking, Heating, and Cooling
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. Propane or solar-heated water are generally better alternatives for heating water than electric water heaters. Good passive solar design can help you save a lot of money ,however, this requires a lot of planning before you start constructing your house/business.
Lighting requires careful study since type, size, voltage and placement can all significantly impact the power required. In a small home, or a boat, 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 more cost-effective. LEDs are now a popular options because they come in all sorts of shapes and forms and can provide the same lighting with much less energy. Investing in LEDs lights are a worthy investment.
Older refrigeration systems such as freezers and refrigerators are extremely inefficient, but recently many new refrigeration systems come in inverter type which are very efficient and use a lot less energy. If you have a freezer or refrigerator or that is older than 10 years old, it’s worth changing them now for newer inverter types.
Standard AC electric motors in washing machines, larger shop machinery and tools consume relatively large amounts of electricity and require large inverters. 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’re wasteful compared to high efficiency motors, which use 50% to 75% less electricity. A standard washing machine uses between 300 and 500 watt hours per load, but new front loading models use less than half 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. 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.