Sharp Electronics knows a thing or two about DC, and we’re not talking about comics! When you look at a battery, it has a positive and negative current that helps power to flow. This is called direct current (DC), which is produced by batteries, fuel cells and solar cells. When power comes from a power plant, it is called alternating current (AC). Power used through a wall socket, in the United States, is 120-volt, 60-cycle AC power. Many power companies use alternating current because a transformer can easily change the voltage of power–thereby, saving money. On the other hand, a DC system has many advantages over AC since the absence of reactive power translates into higher capacity utilization of power generators. This is probably just one of many reasons Sharp is introducing a DC-powered air conditioner this year. As one of the world’s top consumer electronics companies in the world, Sharp announced that their air conditioner will be the first offering in Sharp’s new “DC Appliance” series.
How it started
In 2011, Sharp announced that it was developing DC home appliances. Why? For starters, DC-powered electronics can be powered directly by solar photovoltaic (PV) panels/modules–without needing routing or an inverter. This would be a boon for customers who want to save on energy costs, while utilizing a more environmentally-friendly alternative. In addition, not having to use an inverter means that conversion losses, of up to 10 percent, can be eliminated. Furthermore, air conditioners are known to require a lot of energy–cutting energy costs by 10 percent can make a significant difference.
Benefits of DC
Since electric power distribution is almost all alternating current, it may take some time for mass household conversions. Yet, in a DC system, there isn’t any susceptance (the ease with which AC passes through two conducting plates that hold energy in the form of an electrostatic field) along lines–this means that the effects of charging current and over voltages is removed. As a result, lines receive higher transfer capacity. In fact, Thomas Edison’s first commercial electrical power transmission used direct current.
How it works
A prototype of Sharp’s air-conditioning system was displayed at PVJapan. The outdoor unit was supplied with DC electricity through a rechargeable battery configured outside the house. The compressor is driven by a DC brushless motor. If you were to do this with a conventional air conditioner, you would need to convert DC100V output to AC100V power. Sharp’s DC Air Conditioner, reduces power loss inflicted by DC-AC conversion through effectively increasing a DC100V output from the rechargeable battery to DC200V.
Moreover, Sharp’s Cloud Rechargeable Battery allows solar electricity to be efficiently consumed within the home. Surplus electricity is then sold, and the battery is charged in a manner that focuses on cost savings. The battery is also discharged during hours of low solar power generation, such as in the mornings and evenings. Plus, you save on the cost of using and installing a solar panel inverter.
If vehicles can run on a DC system, why can’t air conditioners? It will be intriguing to see how Sharp’s new DC line is received. Either way, the cost and energy savings can’t be beat.