DC OR AC APPLIANCES: Folks with the smallest solar power systems and few; simple appliances may have no inverter, and use low voltage DC for all lights, radio, TV, and water pump. People using the largest solar power systems sometimes use AC power from an off grid inverter for everything. Usually it is most practical to use both inverter AC and some direct battery DC. AC is most practical for regular household outlets and lights, because most AC appliances are better quality, easier to find, locally available and lower priced than 12 volt DC versions. But a few special DC appliances can save a great deal of energy. Items that drain a small amount of power over long hours can use far less power if DC powered. Some examples would be ceiling fans, phone message machines, motion sensing lights, intercoms, or alarms. This catalog features special refrigerators, freezers, lights, and 120 volt well pumps specially selected to work with inverters, and to avoid excessively draining battery power. Also see the introductions to our Refrigerator section, DC Appliance section, Pump section and Lighting section for discussions of DC vs. AC applications.
GENERATOR POWER SYSTEM: Any off grid power systems even without solar modules, benefit from inverters too. You can fast charge a large battery bank for a few hours a day while the generator runs the water pump, clothes washer, shop tools etc. Later, when only a few watts are needed for lights or TV, the battery and inverter supply that power without the generator. This way power is available 24 hours a day at the turn of a switch but the generator runs only a few hours a day. This saves on generator maintenance, and life gets better! (But it is difficult to get batteries fully charged with just a generator, and serious battery problems are common with just a generator. Backwoods Solar advocates using primarily solar charging).
TRADE-UP TO A BETTER INVERTER: At BackwoodsSolar.com, We accept trade-ins of used inverters bought at Backwoods when you need a larger or better model. We’ll gladly accept your grid tie inverters and Sinewave inverters when you’re in need of upgrading. Contact us today for more information. Used off grid inverter trade-ins are often available. Call, or see our Backwoods Bargains list on our newsletter page.
MODIFIED SINEWAVE OR TRUE SINEWAVE?
MODIFIED SINE WAVE: A modified sine wave is a sales term used for a modified square wave type of AC power which is not quite the same as power company electricity. Modified Sinewave inverters are lower cost, and are slightly more efficient. Some appliances work fine with them, though some may hum louder and run hotter. A few sewing machine speed controls and some computers have difficulty on modified Sine Wave. It can also damage photocopy machines, laser printers, and some cordless tool rechargers. Recently we found the first TV that would not run on any modified wave inverter. If a locally available Energy Star rated refrigerator or freezer will be used, be sure to select a sine wave model since the controls for the refrigerator could be damaged by mod-sine.
TRUE SINE WAVE INVERTERS: The off grid inverters Supply power of better quality than the power company, and works fine with any appliance without the fear of damage. Battery chargers in true sinewave inverters work well with any generator. Some models can automatically start and stop a generator when extra battery charge is needed although we recommend manual operation when possible. A low cost Samlex true sine wave inverter might be used when you have just a few smaller appliances that require true sine wave power.
SIZE: The size of off grid inverters range from under 320 to over 8000 watts. This rating indicates the largest wattage appliance or combination of appliances that the inverter can operate continuously and at the same time. Surge rating is well above the normal power rating, to run larger appliances for a short time, or to start heavy motors. Determine the highest wattage appliance or combination you want to run without using a generator.
STANDBY CHARGER: means the inverter becomes a battery charger when power is supplied to it from a generator or utility source. An automatic transfer switch within the standby inverter connects outside power through to the house circuits to power your appliances while also using it to recharge the batteries.
EFFICIENCY: The efficiency of most power inverters is 85 to 95%. Even though 5 to 15 % of the battery power is lost in converting up to 120 volt AC, the cost savings in AC wiring and other appliances over the cost of DC equipment often makes AC the better choice.
SEARCH MODE: Search mode is a useful feature in some inverters to automatically shut down to nearly no power use whenever all appliances and lights are off.
